The Surface-Specificity of IRRAS in Studying Soluble Organic Acids

A Joint LCGC & Spectroscopy Content Series

Advancing Agriculture For Future Generations

An Interview with Felipe Bachion de Santana

Monitoring Soil Quality Using MIR and NIR Spectral Models 

Polymer Characterization of Plastic Litter Using ATR-FT-IR Spectroscopy

Aaron Acevedo is an assistant editor for LCGC and Spectroscopy at MJH Life Sciences.

Scientists from Xi’an Jiaotong University in Xi’an, China measured the effects of ablation craters on geomaterials occurring as a side effect of laser-induced breakdown spectroscopy (LIBS). Their work was published in 

Spectrochimica Acta Part B: Atomic Spectroscopy

Texture made by rectangular rock tiles pavement | Image Credit: © maciejmatteo - stock.adobe.com

LIBS signal stability is vital when making measurements on geomaterials. However, using LIBS can be complicated by spectral fluctuations caused by variable ablation craters. To investigate the influence of ablation craters caused by LIBS laser shot accumulation, the scientists analyzed the shot-to-shot variation of plasma. Specifically, they measured aspects of shock wave propagation, ablation crater morphology, plasma morphology, and spectral evolution. All these analyses were conducted based on a fiber-optical LIBS (FO-LIBS) system.

An offshoot of LIBS, FO-LIBS has grown in popularity as well, being used in extreme environments like underwater areas and nuclear power plants. According to the scientists, using FO-LIBS “provides an optional and reliable solution for special detection situations that require separating the analysts and equipment from the probe site” (1). For this experiment, a plasma diagnostic system based on a FO-LIBS setup was established with the goal of investigating the characteristics of plasma evolution and optical emission spectra after continuous laser shots. Under various conditions, the propagation of the laser shock was compared and analyzed using the laser shadowgraph method. Afterwards, a pressure sensor monitored the shock wave waveform evolution, helping to establish the relationship between the shock wave signals and ablation crater morphology. Plasma images were created to visualize plasma morphology, and the final step of the experiment involved using optical emission spectroscopy (OES) to study the influence of the ablation craters.

What the scientists first noticed was that in most cases, spectral intensity first increases rapidly and gradually decreases. They attributed this to the conflict between the enhancement of spatial confinement and the plasma cooling phase. Additionally, they noticed strong self-reversal due to laser pulse accumulation, increasing plasma expanding distance. These factors strengthened the scientists’ belief in their system, with their abstract concluding, “This study illustrates the interaction of laser pulses, ablation, and plasma from different aspects, and provides a simple method to track the ablation process” (1).

(1) Shi, M.; Wu, J.; Wu, D.; Guo, X.; Qiu, Y.; Zhou, Y.; Li, J.; Sun, H.; Li, X.; Qiu, A. The Effect of Ablation Crater on Geomaterials Caused by Laser Shot Accumulation on the Laser-Induced Plasma and Shock Wave. 

https://doi.org/10.1016/j.sab.2023.106797

Articles

Scientists from Xi’an Jiaotong University in Xi’an, China measured the effects of ablation craters on geomaterials that occur as a side effect of laser-induced breakdown spectroscopy (LIBS).

LIBS Side Effects on Geomaterials Studied

In a leading-edge achievement, researchers from Thorlabs Crystalline Solutions in Santa Barbara, the Faculty of Physics at the University of Vienna, and the National Institute of Standards and Technology in Gaithersburg have unveiled mid-infrared (MIR) supermirrors with finesse exceeding 400,000. The results of their study, titled "Mid-infrared supermirrors with finesse exceeding 400,000," have been published in the journal 

A mid-infrared mirror with finesse exceeding 400,000 signifies a significant advancement in precision and sensitivity for infrared spectroscopy and trace gas sensing. This high finesse indicates the mirror's ability to minimize optical losses, enhancing signal-to-noise ratios and ensuring accurate detection of faint infrared signals. The breakthrough holds significant implications for improving instrumentation and detection in a variety of scientific and industrial applications.

For years, optical cavities incorporating low-loss mirrors have been crucial for trace gas sensing and precision spectroscopy. While advancements in visible and near-infrared (NIR) spectral regions have achieved finesse values surpassing 1 million, similar progress in the mid-infrared has been lacking. However, the recent research presents a significant breakthrough, demonstrating high-performance MIR mirrors with substrate-transferred single-crystal interference coatings.

The study, authored by Gar-Wing Truong, Lukas W. Perner, D. Michelle Bailey, and their colleagues, showcases these MIR mirrors capable of achieving cavity finesse values from 200,000 to an unprecedented 400,000 near the 4.5 µm spectral region, with optical losses below 5 parts per million (ppm).

In a first-of-its-kind proof-of-concept demonstration, the team achieved the lowest noise-equivalent absorption in a linear cavity ring-down spectrometer, normalized by cavity length. This breakthrough is poised to unlock a multitude of MIR applications, ranging from atmospheric transport and environmental sciences to the detection of fugitive emissions, process gas monitoring, breath-gas analysis, and the verification of biogenic fuels and plastics.

The researchers utilized two coating methods to realize these ultrahigh-finesse MIR mirrors. The first method extended the recently-reported "all-crystalline" architecture, producing a transmission-loss-dominated cavity finesse of 231,000 at 4.5 µm. The second "hybrid" approach yielded even higher finesse, exceeding 400,000. This new paradigm combines two different coating processes—an amorphous sub-stack deposition followed by bonding a crystalline multilayer on top.

These revolutionary MIR mirrors, with their simultaneous achievement of the highest finesse and lowest excess losses in this spectral region, hold promise for advancing sensing technologies.

The finesse and cavity transmission improvements enabled by these mirrors are expected to result in record-low levels of noise-equivalent absorption, as demonstrated by the successful trace gas detection in ultra-high purity nitrogen.

The researchers anticipate that this breakthrough will have far-reaching implications, opening avenues for unprecedented sensitivity and accuracy in a variety of scientific and industrial applications, ultimately pushing the boundaries of what is achievable in mid-infrared sensing technologies.

This article was written with the help of artificial intelligence and has been edited to ensure accuracy and clarity. You can read more about our

(1) Truong, G. W.; Perner, L.W.; Bailey, D. M. et al. Mid-infrared supermirrors with finesse exceeding 400,000. 

https://doi.org/10.1038/s41467-023-43367-z

Researchers from Thorlabs Crystalline Solutions, the University of Vienna, and the National Institute of Standards and Technology have achieved a revolutionary breakthrough, publishing in Nature Communications, with mid-infrared supermirrors exhibiting finesse exceeding 400,000, promising unprecedented sensitivity for applications in trace gas sensing and precision spectroscopy.

Revolutionary Mid-Infrared Supermirrors Pave the Way for Breakthrough Sensing Technologies

, researchers Sicen Dong, Yuping Liu, Hanxiang Yu, Yuqing Wang, and Junchi Wu, from the College of Physics and Optoelectonic Engineering at the Harbin Engineering University in Harbin, China, introduce an innovative approach to baseline correction for Raman spectra. Their paper, titled "An Iterative Curve-Fitting Baseline Correction Method for Raman Spectra Driven by Neural Network," presents a novel method that employs a neural network model to enhance the accuracy of baseline correction.

Baseline correction is a crucial step in spectral preprocessing, particularly for Raman spectra. While iterative polynomial fitting has been a common method, it is deemed less accurate compared to alternative techniques like wavelet transform and penalized least squares (PLS) methods. The drawbacks include potential distortions in results under certain conditions.

The proposed neural network model takes a distinctive approach by dynamically selecting the function basis based on the baseline trend, deviating from the conventional fixed polynomial functions. This results in a more precise fit, especially in cases where the baseline exhibits unusual shapes. The researchers also introduce a method for generating simulation data, crucial for training the neural network model, which subsequently produces reliable results for real spectral data, even in the presence of noise.

The iterative process involves taking a raw spectrum and deriving a neural network model that suggests a fitting vector, providing guidance for correcting the spectrum in each iteration. Once the neural network iterations are complete, the corrected spectrum is generated, showcasing the method's efficacy in improving baseline correction accuracy.

To further validate their approach, the researchers detail how the data and code file can be used to test their method. The entire data-generation process is executed in Rstudio, demonstrating that the method can generate various baselines with different trends. The intensity of the simulation data, ranging from 0 to 1, is crucial for model training. The researchers opted not to upload the entire dataset due to its size, but the model-training process in Python, utilizing the Pytorch package, is thoroughly explained.

In addition to revolutionizing Raman spectra analysis, the study critically evaluates the limitations of conventional iterative polynomial fitting and adaptive iteratively reweighted PLS methods, elucidating why the proposed neural network-driven approach outperforms these methods.

This truly novel research approach marks a significant advancement in the field of spectroscopy, offering a new paradigm for baseline correction in Raman spectra analysis. The implications of this study extend to various scientific disciplines relying on precise spectral data analysis.

(1) Dong, S.; Liu, Y.; Yu, H.; Wang, Y.; Wu, J. An Iterative Curve-Fitting Baseline Correction Method for Raman Spectra Driven by Neural Network. 

A truly innovative approach to Raman spectral analysis is introduced in a newly published Applied Spectroscopy paper, utilizing a dynamic neural network modeling to significantly enhance baseline correction accuracy and offering a paradigm shift in spectral preprocessing.

Revolutionizing Raman Spectra Analysis: A Breakthrough Iterative Curve-Fitting Baseline Correction Method 

Using single cell inductively coupled plasma mass spectrometry (SC-ICP-MS), scientists form Kanazawa, Japan created a new method for detecting cadmium in marine phytoplankton. Their work was published in 

Spectrochimica Acta Part B: Atomic Spectroscopy 

Diatoms, algae under microscopic view, phytoplankton, fossils, silica, golden yellow algae | Image Credit: © elif - stock.adobe.com

Recent studies have reported an uptake in heavy metals by phytoplankton and their cells. Acid digestion for sample preparation is the most common method for detecting intracellular metals, though data from this method has certain limitations. Namely, these experiments only measure the intracellular cadmium (Cd) content of culture populations, meaning that only the average metal content in all cells can be obtained. Cell changes and their average values do not represent the intracellular value of each individual cell.

To address this, a new detection method, single cell inductively coupled plasma mass spectrometry (SC-ICP-MS) was developed. According to the scientists, this method has high sensitivity, allowing for the analysis of extremely trace elements. SC-ICP-MS has been used to analyze various types of single-cell systems, including bacteria, yeast, and cancer cells. By directly analyzing cell suspension fed by pumps, a single cell can be analyzed internally with short residence time, thus avoiding simultaneous detection of multiple cells.

For this study, the scientists used SC-ICP-MS to analyze cadmium content in marine phytoplankton cells. This was previously impossible due to high concentrations of interfering elements (Na+, K+) in seawater. For this system, the team removed the supernatant through centrifugal separation, replacing the culture media of three species, 

 with non-metallic salt solutions, namely (NH4)2SO4 and NH4Cl. Cell images were also studied at different concentrations of replacement solutions, to check for ruptured cells stemming from changes in osmotic pressure.

It was observed that a good number of cells ruptured at low concentrations of the non-metallic salt solutions, but they did maintain integrity between 0.6 and 0.8 M solutions. These surviving cells were successfully determined using SC-ICP-MS, and they showed increased presences of high cadmium-containing cells when the phytoplankton were in high-cadmium-concentration mediums. Based on their findings, the scientists concluded that (NH4)2SO4 and NH4Cl can be suitable replacement solutions for the determination of marine phytoplankton using SC-ICP-MS. With that said, it is believed that different species of marine phytoplankton could have different levels of compatibility with these solutions, implying that more research into this phenomenon should be done.

(1) Zai, Y.; Wong, K. H.; Fujizawa, S.; Ishikawa, A.; Li, M.; Mashio, A. S.; Hasegawa, H. Development of a New Detection Method for Cadmium in Marine Phytoplankton Based on Single Cell Inductively Coupled Plasma Mass Spectrometry. 

https://doi.org/10.1016/j.sab.2023.106801

Using single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS), scientists from Kanazawa, Japan created a new method for detecting cadmium in marine phytoplankton.

Detecting Cadmium in Marine Phytoplankton Using Single-Cell Inductively Coupled Plasma Mass Spectrometry

Recently, Yoshinori Nishiwaki and others examined a novel method that can distinguish polyester fibers in forensic investigations. Their findings, published in 

, show how the researchers employed advanced X-ray analysis techniques that helped reveal the composition of polyester fibers.

In particular, their study is significant because distinguishing individual fibers is essential in forensic analysis. As a result, many conventional methods often do not accomplish the needed objective of the analyst. The researchers sought to find a new method that could aid in forensic analysis, introducing a comprehensive approach that used several X-ray techniques, including semi-microbeam X-ray fluorescence (XRF) spot analysis, nanobeam XRF imaging, and X-ray absorption fine structure analysis (XAFS) using synchrotron radiation (1).

The study focused on uncovering metal compounds within polyester fibers, originating from polymerization and transesterification catalysts alongside matting agents (1). The team analyzed specimens from both commercial polyester products and forensic collections. They encountered success with using semi-microbeam XRF spot analysis, as this technique was able to detect trace metallic elements, such as titanium, manganese, cobalt, germanium, and antimony (1). Surprisingly, certain X-ray intensity ratios exhibited lower reproducibility, particularly those linked to cobalt (1).

The investigation also used nanobeam XRF imaging to visualize the uneven distribution of metallic elements within polyester fibers. These visual markers demonstrated elemental heterogeneity, unraveling the root cause behind the inconsistent X-ray intensity ratios observed in the spot analysis (1).

However, the real breakthrough emerged from XAFS analysis, pinpointing three distinct types of titanium compounds and two varieties of cobalt compounds utilized in various polyester applications. Notably, these chemical states served as crucial indices for discriminating single polyester fibers (1).

Semi-microbeam XRF spot analysis unveiled trace elements, nanobeam imaging revealed distribution patterns, and XAFS pinpointed specific compounds, collectively enhancing the ability for analysts to discern polyester fibers. Nishiwaki and others demonstrated that by using X-ray analysis, discovering the composition of synthetic materials such as polyester, can be realized. This study, therefore, advances forensic analysis, because it offers forensic analysts a new, effective strategy to employ while conducting forensic investigations.

(1) Komatsu, H.; Nakanishi, T.; Seto, Y.; Nishiwaki, Y. Characterization of Metal Components in White-Based Polyester Single Fibers by X-Ray Fluorescence Spectrometry and X-Ray Absorption Fine Structure Analysis Utilizing Synchrotron Radiation for Forensic Discrimination. 

Researchers at Kochi University and RIKEN have unveiled a new method for distinguishing individual polyester fibers in forensic investigations. Published in Spectrochimica Acta Part B: Atomic Spectroscopy, their advanced X-ray analysis refreshes how we unravel the composition of these fibers. 

Unraveling Polyester Fibers with Advanced X-Ray Techniques

Recently, Shintaro Ichikawa of Fukuoka University and his team investigated the chemical states and elemental composition within a printed-circuit board (PCB) powder. Their findings were published in 

, revealing new insights into metal recovery processes from electronic waste (1).

Ichikawa and his research team obtained the powdered sample of the PCB through cryo-milling, which is the process of using liquid nitrogen to lower the temperature of the sample prior to grinding into aa fine powder (1). Then, they analyzed its elemental composition using advanced techniques such as X-ray fluorescence (XRF) and X-ray diffraction (XRD). Using XRF and XRD analysis, the research team examined the various particle fractions, uncovering various elements distributed in the powder, including aluminum (Al), silicon (Si), calcium (Ca), iron (Fe), nickel (Ni), copper (Cu), tin (Sn), barium (Ba), and lead (Pb) (1).

The particle-size distribution revealed distinct fractions, with sizes ranging from 27 to 500 μm. These fractions exhibited specific elemental concentrations, categorizing the components into coarse, moderately sized, and fine-particle fractions, each containing various elements based on their tendencies for accumulation (1).

The researchers discovered through analysis of the particles that the metallic components like aluminum and nickel showcased durability owing to their high ductility, whereas ceramic materials such as calcium carbonate (CaCO

) concentrated in the fine-particle fraction because of their fragile nature.

The research team also used multivariate statistical analyses to learn more about the amorphous components in the powder. They discovered that they were comprised of silicon, calcium, bromine, and tin (1). This distinction in components' chemical states unveiled varying durability properties among the PCB constituents.

The detailed diffraction patterns unveiled the chemical forms in which elements existed within the PCB powder, such as metallic aluminum and Al

, metallic nickel, metallic copper, BaTiO

Understanding the elemental composition and durability properties of PCB components can lead to the creation and implementation of improved recycling techniques for electronic waste. By deciphering the distinct properties of these components based on their chemical states, this research provides a roadmap for targeted recovery processes, ultimately contributing to sustainable electronic waste management.

To conclude, the researchers characterized the ground PCB powder using XRF and XRD. Their study contributes to our understanding of the makeup of PCB powder. The findings in this study can help lead to improving current environmentally conscious practices in electronic waste recycling. As a result, Ichikawa and his team helped contribute to the pursuit of establishing more green, sustainable practices.

(1) Ichikawa, S.; Hirokawa, Y.; Kurisaki, T.; Nakamura, T. Characterization of a printed-circuit board by X-ray fluorescence and X-ray diffraction analyses for metal recovery. 

Spectrochimica Acta Part B: At. Spectrosc. 

Researchers at Fukuoka University unveil intricate elemental composition and durability properties within PCB powder, revolutionizing electronic waste recycling.

Novel Approach Unveils Elemental Composition and Properties of Recycled Printed-Circuit Board (PCB) Powder

The formation of spherulites in polymers is a well-known phenomenon; when the polymer is crystallized by cooling from the melt, crystal lamellae grow out from a nucleation site in a spherical pattern. If the material is annealed on a planar surface, and viewed between crossed polarizers in a microscope, a Maltese cross with a banding pattern is observed. Where the crystals grow in a direction not parallel to the polarizers, the sample lights up. Often banding of the lit regions is observed, and is believed to be due to rotations of the crystal lamellae around the growth direction. Because it is well known that polarized Raman spectra respond to crystal orientation, we thought it would be interesting to try to document the relationship between the banding behavior and Raman polarization/orientation behavior. In this column I will show results of such an investigation of spherulites of poly(hydroxybutyate-co-hydroxyhexanoate) (PHBHx) with varying composition.

 is the Principal Raman Applications Scientist for Horiba Scientific in Edison, New Jersey.

Those of you who follow my column know that PHBHx has been my “favorite” polymer over the last few years, as PET (polyethylene terephthalate) was for many years previously. PHBHx was developed over the last decade or so by Professor Isao Noda who had been working at Procter & Gamble. The polymer is now being produced commercially by Danimer Scientific, Inc. under the trademarked name Nodax. Nodax is produced by fermentation and is degraded by micro-organisms, so there are great hopes that it can be manufactured to replace petroleum-derived polymers that have extremely long lifetimes in the environment. However, like all polymers, its properties must be controlled to make it useful. In the case of polymers, that means to control, among other things, the crystallinity, which, when high, makes the polymer brittle and opaque. Propyl groups of the hydroxyhexanoate comonomer unit (Hx) are added as side-chains to disrupt the crystallinity. My studies are designed to follow crystallization conditions in order to understand how to engineer the properties of the material.

Small amounts of polymer with 0, 3.9, and 13% Hx were dissolved in chloroform and then placed on stainless steel slides. After the chloroform dried, the film was melted on a hot plate and then deposited in an oven at about 70 °C for 24 h to anneal. The films were examined first at 10x and then higher magnification using crossed polarizers in reflected light. For each sample, a spherulite of diameter at least 25 µm was identified and used for study. Figure 1 shows the Maltese cross images of the three spherulites used in this report. In this column we will show vertical (

) line profiles through the center of the spherulite using two possible polarization conditions: VV and HV. Over the summer we also collected full maps of some spherulites to document that the Raman spectra do reflect the crystallite orientation in the spherulite. Figure 2 shows the VV and HH polarized Raman maps for the 0% material for the carbonyl band and the two anomalous bands of the methyl group that appear at unusually high frequency, presumably due to interactions with the carbonyl on the opposite chain in the unit cell (1).

FIGURE 1: Crossed polarizer images of spherulites of PHBHx used for the Raman polarization measurements along a vertical line profile through the middle of the spherulite. From left to right the hydroxyhexanoate composition was (a) 0, (b) 3.9, and (c) 13 %. 

-axes labels are spatial coordinates in μm.

FIGURE 2: Raman maps of a pure PHB spherulite (0% Hx) imaged at the (middle, blue) carbonyl line and the (top, red) two high frequency methyl CH lines that (bottom, green) have been associated with an interaction with the carbonyl oxygen atom. X- and Y-axes labels are spatial coordinates in μm.

Figures 3 and 4 show the results of calculation of 2 MCR factors for the VV and HV line profiles of the 3 samples. Before calculation the spectra were corrected for the instrument response for V and H polarization analysis which is due mostly to the grating’s reflectivities. It is of interest to see if any of the profiles indicate systematic changes consistent with the banding seen in the crossed polar images.

FIGURE 3: The results of a vertical profile using both laser and Raman polarizers along the vertical direction. From top to bottom (a) 0, (b) 3.9%, and (c) 13% Hx in the PHB. Two MCR factors were calculated on each profile and the scores for those factors were plotted as a function of the position on the vertical axis. That plot is shown in the upper left. The large plots show the two factors for each data set, with the darker factor representing the more crystalline material.

FIGURE 4: The results of a vertical profile using the horizontal laser polarization and vertical Raman polarization. From top to bottom (a) 0, (b) 3.9%, and (c) 13% Hx in the PHB. Two MCR factors were calculated for each profile and the scores for those factors were plotted as a function of the position on the vertical axis. That plot is shown in the upper left. The large plots show the two factors for each data set, with the darker factor representing the more crystalline material.

In the future, we will be subjecting these line profiles to two-dimensional correlation spectroscopy (2D-COS) analysis.

The origin of the fringes and rings seen on the crossed polar micrographs is not well understood (2,3). It is believed that as the crystalline lamellae grow along the radial direction, they twist around the 

 axis, which is the direction of fastest growth of the crystals (4). Therefore, in a vertical line scan through the center of the spherulite, the vertical axis will be parallel to 

. This implies that there are testable conditions for the polarized Raman scattering. The normal to the lamellae are parallel to the molecular axis of the polymer which is the 

 axis, will lie in the plane of the lamellae. If the lamellae twist around a direction parallel to 

, depending on the angle of twist. Thus, the VV Raman scattering is predicted to be the 

 component. The HV scattering will vary between the 

 Raman tensor components. The question is whether the HV scattering has similar periodicity to the banding in the polarized micrographs. The banding is clearest in the 13% sample, with a periodicity of 5–8 µm. The banding that is seen in the HV Raman profiles varies between 2 and 8 µm, with the narrowest bands close to the center in the 3.9% sample. The micrograph for the 13% sample in Figure 1 does show banding on the order of 5 µm, except in the center where the image is less clear. In addition, if the carbonyl band is expanded, it is clear that there are more than two components. In addition to the sharp crystal band at 1725 cm

, a second “crystal” band appears near 1732 cm

. This band has been previously identified by Professor Noda and his co-workers (5) as representative of secondary crystallization between the primary lamellae.

Why is the banding in the micrographs of the 0 and 3.9% samples less regular? It is well known that the lower the concentration of the Hx, the higher concentration of crystallinity. Perhaps that means that the lamellae are twisting so rapidly along the radius that the optical focus is not adequate to resolve the changes in polarization/orientation. But the line profiles for the HV spectra do show ripples for all concentrations.

What about the VV profiles? In all cases there is no evidence for banding, but the scores plots of the MCR factors show dips for the crystalline component in the center with complementary maxima in the amorphous component in the center. This is exactly what would be predicted at the center where the crystal phase is initiated by a seed.

My question was “What is the source of the force that would be causing the lamellae to rotate?” A careful reading of reference 1 shows that many possible effects have been considered. If I had to guess, I would say that unequal thickness of the lamellae on the two sides would be a good start. In fact, we will be doing atomic force microscopy (AFM) measurements to determine if this is the case.

This column shows the start to an investigation of using polarized Raman microscopy to complement polarized light micrographs of spherulites in polymers. Our data show self-consistent behavior which means that the polarized Raman can be used to clarify the orientation behavior of the lamellae in the spherulites. In the future we will have AFM measurements that may help to identify which possible mechanism for spherulite twisting is operable in this system. We will also be using 2D-COS with these data sets to determine if the radial development of the lamellae can add anything to our understanding of the crystallization phenomenon. If you are interested, you will be able to find more information in our write-up of this work for the proceedings of the 2DCOS-XII meeting which will be published in the journal 

(1) Sato, H.; Murakami, R.; Padermshok, A.; Hirose, F.; Senda, K.; Noda, I.; Ozaki, Y. Infrared Spectroscopy Studies of CH···O Hydrogen Bondings and Thermal Behavior of Biodegradable Poly(hydroxyalkanoate). 

(2) Lotz, B.; Cheng, S. Z. D. A Critical Assessment of Unbalanced Surface Stresses as the Mechanical Origin of Twisting and Scrolling of Polymer Crystals. 

(3) Woo, E. M.; Lugito, G.; Nagarajan, S. Dendritic Polymer Spherulites: Birefringence Correlation with Lamellae Assembly and Origins of Superimposed Ring Bands. 

(4) Liu, C.; Noda, I.; Martin, D. C.; Chase, D. B.; Ni., C.; Rabolt, J. F. Growth of anisotropic single crystals of a random copolymer, poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] driven by cooperative –CH···O H-bonding. 

, 111–118. DOI: 10.1016/j.polymer.2018.08.046

(5) Noda, I.; Roy, A.; Carriere, J.; Sobieski, B. J.; Chase, D. B.; Rabolt, J. F. Two-Dimensional Raman Correlation Spectroscopy Study of Poly[(R)-3-hydroxybutyrate-

 is the Principal Raman Applications Scientist for Horiba Scientific in Edison, New Jersey. Direct correspondence to: 

The use of polarized Raman microscopy to complement the polarized light micrographs of spherulites in polymers reveals much about the orientation behavior of the lamellae in spherulites.

Raman Spectra Used to Understand the Origins of Banding in Spherulites

Computerized System Validation (CSV) is usually associated with great mountains of paper (GMP). Why should this be the case? Ask yourself, am I lazy? Why write multiple documents if only one is required to validate a spectrometer with a simple intended use? Interested? Read on…

R.C. McDowall is the principle of McDowall Consulting and director of R.D. McDowall Limited, and "Questions of Quality" column editor for LCGC Europe, Spectroscopy's sister magazine.

Today’s the day you have been waiting for! Your brand-new UV-visible (UV-vis) or infrared (IR) spectrometer and controlling software is due to arrive in your regulated laboratory. The instrument’s location and services are ready. The supplier’s engineer is on hand to install and qualify the instrument against your user requirements. You’ve reviewed and approved the supplier’s qualification protocol and reports for installation qualification (IQ) and operational qualification (OQ). All goes smoothly and you are ready to 

 your new toy, when you hear the thud of heavy footsteps behind you. The Compliance Police have arrived to ruin your day!

The Compliance Police (Quality Assurance [QA] ± CSV) have descended and you are about to undergo the third degree questioning:

Where is the instrument user requirement specification?

Have you approved the qualification against the user requirements?

How did you evaluate the supplier quality system/approach to change control?

Where is the software user requirements specification?

Where is the requirements risk assessment?

What user roles have been defined and implemented?

Has QA signed off the supplier qualification documents before execution?

You can’t use the system until all these documents have been generated and approved. What?! All this documentation for a simple spectrometer that is just going to read absorption at specified wavelengths or verify the identity of a substance by comparison with a reference standard? Consider yourself lucky. You could have been asked to write a functional specification as well!

A risk-averse CSV approach can result in writing all these documents, especially if there is a one-size-fits-all procedure that is applied regardless of the intended use of the instrument and software. This is what gets CSV a bad name–inflexible organizations who just want to play it safe.

The needs associated with the software and instrument hardware need to be addressed, and for simple intended use, this can be achieved in an integrated validation document.

To understand the approach, let’s start with regulations. We need to apply a 21 

 211.160(b) scientifically sound (1), flexible, common sense and logical approach to CSV. The key to doing this is understanding the 5 P’s:

 Inputs are the regulations, regulatory guidance, and applicable pharmacopoeial general chapters that result in SOPs and analytical procedures for performing work. Flexible procedures that allow an integrated approach to Analytical Instrument Qualification (AIQ) and Computerized System Validation (CSV) are mandatory. Defining the intended use of the instrument or system (1,2) is the key to determining the required documents for qualification, validation, or both.

Know and understand the process to be automated. Streamline and simplify the process, implement electronic signatures and eliminate dross such as paper and spreadsheets (3–5). This allows the laboratory to define the user requirements and configuration settings to ensure data integrity. Unfortunately, process redesign is not mentioned in the draft FDA Computer Software Assurance (CSA) guidance (6).

The system consists of the instrument and the software that controls it. We must select the right system to digitalize a process with appropriate technical controls for data integrity. There is always an interaction between the product and the process to fine-tune configuration settings. Purchasing the right system that can digitalize a process and ensure data integrity must take precedence over purchasing on price. When application software is involved, it is critical that the supplier’s software development is assessed to see if it can be leveraged into the laboratory validation to reduce the effort required.

 A multi-disciplinary team approach is required between key users, laboratory managers (Data Owner/Process Owner), QA, CSV and IT (System Owner), in addition to the supplier. The team must be trained, flexible, and manage risk effectively to qualify the instrument and validate the system, especially with the amount and extent of documentation required. When it comes to people, the role of the senior management is critical to lead and support the entire 5 P’s approach.

 The 4 P’s above come together in a project covering the definition, selection, qualification, and validation of the system. The scope and extent of the project depends on the intended use, process to be automated, records to be created and managed by the system.

The way the 5 P’s come together for an integrated approach is shown in Figure 1.

FIGURE 1: The 5 P’s of an integrated AIQ and CSV approach.

To determine how much qualification and validation work needs to be performed, we need to time travel back to 2013, when Chris Burgess and I published a system risk assessment for analytical instruments and systems (7). One of the outcomes from the risk assessment was a sentence that referenced an article that described a single Integrated Validation Document (IVD) (8).

In essence, if the controlling software application is GAMP software category 3 and a commercially available non-configured product (9), even if it generates data used for analyses of clinical trial materials, product submissions or product releases, it could be validated using the IVD approach. Before discussing the IVD though, it is important to understand the difference between parameterization and configuration of software.

Knowing how to differentiate between GAMP software categories 3 and 4 typically involves an arm wrestling match (sorry, collaboration) between the laboratory manager and CSV. Category 3 software cannot change the business process it automates; it does exactly what it says in the brochure, nothing more, nothing less. Although run time configuration is possible (for example, definition of user roles and access privileges, report formats), the business process cannot be changed.

A major cause of confusion is parameterization, which can be performed on functions in both category 3 and 4 software. Parameterization is setting the wavelength used to measure absorption of an analyte. If the wavelength is set at 220 nm and then changed to 280 nm, the business process has not changed. The instrument is still measuring the absorbance of an analyte regardless of wavelength, meaning the business process is unchanged. However, many people think this is configuration despite it being parameterization, so it still needs to be controlled when people use the system for things like method validation.

Principle for the Integrated Validation Document

Qualification documents may be combined together, where appropriate, e.g. installation qualification (IQ) and operational qualification (OQ) (10).

The principle of the IVD condenses the whole suite of validation documents into one. From the system risk assessment (7), this approach is only applicable to lower risk systems typically, but not exclusively, GAMP Category 3 software.

A description of the rational and justification can be found in the article by McDowall (8) which is available for free download (

https://onlinelibrary.wiley.com/doi/10.1002/qaj.443

Contents of an Integrated Validation Document

As the name suggests, all key validation requirements for demonstrating intended use are contained in a single document, as shown in Figure 2. An IVD has two main sections: specifications (shown in green) and testing/reporting (shown in yellow).

FIGURE 2: Content of an integrated validation document (IVD).

The size of a typical IVD is in the range of 30–45 pages, depending on the intended use of the system.

User Requirements and Configuration Specifications

The introduction and specifications, shown in green in Figure 2, consist of:

 A simple description of the intended use of the system along with a list of the main components e.g. instrument and software, standalone or networked system.

 Consisting of a series of tables consisting of three columns: requirement number, the requirement and a trace to where the requirement is met; e.g. test procedure, SOP, calibration, supplier documentation, and so forth. There are requirements tables for the function of the system, data integrity, IT support including protection of records, time synchronization, and more. If a user requirement is excluded from testing, this is justified in the section on assumptions, exclusions, and limitations.

 is limited to requirements only essential to achieve the intended use and are statements of what the system must do rather than what it can do. Therefore, just in case requirements are not considered, the discipline for an IVD is to focus purely on what the system will perform now rather than in the future.

 if additional requirements are needed when operational.

 A list or table of the application configuration settings for ensuring data integrity and non-functional settings. For example, unique user names, password expiry and complexity, and so forth.

 Typically, this is a table of the various user roles against the access privileges allotted to each one.

Not shown in Figure 2 is a referenced documents section linking an IVD with regulations, CSV procedures, and applicable SOPs for operation of the system, such as user account management. In addition, supplier assessment and qualification documentation (for example, IQ, OQ, or calibration) will also be referenced and, where possible, used to verify user requirements.

Testing and Reporting of the Configured System

The second section of an IVD, colored yellow in Figure 2, consists of test procedures to confirm intended use, test execution notes to capture unexpected events during testing, and finishing with a reporting section with a simple release statement for operational use:

Confirmation of Application Configuration:

 Confirmation that the configuration settings and policies of the application and user roles with access privileges correspond to those defined in the specification section of the IVD.

 Requirements will define the tests to be performed to demonstrate the system’s intended use, the documented evidence anticipated (both electronic and paper), and acceptance criteria. The latter two are poorly defined in most validation examples I have audited.

 are written for trained users to execute not idiots that require mind-blowing detail; see an earlier column for details (11). This enables sections to be written and executed quickly.

If calculations are performed by the system, 

these must be verified as required by 21 

 211.68(b) (1) and Chapter 6.16 (12). One way will use a validated spreadsheet, but don’t forget to allow for differences in the number of significant figures when setting acceptance criteria.

For the IT spectrometer used for identity testing,

 confirm that the compare function of the application works correctly.

 is explicitly tested using entries generated in earlier test procedures.

 such as backup and recovery, are also included in these test procedures.

 Always remember you are testing software, not chemistry. Select analytical procedures that represent the intended use of the system and only use certified reference standards.

Assumptions, Exclusions, and Limitations:

 As test procedures are developed by the team, it will become apparent why a test is being developed in a particular way. It is important to document any assumptions and limitations of the testing as well as why some requirements are excluded from testing, such as why expiry of passwords is not tested (13).

 The focus is on electronic records with as few as possible paper printouts as evidence of testing. There is a section in each test procedure for a tester to document this, making the review of the testing quicker and simpler to perform. Screenshots will be kept to an absolute minimum, as noted by the draft CSA guidance (6) and GAMP 5 2nd edition (9), and the focus is on the software, including the audit trail, to record evidence of testing. Though paper is a possible output, consider printing to PDF, as it can be a baseline for future data integrity audits and change control requests, such as configuration settings.

Each test procedure has explicitly stated acceptance criteria that determine if testing has passed or failed.

Test Execution Notes and Deviation Handling: 

If there are any problems or deviations when executing the test procedures, there is space in the IVD for documenting and resolving them.

The whole document is reviewed for technical content by the laboratory and approved by QA prior to execution.

After execution by the tester, they complete the Test Summary and Release Statement section of the IVD, stating whether or not the system can be released for operational use. The whole document is reviewed by a second person, who also confirms the release of the system. QA also reviews both the completed IVD and documented evidence.

You may think that this is a new approach to integrated qualification and validation of laboratory systems; however, it has been used for nearly 20 years. There have been minor changes in approach over the intervening years, but it is essentially the same as published. Go on, be lazy. You know it’s common sense, but will the Compliance Police let you?

I would like to thank Paul Smith and Mahboubeh Lotfinia for their constructive review comments in preparation of this article.

 21 CFR 211 Current Good Manufacturing Practice for Finished Pharmaceutical Products. 

(2) United States Pharmacopoeia Convention Inc. 

USP General Chapter <1058> Analytical Instrument Qualification

(3) McDowall, R. D. Pharma 4.0 and the Digital Regulated Laboratory Part 1: Why Digitalize Your Regulated Laboratory? 

(4) McDowall, R. D. Pharma 4.0 and the Digital Regulated Laboratory Part 2: Digital Laboratory Automation Strategy and Process Mapping. 

(5) McDowall, R. D. Pharma 4.0 and the Digital Lab eBook 3: Quick Wins and Project Implementation. 

FDA Draft Guidance for Industry Computer Software Assurance for Production and Quality System Software

(7) Burgess, C.; McDowall, R. D. An Integrated Risk Assessment for Analytical Instruments and Computerized Laboratory Systems. 

(8) McDowall, R. D. Validation of Computerized Systems Using a Single Life Cycle Document (Integrated Validation Document). 

(9) International Society of Pharmaceutical Engineering. Good Automated Manufacturing Practice (GAMP) Guide 5, Second Edition. Tampa, FL, 2022.

(10) European Commission. EudraLex - Volume 4 Good Manufacturing Practice (GMP) Guidelines, Annex 15 Qualification and Validation. Brussels, Belgium, 2015.

(11) McDowall, R. D. Does CSA Mean “Complete Stupidity Assured?” 

(12) European Commission. EudraLex - Volume 4 Good Manufacturing Practice (GMP) Guidelines, Chapter 6 Quality Control. Brussels, Belgium, 2014.

(13) McDowall, R. D. CSA: Much Ado About Nothing? 

 is the director of R.D. McDowall Limited and the editor of the “Questions of Quality” column for 

’s sister magazine. Direct correspondence to: 

Are the integrated Analytical Instrument Qualification (AIQ) and Computerized System Validation (CSV) new approaches to the qualification and validation of laboratory systems, or are they more of the same?

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