Glass Expansion revolutionized spray chamber design for the ICP-OES and ICP-MS analyst by introducing cyclonic spray chambers. Prior to the Glass Expansion Tracey™ cyclonic spray chamber, Scott-style spray chambers were the standard option provided with your ICP. The design of Glass Expansion's cyclonic spray chambers helps the ICP analyst achieve sensitivity gains, reduced washout times, and reduced matrix effects not possible with other designs. 

This article will provide a summary of Glass Expansion's unique cyclonic spray chamber features and describe the advantages of the new Helix™ CT ICP spray chamber with ConstantTorque™ technology.

	Traditionally, ICP-OES and ICP-MS sample introduction systems have relied on o-rings to form a gas-tight seal between the nebulizer and spray chamber. There are several drawbacks with an o-ring seal, such as:

		Potential for contamination due to dead volume around the o-ring seal

		Chemical resistivity of strong acids and organic solvents

		The o-rings are difficult to replace, often requiring tools

		Bonding to the nebulizer can result in breakage

	The evolution of Glass Expansion cyclonic spray chamber design, specifically the advantages of the o-ring free Helix nebulizer-spray chamber interface were summarized in a 2014 article (1). In addition to the Helix interface, the benefits of each Glass Expansion cyclonic spray chamber model are detailed (1), making it easy for the ICP analyst to select the optimum spray chamber to suit their application needs. Glass Expansion is now pleased to introduce the new Helix CT (ConstantTorque) spray chamber, which provides a constant, reproducible, inert, gas-tight seal between the nebulizer and spray chamber (Twister with Helix CT shown in Figure 1).

	The main feature of the Helix CT spray chamber is a new Helix locking screw with built-in torque control mechanism that allows for a consistent seal of the PTFE ferrule against the nebulizer-making it impossible to overtighten or undertighten while ensuring a gas-tight seal each and every time. A new PressFit PTFE ferrule provides a chemically inert seal around the nebulizer, which is immune to strong acids and organic solvents routinely used in ICP sample preparation. The new Helix CT cyclonic spray chamber by Glass Expansion, therefore, eliminates all the drawbacks of the o-ring nebulizer seal, while improving user safety by preventing broken nebulizers.

	The new Helix CT nebulizer interface is also simple to use:

		Fully insert the nebulizer into the Helix CT interface, until the nebulizer side-arm comes into contact with the molded-in positive stop.

		Hand-tighten the Helix CT locking screw until the ConstantTorque mechanism clicks, indicating a secure, gas-tight seal.

	An Agilent 5100 simultaneous dual view ICP-OES was used in combination with the SeaSpray DC nebulizer and Twister cyclonic spray chamber with Helix CT to evaluate washout performance, and the effects of nebulizer depth and torque applied to the nebulizer seal.

	The Helix CT is the only nebulizer-spray chamber interface that significantly reduces the dead volume around the nebulizer. This unique design minimizes washout time with highly concentrated samples, reducing sample-to-sample carryover and improving sample throughput. Figure 2 compares the time required to washout a 10 ppm Molybdenum standard with the Helix CT interface and a "Brand-X" spray chamber with an o-ring interface. The results show that with the Helix nebulizer interface a 10 ppm standard can be washed out in as little as 4 s, whereas "Brand-X" takes 16 s. One can expect this time to significantly increase for more troublesome or "sticky" elements that are more prone to carryover issues.


	Figure 2: 10 ppm Mo washout comparison between Helix and non-Helix spray chambers.

	Glass Expansion's new Helix CT design maintains the positive stop of the original Helix to ensure that the nebulizer is inserted to the correct and optimum depth within the spray chamber. In addition to nebulizer depth, the torque applied to the nebulizer seal is also critical. The data shown in Figure 3 highlights the effects of torque applied to the nebulizer seal versus the observed sensitivity. The applied torque was increased incrementally from 11 N·cm to 29 N·cm. As the torque applied to the nebulizer seal increases, the sensitivity decreased on average by 5%, with greatest difference being 8% (Cu II). The new Helix CT locking screw is set to the optimum torque and will seal the PressFit PTFE ferrule against the nebulizer to the same torque each day. This allows your ICP to achieve the same nebulizer performance every day.


	Figure 3: Helix CT interface sensitivity versus torque.

	The results from our study show how dead volume around the nebulizer seal can affect washout efficiency, and ICP sensitivity is affected by both nebulizer depth within the spray chamber and the torque applied to the nebulizer seal. If consistent performance is crucial to your ICP laboratory, the new Helix CT spray chamber is your solution. The Helix CT spray chamber provides unparalleled, reproducible day-to-day ICP analytical performance.

	Glass Expansion will now equip all of its glass, PFA, and PTFE spray chambers with the new Helix CT interface. However, if you already have a Helix spray chamber, you can easily upgrade to the Helix CT interface. The new Helix CT locking screw and PressFit PTFE ferrule are fully compatible with all Glass Expansion Helix style spray chambers. Achieving consistent day-to-day analytical performance in your ICP laboratory is just a click away with the new Helix CT cyclonic spray chamber, learn more at 

	(1) Glass Expansion October 2014 Newsletter, "ICP Spray Chamber Update." 

http://www.geicp.com/site/GE_Newsletter/GE_Newsletter_October_2014/pubData/source/GE0283%20GE%20Newsletter%20October%202014.pdf


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	tel. (508) 563-1800, fax (508) 563-1802
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Articles

Atomic

Helix CT ICP Spray Chamber with ConstantTorque Technology Provides Consistent Day-to-Day Analytical Performance

Microwave digestion of powdered materials, such as infant formula and dairy powders, have proven to be a difficult task. Powders are inherently non-homogenous and digesting a sample large enough to provide a homogeneous representative sample often leads to excessive venting and incomplete digestion. 

Reconstituting the powdered samples in water greatly improves their homogeneity and yields more consistent and complete digestions. This application note will describe the procedure of reconstitution and digestion of four food powder samples using the MARS 6 microwave digestion system.

	An estimated 1 million infants in the United States are fed formula from birth and, by the time they are three months old, about 2.7 million rely on formula for at least part of their nutrition. Accurate nutritional labeling of food products is a legal requirement in most countries to help consumers make informed healthy choices. This means all label claims need to be supported by accurate scientific measurements. For vulnerable groups such as babies and people requiring clinical nutrition products, infant formula nutrient analyses need to be very specific and able to accurately quantify even very low concentrations of heavy metals such as Pb, As, and Cd. In order to detect the low levels of heavy metal impurities obtaining a large representative sample is critical.

	This application note will focus on the preparation of powdered samples including infant formula, cheese powder, milk powder, and powdered butter. Samples will be reconstituted in warm water and an aliquot of each powder slurry will be prepared in the MARS 6 digestion system using the 75 mL MARSXpress vessel.

	A total of 40 samples were prepared using a CEM Corporation MARS 6 microwave digestion system equipped with iWave technology. iWave is a novel technology advancement that utilizes Light Emitting Technology™ to accurately measure the temperature of the actual sample solution inside the vessel and does not require an internal probe.

	Samples were prepared in CEM 75 mL MARSXpress vessels. This easy to use three-part vessel allows up to 40 samples to be prepared simultaneously and are sealed with a simple hand held torque device. Although the 75 mL MARSXpress vessels were used for the acid digestion for this study, the MARSXpress Plus vessel could be used as an alternative.


	Figure 1: iWave provides precise power control during run.

	In a 250 mL beaker with stir bar, 85 g of ASTM Type II or better water was added and heated to 60 °C on a hot plate. A 15 g powder sample was added and allowed to stir and heat for 10 min until all powder was well incorporated into the slurry. A thermometer was used to confirm the temperature of 60 °C ± 5 °C. A 7 g aliquot was weighed into a disposable pipette or syringe. Based upon a 15% (w/w) the slurry will yield a final sample size of about 1.05 g of powder.


	Figure 2: Samples after reconstitution.

	A 7 g aliquot of reconstituted sample was added to each MARSXpress liner along with 10 mL of concentrated HNO

. Nine vessels for each sample were prepared with the reconstituted sample. Eight of them were spiked with 1 mL of a 10 ppm spike containing Pb, As, and Cd. One vessel was an acid blank. The vessels were capped and placed in the MARS 6 for digestion. The One Touch Method Food was used. The One Touch Technology automatically recognized the vessel type and counted the number of vessels. It then chose the optimized conditions for the acid digestion. The maximum temperature achieved using this method is 200 °C. Food samples in general do not require extremely high temperatures to achieve complete digestion.


	Figure 3: Samples before and after digestion.

	The reconstitution step allows for a larger sampling of the powdered material yielding a more homogenous sample. The MARS 6 with 75 mL MARSXpress vessels and iWave Temperature Control simultaneously digested the four different powder samples in a single batch offering a sufficient digestion solution for high throughput food testing labs. For each sample one blank, one unspiked sample, and 8 samples spiked with Cd, Pb, and As were digested in a single run for a total of 40 samples. Figure 1 illustrates the system automatically adjusts the power to compensate for the varied sample types. The before and after samples shown in Figure 3 demonstrate clear and particulate free digestions.


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Microwave Digestion of Mixed Food Powder Samples

This application note demonstrates the ability of the NIC MA-3000 direct mercury analyzer to analyze new cork samples with accuracy and precision, in compliance with US EPA Method 7473-

Mercury in Solids and Solutions by Thermal Decomposition, Amalgamation, and Atomic Absorption Spectrophotometry.

 (2014) 21: 2108), it was shown that stopper-derived cork is an effective biosorbent towards bivalent mercury at environmentally relevant concentrations and conditions. Only 25 mg/L of cork powder was able to achieve 94% of mercury removal for an initial mercury concentration of 500 µg/L. When cork is employed for remediation, it is important to quantify the absorbed mercury.

	Wine corks are also recycled into other consumer products, where the mercury uptake from the wine may need to be quantified. Mercury is dangerous to both natural ecosystems and humans because it is highly toxic, especially due to its ability to damage the central nervous system. Mercury poses a particular threat to human development in utero and in early childhood. Thus, to prevent mercury poisoning, it is necessary to accurately quantify total mercury in recycled cork and cork used intentionally for mercury remediation.

	Calibration is done using certified aqueous ionic-mercury standard solution diluted to the required concentration. The least-squares regression method is used to create and complete the calibration curve.

	Analysis was performed using the NIC MA-3000 dedicated direct mercury analyzer that selectively measures total mercury by thermal decomposition, gold amalgamation and cold vapor atomic absorption spectroscopy. The MA-3000 analyzer measures mercury in virtually any sample matrix-solid, liquid, and gas-and offers quick results without time-consuming or elaborate sample preparation processes.

	Rice flour (1568a) measured after all cork samples for reliability assurance.

	Rice flour (NIST 1568a): Certificated values 5.3~6.3 µg/kg

	This report demonstrates that NIC MA-3000 analyzes new cork samples with accuracy and precision and analyzes rice flour (NIST 1568a) after repeated analysis of new cork. It is a perfect solution to today's increasing laboratory demand for easy, fast, and accurate mercury measurements.

http://www.who.int/ipcs/assessment/public_health/mercury/en/

https://link.springer.com/article/10.1007%2Fs11356-013-2104-0

http://www.gpo.gov/fdsys/pkg/CFR-2005-title21-vol7/pdf/CFR-2005-title21-vol7-chapI-subchapG.pdf


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Total Mercury in Cork Stoppers Using Direct Mercury Analysis

Commercial testing laboratories often come across a wide mix of sample types for trace metal analysis. One of the key elements that these labs need to quantify is mercury. Traditionally, analytical chemists have had to rely on techniques like CVAA and ICP-MS for mercury determination that involve a time consuming and a labor-intensive sample preparation step. Direct mercury analysis, as described by EPA 7473, is an alternative method to traditional techniques that enables a chemist to run mixed matrices without the need for digesting them and yields results in as little as ~5 min per sample. This makes it significantly faster and cost effective with comparable or better recoveries than CVAA and ICP-MS.

	With the influx of many local and international regulations aimed to minimize environmental and consumer exposure to heavy metals in the recent past, consumer testing laboratories that offer services for trace metals analysis have realized a variety of potential growth opportunities. However, associated with these opportunities is the challenge that these contract laboratories must remain cost-competitive while addressing increased throughput demands and developing methods to successfully prepare and analyze a wide variety of sample matrices.

	Traditional techniques used to analyze mercury involve a sample digestion step, after which they are analyzed on CVAA or ICP-MS. Although effective, sample preparation requires manpower, equipment, handling and disposing large amounts of acid that not only takes hours for completion, but also is very expensive. Alternatively, the U.S. EPA developed a method 7473 for rapid determination of mercury in solids and aqueous samples without sample prep. This method uses an integrated sequence of thermal decomposition followed by catalytic conversion, amalgamation, and atomic absorption spectrophotometry.

	A direct mercury analyzer (DMA-80 Tri-Cell) from Milestone Inc., was used for this experiment. The instrument was configured to sequentially process up to 40 samples placed on the auto-sampler. The auto-sampler automatically aligned and accommodated quartz (1500 µL) and nickel (500 mg) sample boats. All the components of the DMA-80 instrument were contained in a closed system to ensure that the samples were not exposed to outside interferences. Oxygen is used as a carrier gas at 65 psi pressure and a flow rate of 7 L/h.

	The DMA can be calibrated using aqueous standards or standard reference materials (SRM). The DMA-80 used for this experiment had a tri-cell spectrophotometer and covered a dynamic range of 0.0015–1500 ng Hg. Each cell was calibrated using different volumes of 1 ppm and 0.1 ppm stock solutions, prepared from an NIST traceable 1000 ppm Hg standard solution (VHG Labs).

	To test the efficiency of the DMA-80, five standard reference materials (SRM) from five different industries were run sequentially on the DMA-80, with each industry standard reference run in triplicate. Sample mean concentrations, standard and relative standard deviations were calculated and compared to the certified mercury values of the standard reference material.

	The concentrations shown above for a wide variety of standard reference materials were not only in the certified range of mercury concentration but also had very low RSD's, indicating the high accuracy and reproducibility of the DMA-80. Furthermore, testing a sequence of different matrices with concentrations ranging from low ppb to ppm also showed that there was no carryover of mercury from sample to sample.

	Commercial testing laboratories are required to analyze different matrices accurately and quickly, while keeping operating costs under control. The DMA-80 is an excellent productivity tool providing results in ~5 min/sample and proves to be proficient, matrix-independent, and cost effective, while eliminating the challenges of sample preparation posed by conventional mercury analysis techniques.


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Determination of Mercury in Mixed Matrices

Savillex's DST Acid Purification Systems are used by laboratories worldwide for the on-demand production of high purity acid for use with ICP-MS and other metals analysis techniques. Savillex recently expanded the product line with the new DST-4000, which is a high-throughput, fully-automated system capable of producing 4 L of high-purity acid at a time, completely unattended.

	The ultra-low detection limits of ICP-MS necessitate the use of high-purity grade acids for standards, sample dilutions, and, increasingly, even for sample digestion. Although commercially available bottled high-purity (10 ppt grade) acid is readily available, it costs up to 10 times more than trace metal (1 ppb) grade acid. Once opened, and during use, a bottle of high-purity acid can easily become contaminated due to airborne contamination or analyst error. For these reasons, many laboratories are producing their own high-purity acid using the Savillex DST-1000 Acid Purification System. The DST-1000 produces HNO

, HCl, and HF that is as good as or better than commercially available acid (Table I), is easy to use, has a small footprint, and can pay for itself in months, or even weeks, depending on the laboratory's acid needs.

	Although in-laboratory production of high purity acid can easily be justified financially, some laboratories prefer to continue to purchase bottled high-purity acid. This is because there was no system that could either produce enough acid to meet their needs, or be operated completely unattended thus requiring additional labor. Recently, Savillex released the DST-4000. The quality of acid produced by the new DST-4000 is the same as the DST-1000, however the DST-4000 can produce 1 L of acid in 12 h-double the throughput of the DST-1000. In addition, its acid level sensor and auto-shutoff feature allows it to be run completely unattended. Acid (up to 4 L at a time) is simply added to the DST-4000 via the conveniently located front fill tube, the unit is switched on using the external controller, and the user walks away. High-purity acid is collected in a pair of 2 L Purillex™ PFA bottles, and the DST-4000 switches off automatically when the run is completed. The acid in the collection bottles is protected from the environment by specially designed closures, and ready for use when needed. The in-laboratory production of high-purity acid has never been easier or more convenient.


	10321 West 70th St., Eden Prairie, MN 55344-3446
	tel. (952) 935-4100
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On-Demand High-Purity Acid Production Using a Fully-Automated Acid Purification System

	Cannabinoids and opiates have been used for medicinal purposes for thousands of years for relief of pain and seizures. In the early 1900s, an opioid epidemic resulted in restrictions on opiates. Years later, tighter restrictions were also placed on marijuana-one source of cannabinoids-although medical marijuana and cannabinoids have become increasingly legal and available in some states in recent years. The past few years have again seen an increase in opioid overdoses and even tighter regulation to prevent abuse, addiction, and possible deaths. Despite advances in medicine in the interim, there are few therapeutic alternatives to the opioids with the notable exception of cannabinoids.

	At least 100 cannabinoids have been found to have medicinal properties. The most commonly known are CBD (cannabidiol) and THC (tetrahydrocannabinol). These are extracted from hemp and marijuana plants, which are botanically distinct cannabis species. CBD extracted from hemp is available without prescription as a supplement, and contains no THC. Cannibinoids extracted from marijuana include CBD as well as some THC component, and hence are highly regulated because of the psychoactive properties of THC. CBD does not appear to have any intoxicating effects such as those caused by THC. Here, several formulations of cannabinoids are examined using mid-infrared diamond ATR spectroscopy.

	Infrared spectra were collected on an FT-IR spectrometer equipped with the Harrick DiaMaxATR™ single-reflection high-throughput diamond ATR accessory. The system was purged to remove CO

and water vapor. Spectra were collected at 8 cm

resolution and signal averaged over 32 scans. The spectra were referenced to the clean ATR crystal.

	Four formulations were investigated. The capsules and tablets were cut open to examine the enclosed components. Two of the samples were from hemp: Plus+CBD Oil™ softgels (liquid; 5 mg CBDA/CBD in extra virgin olive oil) and Plus+CBD Oil™ capsules (powder; 10 mg CBA in modified food starch, cellulose, silicon dioxide, and magnesium stearate). The other two were medicinal marijuana from different suppliers, designated here as A (liquid from a gel tablet; 8.5 mg THC, 8.5 mg CBD in coconut oil) and B (paste from a capsule; 0.7 mg THC, 4.3 mg CBD in coconut oil). Small aliquots of the samples were placed on the ATR crystal. Pressure was applied to compress the powdered sample against the diamond.

	Figure 1 shows the resulting spectra. The two formulations from hemp have a band at 3010 cm

 which is not present in the marijuana samples. All the samples except the Plus+CBD Oil™ capsules show a weak band at 3477 cm

 due to a phenol OH stretch. The Plus+CBD Oil™ capsules are the only formulation that contains cellulose and the broader OH stretch from cellulose may be masking the phenol OH band. The Plus+CBD Oil™ capsules also have a strong band at 1047 cm

 from cellulose. All four samples show the characteristic bands of cannabinoids around 1624, 1581, 1510, 1462, and 1374 cm


	Figure 1: Diamond ATR spectra of four medicinally beneficial cannaboid formulations: Plus+CBD Oil™ Softgels (black), Plus+CBD Oil™ Capsules (green), A (red), and B (blue).

	The Harrick DiaMaxATR, high throughput, single reflection ATR is effective at revealing spectral differences among the medicinally beneficial cannabinoid formulations available on the market.


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Molecular

A Diamond ATR-FTIR Study of Various Medicinal Cannabinoid Formulations

Using an automated sampling accessory the specular reflectivity of a thin film was characterized. Benefits of automation in terms of spectral optimization, time to complete the experiment, and reduction of spectral errors are discussed.

	Implementing automation into FT-IR sampling protocols offers several advantages such as increased productivity, reduced sampling errors, decreased labor costs, and elimination of monotonous lab tasks. Specular and diffuse reflection and transmission are measurement techniques that are especially adaptable to automation. This application note explores the efficiency of automated specular reflection measurements in the evaluation of a film coating.

	The model sample was a nonstick aluminum foil. Using the Automated VeeMAX III variable angle specular reflection accessory by PIKE Technologies, specular reflectivity was measured at various angles spanning 40–80° (Figure 1). To enhance measurement sensitivity at grazing angles (> 70°), a ZnSe polarizer set to p-polarization was incorporated at all angles. Angle position of the VeeMAX III was controlled by PIKE's AutoPRO 7 software, which interfaces with most FT-IR software packages to trigger data collection. Spectral resolution was set at 4 cm


	Figure 1: Automated VeeMAX III variable angle specular reflection accessory from PIKE Technologies.

	Specular reflection measurements for the analysis of thin films on a reflective substrate are referred to as reflection–absorption, because the beam will reflect off the surface and pass through film reflecting off the substrate. The beam will pass through the coating twice. With its variable angle feature, the VeeMAX III specular reflection accessory allows spectral results to be optimized. Steeper angles of incidence, suitable for thicker films, reduce the pathlength through the film whereas for thinner films the pathlength is easily increased by increasing the incident angle.

	Silicone resin is a primary component of most thin polymer coatings on nonstick aluminum foils. The coating is applied and partially cured, and the final curing step is complete when the foil is heated in bulk. Analyzing the foil via IR specular reflection measurements offers insight into the composition of the coating and the impact of processing parameters on the final film chemistry. Figure 2 shows reflection spectra of the foil sample as a function of angle of incidence from 40 to 80°. At lower angles, little chemical information is available because the pathlength through the polymer film is insufficient. As grazing angle is reached, spectra offer more information about the chemistry of the coating; absorbance bands associated with Si- bonds may be observed.


	Figure 2: IR spectra of a nonstick aluminum foil coating collected at various incident angles using a variable angle specular reflection sampling accessory. 

	By utilizing an automated specular reflection accessory during the IR measurements, the overall time to complete the experiment was reduced and data quality and reliability increased. The accessory's software control allowed for all backgrounds to be collected prior to collecting sample spectra. By leaving the background reference and sample in place between spectral collection angles, there is no substitution error introduced because the same sample spot is analyzed.

	Using an automated specular reflection accessory for IR measurements of coatings makes optimizing data quality and reliability an easy task. Substitution error is eliminated and overall experiment time is decreased.


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Automated Specular Measurements of a Thin Film

Sampling flexibility of Raman enables in-process analysis of solids, turbid media, liquids, and gases

Large volumetric Raman provide representative sampling of heterogenous solids 

	Raman spectroscopy is an analysis technique that provides a "molecular fingerprint" of the sample, enabling analysis of chemical composition and molecular structure without sample preparation. As a measurement technique, Raman imparts application and financial benefits from laboratory discoveries to feedback-control in manufacturing. 

 real-time analysis, compatibility with aqueous systems, nondestructive nature, and high chemical specificity means that a Raman-analyzed sample is representative of the process. Because Raman is a nondestructive technique, the same sample measured by Raman can also be measured by other analytical techniques. These well-known features have been harnessed in pharmaceutical, chemical, polymer, and bioprocessing industries.

	Fiber optic sampling probes enable real-time Raman measurements outside the laboratory. For process or in-line sampling applications, fiber optic probes can be inserted directly in the process. Figure 1 shows variants of fiber-optic probes used in Raman spectroscopy. The sampling flexibility imparted by fiber optic probes means that Raman spectroscopy can be applied to real-time 

 analysis of a variety of materials for applications from early development to manufacturing. The design of fiber optic probes for process environments takes into additional considerations of the material's phase, ability to be immersed in corrosive or hazardous environments, and laser safety.


	Figure 1: Raman measurements outside of a laboratory setting is achieved through fiber optic sampling probes. Sampling probes for Raman spectroscopy enable offset analysis of solids, thin films, and raw materials, or immersion analyses in liquids or gases without needing to customize process hardware.

In-process Raman in Solids and Turbid Media

	For processes that involve solids or turbid media, optical scattering is an important material property that needs to be considered. Understanding the effects of optical scattering on Raman signal recovery will guide the selection of a fiber-optic probe, because there are applications in which optical scattering can be harnessed to maximize sampling volume and there are other applications in which the effects of optical scattering should be minimized. In a recent example of Raman-based control in a process with solid materials, a large volumetric Raman probe was used to acquire information on critical quality attributes of pharmaceutical granules during a continuous blending and tableting process (1). Raman data were acquired quickly and nondestructively and with great chemical specificity, showing that Raman provides detailed 

process knowledge needed for real-time process understanding.

	Sampling flexibility is a significant benefit of Raman spectroscopy. The use of fiber-optic probes expands the capability of an analyzer to meet current and future application needs. Raman provides detailed chemical information without sample homogenization, enabling bulk or cross-sectional analysis during the process. Raman spectroscopy approaches to measuring layered samples may be applied to pharmaceutical tablets, copolymers, or biological materials such as cells or engineered scaffolds. Scientifically and financially successful Raman applications have been demonstrated at all scales, from the laboratory to on-line in manufacturing in PAC and PAT environments. Examples of processes benefiting from Raman spectroscopy include:

		Pharmaceutical formulations: blending, granulation, coating, drying, tableting, content uniformity

		Pharmaceutical API: reaction chemistry, yield, polymorph form identification, crystallization

		Polymer: polymerization blending, extrusion monitoring, crystallinity, density, copolymers

		Bioprocessing: cell culture, fermentation

	(1) B. Nagy et al., "In-line Raman spectroscopic monitoring and feedback control of a continuous twin-screw pharmaceutical powder blending and tableting process," 


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Sampling Flexibility for Raman Spectroscopy

	Modular spectrometers and accessories can be configured into small-footprint systems for measuring the color and absolute or relative irradiance of light sources and displays. Ocean Optics systems are compact, flexible, and simple to deploy in various settings.

	At a recent trade show, we showcased an experiment demonstrating the effectiveness of our Flame model spectrometer to monitor the color and spectral irradiance of digital displays.

	For the demo, we collected a handful of commercially available digital photo frames, taking care to select a combination of backlit LCD and LED displays, each with different dimensions and screen resolution performance (Figure 1). A radiometrically calibrated spectrometer (model Flame-S-RAD) with cosine corrector attached measured the output of the displays. OceanView spectroscopy software calculated color values, color difference, and power and photometry values.


	Figure 1: In this demonstration, a radiometrically calibrated spectrometer with cosine corrector attached (foreground) measures the spectral output and color consistency of emissive displays.

	As with a relative or absolute irradiance measurement, the spectrometer must be calibrated first. In the demo, our emissive color measurement began with an absolute irradiance measurement. Establishing an accurate scale for the spectrometer's response at each wavelength is essential to calculating color and power.

	Color consistency within samples requires color measurements that are repeatable from measurement to measurement. A well-defined method of comparing reflective or emissive color, either within a batch or to an acceptable standard, is also required. Ocean Optics color measurement systems offer both, providing the flexibility to configure the measurement system for various sample types and needs, as well as the software to perform quantifiable color comparisons.

	Delta E is used to quantify the difference between two colors. A delta E (dE) less than or equal to 1.0 indicates that the human eye will perceive two colors as the same. As the dE increases above 1.0, the perceived difference in color increases. The calculation of delta E takes a subjective comparison of color and provides a quantitative value indicating how different the colors appear to the human eye. In some cases, depending on the application, less rigorous dE limits are set where the perception of slight differences in color is acceptable.

	For this demo, we calculated the L*a*b* color difference of different locations within an emissive display as compared to a reference location within the same display (Figure 2). Also, that reference display could have been compared to the other displays in the demo setup. We could easily update the color reference reflection spectrum at any time during the measurements to calculate dE relative to a different color reference.


	Figure 2: With spectral monitoring of emissive displays, the calculation of color parameters and blue light intensity is possible using Ocean Optics spectrometers and software.

	Irradiance is the amount of energy at each wavelength emitted from a radiant sample. From that data, more specific photopic values can be calculated, including lumens, lux, and candela.

	Measurements in absolute irradiance mode require calibration using a source with known power output. For the demo, we used a spectrometer that was radiometrically calibrated at the Ocean Optics calibration lab. The spectrometer came with a calibration file that allowed us to work in absolute irradiance mode.

	The calibration process generates a file with energy response data for each pixel in the CCD, given in µJ/count. Factoring in the surface area of the sampling optic and the integration time allows irradiance measurements in µW/cm

	Why use a cosine corrector as a sampling optic for a diffuse emissive source like a digital photo frame? The cosine corrector has a 180° field of view and samples any light incident on the diameter of its white diffusing surface, and specifically in that plane. Cosine correctors work well for measuring the power incident on a surface like a screen, in which case the corrector should be placed flush with that surface.

	For the demo, we used the Absolute Irradiance mode in OceanView and selected the Photometry, Photons, Power and Energy wizard to calculate power and a range of other values. For calculating photometry values (lumens, lux, candela), the distance from the display surface must be taken into account.

	As part of our emissive displays demo, we monitored blue light in the 400–500 nm range. Blue light has shorter wavelengths and higher energy output than other visible light, so it reaches deeper into the eye. The cumulative effect of this exposure can cause damage to the eyes over time. Blue light exposure has increased with the move from incandescent lighting to compact fluorescent and LED lighting and with our constant exposure to digital screens.

), a Cincinnati, Ohio-based company that provides systems for protection from harmful blue light, we adjusted our spectrometer integration time to cover the blue light range and then reported the power values in uW for three criteria (Figure 2):

		Fatigue range (400–420 nm): eyes can become irritated, strained and tired

		Macular damage range (400–440 nm): may cause permanent damage to the retina

		Sleep range (460–484 nm): nighttime exposure can hinder melatonin production, disrupt circadian rhythms, and lead to trouble sleeping

	Accurate measurement of spectral irradiance and emissive color of digital displays is an important application of spectroscopy, with several use cases:

		Maintaining color consistency in LEDs, LCDs, and other displays

		Calculating color differences within and among displays

		Determining the output of emissive devices at wavelengths associated with blue-light hazards

		Calculating photometry values (lumens, lux, candela)

		Determining the power output of emissive sources


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Monitoring Spectral Irradiance and Color in Digital Displays

	Fats and oils are recognized as essential nutrients in human diets and are presented in varying amounts in many foods. They not only provide the human body with a concentrated source of energy, but also supply essential fatty acids that are precursors for important hormones. The quality of edible fats and oils are assessed through parameters such as: iodine value (IV), trans content, peroxide value (PV), anisidine value (AV), saponification number (SN), free fatty acids (FFA), and solid fat content (SFC). The traditional chemical and chromatographic methods used to analyze edible fats and oils are labor intensive, require the use of solvents and reagents, and are extremely time consuming.

	FT-NIR spectroscopic analysis of fats and oils is fast, requires no sample preparation, and can analyze multiple parameters with a single measurement. An infrared spectrum of an oil contains a wealth of information that can be used to determine important factors. For example, the OH stretching region can indicate the presence of moisture or hydroperoxides, the latter commonly measured by the chemical PV test. The intensities of the bands in the CH region and of the ester linkage absorption are related to the average molecular weight of oil, commonly evaluated by SN determinations. The COOH absorption is indicative of lipolysis or free fatty acid (FFA) content of an oil. The presence of spectral features related to aldehydes and ketones, as well as conjugated dienes, suggests accumulation of secondary oxidation products commonly measured by the thiobarbituric acid (TBA) test or the AV test. The isolated trans band provides a direct measure of isolated trans isomers, and the combination of CH cis and CH trans absorptions provides a measure of total unsaturation or IV. The complete spectrum of a refined, melted fat characterizes its overall triglyceride composition, which in turn can be related to its SFC and also provides information about the relative amounts of saturated, monounsaturated, and polyunsaturated fatty acids in a fat or oil.

	Near-infrared (NIR) spectroscopy contains combination bands and overtones of fundamental vibrations in the infrared region and provides several practical advantages over infrared spectroscopy. For example, while infrared measurements require direct contact with the sample, NIR can measure oil samples in disposable glass vials, significantly reducing the risk of cross contamination. What's more, NIR spectra can be measured online with a fiber optic probe.

	NIR spectroscopy has been recognized by AOCS (American Oil Chemist Association) and AOCS method Cd1e-01 uses FT-NIR to measure Iodine Value (IV). In addition, it proves to be a useful tool in the detection of oil adulteration.

	Various types of fat and oil samples were measured using a QuasIR™ 4000 FT-NIR spectrometer with heatable sample compartment. Oil samples were measured in an 8 mm glass vial at 75 °C following AOCS method Cd1e-01. Three spectra per sample were collected using 8 cm

	Spectral Sage™ PLS Quantitative Analysis software was used to develop partial least square calibrations for various parameters.


	Figure 1: FT-NIR spectra of oils in the range of 4500–9000 cm

	NIR spectra of four different types of oils with varying degrees of unsaturation are shown in Figure 1. Partial least square calibrations were developed for, but not limited to, the following parameters:


	Figure 2: Cross-validation of IV calibration.

	The cross-validation results of iodine value (IV) and linolenic acids calibrations are displayed in Figure 2 and Figure 3, respectively.


	Figure 3: Cross-validation result of C18:3.

	Galaxy Scientific QuasIR FT-NIR brings fast, accurate NIR analysis closer to the point-of-need, by combining portability with superior spectroscopic performance. These next generation field portable platforms which combine next generation optics with advanced software algorithms providing breakthrough solutions to the most challenging point-of-need applications. Samples can then be analyzed in the field, rather than be taken off site to separate laboratories.

	Quantum Analytics is an authorized distributor of the QuasIR FT-NIR instrument, as well as other instruments for food analysis. Contact us today to discuss your application needs.


	3400 East Third Avenue, Foster City, CA 94404
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Analysis of Edible Oils by FT-NIR Spectroscopy

	Confocal Raman microscopy is a versatile, nondestructive and fast method for studying the chemical composition of living and non-living material. It is used to identify and localize not only the molecules in a specimen but also to detect their quantity, degree of crystallinity, and crystal symmetry.

	However, not all samples have a flat and smooth surface. To acquire Raman images from samples with rough, inclined, or irregularly-shaped surfaces, WITec invented topographic Raman imaging.

	With the TrueSurface™ option, Raman spectra are acquired from precisely along a surface or at a set, user-defined distance from a surface. As the sensor actively monitors and maintains a set distance between the objective and sample surface, its closed-loop operation can compensate for any variations during measurements with long integration times. This keeps the measurement area in constant focus and produces sharp confocal Raman images with sub-micrometer resolution. Topographic Raman imaging also allows the distribution of chemical components within the sample to be visualized in three dimensions.


	Figure 1: (a) Topographic Raman image of a pharmaceutical pain tablet containing acetylsalicylic acid, isobutylphenylpropionic acid, caffeine, and auxiliary substances shows the distribution of the components along the tablet's curved surface. (b) Corresponding spectra of the tablet's ingredients.

	Here we demonstrate the technique's capabilities by carrying out Raman imaging of the surface of a curved pharmaceutical tablet (Figure 1) and of cellulose fibers in paper (Figure 2).


	Figure 2: Confocal Raman image of cellulose fibers in paper. Fibers of different orientation are marked with green and blue.

	Investigations on pharmaceutical tablet ingredients, geological samples, composite emulsions, complex semiconductor structures, organic material, and many other applications can benefit from the ease of use, accelerated workflow, and methodological advantages provided by the new TrueSurface™.


	Lise-Meitner-Stra e 6, 89081 Ulm, Germany
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TrueSurface—The Original Topographic Raman Imaging System

Wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometry involves the classification and quantification of several kinds of biological samples. Multiple applications of WD-XRF spectrometry are anticipated in the mining industries, nuclear power industry, medical diagnostics, forensics, environmental, and particularly in agricultural studies. Here, we present a concise review of the quantitative measurements performed to classify and quantify the traces of essential and toxic minerals in wheat seed gall nematodes (

 rhizomes, gallstones, and kidney stones. Based on the studies reported, WD-XRF was found to be a robust analytical tool that is useful for agricultural studies and for the diagnosis of urological and gastroenterological disorders. This review is aimed at analyzing major and trace levels of heavy and toxic minerals in biological specimens related to agricultural crops (wheat grains and 

) and human diseases (gallstones and kidney stones) and shows some interesting prospects for using WD-XRF spectrometry.

	Trace and heavy metal detection in agricultural and biological samples currently is of crucial importance because of the pollution occurring in the environment, particularly in soil and water, which constantly affect human health. Agricultural crops, medicinal herbs, and natural resources used for human benefits are being contaminated by the presence of toxic elements such as lead, arsenic, mercury, chromium, and nickel. These elements then move from soils to plants and then to human beings. They can cause serious diseases such as cancer or stone formation in the human body (gallstones and kidney stones). Hence, a holistic approach is needed to analyze agricultural and biological samples to find the source of these toxic elements and take necessary steps for prevention.

	Over the last few decades, the major aim of research in the field of agricultural and biomedical science has been to determine the concentrations of various toxic elements in many agricultural and biological specimens to find the cause of disease for its prevention. X-ray fluorescence (XRF) spectrometry is a versatile tool in many analytical problems. Major, minor, and trace elements can be qualitatively and quantitatively determined in various kinds of samples: metals, alloys, glasses, cements, minerals, rocks, ores, and polymers as well as environmental and biological materials (1). The application of wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometry allows efficient determination of low-Z elements down to even beryllium (Be) without sample treatment with ensured high quality quantitative results. Because of the nondestructive character of X-ray measurement, XRF spectrometry is widely applied for the analysis of art, for example, museum and archeological objects such as manuscripts, paintings, icons, pottery, ancient glasses, ceramics, and coins.

	XRF is based on the principle that all elements produce secondary "fluorescent" X-rays of characteristic energy when they are exposed to X-rays of appropriate higher energy. The energy and intensity of the emitted X-rays can then be used to determine elemental composition. In principle, the higher the atomic weight of an element, the higher the energy needed to induce fluorescence and the fluorescence energy. It is also easier to detect fluorescence as the atomic weight of an element increases. Because XRF offers many unique capabilities, it has become the technique of choice for many applications requiring accurate elemental analysis for the purpose of meeting tight specifications at high concentration levels (2). High-performance WD-XRF spectrometry is now being used for the determination of traces in plant materials, biological samples, and geological samples. To fulfill today's requirements for quality data, modern instruments must provide high elemental sensitivities to achieve low detection limits and the best spectral resolution to minimize line overlays. In this article, we discuss the use of WD-XRF spectrometry to analyze trace and heavy metal contents in some agricultural and biological samples.

	The studied infected and uninfected wheat grain samples are shown in Figure 1. Figures 1a, 1b, and 1c are images of uninfected wheat grain, low infection wheat seed galls with 

, and high infection wheat seed galls with 

. Microscopic observations revealed the infection in wheat samples with 

 and details can be found in the literature (3). Also, the galls have a similar shape to the uninfected grains but are dark brown in color. The studied 

, which is widely distributed in many tropical and subtropical regions of the world) samples were collected and washed thoroughly to remove all the traces of soils and other possible contaminations. The biological applications and use of 

 can be found in the literature (4). The gallstones and kidney stone samples (5,6) studied using WD-XRF were collected from the Department of Nephrology at Opal Hospital in Varanasi, India.


	Figure 1: Photographs of (a) uninfected wheat grain, (b) wheat seed galls (low infection) with Anguina tritici, and (c) wheat seed galls (high infection) with Anguina tritici. Adapted with permission from reference 3.

, gallstones, and kidney stones, we used an S8 TIGER WD-XRF spectrometer (Bruker) for the determination of traces in these biological samples. The instrument was optimized to obtain better quantitative results, resolution, reproducibility, and reliability for each element with the best excitation and highest intensity over the whole elemental range. The quantitative measurements of the elemental constituents of kidney stones were performed using the same WD-XRF spectrometer. A 4-kW Rh anode X-ray tube (with a voltage of 60 kV max; and current 170 mA max) equipped with proportional flow counter and scintillation counter detectors was used as the energy source. Exposure time per sample was 20 min. The analyzer crystal LiF220 ensured that, in combination with the 0.23° collimator, the best separation was achieved for adjacent elements. The quantitative determination of major and trace elements was done using Quant-Express software (Bruker), which comprises a unique multipurpose preprepared calibration using certified standards. It automatically created the optimal measurement method to match each element and concentration range quickly, simply, and reliably.

Using WD-XRF to Analyze Uninfected and Infected Wheat Gall Nematodes

	Microscopic observations (3) have been performed to identify nematodes in the infected wheat grains that clearly indicated the presence of dead nematodes and fungal spores inside the wheat galls. Figures 2a and 2b depict the nematodes identified as 

 while Figures 2c and 2d show the silicified hairs on the galls. Further, Figures 2e and 2f show the features identified as the fungal spores helminthosporium and alternaria, which originated from air during storage of the wheat grains and caused further grain damage.


	Figure 2: Anguina tritici (a, b), silicified hairs (c, d), helminthosporium (e), and alternaria (f). Adapted with permission from reference 3.

	The typical overlapped WD-XRF spectra of uninfected wheat grain and seed gall nematode (low and high infection) wheat samples are shown in Figure 3 in different energy ranges. The relative intensities of the elements present in the uninfected, low infection, and high infection wheat samples are different, as can be seen in Figure 4, which indicates that their concentrations are different in different samples. The detected and quantified minerals in uninfected, low infection, and high infection wheat samples were potassium (K), sulfur (S), phosphorus (P), chlorine (Cl), calcium (Ca), magnesium (Mg), iron (Fe), silicon (Si), zinc (Zn), copper (Cu), sodium (Na), chromium (Cr), manganese (Mn), nickel (Ni), and aluminium (Al). The relative concentrations of these elements present in wheat samples are plotted in Figure 5. Among minerals, K, P, and S were predominant in uninfected grains as compared to Ca, Mg, Fe, Si, Cu, and Zn. The observed order of elemental concentration, particularly S, P, Ca, Mg, Fe, and Si, was found as follows: high infection wheat samples > low infected wheat samples > uninfected wheat samples. The concentration of K and Cl was highest in the low infection wheat sample. The concentration of Zn was higher for high infection wheat samples, a trend that may be correlated to the infection of grains caused by the nematodes. The elements Cr, Mn, and Ni were detected only in low infection and high infection wheat samples and they were completely absent in uninfected wheat samples which may be attributed to the activity of nematodes. Cu was only detected in uninfected and high infection wheat samples and was absent in low infection wheat samples. The mineral Na was only detected in low infection samples and Al was only detected in high infection wheat samples.


	Figure 3: Typical WD-XRF spectra of uninfected and infected wheat grains in energy ranges (a) 0.5–1.5 KeV indicating the presence of Mg and Al; (b) 1.7–3.3 KeV indicating the presence of Si, P, S, and Cl; (c) 3.3–5 KeV indicating the presence of K and Ca; and (d) 5–11 KeV indicating the presence of Cr, Mn, Fe, Ni, Cu, and Zn. Adapted with permission from reference 3.

	The toxic elements Al, Cr, and Ni were only detected in infected wheat samples and were not found in uninfected wheat samples. This result may be due to the presence of infected areas in grains because of the fungus and nematodes. The detected concentration of Al up to 600 ppm clearly indicated the toxic effect of Al in gall formation in wheat samples (7). Also, the presence of Cr and Ni at excessive levels in infected wheat samples were also the important reasons of gall formation in wheat grains. Thus, it was concluded that their presence was one of the factors leading to this disease and the formation of galls in wheat samples. The maximum concentration of Zn high infection wheat samples was responsible for the change in color of infected wheat samples from light brown to black. Along with WD-XRF, the authors also applied Fourier transform infrared (FT-IR) spectroscopy to study the molecular compositions of the infected and uninfected wheat grain samples. Diffuse reflectance measurements of uninfected and infected wheat samples were also used to identify spectral differences among wheat samples.


	Figure 4: Bar diagrams showing the concentration of elements present in uninfected, low infection, and high infection wheat samples as measured using WD-XRF. Adapted with permission from reference 3.

	The spectroscopic revolution has not only been regarded as the milestone for physical sciences, but also has opened the possibilities of new avenues in plant science and applied science. These findings underline the value of considerable supporting information using XRF spectrometry to avoid risks caused by microrganisms and are also helpful in avoiding damage to the environment, thus offering new investigation routes of agriculture- and disease-related issues.

	The high numbers of inorganic mineral elements present in nearly all plants ensure the successful growth and development of both vegetative and reproductive tissues. Currently, Fe, Zn, Mn, Cu, boron (B), Cl, molybdenum (Mo), and Ni have been recognized as micronutrients that are found at concentrations less than 0.01% of dry tissue weight (4). A few other minerals, such as cobalt (Co), sodium (Na), silicon (Si), selenium (Se), iodine (I), and vanadium (V), have also been shown to be essential and beneficial for certain plant species (4). Many other elements can be found in plants, but these are thought to enter plants nonselectively. Most of these nonessential elements confer no known benefit to the plant and many, such as cadmium (Cd) or Cr, are actually harmful to plant growth.

 family and is widely distributed in many tropical and subtropical regions of the world. It is also known as purple nut sedge or nut grass and is a common weed found mostly in the fields, agricultural land, and moist waste land of all over India (4). The tubers of 

 have a wide range of medicinal and pharmacological applications. They are generally used as anthelmintic, aphrodisiac, diuretic, sedative, carminative, stimulant, tonic, and stomachic. They are also used as a remedy for renal colic and dysentery. Furthermore, the plant possesses different biological activities such as antioxidant, cytotoxic, antiallergic, antipyretic, anti-inflammatory, antiemetic, hypotensive, anticonvulsant, antimalarial, antimicrobial, antidiarrhoeal, antidiabetic, hepatoprotective, and insecticide (4).

	The typical overlapped WD-XRF spectra of 

 samples are shown in Figure 5. The macro- and micronutrient minerals detected and quantified in 

 sample using WD-XRF were C, O, Na, Cl, Mg, Si, K, Ca, S, P, Al, Fe, Zn, Mn, Pd, Ru, Cr, Mo, Sr, Cu, and Ni. The concentrations of macronutrients Ca, Mg, K, P, and S were 0.36%, 0.46%, 0.38%, 0.20%, and 0.26%, respectively. The detected concentrations some micronutrients such as Al, Fe, Si, Na, and Cl were 0.06%, 0.05%, 0.42%, 0.8%, and 0.65%, respectively. Other micronutrients including some heavy minerals were detected at low levels ranging from 7 ppm to 44 ppm. The presence of elements found in 

 species were discussed in the literature (4). For the first-time, we used WD-XRF techniques to determine the macro- and micronutrient mineral contents of 

 rhizomes. Our results revealed that WD-XRF is a promising technique that is capable of analyzing plant samples with complex matrices used for medicinal purposes. Furthermore, the results obtained in the present paper show interesting prospects for WD-XRF to study plant samples. Other techniques, such as FT-IR and ultraviolet–visible (UV–vis) spectroscopy, have also been used for molecular analysis of c

 which revealed the capability of those techniques for the study of medicinal plants.


	Figure 5: Typical WD-XRF spectrum of Cyperus rotundus (snapshot shown in inset) in different energy regions indicating the presence of macro- and micronutrient minerals. Details about spectral information can be found in reference 4.

Using WD-XRF to Analyze Heterogeneous Gallstones

	Stone formation (gallstone and kidney stones) inside human organs are common diseases and constitute a major health problem worldwide (8–10). These stones are the result of a buildup of chemical particles in the gallbladder and kidneys, respectively. The chemical composition of stones is complex and varied. Trace elements are essential components of biological structures and are necessary for a multitude of vital functions in the human body. The precise role of trace constituents in the pathogenesis of stones is still unclear and under debate, but researchers are increasingly focusing on the role of trace elements in their pathogenesis (8–10). To understand the formation of these stones and their growth, it is important to study their chemical and elemental compositions as well as the function of the different elements as affected by the stone type. Determining and studying the chemical composition of stones is often among urologists' main means of shedding light on the pathogenesis of stones. Analytical techniques such as atomic absorption spectroscopy (AAS), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), XRF, proton-induced X-ray emission (PIXE), X-ray diffractometry (XRD), Raman spectroscopy and microscopy, FT-IR spectroscopy, and laser-ablation inductively coupled plasma–mass spectrometry (LA-ICP-MS) are currently being used to answer questions about the composition of stones worldwide (8,9). Routine analysis in the field of medical science is still based on X-ray, ion-beam, and spectroscopic techniques. Each technique has its own merits and demerits. Most of the recently developed optical techniques such as laser-induced breakdown spectroscopy (LIBS) are based on the detection of the radiation emitted by the elements present in the biological samples (8–10).

	The WD-XRF spectra of these gallstone samples have been recorded and analyzed thoroughly (for more details see references 5 and 6). The major, trace, and heavy elements detected and quantified in gallstone (GS1, GS2, and GS3) were Ca, Na, K, P, Mg, Mn, Zn, Na, Cu, Fe, P, S, Si, Cl, Al, Br, Pd, and Ru. The relative concentrations of these elements are shown in the bar diagram in Figure 6. The observed concentrations of the elements Ca, Mg, Na, Cl, P, and S were higher in comparison to other elements. All other heavy elements were detected at trace amounts (parts-per-million range).

Application Notebook-02-01-2018