Our annual review of products introduced at Pittcon, or during the previous year.

	As in the past, this year's edition of our annual review of new spectroscopy products includes products launched at Pittcon 2019 or elsewhere during the past twelve months (Table I). Given the extensive scope of this review, we are only able to include products for which the manufacturer submits a completed form, in response to the survey sent out by 

 or our additional, and rather intensive, efforts to encourage submissions. One of the points of interest in the instruments featured here is a definition of those instruments that are of most interest, or are considered the most innovative, or are the most important to the field. This is, of necessity, a subjective evaluation, and involves a selection process from all the products submitted.

	In this annual review, we like to highlight the product awards given out by the Pittcon organization. Starting two years ago, the selection methods and criteria were changed from what were then called the 

awards, as well as the nature of the awards. The awards are now called the 

. A selection committee, consisting of a blue-ribbon panel of experts, evaluates the entries based on ingenuity, creativity, implementation, and outcomes. Also, companies are segregated into small, medium, and large categories, based on sales figures. This division allows companies in each class to compete with others within that same class. Therefore, there are three awards of each type (gold, silver, and bronze) in each company category, for a total of nine awards. We are pleased to note that some spectroscopy companies were winners in this competition. These include:

		In the small company category: (<$10,00,000), Pendar Technologies won bronze for its system for standoff Raman and Raman measurements of dark materials.

		In the medium-sized company category ($10,000,000 to $100,000,000), Raptor Photonics won gold for its high-definition indium gallium arsenide (InGaAs)–based infrared (IR) camera.

		In the large company category (>$100,000,000), Bruker won bronze for a new XRF analyzer that is fully automated and faster than previous XRF instruments.

	There is another first among these Total Excellence Awards: Previously, no company or product won twice in two successive years, or for the same product. Last year, Gate Scientific won an Excellence award for its temperature-sensing stir bar; this year, it also won for it pH-sensing stir bar, making it the first time a company has won two excellence awards for substantially similar products. Although this product does not involve spectroscopy, the phenomenon of a double-winner caught our attention.

	The review that follows is organized alphabetically, and categorized by wavelength region or type of spectroscopy (mid-IR, X-ray, Raman, and so on), except that we put the two noninstrument categories (accessories and components) at the end. We arrange our review to allow readers to compare instruments from different manufacturers, although this process sometimes classifies handhelds with high-end research tools. The categories used to classify the products are:

	Atomic spectroscopy
	Fluorescence
	Imaging
	Mass spectrometry (MS)
	Mid-infrared (IR) spectroscopy
	Near-infrared (NIR) spectroscopy
	Nuclear magnetic resonance (NMR)
	Raman spectroscopy
	Software
	UV-visible spectroscopy
	X-ray
	Accessories
	Components

	Our included categories fluctuate year to year, depending upon trends in the submissions. The core spectroscopy headings are consistent, but imaging, for example, has been transient. This year, we did receive products classified as imaging, which warranted that being a category in itself, rather than having us only include imaging versions of various technologies under the parent instrument type. Another category that had been absent for a long time, but is showing up again, is fluorescence. As in the past, the accessories section includes tools used with an instrument (such as sample preparation or attenuated total reflection [ATR] devices), whereas the components section covers parts used within instruments (such as lasers or detectors). The software category covers instrument control and data processing, storage, and transmission, as well as spectral databases (libraries) and other collections of specialized information, including programs that analyze the data.

	We've always tried to identify early indicators of future tendencies. In the past, we could sometimes isolate some spectroscopy-specific trends that were noteworthy. This year, some of the major trends that are likely to affect the universe of spectroscopy are not so specific, but rather are more nearly side effects of large-scale trends that affect the greater digital universe we inhabit. The continuing growth and development of computer technology, and the concomitant growth in the associated technology of the Internet, superimpose their own trends on our own, somewhat smaller, universe. Items that have been showing up in the larger digital world for a while are now starting to appear in ours. These may become trends in the future, and therefore may bear watching for their influence on our activities, and include these not-entirely-independent categories:

	Networking
	Internet of Things (IoT)
	Security
	Artificial Intelligence (AI)
	"The Cloud"

	Some current (and even past) practices may become future trends, if and when they become more widespread and generalized. In the meantime, sporadic mentions of these practices appear in advertisements, in scientific literature, and even in this review. For example, some instrument manufacturers have created a capability of remotely controlling and collecting data from their own instruments (networking) for a long time. I myself was involved in a project like that as long ago as 1986. When that capability expands to include more than one type of instrument, then it would be fair to rename that localized networking as belonging to the "Internet of Things" (IoT), but, in my opinion, I think not until then. Similarly, can the current capabilities of the application of chemometric analysis to instrument data, to perform quantitative and qualitative analysis, be called 

 (AI), or is that a different type of activity? Only the future will tell.

	As we've noted almost since first trying to detect instrument trends, the trend toward hyphenated techniques has been coming along slowly, but surely, over the years. A recent twist on that concept, broadening the idea of applying multiple technologies to an analysis, is the packaging of dissimilar, and indeed sometimes even orthogonal, technologies in a single instrument package, without the two technologies necessarily interacting (as hyphenated methods do). In this review, for example, we have at least one instrument giving the capability of applying infrared and Raman spectroscopy to the same sample, and one that incorporates laser induced breakdown spectroscopy (LIBS) with Raman.

	Your reviewers are human, and also finite, and, try as we might, cannot know how the future will develop. We therefore solicited some assistance from the people who are on the front lines of the future impact: the companies that will be affected by it, those reported on in this review. While not advanced enough to be called trends yet, sporadic mention of those activities in scientific papers, advertisements, and other discussions and descriptions of instrument performance potentially point in directions that indicate where the future of instrumentation is going.

	Table II describes the instruments included in the atomic spectroscopy category.

	Advion offers a 90° quadrupole deflector, which has lower interference and improved signal-to-noise ratio, preventing contamination, and thereby produces reliable results quickly and easily.

	Agilent's water analyzers reduce the time needed to run water testing methods according to government standards.

	LTB Lasertechnik announced has a combination LIBS atomic emission spectrometer and a Raman spectrometer in a single unit.

	Milestone's 7th generation Mercury Analyzer completes an analysis in just 5 min, resulting in lower running costs.

	PS Analytical provides several dedicated variations of atomic fluorescence mercury monitoring systems to suit specific sampling and measurement situations.

	Spectro now has a radial dual side-on interface (DSOI) that is said to provide twice the sensitivity of conventional radial plasma-view instruments and equal the sensitivity of newer vertical-torch dual-view systems, with less complexity. This technology is designed to provide advantages in determining trace element concentrations and handling samples with challenging matrices, including certain wastewaters, soils, and sludges, as well as petrochemical, chemical, high-salts, and metal samples.

	Looking at these offerings in the atomic spectroscopy category, a potential emerging trend is for companies to offer specialized products to address occupational health and safety (OHS) concerns and stricter environmental requirements.

	There is just one new fluorescence spectrometer this year (Table III). The PerkinElmer FL 8500 is designed to be an easy-to-use instrument with flexibility to analyze a broad range of sample types and volumes while maintaining sample integrity, with pulse and continuous wave options. The improved signal-to-noise performance allows lower level analyte detection. The device also enables many different experimental setups. Features include phase range, wider wavelength coverage, intuitive software, and interchangeable accessories.

	Agilent is showing an IR imaging instrument that is said to offer high definition, spatially-resolved images of the chemical components on a flat surface, showing which chemicals are present, and their spatial location.

	Malvern Panalytical's Morphologi 4 series of Raman imaging instruments offers sharp and fast measurement of particle size, shape, and chemical identification.

	Middleton introduced a multi-mode hyperspectral imaging system for high-volume sampling and "big data" output. The system supports two spectral cameras for sequential hyperspectral imaging of a sample.

	Videometer utilizes laser light scattering to measure transmission and reflection spectra. Several models are available, each designed for a different specific measurement situation.

	Advion offers an ICP-MS instrument that has a 90° quadrupole deflector, to provide lower interference and an improved signal-to-noise ratio and prevent contamination, thereby producing reliable results quickly and easily.

	Agilent's ICP-MS water analyzers reduce the time needed to run water testing methods when applying government analysis standards.

	Excellims has a high-resolving-power ion-mobility mass spectrometer optimized for cleaning validation and similar applications.

	Ohio Lumex combines the selectivity of GC with the sensitivity of an ion mobility spectrometer for the analysis of volatiles in the headspace of liquid and solid samples without any sample pretreatment.

	The Waters DART QDa combines direct analysis in real time (DART) ionization with their QdA mass detector to create a direct-from-sample analytical system to perform real-time sample recognition. It is aimed at applications in the food market, such as verifying sample authenticity or for detecting adulteration.

	Table V presents the mass spectrometry related products for this year's review.

	The 700 series FT-IR instruments from California Analytical Instruments are designed for fast and easy measurement of multiple hot wet gases that absorb in the IR spectral region. Levels can be detected from ppb to the percent range.

	Keit shows a rugged process FT-IR spectrometer for in situ monitoring of chemical concentrations in liquids and slurries at pH levels from 0 to 14 in various environments. This instrument also comes in a high-temperature version that can operate with samples at temperatures up to 200 °C.

	Ocean Optics' MZ5 is a compact, fully integrated ATR-mid IR spectrometer that measures liquid samples from 1818–909 cm

 (5.5–11 µm). The MZ5 comprises a sample interface, light source, detector, and software, and provides a fast, convenient mid-IR alternative to traditional FT-IR spectroscopy for laboratory research.

	Photothermal Spectroscopy Corp. has a dual-function spectrometer. Infrared and Raman spectra and images can be measured and collected simultaneously from the same measurement point of a sample.

	Thermo has two new FT-IR spectrometers based on their IS-5, equipped with a multicolored LED scan bar, displaying instrument status, which allows users to swiftly execute workflows for improved productivity. The second unit is based on the Nicolet Summit spectrometer, and is a compact and rugged unit for busy, multi-user quality assurance (QA) and quality control (QC) laboratories in a variety of industries, such as polymer-chemical, pharmaceutical, food and beverage, forensics, environmental, electronics, and geology.

	Tiger Optics offers an instrument claiming the ultimate low-detection of moisture and speed of response.

	Verder Scientific incorporates an infrared cell to enable measurement of carbon and sulfur (C/S) for inorganic samples in difficult matrices.

	Table VI presents this year's new mid-infrared products.

	The NIR sector is seeing the pharmaceutical industry, a major customer, moving to lower cost, smaller, more efficient in-line continuous processing spectrophotometers, requiring a new generation of monitoring instruments, and thus the manufacturers are releasing products to fill that need.

	Brimrose provides a wireless, free-space communicating spectrometer, designed to fit into smaller, compact spaces. It is ruggedized, with an Ingress Protection (IP) rating of 65.

	Si-Ware Systems offers a miniature and low-cost spectral sensor based on FT-NIR technology. The sensor operates from 1350 to 2500 nm, and is designed for high-volume production with minimal external components. The sensor is intended for applications in farming, food, healthcare, and industry, as well as in consumer-facing applications.

	Spectral Evolution has a family of instruments operating in the NIR spectral region. They share a core capability of high resolution with high sensitivity field spectroradiometric operation, and are intended for high-altitude or satellite-based measurements. One member of the family extends to the capability of operation via the IoT, and another member includes an integrating sphere for absolute radiometric calibration.

	Table VII presents the near-infrared (NIR) instruments.

	Future trends within the NMR marketplace involve the pharmaceutical industry, a major source of revenue within that market, seeking lower cost, smaller, more efficient in-line continuous monitoring instruments. To meet that need, Nanalysis offers a high-performance benchtop NMR spectrometer (Table VIII).

	Acutech provides a pocket-size, lightweight, handheld Raman analyzer for both laboratory and field detection, providing identification of chemicals without sample preparation or contact. Specialized, dedicated versions are available for process monitoring, and for gemstone identification and analysis.

	B&W Tek is announcing several models of handheld Raman instruments, each designed for a specialized set of applications.

	Cloudminds announced a smartphone based Raman spectrometer, the XI, claimed to be the world's first cloud AI handheld Raman spectrometer. Connecting to the cloud via cellular, WiFi, or bluetooth, this platform allows the user to share data and synchronize instant updates on all devices. Operation of XI is fully automated with an intuitive interface. The device adopts AI deep learning algorithms, enabling faster data analysis with high accuracy.

	LTB Lasertechnik launched an instrument that combines a LIBS atomic emission spectrometer and a Raman spectrometer into a single unit.

	Photothermal Spectroscopy Corp. has a dual-function spectrometer. Infrared and Raman spectra and images can be measured and collected simultaneously from the same point on a sample.

	Renishaw presents a compact benchtop Raman imaging system, designed for biological and clinical research. This instrument enables the rapid collection of detailed information from a range of biological samples, including tissues and biofluids.

	Rigaku combines a standard library of over 13,000 chemicals using a 1064 nm laser for identifying colored substances, or scanning through colored packaging.

	Spectra Solutions showed two Raman products. One is a portable battery-operated Raman spectrometer, and the other is a removable fiber optic Raman measurement probe.

	Tec5USA's Raman spectrometer, designed for industrial environments, includes multiple lasers as the sources for the Raman excitation.

	WITec's ParticleScout is a particle analysis tool for the alpha300 Raman microscope series. The device surveys, categorizes, analyzes, quantifies, and identifies particles, even over large sampling areas.

	Table IX presents the properties of the new Raman instruments.

, in the context of this review, consists of several different, albeit related, types of products. Actual computer programs, compilations of spectra, databases, and collections of chemometric calibration models are all included in this category.

	The ability to share information via vendor neutral archiving using the public domain data standard, Analytical Information Markup Language (AnIML), is a desirable goal. However, it remains to be seen if this will be widely implemented by the spectroscopy community. If so, this capability will enable detail reviewing, visualization, and reporting, even across different techniques and platforms.

	Domain-specific processing and data sharing capabilities are upcoming requirements for research and development (R&D) and QC departments within the spectroscopy user community. The AnIML industry data standard and related software implementations greatly help to enforce these requirements in a regulatory-compliant manner.

	Operators of laboratory and at-line instrumentation are becoming increasingly responsible for many other duties in production plants, reducing the time and resources available to spend on training and learning underlying technologies. Instrument networking allows production plants to train operators to analyze samples and perform basic diagnostic tests, while remote internal or supplier experts are able to configure, monitor, and troubleshoot instrumentation.

	Ametek now provides basic and Pro versions of TruVu software to integrate with the Spectro Scientific MiniLab on-site oil analysis system. The TruVu 360 Basic system for a single user can be installed on either a local computer or a company network server. It features multiple user licenses, which include site user, operator and reader privileges.

	Bio-Rad offers a new software package for identification of unknowns using Raman or IR spectra, combined with an appropriate corresponding spectral library.

	BSSN Software GmbH harmonizes data sets from biology and other measurement techniques, and brings raw data, results, and metadata to the user's fingertips.

	Eigenvector has upgraded both the PLS Toolbox and the Solo stand-alone software, to include new chemometric methods of analyzing the data.

	Tornado offers security, productivity, and industrial control modules, with each module integrating a single platform, and allowing fast and accurate results.

	Unity Scientific provides an advanced suite of digital tools designed for the secure configuration, monitoring, and data reporting of NIR analyzers over the internet.

	Wiley continues to expand its libraries of spectra collections.

Articles

FEATURE ARTICLES

Our annual review of products introduced at Pittcon or during the previous year

Review of New Spectroscopic Instrumentation 2019

In this third installment of our examination of the infrared spectra of organic nitrogen compounds, we finish our look at the amine family by discussing secondary and tertiary amines. As we see, secondary amines can be distinguished from primary amines based on their infrared spectra. IR can also be used to differentiate between saturated secondary and aromatic secondary amines. We discover that tertiary amines are hard to see using infrared spectroscopy. We examine why, and what to do about it.

	As noted in our last installment (1), the amine functional group consists of carbon, hydrogen, and nitrogen atoms, and contain C-H and C-N bonds. Amines are divided into three categories, called 

 amines, based on the number of alpha carbons attached to the amine nitrogen; their molecular structures are seen in Figure 1. Also note that, as the number of alpha carbons goes up, the number of N-H bonds goes down.


	Figure 1: The molecular structure of primary, secondary, and tertiary amines. Note the locations of the amine nitrogen and alpha carbon.

	Also in the last column (1), we introduced the amine family, and discussed the infrared spectroscopy of the primary amine group. Here we finish our discussion of amines by looking at the structures and infrared spectra of secondary and tertiary amines, and discuss infrared spectroscopy's ability to detect methyl groups attached to nitrogen.

	Structurally, what sets secondary amines apart from their amine brethren is that they contain one N-H bond, whereas primary amines contain two N-H bonds, and tertiary amines contain no N-H bonds. Also, recall that amines are described using two adjectives: the adjectives 

 describe the number of C-N bonds, and the adjectives 

 describe the nature of the carbon(s) attached to the nitrogen. But since secondary amines contain two alpha carbons, it can happen that a molecule can contain both a saturated and an aromatic carbon, as illustrated by the structure of N-methylaniline seen in Figure 2. Is this molecule a saturated or aromatic amine?


	Figure 2: The chemical structure of N-methylaniline, a secondary aromatic amine.

	The answer is that aromaticity wins. If any of the alpha carbons in an amine are aromatic, the amine is considered aromatic. Thus, N-methylaniline is a secondary aromatic amine.

	Recall from the last column (1) that organic nitrogen atoms form somewhat polar N-H bonds, and that these functional groups can form hydrogen bonds.

	The hydrogen bonding of amine groups to each other is seen in Figure 3. Because of electronegativity differences, the nitrogen carries a partial negative charge, and the hydrogen a partial positive charge, and they coordinate with each other as shown. Hydrogen bonding is a type of strong intermolecular interaction, and the spectral signature of this results in broadened spectral peaks (1,2).


	Figure 3: An illustration of the hydrogen bonding that takes place in amines.

	However, because N-H bonds are less polar than -O-H bonds, noting that nitrogen is less electronegative than oxygen, N-H stretching peaks are not as wide as -O-H stretching peaks. We saw this when I first introduced organic nitrogen compounds, and we then compared the peak widths in the spectra of ethanol and propylamine (3). The peak widths in the former are several times broader than in the latter. As previously noted (1–3), both O-H and N-H stretches fall around 3300 cm

, but we can distinguish them from each other based on peak width differences. One of the ongoing themes of this column series is to integrate peak position, height, and width information to identify functional groups, and distinguishing O-H and N-H stretches is an important example of using peak width information to accomplish this.

	One of the things we would like infrared spectroscopy to do is distinguish between primary, secondary, and tertiary amines. This turns out to be relatively easy. As we saw previously (1), primary amines have two N-H bonds, and therefore two N-H stretching peaks; secondary amines have one N-H bond, and hence one N-H stretching peak; and tertiary amines have no N-H bonds, and hence no N-H peaks. The N-H stretching peak of a secondary amine, N-methylcyclohexylamine, is seen in Figure 4, labeled A at 3284 cm

 (assume all peak positions going forward are in cm

). Again, note its intermediate peak width and heigfht compared to an O-H stretch, but that the peak is broader than the C-H stretches below 3000. Like primary amines (1), the secondary amine N-H stretch also discloses whether the amine is saturated or aromatic. For saturated secondary amines the N-H stretching peaks falls from 3320 to 3280 as seen in Figure 4, while for aromatic secondary amines it is found near 3400.


	Figure 4: The infrared spectrum of N-methylcyclohexylamine, a secondary amine.

	The only other useful group wavenumber for secondary amines is the N-H out-of-plane bend, more simply called the 

. Imagine the N-H bond bending above and below the plane of this page. It is labeled D in Figure 4 at 736. In general, this peak falls from 750 to 700. Note that this peak is considerably broader than its neighbors, again due to hydrogen bonding. Unlike the N-H stretch, the secondary amine N-H wagging peak position is not sensitive to whether the amine is saturated or aromatic.

	Primary amines also have a wagging vibration involving the NH

group whose peak falls from 850 to 750 (1), and is similar in size and width to peak D in Figure 4. Thus, in addition to the number of N-H stretching peaks, the position of the N-H wagging peaks of primary and secondary amines can also be used to distinguish them. For primary amines, the wagging peak falls from 850 to 750, whereas for secondary amines it falls from 750 to 700. Table I summarizes the group wavenumbers for secondary amines.

	The peak labeled C in Figure 4 is the C-N-C asymmetric stretching peak, and falls from 1180 to 1130 for saturated secondary amines, and from 1350 to 1250 for aromatic secondary amines. Note that this peak's position, in addition to the position of the N-H stretching peak, can be used to distinguish between secondary saturated and secondary aromatic amines. However, note that this peak is relatively weak, and falls in the busy fingerprint region of the spectrum. The reason that this peak is weaker than C-O stretches, which have intense peaks in this region, is because nitrogen is less electronegative than oxygen, and the dipole moment and hence dµ/dx values for C-N stretches are smaller than for C-O stretches. This means this peak is not always reliable, and is an example of a secondary group wavenumber peak that shouldn't be used for identification, but can be used for confirmation.

	Tertiary amines are molecules that contain three C-N bonds, and no N-H bonds. The structure of a tertiary amine, N,N-dimethylaniline, is seen in Figure 5.


	Figure 5: The chemical structure of N,N-dimethylaniline, a tertiary aromatic amine.

	The amine nitrogen here has two saturated and one aromatic carbon attached to it, but, consistent with what we said above, this compound is a secondary aromatic amine.

	I have stated previously that the best group wavenumbers for determining the presence of organic nitrogen atoms in a spectrum are the N-H stretching and bending bands (3). Because tertiary amines do not contain these bonds, these peaks are absent from their spectra. Tertiary amines do have C-N stretching peaks that fall from 1250 to 1020, but I am not going to show you any spectra of tertiary amines. That is because the C-N stretching peaks of tertiary amines are weak to medium in intensity, due to the lack of polarity of the C-N bond, and are found in one of the busiest regions of the spectrum. This makes this one peak not particularly useful as a group wavenumber, and it turns out that tertiary amines are one of those functional groups that are particularly difficult to detect via infrared spectroscopy. I have stated several times throughout my columns over the years that we will focus on functional groups that are readily detected by IR spectroscopy; therefore, no more will be said about tertiary amines.

	Then how can one detect tertiary amines in a sample? As always, other molecular spectroscopy techniques such as nuclear magnetic resonance (NMR), mass spectrometry (MS), and Raman spectroscopy can be used. However, by making a derivative of your tertiary amine sample, you can still use FT-IR to detect them. To do this mix 1 mL of liquid tertiary amine, or tertiary amine dissolved in an organic solvent, with 1 ml of 50:50 hydrochloric acid (HCl) in ethanol. If there is a tertiary amine present the amine salt will form and precipitate from solution. Collect the precipitate via filtration, dry, and measure its infrared spectrum. Unlike tertiary amines, tertiary amine salts have a bunch of unique and intense infrared features that makes them easy to identify. We will discuss the spectra of amine salts in the next installment of this column.

Methyl Groups Attached to Nitrogen, Oxygen, and Carbon

	You may be curious about what the N-methyl designation in N-methylaniline, and N-methylcyclohexylamine stands for, and what the N,N-dimethyl term signifies in the name of N,N-dimethylaniline. Examples of their structures are seen in Figures 2 and 5. N-methyl means there is one methyl or CH

 group attached to a nitrogen, while N,N-dimethyl means there are two methyl groups attached to a nitrogen. This designation is needed to make it clear that these methyl groups are attached to a nitrogen, rather than to one of the other types of atom present in a molecule.

	Methyl groups attached to nitrogen are relatively common, and fortunately for us there are some unique peaks to help identify them. If you look closely at the spectrum in Figure 4 of N-methylcyclohexylamine, there is peak labeled B at 2784. Note that this peak is sharp, of medium intensity, and falls just below where typical saturated C-H stretches fall. This peak is due to the symmetric stretching of the N-methyl group. For saturated amines, this peak typically falls from 2805 to 2780, whereas for aromatic amines it is found from 2820 to 2810. When the N,N-dimethyl group is part of a saturated amine, it exhibits two peaks, from 2825 to 2810 and 2775 to 2765. When the N,N-dimethyl group is part of an aromatic amine, it exhibits one peak in the range 2810 to 2790. This information is summarized in Table II.

	In previous columns, we have studied the symmetric stretch of a methyl group attached to an oxygen called a methoxy group (4), and the symmetric stretch of methyl groups attached to a carbon (5). Methoxy groups are similar to N-methyl groups in that they also have a sharp, medium intensity low wavenumber methyl symmetric stretch, which falls at 2830 ± 10. The C-CH

 group symmetric stretch falls at 2872 ± 10. This information is summarized in Table III. Note that the methyl symmetric stretches in Table III are sufficiently well separated, so that this peak position can be used to distinguish C-CH

, the symmetric methyl stretch gets lower in wavenumber, apparently due to a lowering of the force constants in the methyl group C-H bonds (6).

	Secondary amines contain one N-H bond and hence have one N-H stretching peak, as opposed to the two N-H stretching peaks for primary amines. Thus the number of N-H stretching peaks can help distinguish between primary and secondary amines. Secondary amines also have a N-H wag peak different from primary amines, so this peak position can also be used to distinguish these two amine types. Tertiary amines contain no N-H bonds, and hence have no useful infrared peaks. However, making an amine salt derivative and measuring its spectrum will allow infrared spectroscopy to be used to identify tertiary amines. A number of amines have one or two methyl groups attached to the nitrogen, denoted as the N-methyl or N,N-dimethyl groups. These compounds have a unique low wavenumber symmetric stretch that makes them easy to identify.

Infrared Spectral Interpretation: A Systematic Approach 

 is founder and CEO of Big Sur Scientific, a maker of portable mid-infrared cannabis analyzers. He has over 30 years experience as an industrial infrared spectroscopist, has published numerous peer reviewed papers, and has written three books on spectroscopy. As a trainer, he has helped thousands of people around the world improve their infrared analyses. In addition to writing for 

, Dr. Smith writes a regular column for its sister publication 

 and sits on its editorial board. He earned his PhD in physical chemistry from Dartmouth College. He can be reached at: 

IR Spectral Interpretation Workshop

A detailed guide to interpreting the infrared spectra of organic nitrogen compounds, including secondary and tertiary amines.

Organic Nitrogen Compounds III: Secondary and Tertiary Amines

There are well recognized difficulties in measuring nanoparticles (NPs) accurately by conventional single-quadrupole inductively coupled plasma–mass spectrometry (ICP-MS), because many natural and engineered NPs are based on elements that are challenging to measure at trace level by ICP-MS, such as iron, titanium, and silicon. This month's "Atomic Perspectives" column discusses how complex isobaric and polyatomic spectral interferences can be mitigated using triple-quadrupole ICP-MS (ICP-MS/MS) utilizing a collision-reaction cell (CRC), allowing for the multielement characterization and detection of smaller nanoparticle sizes.

	Metal-based engineered nanoparticles (NPs) are widely used in industrial and technological processes, medical applications, foods, and personal care products. NPs exhibit unique physical and chemical properties compared to bulk chemicals, because of the large surface area of particles with one or more external dimensions ranging in size from 1 to 100 nm. While scientists and specialty chemical suppliers are beginning to harness these novel properties to develop new applications, much remains unknown about the impact of NPs on biological and aquatic systems. Given the potential for NP release during production, use, or disposal, reliable measurement methods are required to assess the concentration of NPs in a range of samples.

	Single-particle inductively coupled plasma-mass spectrometry (SP–ICP-MS) is fast-becoming an accepted technique for the characterization of NPs in liquid samples (1). The technique provides valuable information on the mean size, size distribution, and number of nanoparticles in the sample, as well as the concentration of the element dissolved in the solution. A number of early studies used conventional single-quadrupole ICP-MS instruments to characterize simple, spherical nanoparticles composed of a single element, such as silver, gold, or zirconium (2,3). However, large quantities of NPs are manufactured from various oxides of iron, zinc, titanium, and silicon. Because these NPs are composed of elements that are much more difficult to measure at trace levels by conventional ICP-MS, and because of overlaps from polyatomic interferences, SP-ICP-MS methods have been developed using triple quadrupole ICP-MS (ICP-MS/MS) (4).

	In ICP-MS/MS, an additional mass filter (Q1) is located before the instrument's collision–reaction cell (CRC), enabling a double mass selection capability known as 

. Q1 controls the ions that can enter the cell, ensuring that the reaction processes in the cell are controlled and consistent. This extra selection step enables the more predictable and reliable removal of interferences on elements such as aluminum (Al), sulfur (S), and iron (Fe), using reactive cell gases, compared to conventional ICP-MS (5).

	When using reactive gases, ICP-MS/MS avoids isobaric and polyatomic interferences by utilizing either on-mass or mass-shift mode. In on-mass mode, the target isotope is measured at its original mass, and the interference or interferences are shifted to a different mass. In mass-shift mode, the target isotope is measured as a reaction product ion at a different mass, free from the interference. This is exemplified in Figure 1, which shows how ICP-MS/MS on-mass mode avoids polyatomic interferences from argon ion (ArO

56 via proton transfer with ammonia in the CRC. Figure 1 also demonstrates how ICP-MS/MS mass-shift mode for titanium (

Ti) avoids an isobaric interference from 

 48 to pass to the cell, while all other ions are rejected. 


	Figure 1: A schematic to show how (a) the on-mass mode, and (b) the mass-shift mode are used in triple quadrupole ICP-MS (ICP-MS/MS) CRC to remove interferences. 

Multiple Element Nanoparticle Characterization

	To date, most SP-ICP-MS applications have been used to determine samples with a known NP content, but many natural samples contain mixtures of NPs of unknown or variable composition. Also, some NP samples contain more than one metal. In this study, SP-ICP-MS has been further developed to determine multiple element NPs in samples containing a mix of NPs using ICP-MS/MS to provide high sensitivity while removing interferences that can be challenging to eliminate using single-quadrupole ICP-MS. The method has the potential to more fully characterize the NP content of products, chemicals, and environmental samples, as part of a routine monitoring program.

	With appropriate sample preparation and dilution, SP-ICP-MS enables NPs to be detected from the elemental signals generated from individual particles as they pass through the plasma. The signal generated by a single NP lasts for about 1 ms, so rapid data analysis software is needed to capture the transient signal. This is done using fast time resolved analysis (TRA) acquisition, which allows single element acquisition at a sampling rate of 100 µs (10,000 measurements per second). With the option of using no settling time between measurements of a particular element, the software can integrate multiple points across the ion plume for each single-particle event, providing sufficient points to define the nanoparticle peak shape (~5 to 10 points/peak). For the SP-ICP-MS analysis of multiple elements, additional rapid acquisition software has been developed that can collect data for up to 16 elements in a single sample, and also optimize the method parameters, thus simplifying the analysis.

	Using a rapid multielement NP analysis program, data are collected sequentially for multiple elements, using optimum conditions for the measurement of each individual element. The results for each NP are automatically collated into a single table of results, speeding up the analysis compared to measuring each element individually. Sampling in this manner also prevents agglomeration, or settling of the sample, so a more representative aliquot is analyzed for each analyte under the same analytical conditions. This is demonstrated in Figure 2, which shows a schematic representation of conventional (one element at a time, requiring sample uptake and rinse steps for each element) and rapid multielement NP acquisitions (requiring just one sample uptake and rinse time for all analytes).


	Figure 2: Example of (a) the conventional single element SP-ICP-MS method (top three batches) as compared to (b) a multi-element SP-ICP-MS method (bottom).

Reference Materials, Samples, and Sample Preparation

	Two platinum (Pt) reference materials from nanoComposix (San Diego, CA, US) were used to confirm the accuracy of the method. The reference materials contained 30 and 50 nm sized particles, and were diluted with deionized water (DIW) to a particle concentration that was calculated to give approximately 200–500 particle counts per min. The solutions were sonicated for ~3 min before analysis, to ensure sample homogeneity.

	A stainless steel nanopowder containing multiple nanoparticles was prepared for analysis by placing 41.6 mg of the nanopowder into 10 mL of 0.1% ethanol, and making up to 50 mL with DIW. The solution was sonicated, and then diluted an additional 10,000 times with DIW in a 50 mL vial and 50 µL of ethanol was added to aid suspension.

	A sample of moat water and bottled drinking water were sonicated as received for about 3 min. Two separate tap water samples were diluted 100x using DIW before sonication. Various natural waters were collected, including a river estuary sample, a sample collected upstream of a drain, water from a runoff drain, water downstream of the drain, and a seawater sample. These water samples were diluted 1000 times, using DIW before sonication. The reagents as 1% tetramethylammonium hydroxide (TMAH), 1% sulfuric acid (H

), 1% hydrochloric acid (HCl), 1% nitric acid (HNO

OH) were prepared using 0.5 mL of the reagent into 50 mL of DIW. Then, 50 µL of ethanol was added to all samples before analysis, to aid suspension of insoluble NPs in solution.

	An 8900 Triple Quadrupole ICP-MS instrument (Agilent Technologies) was used for the analysis of NPs in the reference materials, stainless steel nanopowder, environmental samples, and laboratory reagents. The instrument's ion lens system was configured for maximum sensitivity, together with a PFA microflow nebulizer. The samples were delivered via the SPS4 autosampler (Agilent Technologies) through a peristaltic pump. Hot plasma conditions were used initially to confirm the sample preparation method, and to assess the accuracy of the method for the determination of the Pt NP reference materials. Following a successful initial evaluation, the system was further optimized based on the evaluation of a gold (Au) NP reference materials from nanoComposix (San Diego, California). Warm plasma conditions were used as a compromise between high sensitivity and low background for the measurement of Cr, Al, Fe, Ni, Cu, and Au NPs. Instrument operating parameters are given in Table I.

	To convert the signals measured using SP-ICP-MS to the particle content of the original sample, it is necessary to calculate the nebulization efficiency, which is the ratio of the amount of analyte entering the plasma to the amount of analyte delivered to the nebulizer. Here, the nebulization efficiency was calculated by measuring a reference material of known particle size. A 60 nm Au NP reference material dispersed in 0.1% ethanol in deionized water and a 1.0 ppb ionic gold solution in (1% nitric acid in 0.5% hydrochloric acid) were measured. The single NP software automatically calculated the nebulization efficiency of 4.9% and 3.2% for the hot and warm plasma conditions, respectively. The time-resolved signal and size distribution graphs of Au NPs in 0.1% ethanol in deionized water are shown in Figure 3.


	Figure 3: Time-resolved signal and size distribution of (a) 60 nm, and (b) 30 nm gold nanoparticles (Au NPs) in 0.1% ethanol in deionized water solution.

	The 50 nm and 30 nm Pt NP reference materials were measured in duplicate, as shown in Figure 4. The respective measured mean size of 48.5 nm and 31 nm and median size of 48.5 nm and 31 nm agreed well with the certificate values of 46 + 5 nm and 30.6 + 3.1 nm obtained by transmission electron microscopy (TEM)-ultraviolet-visible (UV-vis), and dynamic light scattering (DLS).


	Figure 4: Size distribution results in duplicate of (a, b) 50 nm, and (c, d) 30 nm platinum nanoparticles (Pt NPs) as reference materials.

	The 60 and 30 nm Au NP reference materials were also measured in duplicate, as shown in Figure 5. The respective measured 60 nm and 27.5 nm for both the mean and median size agreed well with the certificate values of 60 + 6 nm and 31 + 3 nm obtained by TEM, UV-vis, and DLS.


	Figure 5: Size distribution results in duplicate of (a, b) 60 nm, and (c, d) 30 nm gold nanoparticles (Au NPs) as reference materials.

Analysis of Multiple Element NPs in Stainless Steel

	The multielement SP-ICP-MS method was used to analyze a stainless steel nanopowder, to demonstrate that the method could determine multiple NPs in a complex material. The time resolved signal and size distribution for Cr, Al, Fe, and Cu NPs are shown in Figure 6. The results in Table II show that good reproducibility was obtained for the mean and median particle sizes, although some elements showed size variability as the NP's were not all uniform in diameter.


	Figure 6: Time-resolved data (left) and particle size distribution (right) for chromium (Cr), aluminum (Al), iron (Fe), and copper (Cu)-containing nanoparticles (NPs) in a stainless steel nanopowder.

Application of the Method to the Analysis of Natural Waters and Chemicals

	Once a multiple element NP method has been established, it can easily be applied to the analysis of a wide range of samples. As a proof-of-concept, a series of environmental samples including a bottled drinking water, a sample taken from a large pool of water located outside of an office complex, and various river and seawaters, were analyzed using the method, together with six common laboratory reagents. The results given in Tables III and IV show that relatively high levels of Al and Fe-based NPs were present in the environmental samples, especially the moat, river, and sea waters. Relative to this group of samples, the concentration of Cr NPs was highest in the moat water and in tetramethylammonium hydroxide.

	Because Fe is a common component of the process equipment used in general manufacturing of chemicals and products, there is an increasing demand to measure Fe-based NPs. The concentration of Fe (and Cr) NPs in tetramethylammonium hydroxide and NH

OH was relatively high compared to the other reagents.

	The mean size of the particles ranged from as small as 10 nm up to 95 nm. However, for the analysis of the smallest-sized particles, ICP-MS instrumentation with very high sensitivity and low background is essential to support detection.

	The determination of multiple element nanoparticles by SP-ICP-MS is a relatively new application. This study has shown that a triple quadrupole ICP-MS with a double mass selection capability (MS/MS mode) has delivered the high sensitivity, low background, and interference control necessary for the characterization of Cr, Al, Fe, Ni, Cu, Pt, and Au nanoparticles.

	The study has also showed that environmental and industrial chemical samples containing nanoparticles composed of different or multiple elements can be determined quickly using SP-ICP-MS/MS. Compared to acquiring data separately for each NP, specially developed rapid acquisition software was used to simplify the analytical method and significantly shorten the sample run times.

	Given that regulations are likely to be introduced for nanoparticles across different industry-sectors, ICP-MS is expected to play a central role in the enforcement and development of any new guidelines. Multiple element SP-ICP-MS methods have the potential to more fully characterize the NP content of bulk chemicals, foods, consumer products, medicines, and environmental samples, as well as supporting research projects.

	(1) F. Laborda, E. Bolea, and J. Jiménez-Lamana, 

	(2) J. Tuoriniemi, G. Cornelis, and M. Hassellöv, 

	(3) C. Degueldre, P.-Y. Favarger, and C. Bitea, 

	(4) E. Bolea-Fernandez, D. Leite, A. Rua-Ibarz, L. Balcaen, M . Aramendía, M. Resano, and F. Vanhaecke, 

	(5) E. Bolea-Fernandez, L. Balcaen, M. Resano and F. Vanhaecke, 

 is an Application Scientist at Agilent, in Santa Clara, California. Craig has been with Agilent since 2004, and has been involved with multiple type of applications for ICP-MS, including environmental, pharmaceutical, nutraceutical, semiconductor, geologic, and clinical analyses, to name a few. Craig obtained a bachelor of science degree in chemistry from Fort Lewis College, in Durango, Colorado.

 is a Product Specialist at Agilent in Elm Mott, Texas, specializing in advanced ICP-MS and ICP-MS/MS techniques. He received his undergraduate and graduate degrees from Texas A&M University, in College Station, Texas. Prior to Agilent, Mark was a senior research scientist and research group manager with Southern Research Institute, in Birmingham, Alabama, where he focused on low-level analytical chemistry, method development, and research program management.

 is an ICP-MS Product Specialist at Agilent, in Seattle, Washington. He received his undergraduate degree from Cornell University. Prior to Agilent, he worked at Brookhaven National Labs studying acid rain in the Adirondack Mountains of northern New York, and then went on to work at a number of commercial analytical labs operating GC and GC/MS. Direct correspondence to: 

 column editor of "Atomic Perspectives," is the principal of Scientific Solutions, a consulting company that serves the application and writing needs of the trace element user community.

Atomic Perspectives

Complex isobaric and polyatomic spectral interferences can be mitigated using triple quadrupole ICP-MS (ICP-MS/MS) with a  collision–reaction cell (CRC). This configuration allows for the multielement characterization and detection of smaller nanoparticle sizes.

Rapid Multielement Nanoparticle Analysis Using Single-Particle ICP-MS/MS

Medicine counterfeiting is a public health threat that contributes to morbidity and mortality worldwide. In cardiovascular disease in particular, counterfeit medicines can lead to unpredicted adverse effects, especially among patients who take multiple medicines to treat multiple conditions. Therefore, a rapid approach for authenticating cardiovascular medicines would be ideal. This work used portable near-infrared (NIR) spectroscopy to authenticate eight different cardiovascular medicines. Thirty-five products of these medicines, purchased from eight different counties worldwide, were tested. NIR spectra were processed using spectral pretreatment combined with correlation in wavelength space (CWS) and principal component analysis (PCA). For the CWS method, an 

 value of 0.95 was considered to be the threshold. CWS provided a quick answer regarding the authenticity of the test products, showing that five products passed (

 values > 0.95) and three failed, possibly indicating that failed products were counterfeit or substandard. The latter results were confirmed by PCA, where clear clusters were distinct between the reference and test products of the three medicines that did not meet the CWA threshold. This study demonstrates that portable NIR spectroscopy potentially offers a quick and mobile method for authenticating cardiovascular medicines that is useful in critical situations.

	Medicine counterfeiting represents a global expanding problem that affects all countries worldwide. Counterfeit medicines are those that are deliberately or fraudulently mislabeled in relation to their identity or source (1,2). They may contain no active pharmaceutical ingredient (API), or insufficient amount of API, or the wrong API entirely. On the other hand, substandard medicines are those that fail to match the manufacturer's specification or quality standards. The public health impact resulting from counterfeit or substandard medicines can range from treatment ineffectiveness to lethality (3).

	Medicine counterfeiting is not exclusive to a specific class of medicines (4). However, the harmful effects within the class known as 

could be more pronounced, especially among patients with non-communicable diseases (NCDs). NCDs are defined by the World Health Organization (WHO) as long-term diseases that have no permanent cure, but can be controlled by modification of diet and lifestyle factors (5). NCDs include cardiovascular diseases (CVDs), diabetes, respiratory diseases, and cancer. CVDs are diseases associated with the heart or blood vessels, and contribute to morbidity and mortality worldwide (6). According to the WHO, CVDs contribute to 31% of global deaths. Patients with CVDs often have multiple morbidities, and thus take multiple medicines that could result in drug–drug interactions or drug–disease interactions (7).

	Subsequently, having the wrong API or the wrong dose in a cardiovascular medicine not only can interfere with treatment effectiveness, but also can cause adverse effects, drug–drug interactions, and drug–disease interactions. Cardiovascular (CV) medicines can be encountered anywhere across the supply chain, including in patients' homes, hospitals, and pharmacies. Therefore, a portable approach that carries the laboratory to the sample would be ideal (8,9), especially where a life-threatening situation is encountered. Portable near- infrared (NIR) spectroscopy offers the advantage of being mobile, rapid, and nondestructive, features that are ideal in medicine authentication (10,11). NIR spectroscopy has a further advantage over other techniques in detecting not only the chemical constituents of a sample, but also the physical properties that are important for spotting a counterfeit or substandard medicine, especially in cases of organized crime, where a medicine of the sample source may be distributed in different countries worldwide (12).

	Therefore, this work aimed to evaluate portable NIR spectroscopy for authenticating CV medicines obtained from different countries worldwide. Moreover, the work further assessed the potential of portable NIR spectroscopy for detecting differences in physical properties among authentic products of different manufacturers.

	A total of 35 individual products of eight different cardiovascular medicines were evaluated in this study (Table I). Reference products were purchased from the UK. Test products were purchased from nine different countries: Australia, Egypt, France, India, Lebanon, Saudi Arabia, Syria, Turkey, and the UK. The medicines were of four pharmacological classes, and of three types of cardiovascular medicines: antiarrhythmic, anticoagulant, and antihypertensive. The pharmacological classes of the medicines were angiotensin converting enzyme inhibitor (

 = 1). Angiotensin converting enzyme inhibitors used were captopril and enalapril. Receptor blockers were losartan, olmesartan, and valsartan. The two beta-blockers used were atenolol and propranolol. The P2Y

 platelet inhibitor used was clopidogrel. The concentration of the API in the measured medicines ranged from 8.4 to 48.4% m/m, where % m/m is percentage mass per mass.

	The aforementioned products were tablets, and were measured "as received" from both sides by rotating or flipping the tablet after each measurement using the PerkinElmer Spectrum Two N FT-NIR spectrometer with the Near-Infrared Reflectance Module (NIRM). Each spectrum was the sum of 32 scans over the range 10000–4000 cm

	NIR spectra were exported into Matlab 2014b, where spectral pretreatment and treatment were applied. Spectral pretreatment algorithms used were multiplicative scatter correction-first derivative (MSC-D1), and spectral treatment algorithms used were correlation in wavenumber space (CWS) and principal component analysis (PCA). For CWS method, the correlation coefficient (

) value of each test product was compared against the reference product. CWS method yields theoretical correlation values in the range of -1 to +1, where -1 indicated that the compared products were completely dissimilar, and +1 indicated they were identical. The threshold taken for authenticity was 

 value greater than 0.95. Note that PCA scores allowed visualization of clusters among reference and test products. Thus, the first two PCA scores of reference and test products were plotted, and clusters of the products were compared.

	The evaluated medicinal products were chosen on the basis of being used for critical cardiovascular conditions, including arrhythmia, hypertension, ischemic heart disease, and myocardial infarction. As patients with CVDs often have polypharmacy and suffer from multiple comorbidities, substandard or counterfeit medicines encountered will negatively affect the treatment outcome. It is also noteworthy to mention that the medicinal products had wide variations in color, shape, and percentage of API. The percentage of API in the aforementioned medicinal products was in the range 8.14–48.4% m/m. The number of excipients in the medicinal products ranged between 3 and 12 excipients. Yet, the most common excipients encountered were lactose, maize starch, and microcrystalline cellulose (MCC). Having the excipients alongside the API was key information for authenticating the medicinal products as part of the physicochemical fingerprinting of the products.

	NIR spectroscopy offered the advantage of inspecting the physicochemical properties of medicinal products nondestructively. Having a portable NIR device offered further benefits in mobility, so the instruments could be carried to the sample without the need for distinctive laboratory settings. Additionally, obtaining a spectral signature required a few seconds, up to minutes. The software allowed spectra to be exported to external software, where offline analysis could be applied.

Spectral Evaluation of Reference Products

	In this respect, the spectra of the reference medicinal products were compared against the spectra of the main excipients within each product (Figure 1). Often, spectra matched their main excipient, especially among products with the lowest percentage m/m of API. Therefore, propranolol has the lowest percentage of API (8.14% m/m) among the evaluated medicinal products, and gave higher values for lactose, hypromellose, and MCC that corresponded to 0.82, 0.76, and 0.72, respectively. However, none of the aforementioned values could be considered, because they were below the threshold of 0.95. High correlation values were also observed for additional products with low percentage m/m of APIs (< 20%). In this respect, captopril (API of 13.9% m/m) and olmesartan (API of 13.2% m/m) gave correlation (

) values of 0.71 and 0.70 for lactose, and 0.79 and 0.88 for MCC, respectively. As the percentage m/m of API in a product increased, the correlation (

) values against the excipients decreased, but high correlation (

) values were still observed for some of the excipients. Hence, losartan, clopidogrel, and atenolol had percentage m/m of APIs of 22.1, 24.1, and 29.8% m/m, respectively. Losartan gave correlation (

) values of 0.79, 0.74, and 0.84 against hypromellose, lactose monohydrate, and MCC. Clopidogrel that had higher percentage m/m of API showed lower correlation (

) values for the aforementioned three excipients that were 0.71, 0.66, and 0.77, respectively. Atenolol had very low correlation (

) values against all excipients that were below 0.51. Likewise, valsartan had 48.4% of API, and gave correlation (


	Figure 1: Multiplicative scatter correction-first derivative (MSC-D1) treated NIR spectra of (a) lactose, (b) maize starch, (c) microcrystalline cellulose, (d) talc, (e) atenolol, (f) propranolol, (g) clopidogrel, (h) captopril, (i) enalapril, (j) losartan, (k) olmesartan and (l) valsartan measured using an FT-NIR spectrometer with near-infrared reflectance module (NIRM).

	Because the reference medicinal products had common excipients, CWS was applied to observe any type I or type II errors that could be encountered in identification of the aforementioned medicines. A type I error occurs when a product is misidentified as itself (giving a correlation [

Portable NIR spectroscopy is demonstrated as a rapid and mobile analysis method for authenticating cardiovascular medicines in critical situations, and to indicate whether formulations are counterfeit or substandard.

Spectroscopy-05-01-2019

Review of New Spectroscopic Instrumentation 2019

Organic Nitrogen Compounds III: Secondary and Tertiary Amines

Rapid Multielement Nanoparticle Analysis Using Single-Particle ICP-MS/MS

The Use of Portable Near-Infrared Spectroscopy for Authenticating Cardiovascular Medicines

Vol 34 No 5 Spectroscopy May 2019 Regular Issue PDF