Within-laboratory Reproducibility Research Articles

Method development and validation for the simultaneous determination of 21 antiviral drugs by ultra-high performance liquid chromatography-tandem mass spectrometry in chicken muscle and liver.

The recent unauthorization of antiviral drugs in food-producing animals according to Commission Delegated Regulation (EU) 2022/1644 have increased the need for food control laboratories to develop analytical methods and perform official controls. In this work, a simple and fast analytical methodology was developed for the simultaneous determination of 21 antiviral drugs in chicken muscle and liver by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Chromatographic separation was achieved by an HILIC BEH amide column; followed by detection with a electrospray ionization source in positive and negative modes. Based on extraction efficiencies, critical parameters affecting sample treatment were optimized including the evaporation and clean up steps to extract the largest number of antiviral drugs and reduce interferences. The method was validated according to Commission Implementing Regulation (EU) 2021/808 in chicken muscle and liver. Most compounds showed a linearity of R2>0.9800, while decision limits were between 0.18 and 7.05 μg kg-1 and 0.19 and 36 μg kg-1 for chicken muscle and liver, respectively. Trueness and within-lab reproducibility were determined at three levels (n = 7) and the results showed values ranging from 81 to 133 % and 4.2-57 % for chicken muscle, and 71-136 % and 4.6-106 % for chicken liver, respectively. The applicability of the developed method was demonstrated by the analysis real samples. 20 samples from the National Residue Control Plan in the Netherlands were analyzed and although none of targeted compounds were detected it is important to continue the analysis of larger set of samples to address any possible food safety risks.

Determination of 16 Hydroxyanthracene Derivatives in Food Supplements Using LC-MS/MS: Method Development and Application.

Hydroxyanthracene derivatives (HADs) are plant substances produced by a variety of plant species, including different Aloe, Rheum, and Rhamnus species and Cassia senna. These plants are often used in food supplements to improve bowel function. However, recently, the European Commission prohibited a number of HADs due to toxicological concerns. These HADs included aloin (aloin A and aloin B), aloe-emodin, emodin, and danthron. Most of the currently available analytical methods are restricted to the analysis of only these compounds and do not include other HADs. In this view, a multi-analyte method could be useful for both regulatory analysis and dietary intake studies. To this end, such a method, employing liquid chromatography-tandem mass spectrometry and targeting 16 different HADs, was developed and validated in this study. Limits of quantification were in the range from 0.025 mg kg-1 to 1 mg kg-1. The recovery of the method was within the acceptable range of 80% to 120%, with the exception of physcion. Repeatability varied from 0.5% to 11.6%, and the range for within-laboratory reproducibility was from 3.4% to 16.3%. The expanded measurement uncertainty was below 50% for all HADs. Subsequently, 24 commercial samples of food supplements and herbal infusions sourced in Belgium were analyzed. The results indicated that although the industry put a great effort into minimizing the amount of aloin and danthron present in food supplements, more than half of the products still exceeded the maximum tolerated levels suggested for aloe-emodin and emodin.

Paralytic Shellfish Poisoning (PSP) Toxins in Bivalve Molluscs from Southern Italy Analysed by Liquid Chromatography Coupled with High-Resolution Mass Spectrometry (UHPLC-HRMS/MS).

A new method for simultaneous determination by liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS/MS) of 14 paralytic shellfish poisoning toxins (PSP), that is, Saxitoxin, Neosaxitoxin, Gonyautoxins and their respective variants, in bivalve molluscs, is herein described. The samples were extracted by acetic acid solution, then analysed by UHPLC coupled with a Q-Exactive Orbitrap Plus high resolution mass spectrometer, by electrospray ionization mode (ESI) with no further clean up step. The analysis was carried out by monitoring both the exact mass of the molecular precursor ion of each compound (in mass scan mode, resolution at 70,000 FWHM) and its respective fragmentation patterns (two product ions) with mass accuracy greater than 5 ppm. The analytical performance of the method was evaluated calculating trueness, as mean recoveries of each biotoxin, between 77.8% and 111.9%, a within-laboratory reproducibility (RSDR) between 3.6% and 12.2%, the specificity, the linearity of detector response, and the ruggedness for slight changes The results of the validation study demonstrate this method fits for the purposes of the official control of PSP toxins in molluscs. The results of two years of monitoring in local mussel farms are also reported, showing that no significant concerns for food safety in the monitored productions.

Detection of Ochratoxin A in Maize and Its Potential Impact on Avian Pathology in Romanian Farms.

Ochratoxin A (OTA) is a nephrotoxic mycotoxin that commonly contaminates maize, posing significant health risks to both poultry and humans. In this study, a rapid and sensitive method utilizing ultra-performance liquid chromatography coupled with fluorescence detection (UPLC-FLD) was developed for the quantification of OTA levels in maize. The method utilizes immunoaffinity column purification for improved specificity. Accuracy and precision were validated in line with European Union Reference Laboratory (EURL-MP) guidelines, meeting regulatory standards for linearity, trueness, detection and quantification limits, precision, and uncertainty, as per European Commission Regulation (EC) No. 401/2006 and its amendments. The method demonstrated an average recovery rate of 116.78% for maize, with RSDwR values (within-laboratory reproducibility) of 12.72%. Furthermore, OTA occurrence and its possible effects were investigated in several farms in South Romania, where necropsy and histopathological analyses of poultry revealed severe kidney damage, including renal tubular degeneration.

Determination and Residue Survey of Novel Nicotinic AcetylcholineReceptor Modulator Pesticides in Brown Rice by LC-MS/MS

Nicotinic acetylcholine receptors (nAChRs) are neurotransmitter receptors found in the nervous system of many organisms, including humans. Neonicotinoid pesticides act as nAChRs modulators that affect neurotransmission. Due to toxicity effects, their use has been restricted. However, a new class of modulators (nAChRMs) have been developed, but analytical methods for the detection of residues of these new pesticides in agricultural crops have not been established. Therefore, this study aimed to develop and validate an accurate determination method for novel nAChRMs, such as sulfoxaflor, flupyradifurone, flupyrimin, and triflumezopyrim in brown rice using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The method was applied to commercially available brown rice samples from Tokyo, Japan. Target analytes were extracted with acetonitrile, cleaned with GC/PSA, and then cleaned again with MonoSpin PBA. In accordance with the method validation guidelines for residual pesticides in foods, the performance characteristics were evaluated, with trueness ranging from 86.3% to 98.2%, repeatability of less than 6.5% relative standard deviation (RSD), and within-laboratory reproducibility of less than 6.5% RSD. These results indicate that the developed method can be applied to residue surveillance of target analytes using solvent standard calibration curves. By applying the developed method to 53 brown rice samples commercially available in Tokyo, sulfoxaflor residues were found in two samples at concentrations of 3.7 and 21.9 ng/g. This is the first report of the detection of sulfoxaflor residues in domestic agricultural products.

Single-Laboratory Validation Study of Simultaneous Determination Methodfor Five Organochlorine Unstable Pesticides in Agricultural Products by GC-MS/MS

A method was developed for determining five organochlorine unstable pesticides (captan, chlorothalonil, dichlofluanid, folpet, and tolylfluanid) in agricultural products using GC-MS/MS. To prevent pesticide degradation, the food sample was maintained at -20℃ until the initiation of the extraction process. The sample underwent homogenization with acetonitrile and salting out using anhydrous magnesium sulfate and sodium chloride in the presence of citrate salts. Cleanup was executed using Graphite Carbon and C18 SPE cartridges. The validation of this method was tested on five agricultural products at two concentrations (0.01 and 0.1 μg/g). The recovery rates varied between 86.7% and 96.1%. RSDs for repeatability were less than 15.2% and 8.8%, while the RSDs for within-laboratory reproducibility were under 19.9% and 12.7%. These results meet the criteria established by the validation guidelines in Japan.

Investigation of insecticide residues in fig and health risk assessment

This study aimed to detect insecticide, acaricide, and nematicide residues in 92 fresh and 50 dried fig samples collected from locations with intensive fig, Ficus carica L. (Rosales: Moraceae) production in Aydın, Türkiye in 2022. The analysis method was validated according to SANTE 11312/2021 guidelines. The recoveries ranged between 70% and 120%, with repeatability (RSDr) and within-laboratory reproducibility (RSDwR) ≤ 20% and expanded measurement uncertainties below 50% for all insecticides indicating satisfactory analytical performance. In total, 114 different insecticides were screened, revealing residues in 27 samples. Bifenazate was detected in 13 samples, etoxazole in 3 samples, spiromesifen in 5 samples, and both bifenazate and spiromesifen in 6 samples. No detectable residues were found in the dried fig samples. All samples in which bifenazate was detected were above the European Union Maximum Residue Limits (EU-MRL). Etoxazole and spiromesifen, unauthorized in figs, showed etoxazole residues above EU-MRLs, while spiromesifen residues were below EU-MRLs. The acute and chronic health risk indices for the insecticides were found to be below 1, indicating low health risks associated with fig consumption. The risk assessment suggests that fig consumption is safe for consumers.

Carbon-13-isotopomics and metabolomics of fatty acids from triacylglycerols: overcoming the limitations of GC-C-IRMS for short- and medium-acyl chains.

Carbon-13 isotopomics of triacylglycerol (TAG) fatty acids or free fatty acids in biological matrices holds considerable potential in food authentication, forensic investigations, metabolic studies, and medical research. However, challenges arise in the isotopic analysis of short- and medium-chain (C4 to C10) fatty acid methyl esters (SMCFAMEs) through gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The high volatility of these esters results in losses during their preparation, leading to isotopic fractionation. Moreover, the methoxy group added to acyl chains requires the correction of δ13C values, thereby increasing the uncertainty of the final results. Analyzing free fatty acids (FFAs) addresses both issues encountered with SMCFAMEs. To achieve this objective, we have developed a new protocol enabling the isotopomics of individual fatty acids (FAs) by GC-C-IRMS. The same experiment also provides the FA profile, i.e., the relative percentage of each FA in the TAG hydrolysate or its concentration in the studied matrix. The method exhibited high precision, as evidenced by the repeatability and within-lab reproducibility of results when tested on TAGs from both animal and vegetal origins. Compared to the analysis of FAMEs by GC-C-IRMS, the current procedure also brings several improvements in alignment with the principles of green analytical chemistry and green sample preparation. Thus, we present a two-in-one method for 13C-isotopomic and metabolomic biomarker quantitation within quasi-universal TAG compounds, encompassing the short- and medium-acyl chains.

Determination of tetracycline residues in potatoes and soil by LC-MS/MS: Method development, validation, and risk assessment

A method utilizing liquid-liquid extraction (LLE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated according to the Commission Implementing Regulation (CIR) EU 2021/808 for quantifying four tetracyclines (TCs) in potatoes and soil. The method demonstrated recovery values ranging from 70 to 121% and precision (repeatability and within-laboratory reproducibility), with coefficient of variation (CV) values below 18% for all TCs in both matrices. The limits of quantification (LOQs) for the TCs ranged from 0.90 to 1.87 μg/kg in potatoes and from 0.68 to 1.25 μg/kg in soil. The decision limit (CCα) and detection capability (CCβ) ranged from 10.4 to 12.3 μg/kg and 11.9 to 14.3 μg/kg, respectively. Analysis of 538 potato and soil samples from Egyptian farms revealed a 13.2% occurrence of TC residues, with a higher frequency in soil (19.33%) than in potatoes (7.06%). Target hazard quotient (THQ) values indicated that TC residues in potatoes do not pose a health risk to Egyptian consumers.

Development and Application of a Liquid Chromatography-Tandem Mass Spectrometry Method for the Analysis of 20 Perfluoroalkyl Substances in Fruit and Vegetables at Sub-Parts-per-Trillion Levels.

In response to the European Food Safety Authority's establishment of a tolerable weekly intake (TWI) for the sum of PFOA, PFNA, PFHxS, and PFOS, a method was developed to quantify and confirm 20 PFASs at the sub-parts-per-trillion level in fruit and vegetables. Improved sensitivity was achieved by (i) increasing the sample intake, (ii) decreasing the solvent volume in the final extract, and (iii) using a highly sensitive mass spectrometer. Except for PFTrDA, target PFASs could be quantitatively determined with an apparent recovery of 90-119%, limits of quantitation down to 0.5 ng/kg, and a relative standard deviation under within-laboratory reproducibility conditions of <28%. The method was successfully applied to 215 fruit and vegetable samples obtained from local grocery stores and markets. Leafy vegetables prove to be the main vegetable category responsible to PFAS exposure, mainly of PFOA, followed by PFHpA and PFHxA.

A Deep Learning Approach to Investigating Clandestine Laboratories Using a GC-QEPAS Sensor

Illicit drug production in clandestine laboratories involves the use of large quantities of different chemicals that can be obtained for legitimate purposes. The identification of these chemicals, including reagents, catalyzers and solvents, is crucial for forensic investigations. From a legal point of view, a drug precursor is a material that is specific and critical to the production of a finished chemical and that constitutes a significant portion of the final molecular structure of the drug. In this study, a gas chromatography quartz-enhanced photoacoustic spectroscopy (GC-QEPAS) sensor—in conjunction with a deep learning model—was evaluated for its effectiveness in the detection and identification of interesting compounds for the production of amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA), phenylcyclohexyl piperidine (PCP), and cocaine. The GC-QEPAS sensor includes a gas sampler, a fast GC for separation, and a QEPAS detector, which excites molecules exiting the GC column using a quantum cascade laser to provide the infra-red (IR) spectrum. The on-site capability of the GC-QEPAS system offers significant advantages over the current instruments employed in this field, including rapid analysis, which is crucial in field operations. This allows law enforcement to quickly identify specimens of interest on site. The system’s performance was validated by taking into account the limit of detection, repeatability, and within-laboratory reproducibility. The results showed excellent repeatability and reproducibility for both the GC and QEPAS modules. The deep learning model, a multilayer perceptron neural network, was trained using IR spectra and retention times, achieving very high classification accuracy in the testing conditions. This study demonstrated the efficacy of the GC-QEPAS sensor combined with a deep learning model for the reliable identification of drug precursors, providing a robust tool for law enforcement during criminal investigations in clandestine laboratories.

Validation Study on Spectrophotometric Measurement of Ethanol from Beer and Non-Alcoholic Beer Samples Distilled by Micro Steam Distillation Method

The method validation technique for determining the ethanol percentage (v/v) in beer and non-alcoholic beer is presented in this study. The underlying idea is to use the micro water vapor method to distill the ethanol from beer and then use the spectrophotometric method, which uses the oxidation of sodium dichromate to measure the amount of ethanol. The Harmonized Guidelines for Single-Laboratory Validation of Methods of Analysis were used to validate the analytical method that we provided. The following aspects of the method were assessed: precision, recovery, linearity, measuring range, detection and quantification limitations, method detection limit, and measurement uncertainty. The following were the limits of detection (LOD) and quantification values (LOQ), and the method detection limit (MDL): ethanol, 0.04%, 0.05%, and 0.15. For both repeatability and within-laboratory reproducibility, the relative standard deviation values were less than 2.36 and 4.12%, respectively. The spiked samples had recovery rates ranging from 97% to 102%. These findings fulfilled the minimal performance standards set forth in AOAC Official Methods of Analysis Appendix F: Guidelines for Standard Method Performance Requirements. As a result, the process can be used for the regular analysis of ethanol in the beer and non-alcoholic beer under study.

Measurement uncertainty in clinical chemistry: ISO 20914 versus nordtest or intermediate precision versus bias

Aim Measuring uncertainty (MU) is crucial to ensure the accuracy and precision of laboratory results. This study compares the ISO 20914 and Nordtest guidelines to analyze the MU values for 20 clinical chemistry analytes over six months. Methods The researchers calculated MU components, including within-laboratory reproducibility (Rw), laboratory analytical performance bias (u(bias)), and combined standard uncertainty (u c), based on internal quality control and external quality assessment data. The final expanded uncertainty (U) values were determined by multiplying the combined uncertainty with a coverage factor (k = 2 for 95% Confidence Interval), following each guideline’s respective procedures. Clinical chemistry analytes were analyzed on Roche Cobas 6000 c501 auto analyzer (Roche Diagnostics, Mannheim, Germany) and manufacturer’s kits were used analysis. Results The results show that 11 out of 20 clinical chemistry analytes met the targeted maximum allowable measurement uncertainty (MAU) values when calculated according to ISO 20914 guideline. Also, 11 out of 20 clinical chemistry analytes’ MU values met the MAU values with the Nordtest guideline’s recommended calculations. However, some tests met the MAU in the ISO 20914 approach but not in the Nordtest guideline, and vice versa. Conclusions The study found that intermediate precision (u Rw) in the ISO 20914 approach and performance bias (u(bias)) in the Nordtest approach significantly impacted MU values. The research highlights the importance of standardization in MU calculation approaches across clinical laboratories. These findings have implications for patient care and clinical decision-making, emphasizing the importance of selecting appropriate laboratory guidelines for routine use.

Within-laboratory reproducibility of Ames test results: Are repeat tests necessary?

The Ames test is required by regulatory agencies worldwide for assessing the mutagenic and carcinogenic potential of chemical compounds. This test uses several strains of bacteria to evaluate mutation induction: positive results in the assay are predictive of rodent carcinogenicity. As an initial step to understanding how well the assay may detect mutagens present as constituents of complex mixtures such as botanical extracts, a cross-sector working group examined the within-laboratory reproducibility of the Ames test using the extensive, publicly available National Toxicology Program (NTP) Ames test database comprising more than 3000 distinct test articles, most of which are individual chemicals. This study focused primarily on NTP tests conducted using the standard Organization for Economic Co-operation and Development Test Guideline 471 preincubation test protocol with 10% rat liver S9 for metabolic activation, although 30% rat S9 and 10 and 30% hamster liver S9 were also evaluated. The reproducibility of initial negative responses in all strains with and without 10% S9, was quite high, ranging from 95% to 99% with few exceptions. The within-laboratory reproducibility of initial positive responses for strains TA98 and TA100 with and without 10% rat liver S9 was ≥90%. Similar results were seen with hamster S9. As expected, the reproducibility of initial equivocal responses was lower, <50%. These results will provide context for determining the optimal design of recommended test protocols for use in screening both individual chemicals and complex mixtures, including botanicals.

Determination of nitrofuran metabolites in muscle by LC-MS/MS and LC-MS/MS/MS: Alternative validation according to Commission Implementing Regulation (EU) 2021/808

Nitrofurans are banned in food of animal origin in the European Union. A rugged liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and LC-MS/MS cubed (LC-MS/MS/MS) analytical method allowing the confirmation of five metabolites of nitrofuran antibacterial agents, furaltadone, furazolidone, nifursol, nitrofurantoin and nitrofurazone in animal muscle tissue was developed and validated. The validation of 1-aminohydantoin (AHD), 3-amino-5-methyl-morpholino-2-oxazolidinone (AMOZ), 3-amino-2-oxazolidinone (AOZ), 3,5-dinitrosalicylic acid hydrazide (DNSH) and semicarbazide (SEM) was carried out according to Commission Implementing Regulation (EU) 2021/808, by the adoption of a matrix-comprehensive in-house validation concept and the standard addition calibration. Validation was successfully performed, starting from 0.4 µg kg−1. Decision limit (CCα), recovery, repeatability, within-laboratory reproducibility and uncertainty of measurement were determined together with a factorial effect analysis. The procedure was verified through the analysis of two certified reference materials. The sample preparation consisted in acid hydrolysis and derivatization steps, followed by a liquid-liquid extraction of the analytes with ethylacetate.

A novel alternative for pyrogen detection based on a transgenic cell line

Pyrogen, often as a contaminant, is a key indicator affecting the safety of almost all parenteral drugs (including biologicals, chemicals, traditional Chinese medicines and medical devices). It has become a goal to completely replace the in vivo rabbit pyrogen test by using the in vitro pyrogen test based on the promoted ‘reduction, replacement and refinement’ principle, which has been highly considered by regulatory agencies from different countries. We used NF-κB, a central signalling molecule mediating inflammatory responses, as a pyrogenic marker and the monocyte line THP-1 transfected with a luciferase reporter gene regulated by NF-κB as an in vitro model to detect pyrogens by measuring the intensity of a fluorescence signal. Here, we show that this test can quantitatively and sensitively detect endotoxin (lipopolysaccharide from different strains) and nonendotoxin (lipoteichoic acid, zymosan, peptidoglycan, lectin and glucan), has good stability in terms of NF-κB activity and cell phenotypes at 39 cell passages and can be applied to detect pyrogens in biologicals (group A & C meningococcal polysaccharide vaccine; basiliximab; rabies vaccine (Vero cells) for human use, freeze-dried; Japanese encephalitis vaccine (Vero cells), inactivated; insulin aspart injection; human albumin; recombinant human erythropoietin injection (CHO Cell)). The within-laboratory reproducibility of the test in three independent laboratories was 85%, 80% and 80% and the interlaboratory reproducibility among laboratories was 83.3%, 95.6% and 86.7%. The sensitivity (true positive rate) and specificity (true negative rate) of the test were 89.9% and 90.9%, respectively. In summary, the test provides a novel alternative for pyrogen detection.

Simultaneous determination of five carbapenems, highly polar antibiotics, in milk by LC-MS/MS

The simultaneous determination of five carbapenems (biapenem, doripenem, ertapenem, imipenem, and meropenem) in raw and pasteurised bovine milk samples using LC-MS/MS was achieved and validated. Chromatographic separation was conducted on an InertSustain® AQ-C18 column using 0.1% formic acid in water and acetonitrile as the mobile phase. Target compounds were extracted using acetonitrile/water (20:80, v/v). After the removal of lipids with acetonitrile-saturated hexane, the dissolved protein was denatured with acetic acid. A portion of the supernatant was passed through an Oasis® PRiME HLB cartridge to remove the matrix. This novel method was validated in accordance with the Japanese validation guidelines and exhibited good trueness, ranging from 86.3% to 96.2%, using matrix-matched calibration curves. The relative standard deviation of repeatability ranged from 1.0% to 6.3%, and that of within-laboratory reproducibility ranged from 1.6% to 7.1%. The limit of quantification was 1.0 µg kg−1 for all analytes. None of the 60 milk samples commercially available in Tokyo contained any analytes. This novel method exhibited high-quality performance and can easily be implemented for the routine monitoring of carbapenems, which are highly polar antibiotics in milk.

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.

Analytical Validation of the PreciseDx Digital Prognostic Breast Cancer Test in Early-Stage Breast Cancer

BackgroundPreciseDx Breast (PDxBr) is a digital test that predicts early-stage breast cancer recurrence within 6-years of diagnosis. Materials and MethodsUsing hematoxylin and eosin-stained whole slide images of invasive breast cancer (IBC) and artificial intelligence-enabled morphology feature array, microanatomic features are generated. Morphometric attributes in combination with patient's age, tumor size, stage, and lymph node status predict disease free survival using a proprietary algorithm. Here, analytical validation of the automated annotation process and extracted histologic digital features of the PDxBr test, including impact of methodologic variability on the composite risk score is presented. Studies of precision, repeatability, reproducibility and interference were performed on morphology feature array-derived features. The final risk score was assessed over 20-days with 2-operators, 2-runs/day, and 2-replicates across 8-patients, allowing for calculation of within-run repeatability, between-run and within-laboratory reproducibility. ResultsAnalytical validation of features derived from whole slide images demonstrated a high degree of precision for tumor segmentation (0.98, 0.98), lymphocyte detection (0.91, 0.93), and mitotic figures (0.85, 0.84). Correlation of variation of the assay risk score for both reproducibility and repeatability were less than 2%, and interference from variation in hematoxylin and eosin staining or tumor thickness was not observed demonstrating assay robustness across standard histopathology preparations. ConclusionIn summary, the analytical validation of the digital IBC risk assessment test demonstrated a strong performance across all features in the model and complimented the clinical validation of the assay previously shown to accurately predict recurrence within 6-years in early-stage invasive breast cancer patients.

Quantitative image analysis of microplastics in bottled water using artificial intelligence

The ubiquitous occurrence of microplastics (MPs) in the environment and the use of plastics in packaging materials result in the presence of MPs in the food chain and exposure of consumers. Yet, no fully validated analytical method is available for microplastic (MP) quantification, thereby preventing the reliable estimation of the level of exposure and, ultimately, the assessment of the food safety risks associated with MP contamination. In this study, a novel approach is presented that exploits interactive artificial intelligence tools to enable automation of MP analysis. An integrated method for the analysis of MPs in bottled water based on Nile Red staining and fluorescent microscopy was developed and validated, featuring a partial interrogation of the filter and a fully automated image processing workflow based on a Random Forest classifier, thereby boosting the analysis speed. The image analysis provided particle count, size and size distribution of the MPs. From these data, a rough estimation of the mass of the individual MPs, and consequently of the MP mass concentration in the sample, could be obtained as well. Critical materials, method performance characteristics, and final applicability were studied in detail. The method showed to be highly sensitive in sizing MPs down to 10 μm, with a particle count limit of detection and quantification of 28 and 85 items/500 mL, respectively. Linearity of mass concentration determined between 10 ppb and 1.5 ppm showed a regression coefficient (R2) of 0.99. Method precision was demonstrated by a repeatability of 9–16% RSD (n = 7) and within-laboratory reproducibility of 15–27% RSD (n = 21). Accuracy based on recovery was 92 ± 15% and 98 ± 23% at a level of 0.1 and 1.0 ppm, respectively. The quantitative performance characteristics thus obtained complied with regulatory requirements. Finally, the method was successfully applied to the analysis of twenty commercial samples of bottled water, with and without gas and flavor additives, yielding results ranging from values below the limit of detection to 7237 (95% CI [6456, 8088]) items/500 mL.