Interlaboratory Validation Research Articles

Determination of Total Aflatoxins in Polished Rice by Liquid Chromatography-Fluorescence Detection with Multifunctional Column Cleanup and Precolumn Derivatization: Single-Laboratory and Inter-Laboratory Validation Studies.

Aflatoxins are toxic metabolites produced by Aspergillus spp. Because aflatoxins are potent carcinogens in humans and animals, many countries have set regulatory limits for aflatoxins in foods to prevent dietary exposure. From a global food safety perspective, in 2023, the Codex Alimentarius Commission established the maximum level (ML) of total aflatoxins in certain cereals and cereal-based products, including polished rice. Therefore, validated analytical methods for aflatoxin detection are necessary. In this study, a high performance liquid chromatography (HPLC)-fluorescence method coupled with multifunctional column clean-up and trifluoroacetic acid derivatization was developed for the determination of aflatoxin levels in polished rice. Our method was validated in a single laboratory study using aflatoxin-spiked materials, followed by an inter-laboratory validation study. Twelve laboratories participated in the inter-laboratory validation study, and five polished rice test samples artificially contaminated with aflatoxins were analyzed. In a single laboratory study, the ranges of mean recoveries of aflatoxin B1, B2, G1, G2, and total aflatoxins were 101%, 100-103%, 93-96%, 95-98%, and 97-99%, respectively. The relative standard deviations for within-day and between-day variations were all ≤ 4.4%. In the inter-laboratory validation study, the relative standard deviations for repeatability and reproducibility were from 0.7 to 2.7% and 3.3 to 8.9% for all analytes, respectively. In response to the Codex ML and method performance criteria for aflatoxins in polished rice, an analytical method based on HPLC-fluorescence detection was developed. All method performance parameters estimated from the testing results of the single-laboratory and inter-laboratory validation studies met the criteria required by the Codex. Single- and inter-laboratory studies for the validation of an analytical method for aflatoxin level determination in polished rice were successfully performed. This analytical method will be suitable to determine aflatoxin levels around the Codex ML set for polished rice.

Clinical Performance of the Line Immunoassay and Digital Liquid Chip Method for Detecting Autoimmune Liver Disease Autoantibodies.

The identification of autoantibodies associated with autoimmune liver disease (ALD) is crucial for diagnosis and management. Various laboratory methods have been introduced to detect autoantibody profiles. However, the variable performance of these assays may create challenges for clinicians and patients. To investigate the concordance rates and diagnostic performance of 2 commercially available assays, line immunoassay (LIA) and digital liquid chip method (DLCM), in patients with ALD. A total of 291 serum samples were collected, consisting of 180 sera from patients with ALD and 111 sera from controls. The samples were detected through LIA and DLCM. The agreement and diagnostic performance of each assay were analyzed. There was substantial to almost perfect agreement among prevalent autoantibodies (anti-mitochondrial antibody M2, antibodies against gp210, Sp100, and Ro52). Nevertheless, the Cohen κ coefficient of some uncommon autoantibodies (anti-LKM-1, anti-LC-1, and anti-SLA/LP) between the 2 methods was not ideal. LIA showed slightly better sensitivity, accuracy, and negative predictive value, while DLCM exhibited slightly higher specificity and positive predictive value. LIA and DLCM demonstrated comparable performance for the detection of common ALD-related autoantibodies. LIA seemed to be more sensitive, while DLCM displayed more specificity. However, standardization of ALD autoantibody detection still faces challenges between these diverse detection systems. Comprehensive interlaboratory validation is essential to mitigate potential misunderstanding and confusion among patients and clinicians.

Interlaboratory validation and one-year retrospective review of hemp and marijuana decision-point assays

After the passage of the Agriculture Improvement Act of 2018 (Farm Bill) that defined hemp as Cannabis sativa L. if it contained ≤0.3 % Δ9-THC on a dry weight basis, forensic laboratories were faced with the challenge of distinguishing marijuana from hemp in seized drug samples. This study reports the results of an interlaboratory validation of a previously developed qualitative decision-point assay for the differentiation of illegal marijuana from legal hemp, utilizing gas chromatography-mass spectrometry (GC–MS) with a 1 % Δ9-THC threshold. The method was validated in terms of selectivity, linearity, carryover, precision, accuracy, extract stability, dilution integrity, and measurement uncertainty. Other elements such as decarboxylation rate and potential for CBD interference were also evaluated. Specificity and positive predictive value were both 100 % using known cannabis reference materials. A total of 8 false negative results were observed among the 280 analyses, resulting in an overall assay sensitivity of 94 % and a negative predictive value of 95 %. The small number of false negative results near the 1 % threshold were attributed to decarboxylation inefficiency in some laboratories. While qualitative in nature, the measurement uncertainty of the assay at the 0.3 % Δ9-THC cutoff (legal threshold) using a 95.45 % confidence interval (k = 2) ranged from 12.2 % to 21.8 % among laboratories (equivalent to 0.3 % ± 0.04 % to 0.07 % Δ9-THC by weight). A one-year retrospective study across three agencies and fifteen laboratories was undertaken. Among the three agencies participating in the original study, 93–96 % of all suspected cannabis seizures yielded results above the administrative threshold of 1 % Δ9-THC (n = 3,288). The interlaboratory method development highlighted differences in performance between sites, ultimately improving the overall robustness of the method. Observations highlight the need for site-specific validation and vigilance. While multi-agency collaborations and interlaboratory validations are valuable, they do not replace the necessity for full, independent, and rigorous validation.

Dried blood spot (DBS) analysis of synthetic cathinones by different liquid chromatography-mass spectrometry techniques and interlaboratory validation for application in forensic toxicology

Dried Blood Spot (DBS) technique was employed as sample pretreatment for the detection of synthetic cathinones in blood samples, including from postmortem caseworks, by Liquid Chromatography-tandem Mass spectrometry (LC-MS/MS) techniques. The study involved the interlaboratory validation to evaluate the applicability of the method with different instruments, to assess the applicability and the ruggedness of the method for its wide application. The stability of cathinones in DBS was also evaluated.Authentic casework from drug-related deaths (DRD) involving synthetic cathinones were analysed and results compared in the two laboratories, using the developed methods. Metabolites were studied by two different LC-HRMS methods, orbitrap and Q-TOF.Validation results obtained in both laboratories demonstrated the suitability of DBS as sample storage and pre-treatment technique, allowing good sensitivities, repeatability, matrix effect and %bias. Limits of detection LOD and of quantification LOQ ranged between 0.3 and 1 ng/ml and between 0.5 and 10 ng/mL, respectively, for the studied cathinones in both laboratories. Stability studies demonstrated the high percent of degradation of cathinones, depending on their molecular structure, not attributable to DBS. The analysis of forensic caseworks containing α-PHP and MDPHP by DBS allowed their identification and quantification and the detection of various metabolites in postmortem blood samples. α-PHP degraded over time, while MDPHP concentration did not show significant differences in a three-months period, probably due to the presence of the metylendioxy moiety.These results demonstrate DBS to be a rapid and efficient technique for the analysis of cathinones, and that quantitative results for these analytes should be carefully interpreted due to their possible degradation.

A validated real-time PCR test for simultaneous detection of Gallus gallus and Meleagris gallopavo in feed instead of an impossible poultry test

Description of the subject. Use of all processed animal proteins (PAPs) in animal feeds was banned in the EU due to the outbreak of bovine spongiform encephalopathy (BSE). This total feed ban was progressively lifted for non-ruminant PAPs from 2013 onwards. Use of ruminant PAPs in feed remains totally prohibited. In order to extend the reintroduction of poultry PAPs in pig feed, and of pig PAPs in poultry feed, as recently decided, poultry species and pig detection tests were required to check that there is no intra-specific recycling. Objectives. In this study, we describe the official EURL-AP real-time PCR method for the simultaneous detection of chicken (Gallus gallus L.) and turkey (Meleagris gallopavo L.), the two most widely used poultry species in PAPs. Method. Classic quality criteria for the validation of a PCR method are considered. A cut-off is required for the interpretation of results. Transferability was tested through an interlaboratory study. Results. The developed PCR assay amplifies an 84 bp fragment encompassing the mitochondrial DNA on 12S ribosomal RNA, tRNA-Val and 16S ribosomal RNA sequences. The qualitative method was successfully assessed for several performance criteria: specificity, sensitivity, efficiency and robustness. The applicability of the test was verified on poultry PAPs and on compound feed containing 0.1% in mass fraction of poultry PAPs. An interlaboratory validation study demonstrated that the proposed real-time PCR method is transferable. Conclusions. The combined chicken-turkey real-time PCR assay is fit for the purpose of detecting poultry PAPs.

Interlaboratory validation of the ToxTracker assay: An in vitro reporter assay for mechanistic genotoxicity assessment.

ToxTracker is a mammalian cell reporter assay that predicts the genotoxic properties of compounds with high accuracy. By evaluating induction of various reporter genes that play a key role in relevant cellular pathways, it provides insight into chemical mode-of-action (MoA), thereby supporting discrimination of direct-acting genotoxicants and cytotoxic chemicals. A comprehensive interlaboratory validation trial was conducted, in which the principles outlined in OECD Guidance Document 34 were followed, with the primary objectives of establishing transferability and reproducibility of the assay and confirming the ability of ToxTracker to correctly classify genotoxic and non-genotoxic compounds. Reproducibility of the assay to predict genotoxic MoA was confirmed across participating laboratories and data were evaluated in terms of concordance with in vivo genotoxicity outcomes. Seven laboratories tested a total of 64 genotoxic and non-genotoxic chemicals that together cover a broad chemical space. The within-laboratory reproducibility (WLR) was up to 98% (73%-98% across participants) and the overall between-laboratory reproducibility (BLR) was 83%. This trial confirmed the accuracy of ToxTracker to predict in vivo genotoxicants with a sensitivity of 84.4% and a specificity of 91.2%. We concluded that ToxTracker is a robust in vitro assay for the accurate prediction of in vivo genotoxicity. Considering ToxTracker's robust standalone accuracy and that it can provide important information on the MoA of chemicals, it is seen as a valuable addition to the regulatory in vitro genotoxicity battery that may even have the potential to replace certain currently used in vitro battery assays.

Sugar Profile Method by High-Performance Anion-Exchange Chromatography with Pulsed Amperometric Detection in Food, Dietary Supplements, Pet Food, and Animal Feeds: Interlaboratory Validation Study, Final Action 2018.16.

A method for sugar profile analysis granted First Action 2018.16 was subjected to a multi-laboratory study. Perform a multi-laboratory study with this method to determine the performance parameters of repeatability and reproducibility against the AOAC Standard Method Performance Requirements (AOAC SMPR 2018.001) for Final Action status. Eleven laboratories from three different countries participated in the study. Each laboratory was provided practice materials for successful method setup. Each laboratory then proceeded with analysis of blind duplicates of 10 different products covering the scope of the method. Results were reported to the study directors with any modifications and assessed following the procedures of Appendix D of the AOAC Official Methods of AnalysisSM (guidelines for collaborative study procedures). The majority of results from the study met the SMPR requirements. The data is presented along with any outlying observations or modifications. The method was proven to be flexible across different instrumentation and laboratories, and the method was updated to provide further system suitability and guidelines to maintain the performance of the method across the large scope of matrixes. The results from the collaborative study supported the method for Final Action status. The Expert Review Panel reviewed and voted to move the method forward to Final Action and was followed by review from the Official Methods Board and granted approval. The method was granted Final Action Official Methods status.

The inter-laboratory validation study of EpiSensA for predicting skin sensitization potential.

The Epidermal Sensitization Assay (EpiSensA) is a reconstructed human epidermis (RhE)-based gene expression assay for predicting the skin sensitization potential of chemicals. Since the RhE model is covered by a stratified stratum corneum, various kinds of test chemicals, including lipophilic ones and pre-/pro-haptens, can be tested with a route of exposure akin to an in vivo assay and human exposure. This article presents the results of a formally managed validation study of the EpiSensA that was carried out by three participating laboratories. The purpose of this validation study was to assess transferability of the EpiSensA to new laboratories along with its within- (WLR) and between-laboratory reproducibility (BLR). The validation study was organized into two independent stages. As demonstrated during the first stage, where three sensitizers and one non-sensitizer were correctly predicted by all participating laboratories, the EpiSensA was successfully transferred to all three participating laboratories. For Phase I of the second stage, each participating laboratory performed three experiments with an identical set of 15 coded test chemicals resulting in WLR of 93.3%, 93.3%, and 86.7%, respectively. Furthermore, when the results from the 15 test chemicals were combined with those of the additional 12 chemicals tested in Phase II of the second stage, the BLR for 27 test chemicals was 88.9%. Moreover, the predictive capacity among the three laboratories showed 92.6% sensitivity, 63.0% specificity, 82.7% accuracy, and 77.8% balanced accuracy based on murine local lymph node assay (LLNA) results. Overall, this validation study concluded that EpiSensA is easily transferable and sufficiently robust for assessing the skin sensitization potential of chemicals.

Multianalyte analysis of volatile compounds in virgin olive oils using SPME‐GC with FID or MS detection: results of an international interlaboratory validation

AbstractThe organoleptic assessment (Panel test) is the only procedure within the official methods for determining the quality of virgin olive oils that involves an expert panel. There is an urgent need for analytical methodology that can reliably measure volatile compounds in virgin olive oils that is capable of supporting and anticipating the official Panel test. For this reason, a new method based on solid‐phase microextraction–gas chromatography with the choice of two possible detectors (FID or MS) was subjected to a large international interlaboratory validation study. The study involved a two‐stage process: first, a pretrial phase in which 7 participants were exposed to the method for the first time to identify any initial problems with the methodology; then, a formal validation stage (trial proper), which involved 20 laboratories from Europe, USA, Japan and China. The performance of the different detectors was investigated. While both methods have advantages, the method using FID provided better results for 11 compounds, in terms of reproducibility, compared to MS. This information will allow to implement the method with accurate information of the method performance depending on the detector used.Practical applications: This study provides information from an interlaboratory validation of a method for measuring volatile compounds in virgin olive oils conducted with laboratories (from industry and academia) working in the olive oil sector. The information on the expected analytical errors in the determination of each volatile compound is necessary to apply this method for supporting the official Panel test (sensory analysis). The SPME‐GC‐MS/FID methods proposed in this work can be used for the internal quality control of a company/distributor/quality control laboratory and could also be used in cases of difficult/contradictory organoleptic assessment, or to confirm results from sensory panels in cases of disputes/disagreement (Reg. EU 2022/2105).

Polar pesticides in food of animal origin: interlaboratory validation to evaluate method fitness-for-purpose of official control

The present work reports on the design, execution and evaluation of results of an interlaboratory validation study aimed at verifying the fitness-for-purpose of a LC-MS/MS method for the detection of polar pesticides in food of animal origin in official control and monitoring programmes. To this scope, five participant laboratories, with relevant expertise, were recruited. After passing a pre-trial test, the participants were asked to analyse test samples of bovine fat, chicken eggs and cow’s milk, contaminated with 11 polar pesticides (group A: Aminomethyl phosphonic acid (AMPA), cyanuric acid, ethephon, glyphosate, fosetyl aluminium, 2-hydroxyethyphosphonic acid (HEPA), maleic hydrazide, N-acetyl-glyphosate, group B: N-acetyl glufosinate (NAG), 3-methylphosphinicopropionic acid (MPP) and glufosinate ammonium) at two different levels (0.05 and 0.25 mg/kg−1 and 0.01 and 0.05 mg/kg−1 for group A and B respectively. The method was based on acidified methanol/water extraction followed by dSPE clean up with C18 sorbent. For LC-MS/MS analysis isotopically labelled standards were used for all targeted analytes. With a couple of exceptions, average recoveries ranged from 85% to 110%, with repeatability (RSDr) ranging from 3% to 25%, and reproducibility (RSD R ) from 4% to 26%. The assessment by different laboratories provided also insights on key factors impacting method performance characteristics and its implementation by new users.

Inter-laboratory validation of liquid chromatography-tandem mass spectrometry multi-mycotoxin determination in animal feed - method transfer from the reference laboratory to regional laboratories.

The results are presented of the inter-laboratory validation of a liquid chromatography-tandem mass spectrometry method for the determination of eight mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1, fumonisin B2, ochratoxin A, toxin T-2, toxin HT-2 and zearalenone) in animal feeds. This study was an essential part of the method's transfer from the National Reference Laboratory to six regional laboratories in Poland working in the official survey of mycotoxins in feed. The laboratories received a batch of standard solutions, blank samples and quality control materials on which to perform analysis with one procedure and different liquid chromatography-tandem mass spectrometry conditions. The validation results show good precision (reproducibility coefficient of variation 3.7-20.5%) and accuracy of the method (recovery 89-120% and trueness 94-103%) and sufficient skills of the laboratory personnel. The study is an example of the successful transfer of the method among laboratories.

Evaluation of a high-throughput H295R homogenous time resolved fluorescence assay for androgen and estrogen steroidogenesis screening

The H295R test guideline assay evaluates the effect of test substances on synthesis of 17β-estradiol (E2) and testosterone (T). The objective of this study was to leverage commercial immunoassay technology to develop a more efficient H295R assay to measure E2 and T levels in 384-well format. The resulting Homogenous Time Resolved Fluorescence assay platform (H295R-HTRF) was evaluated against a training set of 36 chemicals derived from the OECD inter-laboratory validation study, EPA guideline 890.1200 aromatase assay, and azole fungicides active in the HT-H295R assay. Quality control performance criteria were met for all conditions except E2 synthesis inhibition where low basal hormone synthesis was observed. Five proficiency chemicals were active for both the E2 and T endpoints, consistent with guideline classifications. Of the nine OECD core reference chemicals, 9/9 were concordant with outcomes for E2 and 7/9 for T. Likewise, 9/13 and 11/13 OECD supplemental chemicals were concordant with anticipated effects for E2 and T, respectively. Of the 10 azole fungicides screened, 7/10 for E2 and 8/10 for T exhibited concordant outcomes for inhibition. Generally, all active chemicals in the training set demonstrated equivalent or greater potency in the H295R-HTRF assay, supporting the sensitivity of the platform. The adaptation of HTRF technology to the H295R model provides an efficient way to evaluate E2 and T modulators in accordance with guideline specifications.

Interlaboratory validation of a multiplex qPCR method for the detection of Listeria monocytogenes in a ready-to-eat seafood product

Interlaboratory validation of a multiplex qPCR method for the detection of Listeria monocytogenes in a ready-to-eat seafood product

Implementation of DNA Methylation Array Profiling in Pediatric Central Nervous System Tumors: The AIM BRAIN Project: An Australian and New Zealand Children's Haematology/Oncology Group Study

DNA methylation array profiling for classifying pediatric central nervous system (CNS) tumors is a valuable adjunct to histopathology. However, unbiased prospective and interlaboratory validation studies have been lacking. The AIM BRAIN diagnostic trial involving 11 pediatric cancer centers in Australia and New Zealand was designed to test the feasibility of routine clinical testing and ran in parallel with the Molecular Neuropathology 2.0 (MNP2.0) study at Deutsches Krebsforschungszentrum (German Cancer Research Center). CNS tumors from 269 pediatric patients were prospectively tested on Illumina EPIC arrays, including 104 cases co-enrolled on MNP2.0. Using MNP classifier versions 11b4 and 12.5, we report classifications with a probability score ≥0.90 in 176 of 265 (66.4%) and 213 of 269 (79.2%) cases, respectively. Significant diagnostic information was obtained in 130 of 176 (74%) for 11b4, and 12 of 174 (7%) classifications were discordant with histopathology. Cases prospectively co-enrolled on MNP2.0 gave concordant classifications (99%) and score thresholds (93%), demonstrating excellent test reproducibility and sensitivity. Overall, DNA methylation profiling is a robust single workflow technique with an acceptable diagnostic yield that is considerably enhanced by the extensive subgroup and copy number profile information generated by the platform. The platform has excellent test reproducibility and sensitivity and contributes significantly to CNS tumor diagnosis.

Metabarcoding for the authentication of complex seafood products: The fish burger case

The species composition of fish burgers - declared as composed by European seabass (Dicentrarchus labrax) - collected in the context of a seafood company self-control was assessed using metabarcoding. Positive/negative controls, replicates, samples processed in dirty laboratory environment were also included as quality measures. A ≈ 200 bp of the 16S rRNA gene was selected as molecular target. The sequencing was performed on Illumina platform, and the data were analysed using DADA2 R package. The species taxonomic assignment was performed using Blastn against GenBank (identity value ≥ 99 %). The sequences assigned to D. labrax were highly predominant in all the products, with percentages ≥ 99.34 %, except for one, where also a high number of sequences assigned to Atlantic salmon (Salmo salar) were found (12.41 %). Sequences identified with other species (seafood, mammals, insects) were in percentage ≤ 0.57 %, and in the 14 % of the cases they even did not achieve the 0.001 %. A threshold value of 3.3 % to remove false positives was fixed based on the results of the positive controls. Overall, metabarcoding was proved as effective technique to assess the ingredients contained in complex seafood products. However, further investigation including a higher sample number and inter-laboratory validation should be performed to validate the procedure.

Inter-laboratory validation by event-specific qPCR methods for the detection of genetically modified insect and herbicide-tolerant maize DBN9501

Inter-laboratory validation by event-specific qPCR methods for the detection of genetically modified insect and herbicide-tolerant maize DBN9501

Establishment of analysis method for the quantification of residues of halquinol and its metabolites in livestock and fishery products using liquid chromatography–tandem mass spectrometry

In this study, an analysis method was established for the quantification of residues of halquinol and its metabolites in livestock and fishery products using liquid chromatography–tandem mass spectrometry (LC–MS/MS). We selected beef, pork (muscle and fat), chicken, egg, milk, flat fish, eel, and shrimp as target samples for validation of the method owing to them being typical livestock and fishery products. Validation of the developed analysis method was performed using liquid chromatography–tandem mass spectrometry (LC–MS/MS) at three concentration levels (0.5, 1, and 2 × the maximum residue limits) following the Codex Alimentarius (CODEX) guidelines (CAC/GL 71–2009). For all samples, correlation coefficients (R2) exceeded 0.99, recoveries ranged between 75.59 and 119.36%, and coefficients of variation (CV) ranged between 1.39 and 28.66%, thus satisfying CODEX guidelines. In addition, inter-laboratory validation was conducted, and the resulting recoveries and CVs satisfied the CODEX guidelines; LOQ was established as 10 μg kg–1 for pig muscle and 5 μg kg–1 for the other samples. Therefore, the analysis method developed in this study can accurately and precisely screen for and quantify halquinol and its metabolites in livestock and fishery products.

QPOLE: A Quick, Simple, and Cheap Alternative for POLE Sequencing in Endometrial Cancer by Multiplex Genotyping Quantitative Polymerase Chain Reaction.

Detection of 11 pathogenic variants in the POLE gene in endometrial cancer (EC) is critically important to identify women with a good prognosis and reduce overtreatment. Currently, POLE status is determined by DNA sequencing, which can be expensive, relatively time-consuming, and unavailable in hospitals without specialized equipment and personnel. This may hamper the implementation of POLE-testing in clinical practice. To overcome this, we developed and validated a rapid, low-cost POLE hotspot test by a quantitative polymerase chain reaction (qPCR) assay, QPOLE. Primer and fluorescence-labeled 5'-nuclease probe sequences of the 11 established pathogenic POLE mutations were designed. Three assays, QPOLE-frequent for the most common mutations and QPOLE-rare-1 and QPOLE-rare-2 for the rare variants, were developed and optimized using DNA extracted from formalin-fixed paraffin-embedded tumor tissues. The simplicity of the design enables POLE status assessment within 4-6 hours after DNA isolation. An interlaboratory external validation study was performed to determine the practical feasibility of this assay. Cutoffs for POLE wild-type, POLE-mutant, equivocal, and failed results were predefined on the basis of a subset of POLE mutants and POLE wild-types for the internal and external validation. For equivocal cases, additional DNA sequencing is recommended. Performance in 282 EC cases, of which 99 were POLE-mutated, demonstrated an overall accuracy of 98.6% (95% CI, 97.2 to 99.9), a sensitivity of 95.2% (95% CI, 90.7 to 99.8), and a specificity of 100%. After DNA sequencing of 8.8% equivocal cases, the final sensitivity and specificity were 96.0% (95% CI, 92.1 to 99.8) and 100%. External validation confirmed feasibility and accuracy. QPOLE is a qPCR assay that is a quick, simple, and reliable alternative for DNA sequencing. QPOLE detects all pathogenic variants in the exonuclease domain of the POLE gene. QPOLE will make low-cost POLE-testing available for all women with EC around the globe.

Applications of functional materials-based solid phase microextraction technique in forensic science

Sample extraction is a crucial step in forensic analysis, especially when dealing with trace and ultra-trace levels of target analytes present in various complex matrices (e. g., soil, biological samples, and fire debris). Conventional sample preparation techniques include Soxhlet extraction and liquid-liquid extraction. However, these techniques are tedious, time-consuming, labor-intensive and require large amounts of solvents, which poses a threat to the environment and health of researchers. Moreover, sample loss and secondary pollution can easily occur during the preparation procedure. Conversely, the solid phase microextraction (SPME) technique either requires a small amount of solvent or no solvent at all. Its small and portable size, simple and fast operation, easy-to-realize automation, and other characteristics thus make it a widely used sample pretreatment technique. More attention was given to the preparation of SPME coatings by using various functional materials, as commercialized SPME devices used in early studies were expensive, fragile, and lacked selectivity. Examples of those functional materials include metal-organic frameworks, covalent organic frameworks, carbon-based materials, molecularly imprinted polymers, ionic liquids, and conducting polymers, all widely used in environmental monitoring, food analysis, and drug detection. However, these SPME coating materials have relatively few applications in forensics. Given the high potential of SPME technology for the in situ and efficient extraction of samples from crime scenes, this study briefly introduces functional coating materials and summarizes the applications of SPME coating materials for the analysis of explosives, ignitable liquids, illicit drugs, poisons, paints, and human odors. Compared to commercial coatings, functional material-based SPME coatings exhibit higher selectivity, sensitivity, and stability. These advantages are mainly achieved through the following approaches: First, the selectivity can be improved by increasing the π-π, hydrogen bonds, and hydrophilic/hydrophobic interactions between the materials and analytes. Second, the sensitivity can be improved by using porous materials or by increasing their porosity. Third, thermal, chemical, and mechanical stability can be improved by using robust materials or fixing the chemical bonding between the coating and substrate. In addition, composite materials with multiple advantages are gradually replacing the single materials. In terms of the substrate, the silica support was gradually replaced by the metal support. This study also outlines the existing shortcomings in forensic science analysis of functional material-based SPME techniques. First, the application of functional material-based SPME techniques in forensic science remains limited. On one hand, the analytes are narrow in scope. As far as explosive analysis is concerned, functional material-based SPME coatings are mainly applied to nitrobenzene explosives, while other categories, such as nitroamine and peroxides, are rarely or never involved. Research and development of coatings is insufficient and the application of COFs in forensic science has not yet been reported. Second, functional material-based SPME coatings have not been commercialized as they don't yet have inter-laboratory validation tests or established official standard analytical methods. Therefore, some suggestions are proposed for the future development of forensic science analyses of functional material-based SPME coatings. First, research and development of functional material-based SPME coatings, especially fiber coatings with broad-spectrum applicability and high sensitivity, or outstanding selectivity for some compounds, is still an important direction for SPME future research. Second, a theoretical calculation of the binding energy between the analyte and coating was introduced to guide the design of functional coatings and improve the screening efficiency of new coatings. Third, we expand its application in forensic science by expanding the number of analytes. Fourth, we focused on the promotion of functional material-based SPME coatings in conventional laboratories and established performance evaluation protocols for the commercialization of functional material-based SPME coatings. This study is expected to serve as a reference for peers engaged in related research.

Multi-Allergen Quantification in Food Using Concatemer-Based Isotope Dilution Mass Spectrometry: An Interlaboratory Study.

Food allergen analysis is essential for the development of a risk-based approach for allergen management and labeling. MS has become a method of choice for allergen analysis, even if quantification remains challenging. Moreover, harmonization is still lacking between laboratories, while interlaboratory validation of analytical methods is necessary for such harmonization. This interlaboratory study aimed to evaluate the potential of MS for food allergen detection and quantification using a standard addition quantification strategy and a stable isotope-labeled (SIL) concatemer as an internal standard. In-house-produced test material (cookies), blank and incurred with four allergens (egg, milk, peanut, and hazelnut), allergen standards, an internal standard, and the complete methodology (including sample preparation and ultra-HPLC-MS/MS method) were provided to nine laboratories involved in the study. Method sensitivity and selectivity were evaluated with incurred test material and accuracy with spiked test material. Quantification was based on the standard addition strategy using certified reference materials as allergen protein standards and a SIL concatemer as an internal standard. All laboratories were able to detect milk, hazelnut, and peanut in the incurred cookies with sufficient sensitivity to reach the AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR® 2016.002). Egg detection was more complicated due to food processing effects, yet five laboratories reached the sensitivity requirements. Recovery results were laboratory-dependent. Some milk and hazelnut peptides were quantified in agreement with SMPR 2016.002 by all participants. Furthermore, over 90% of the received quantification results agreed with SMPR 2016.002 for method precision. The encouraging results of this pioneering interlaboratory study represent an additional step towards harmonization among laboratories testing for allergens. In this pioneering interlaboratory study, food allergens were analyzed by MS with characterized incurred and spiked test materials, calibrated with a certified reference material, and a single SIL concatemer used as an internal standard.