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AbstractArsenic (As) occurs naturally in different forms and oxidation states. Amongst them, inorganic arsenic (iAs) is classified as both genotoxic and carcinogenic whilst other organic arsenic species are considered less toxic. As in rice is mainly present in the form of iAs which therefore poses a health risk to populations that consume rice as a staple food. In 2011, the Joint Food and Agriculture Organisation/World Health Organisation Expert Committee on Food Additives determined the iAs benchmark dose lower confidence limit for a 0.5% increased incidence of lung cancer in humans (BMDL0.5) which computed to be 3.0 μg/kg body weight (bw)/day. However, the European Food Safety Authority (EFSA) has recently lowered the BMDL0.5 of iAs to 0.06 μg iAs/kg bw per day based on a low risk of bias case–control/cohort study on skin cancer as a Reference Point (RP). Subsequently, EFSA established a BMDL10 of 18.2 mg monomethylarsenic (V) (MMA(V))/kg bw/day and 1.1 mg dimethylarsenic (V) (DMA(V))/kg bw/day as RPs with reference to studies on skin cancer and urinary bladder tumours in rats respectively. Therefore, As speciation is essential when conducting dietary exposure assessment. Recent studies showed thiolated counterparts of MMA and DMA were found in certain foodstuffs, especially grain. However, these thiolated As species were not recognised in acidic, basic or peroxide systems as they transformed to MMA and DMA in these extractants. Therefore, one of the objectives of this review was to assess whether published analytical methods are fit for As speciation analysis, especially for iAs, MMA and DMA, in foodstuffs. Besides, discussion was conducted on whether limits of detection are sufficiently low for dietary exposure assessment with respect to recently established RPs of iAs, MMA and DMA when an upper bound approach is applied. Moreover, possible future research gaps are identified based on current knowledge and existing literature. [ABSTRACT FROM AUTHOR]

Consumption of low levels of egg already can evoke harmful physiological responses in humans in those allergic to eggs. By detection of egg in food products, using Egg ELISA kits to determine its unintended presence, food producers can respond to avoid potential safety or quality risks of their products. Selection of an ELISA kit fit for the issue at hand is challenging due to, amongst others, lack of information on assay performances with specified matrices. In this study, performances of seven commercial egg ELISA kits are compared for nine different relevant matrices: cookie, chocolate, pasta, dressing, stock cube, wine, vegetable drink and milk, ice cream and meat/meat replacers. The presence of egg was unified for all ELISA kits to mg total egg protein kg−1 food product. In every matrix, kit performances for recovery, intra- and interassay were compared, and also processing is accounted for by determination of egg in incurred samples. All seven kits were able to detect egg qualitatively at the VITAL3 ED01 level of 0.2 mg total egg protein and the corresponding relevant portion size for each matrix. For quantitative results, each ELISA kit showed an increase in detected egg concentration with increased egg levels and performed within the set criteria for recovery for the cookie, chocolate, stock cube and wine. For pasta, vegetable drink and milk, ice cream, and salad dressing, recovery of egg was within the set criteria for at least 4 ELISA kits. Most challenging matrices were meat/meat replacers, showing high matrix effects which could not be explained by the possible egg presence in the cognate blank. Only one ELISA kit was able to recover egg within the set criteria for the meat/meat replacer matrix. Results enable food industry to choose for ELISA kits suitable for egg detection in the matrix of interest.

Supercritical fluid chromatography is proving to be a good separation and sample preparation tool for various analytical applications and, as such, has gained the attention of the anti‐doping community. Here, the applicability of supercritical fluid chromatography hyphenated to tandem mass spectrometry for routine doping control analysis was tested. A multi‐analyte method was developed to cover 197 drugs and metabolites that are prohibited in sport. More than 1000 samples were analyzed by applying a "dilute and inject" approach after hydrolysis of glucuronide metabolites. Additionally, a comparison with routinely used liquid chromatography‐mass spectrometry was performed with 250 of the 1000 samples and a number of past positive anti‐doping samples. It revealed some features where supercritical fluid chromatography‐tandem mass spectrometry was found to be complementary or advantageous to liquid chromatography‐mass spectrometry for anti‐doping purposes, such as better retention of analytes that are poorly retained in reversed‐phase liquid chromatography. Our results suggest that supercritical fluid chromatography‐tandem mass spectrometry is sensitive (limit of detection <50% relevant minimum required performance level required by the World Anti‐Doping Agency for anti‐doping analysis), reproducible, robust, precise (analytes of interest area coefficient of variation <5%; retention time difference coefficient of variation <1%) and complementary to existing techniques currently used for routine analysis in the World Anti‐Doping Agency accredited laboratories. [ABSTRACT FROM AUTHOR]

An HPLC method with UV detector was developed for the determination of DEHP phthalate ester in the alcoholic beverage "Ouzo". Phthalate esters are added to plastic packaging for food and beverages to increase flexibility, transparency, strength, and longevity. When these substances come into contact with food or beverages, they can lead to the migration of phthalate residues into the product. This paper presents a two-step process involving extraction of the sample with hexane and separation of the phthalates by HPLC. The method was validated for specificity, linearity, limit of quantification, accuracy, precision, range, and ruggedness. The linear range is 0.3–1.5 mg/L DEHP, with a lower limit of quantification of 0.06 mg/L. The precision study showed acceptable RSD values, and the working range is 0.3 to 1.5 mg/L DEHP. The relative standard uncertainty of DEHP determination in Ouzo was ±8%. The results show that the in-house method is suitable, reliable, and fit-for-purpose. [ABSTRACT FROM AUTHOR]

ISO/IEC 17025: 2017 requires laboratories to verify the performance of methods before introducing them. ISO 16140-3: 2021 employs LOD50 (the level of detection for which 50％ of tests give a positive result) as an index for evaluating the performance of microbial qualitative methods. While fecal coliforms and Staphylococcus aureus qualitative methods are widely implemented in Japan, their LOD50 values have not been established, making performance evaluation of these methods impossible at the time of introduction. As a result, we looked into estimating the LOD50 values of fecal coliforms and S. aureus qualitative methods to evaluate the index of method performance. The fecal coliforms method had an LOD50 value of 19‒31 CFU/mL and the S. aureus method had an LOD50 value of 29‒49 CFU/mL by laboratory personnels using samples without food matrix. We estimated LOD50 of six food samples using each method in a single laboratory. The LOD50 values of all foods calculated using the fecal coliforms method were in the range of 14‒27 CFU/g and those calculated using the S. aureus method were in the range of 25‒ 48 CFU/g, indicating that these methods did not have low levels of sensitivity detection compared with skill variation. LOD50 values for food samples with the highest or lowest LOD50 in each method were compared among five laboratories. Because the estimated LOD50 values of both the methods were within four times of each laboratory result, which is the acceptable limit specified in ISO 16140-3: 2021, they were assumed to be suitable values. This study is expected to be utilized as a benchmark in the verification of method performance in each laboratory. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The availability of reliable sensitive multi-analyte methods for unambiguous determination of mycotoxins is crucial for ensuring food and feed safety, considering their adverse health effects and (co-)occurrence in various foods. Accordingly, a multi-mycotoxin confirmatory method for simultaneous determination of 11 mycotoxins regulated in cereals within the European Union (EU) using ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was developed and in-house validated to fit the EU legislation requirements for analytical methods. A simple sample preparation was based on a solid–liquid extraction using a solvent mixture acetonitrile/water/formic acid (79/20/1, v/v/v) and a dilution of raw extract using water/acetonitrile/formic acid (79/20/1, v/v/v) before instrumental analysis. Average recoveries in all three validated cereal crop types (maize, wheat, and barley), spiked at multiple levels, were found acceptable for all analytes when matrix-matched calibration was used, ranging from 63.2% to 111.2% and also showing very good repeatability, with relative standard deviations below 20%. Matrix effect (SSE) evaluation revealed maize as the most complex of the three analyzed cereal matrices, with strong SSE (<50% and >150%) recorded for all 11 analyzed mycotoxins. An additional method verification was performed through successful participation in proficiency testing schemes, with the achieved z-scores generally in the acceptable range of −2 ≤ z ≤ 2. The obtained validation results demonstrated the suitability of the developed confirmatory multi-mycotoxin UHPLC-MS/MS method based on a dilute-and-shoot principle for the simultaneous determination of low concentrations of 11 EU-regulated mycotoxins in cereals, including aflatoxins B1, B2, G1 and G2, deoxynivalenol, fumonisins B1 and B2, zearalenone, T-2 and HT-2 toxins, and ochratoxin A. [ABSTRACT FROM AUTHOR]

Objective The aim of this study was to validate a gas chromatography-mass spectrometry (GC-MS) method for the measurement of 5α-cholestanol in the clinical laboratory in agreement with ISO 15189:2012. Materials and Methods The GC-MS performance was evaluated and proficiency testing data were used to estimate the measurement uncertainty of the method considering the recommendations of international guidelines. Results The calibration curves were linear from 6 to 50 μmol/L, with r 2 >.99. The limit of detection and limit of quantitation were determined to be 0.36 and 2.58 μmol/L, respectively. The bias ranged from –18.9% to 15.2% for 6.5, 18.3, and 66 μmol/L. The intra- and interassay reproducibility was <20% at the various concentrations studied. The expanded uncertainty was determined to be 50.9%. Conclusion The GC-MS method for the measurement of 5α-cholestanol has proved to have acceptable analytical performance for use in the clinical laboratory. [ABSTRACT FROM AUTHOR]

Background: Sigma metric calculations provide laboratories an objective means to assess analytical method performance. Methods with higher sigma values are desirable because they are more reliable and may use less frequent quality control in order to maintain optimal performance. Sigma metrics can also serve as a tool when comparing method performance across assay and manufacturer platforms. Methods: Sigma values were calculated for 28 common chemistry and 24 immunoassay assays across 3 academic medical centers. Method imprecision and percent bias relative to peer group means was tabulated from Bio-Rad quality control (QC) data. Sigma values were calculated for each method using allowable total error (TEa) from either the CLIA evaluation limits or desirable biological variation. Average sigma values were generated for each site and graded as optimal: >6 sigma; good: 5–6 sigma; marginal: 3–5 sigma; or poor: <3 sigma. Analysis of NIST SRM1950 standards for a subset of analytes allowed an estimation of absolute bias. Results: Clinical chemistry assays displayed similar method performance across all 3 study sites. Immunoassays showed significant differences between manufacturers, and a majority of assays failed to meet an optimal level of performance. Different TEa values produced different sigma metrics with more stringent TEa limits based on biological variation, resulting in poorer performance estimates than the wider CLIA limits. Analysis of NIST standards revealed similar performance. Conclusions: Sigma metrics are comparable for chemistry but not immunoassay platforms. The selection of total allowable error goals led to differences in sigma metrics. [ABSTRACT FROM AUTHOR]

Abstract Background Membrane proteins constitute up to 30% of the human proteome. These proteins have special properties because the transmembrane segments are embedded into lipid bilayer while extramembranous parts are in different environments. Membrane proteins have several functions and are involved in numerous diseases. A large number of prediction methods have been introduced to predict protein subcellular localization as well as the tolerance or pathogenicity of amino acid substitutions. Results We tested the performance of 22 tolerance predictors by collecting information on membrane proteins and variants in them. The analysis indicated that the best tools had similar prediction performance on transmembrane, inside and outside regions of transmembrane proteins and comparable to overall prediction performances for all types of proteins. PON-P2 had the highest performance followed by REVEL, MetaSVM and VEST3. Further, we tested with the high quality dataset also the performance of seven subcellular localization predictors on membrane proteins. We assessed separately the performance for single pass and multi pass membrane proteins. Predictions for multi pass proteins were more reliable than those for single pass proteins. Conclusions The predictors for variant effects had better performance than subcellular localization tools. The best tolerance predictors are highly reliable. As there are large differences in the performances of tools, end-users have to be cautious in method selection.

Global deterioration of marine ecosystems, together with increasing pressure to use them, has created a demand for new, more efficient and cost-efficient monitoring tools that enable assessing changes in the status of marine ecosystems. However, demonstrating the cost-efficiency of a monitoring method is not straightforward as there are no generally applicable guidelines. Our study provides a systematic literature mapping of methods and criteria that have been proposed or used since the year 2000 to evaluate the cost-efficiency of marine monitoring methods. We aimed to investigate these methods but discovered that examples of actual cost-efficiency assessments in literature were rare, contradicting the prevalent use of the term “cost-efficiency.” We identified fve different ways to compare the cost-efficiency of a marine monitoring method: (1) the cost–benefit ratio, (2) comparative studies based on an experiment, (3) comparative studies based on a literature review, (4) comparisons with other methods based on literature, and (5) subjective comparisons with other methods based on experience or intuition. Because of the observed high frequency of insufficient cost–benefit assessments, we strongly advise that more attention is paid to the coverage of both cost and efficiency parameters when evaluating the actual cost-efficiency of novel methods. Our results emphasize the need to improve the reliability and comparability of cost-efficiency assessments. We provide guidelines for future initiatives to develop a cost-efficiency assessment framework and suggestions for more unified cost-efficiency criteria. [ABSTRACT FROM AUTHOR]

With the upcoming EU regulation on the use of in-vitro diagnostic devices, a critical evaluation of the current status of our in-house developed LC-MS/MS methods is timely and of great relevance. Recently, much attention has been devoted to the need for better specification of analytical and clinical performance. Appropriate reporting of the actual achieved analytical performance is an important determinant of the clinical performance and subsequent clinical effectiveness of a test. We advocate for the application of CLSI C62-A guidelines for method validation and suggest some adaptations for analytical validation of in-house developed LC-MS/MS methods for endogenous substances. Additionally, we underline the importance of well-equipped reviewers and standardized method description, including the presentation of figural evidence of obtained method performance. Achieving this ensures future quality of our in-house developed LC-MS/MS methods. [ABSTRACT FROM AUTHOR]

Monitoring local occupancy and the regional distribution of wild mammals is essential to guide species management and set conservation priorities. However, variables such as weather, substrate hardness, or habitat characteristics may indirectly affect the performance of the methods employed for monitoring mammal occurrence. Little information exists about the influence of spatio‐temporal factors on the performance of survey methods and its implications for mammal monitoring. Using data from a heterogeneous region in the Guadiamar River basin, SW Spain, which encompass forest, agricultural, and mosaic landscapes, we (1) explore whether four widely used detection methods, namely camera traps, scent stations, track surveys, and scat surveys, differ in efficiency; (2) test the hypothesis that spatio‐temporal factors do not affect method efficiency; and (3) examine the effect of landscape on the replication effort needed to detect target species. After controlling for variation in mammal occurrence across space and over time, the interaction between spatio‐temporal factors and detection methods was not significant. Likewise, we found a negligible influence of landscape type on the replication effort needed to detect species actually present. When compared to camera traps, scent stations, and scat surveys, track surveys were the most efficient and fastest methodology for surveying mammals in our study landscapes. Monitoring programs of mammal occurrence are often applied to broad and heterogeneous regions and/or during extended periods. Therefore, survey methods should describe not only spatio‐temporal variation in mammal abundance or activity but also maintain high detection efficiency in a variety of environmental conditions. The detection efficiency of each survey method changed little regardless of considerable environmental variation, making more reliable the marked differences between methods in their ability to detect target species. We recommend accounting for the effect of spatio‐temporal factors as potential sources of variation in order to test whether our results can be generalized and to increase the quality of large‐scale monitoring of mammal occurrence. [ABSTRACT FROM AUTHOR]

Evaluation of method performance involves the consideration of numerous factors that can contribute to error. A variety of measures of performance can be borrowed from the signal detection literature and others are drawn from statistical science. This article demonstrates the principles of performance evaluation by applying multiple measures to osteometric sorting models for paired elements run against data from known individuals. Results indicate that false positive rates are close, on average, to expected values. As assemblage size grows, the false positive rate becomes unimportant and the false negative rate becomes significant. Size disparity among the commingled individuals plays a significant role in method performance, showing that case-specific circumstances (e.g. assemblage size and size disparity) will determine method power.

The reference evapotranspiration (ETo) is a parameter applied in meteorological, climatological and hydrological studies being of great importance for the planning, management and management of water resources. Due to the need for knowledge about the loss of water from vegetated surfaces, researchers have developed a variety of methods for estimating ETo, some of which are well accepted, while others are criticized, such as the Penman-Monteith-FAO (PM-FAO) meteorological data, which is not always available by limiting its use. The PM-FAO method has been used for decades to be considered internationally and most appropriate for ETo estimates. This method represents the physical phenomenon of evapotranspiration that involves almost all meteorological elements analyzed in automatic and conventional meteorological stations. On the other hand, when this method is impossible to apply due to the lack of some input data, alternative methods are justified (Hargreaves-Samani, Blaney-Criddle, Priestley-Taylor, Jensen-Haise, Camargo, Makkink, Kharrufa, Linacre, Class A tank, Thornthwaite and solar radiation) according to soil and climatic conditions. [ABSTRACT FROM AUTHOR]

An accurate and sensitive liquid chromatography-electrospray ionisation/multi stage mass spectrometry (LC–ESI–MS/MS) method has been developed for the characterization and quantitation of nine heterocyclic amine (HCA) compounds. We were identified 2-Amino-3-methyl-3H-imidazo[4,5-F]quinoline (IQ), 2-Amino-3-methyl-3H-imidazo[4,5-f]quinoxaline (IQx), 2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ), 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-Amino-3,7,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (7,8-DiMeIQx), 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine as polar molecules, and they were eluted accordingly at the beginning of the analysis. However, Norharman, Harman and AαC were identified as a non-polar molecules and were eluted last. The excellent selectivity and sensitivity achieved by the selected reaction monitoring mode permitted satisfactory quantitation and confirmation of the injected HCA compounds with limit of detection and quantitation ranges from 0.17 to 1.44 pg and 0.53 to 4.57 pg, respectively. The recoveries ranged from 74 to 108%, with an interday and intraday precision of 1.6–1.9% and 0.1–0.9%, respectively. The method was successfully applied to identify and quantify the studied HCAs in fried and grilled chicken. [ABSTRACT FROM AUTHOR]

Quantitation of gluten in gluten-free products is a great challenge as it is hindered by several factors including the lack of certified reference materials. To resolve this problem, our research group, in cooperation with other international experts, started a series of experiments with the goal of the production of a suitable gluten reference material. As a part of this research, several different wheat cultivars and their isolated gluten proteins were characterized by different methods, including enzyme-linked immunosorbent assay (ELISA). However, we need to know the performance of the ELISA methods used for this special area of research. During the present work we investigated the accuracy and precision of two different ELISA methods for our own laboratory conditions and special sample matrices (wheat flours and gliadin isolate). We have found that the tested performance characteristics of the methods seem to be appropriate on a case-by-case basis, but the long-term measurement uncertainty is higher, which makes it difficult to evaluate the results obtained with the ELISA method for these types of samples. [ABSTRACT FROM AUTHOR]

Despite the availability of a large number of antibody and DNA based methods for detection and quantification of allergens in food there remain significant difficulties in selecting the optimum technique to employ. Published methods from research groups mostly contain sufficient detail concerning target antigen, calibration procedures and method performance to allow replication by others. However, routine allergen testing by the food industry relies upon commercialised test kits and frequently the suppliers provide disappointingly little specification detail on the grounds that this is proprietary information. In this review we have made a critical assessment of the published literature describing the performance of both commercial and non-commercial test kits for food allergens over the period 2008–2018. Mass spectrometric methods, which have the potential to become reference methods for allergens, are not covered in this review. Available information on the specifications of commercial ELISA and LFD test kits are tabulated for milk, egg and peanut allergens, where possible linking to publications concerning collaborative studies and proficiency testing. For a number of commercial PCR test kits, specifications provided by manufacturers for detection of a small selection of allergen are tabulated. In conclusion we support the views of others of the critical need for allergen reference materials as the way forward to improve the comparability of different testing strategies in foods. [ABSTRACT FROM AUTHOR]

Evaluation of method performance involves the consideration of numerous factors that can contribute to error. A variety of measures of performance can be borrowed from the signal detection literature and others are drawn from statistical science. This article demonstrates the principles of performance evaluation by applying multiple measures to osteometric sorting models for paired elements run against data from known individuals. Results indicate that false positive rates are close, on average, to expected values. As assemblage size grows, the false positive rate becomes unimportant and the false negative rate becomes significant. Size disparity among the commingled individuals plays a significant role in method performance, showing that case-specific circumstances (e.g. assemblage size and size disparity) will determine method power. [ABSTRACT FROM AUTHOR]

Background: Chloride is the main anion in human body. A simple and accurate method for serum chloride measurement was developed using ion chromatography (IC) in China. Methods: In the measurement, serum samples were diluted 500 times with water, filtered and injected into ion chromatography column. A mixed eluent (2 mmol/L CO32- + 12 mmol/L OH-) was used and peak area signal was collected. Five calibrators made from Standard Reference Material (SRM) 919b were used in the bracketing method. The IC method was applied as the comparative method and six ion selective electrode (ISE) measurement systems were evaluated using 60 individual patient serums. Results: The IC method was proven to be accurate. The precision was 0.18% - 0.30%, the recovery was 99.66% - 100.60%, the bias was 0.19% to -0.06%, and the related expanded uncertainty was 0.775% (k = 2). The precisions of the ISE systems were smaller than the 0.9% tolerable CV except for the Beckman DXC (0.91% - 1.16%). In comparison, the results of linear regression analysis showed that the correlation coefficients were 0.9876 to 0.9979. For all systems, the range of mean biases was -5.96 - 1.48 mmol/L (-5.57% - 1.36%); the expected biases at the medical decision levels were -4.97% - 0.84% at 90 mmol/L and -6.02% - 1.76% at 120 mmol/L. All biases of the Beckman AU met the requirement of within ± 1.5%. Conclusions: The IC measurement method is proven to be of high precision and trueness, and the quality of routine ISE measurement of serum chloride still needs significant improvement. The establishment of the IC method can improve the measurement quality and promote its standardization process in China. [ABSTRACT FROM AUTHOR]

This paper presents a semi-analytical solution for the 3D problem of a cylindrical tunnel embedded in an elastic half-space subject to plane harmonic compressional and shear waves. Both the tunnel and soil are modelled as an elastic continuum. Conformal mapping is employed to transform the original physical domain with boundary surfaces of two different types onto an image domain with surfaces of the same type, which makes the problem easier to solve. The total wave field in the half-space consists of incident and reflected (from the half-space surface) plane waves, as well as directly and secondary scattered cylindrical waves, while the total wave field in the tunnel consists of refracted cylindrical waves. The secondary scattered waves, generated when the cylindrical waves directly scattered from the tunnel meet the half-space surface, are represented by cylindrical waves that originate from an image source, which is in line with the spirit of the method of images. The unknown amplitude coefficients of the cylindrical waves are determined from the boundary and continuity conditions of the tunnel–soil system by projecting those onto the set of circumferential modes, which results in a set of algebraic equations. Results show that the present method converges for a small number of circumferential modes. We observe very good agreement between the obtained results and those in literature. In a systematic evaluation, we demonstrate that the method works well for the frequency band of seismic waves, as well as for the complete considered ranges of the tunnel/soil stiffness ratio, the embedded depth of the tunnel, the vertical incident angle and the tunnel thickness. However, the results obtained for a moderate tunnel–soil stiffness contrast under the incident compressional wave are inaccurate when Hankel functions are used to represent the cylindrical waves in the tunnel, which is due to the refracted shear waves in the tunnel transitioning from propagating to evanescent (in the 3D case). These inaccuracies can be perfectly overcome by representing the waves in the tunnel by Bessel functions. We also find that the present method generally works better for the incident compressional wave than for the incident shear wave, as the condition number of the matrix (related to the mentioned algebraic equations) is often larger in the latter case. In view of engineering practice, we conclude that the tunnel is safer when the surrounding soil is stiffer, the tunnel is thicker and the vertical incident angle is larger. Finally, the present method, which is in general fast, elegant and accurate, can be used in preliminary design so as to avoid pronounced resonances, and to assess stress distributions and ground vibrations. • The method of conformal mapping has been extended successfully from 2D to 3D. • The method performs well for frequencies inside the seismic frequency band. • It is beneficial to use Bessel functions instead of Hankel functions to represent the waves in the tunnel. • A parametric study shows that the tunnel is safer when the soil is stiffer, the tunnel is thicker and the vertical incident angle is larger. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrates are used commonly as water-quality indicators in wadeable streams and rivers. However, increased depth and overall complexity of large rivers may cause inaccessibility or unacceptable index and metric variability when attempting a single wadeable method. Significant increases in sampling effort and time expenditure have been recommended to compensate for the increased variability when assessing large rivers. However, the transition between wadeable streams and nonwadeable rivers is not well defined, especially for free-flowing systems. We evaluated the utility of a modified wadeable-stream collection method for sampling large and complex semiwadeable rivers. Our results suggest that water-quality measurements across the width of a river can be used to identify influences of multiple water sources. This spatial information and a single-habitat (e.g., riffle-run) approach could be used with a modest increase in sampling effort to reduce metric variability and provide important source-tracking information. These supplementary data and a grasp of the complex ecological processes that exist in large rivers are essential for recognizing why biological communities differ among sites and for using macroinvertebrates to assess large river systems. [ABSTRACT FROM AUTHOR]

More and more testing procedures with different principles are being developed covering both quantitative and qualitative analyses. To ensure the reliability of them and relevant testing results, performance evaluation and method validation are necessary. Following the investigation into a variety of testing procedures, this paper is intended to discuss the rational classification of them according to the nature and purpose of testing. Five kinds of testing procedures are summarized according to different combination of input and output properties of the testing model, which are properties on nominal, ordinal, interval and ratio scales. On this basis, the method validation and performance evaluation parameters, statistical approaches and tools available for each group of testing procedures are discussed. The classification of testing procedures seems helpful for inter-comparison of testing procedures with different purposes and application fields, and the development of some general rules for the performance evaluation and validation of them. [ABSTRACT FROM AUTHOR]

Crystallization with additives is developed and standardized on wheat samples from different origins and varieties. When an aqueous cupric chloride dihydrate solution crystallizes in the presence of wheat flour as additive, specific patterns emerge which can be evaluated by image analysis. Performance tests are evaluated by structure analysis of the resulting crystallization patterns. Different factors of influence were tested, from which milling of the kernels in the sample preparation and the mixing ratio of cupric chloride and additive on the plate and the evaporation and crystallization were identified as the most crucial ones which have to be standardized. Comparisons between different laboratories indicate that the method can be used in another laboratory, but chamber conditions have to be documented and controlled. [ABSTRACT FROM AUTHOR]

The discovery of many noncanonical peptides detectable with sensitive mass spectrometry inside, outside, and on cells shepherded the development of novel methods for their identification, often not supported by a systematic benchmarking with other methods. We here propose iBench, a bioinformatic tool that can construct ground truth proteomics datasets and cognate databases, thereby generating a training court wherein methods, search engines, and proteomics strategies can be tested, and their performances estimated by the same tool. iBench can be coupled to the main database search engines, allows the selection of customized features of mass spectrometry spectra and peptides, provides standard benchmarking outputs, and is open source. The proof-of-concept application to tryptic proteome digestions, immunopeptidomes, and synthetic peptide libraries dissected the impact that noncanonical peptides could have on the identification of canonical peptides by Mascot search with rescoring via Percolator (Mascot+Percolator)., (© 2022 The Authors. Proteomics published by Wiley-VCH GmbH.)

The importance of the density functional theory (DFT) methods on the computation of cluster hyperpolarizabilities is discussed. The performance of the conventional BLYP, BP86, BPW91, B3LYP, B3PW91, and B3P86 functionals in the computation of the second hyperpolarizability of aluminum phosphide prolate clusters up to 60 atoms is compared with the 'half and half functionals' BHandH and BHandHLYP and to the long-range corrected functionals LC-(BLYP, BP86, BPW91), CAM-B3LYP, and wB97XD. The presented results demonstrate that when long-range corrections are incorporated on pure and hybrid functionals their performance is vastly affected. What is more, the obtained DFT results are compared with second-order Møller-Plesset perturbation theory (MP2) all electron calculations. It is shown that all the long-range outcomes are bracketed by the MP2 and Hatree-Fock (HF) values. The relative ordering of the obtained longitudinal hyperpolarizabilities follows strictly the trend MP2 > CAM-B3LYP > wB97XD > LC-(BLYP, BP86, BPW91) > HF. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

Many organizations in the USA collect aquatic bioassessment data using different sampling and analysis methods, most of which have unknown performance in terms of data quality produced. Thus, the comparability of bioassessments produced by different organizations is often unknown, ultimately affecting our ability to make comprehensive assessments on large spatial scales. We evaluated a pilot approach for determining bioassessment performance using macroinvertebrate data obtained from several states in the Southeastern USA. Performance measures evaluated included precision, sensitivity, and responsiveness to a human disturbance gradient, defined in terms of a land disturbance index value for each site, combined with a value for specific conductance, and instream habitat quality. A key finding of this study is the need to harmonize ecoregional reference conditions among states so as to yield more comparable and consistent bioassessment results. Our approach was also capable of identifying potential areas for refinement such as reevaluation of less precise, sensitive, or responsive metrics that may result in suboptimal index performance. Higher performing bioassessments can yield information beyond 'impaired' versus 'unimpaired' condition. Acknowledging the limitations of this pilot study, we would recommend that performance evaluations use at least 50 sites, 10 of which are ecoregional reference sites. Efforts should be made to obtain data from the entire human disturbance gradient in an ecoregion to improve statistical confidence in performance measures. Having too few sites will result in an under-representation of certain parts of the disturbance gradient (e.g., too few poor quality sites), which may bias sensitivity and responsiveness estimates. [ABSTRACT FROM AUTHOR]

The Performance Evaluation Program for HIV-1 incidence tests provided quality assurance services to laboratories conducting the serological testing algorithm for recent HIV seroconversion by use of a modified less-sensitive version of the Vironostika HIV-1 MicroElisa System assay. We report on the performance of the assay using proficiency testing and quality control materials tested from 2001 to 2008.Two sets of 5 blinded serum panels using common calibration and quality control materials were tested. The mean, standard deviation, and coefficient of variation were calculated. Results were analyzed for misclassifications: false recent HIV infection errors (long-term infection classified as HIV infection less than 1 year), false long-term infection errors (HIV infection less than 1 year classified as long-term infection), and differences in standardized optical density means and variances over time.The false recent error rate was 1.26% (n = 2219). The false long-term error rate was 0.25% (n = 1618). No significant trends were observed for misclassification rates by year, and no significant trend in the standardized optical density over 7 years was observed.Laboratories using the less-sensitive Vironostika HIV-1 assay produced consistent results by use of a common calibrator and quality control materials. [ABSTRACT FROM AUTHOR]

Abstract: Interlaboratory comparison by means of method performance precision and bias studies and proficiency testing schemes are described. The set-up of the experiments as well as the evaluation of the data by means of graphical and statistical methods are considered. The use of interlaboratory data for the estimation of measurement uncertainty is also addressed. [Copyright &y& Elsevier]

Abstract: Proficiency testing (PT) is critical in the pesticides field, as this area places more demands than most on the analyst, in terms of needing to monitor a wide range of pesticides in a great range of differing matrices. We have looked for trends in performance using results from three different PT schemes (two commercial, and one organized by the European Commission – the European Proficiency Test). ‘Difficult’ and ‘easy’ individual pesticides in ‘difficult’ and ‘easy’ matrices are identified, and relative levels of performance are reported. We have assessed an overview of analytical methods used by PT participants, where possible looking for correlations between performance and choice of method (in particular choice of instrumental technique). [Copyright &y& Elsevier]

Abstract: The proficiency testing program in food microbiology RAEMA (Réseau d’Analyses et d’Echanges en Microbiologie des Aliments), created in 1988, currently includes 450 participating laboratories. This interlaboratory comparison establishes proficiency in detection of Salmonella and Listeria monocytogenes, as well as enumeration of aerobic micro-organisms, Enterobacteriaceae, coliforms, β-glucuronidase-positive Escherichia coli, anaerobic sulfito-reducing bacteria, Clostridium perfringens, coagulase-positive staphylococci, and L. monocytogenes. Twice a year, five units samples are sent to participants to assess their precision and trueness for enumeration and detection of micro-organisms. Most of participating laboratories use standard or validated alternative methods, they were 50–70% in 1994 and, for 5 years, they are 95%. An increasing use of alternative methods was also observed. This phenomenon is all the more significant as standard methods are laborious and time consuming; thus, 50% of the laboratories use alternative methods for the detection of Salmonella and L. monocytogenes. More and more laboratories use ready-to-use media and although the percentage is variable according to the microflora, we can consider that, today, 50–60% of the laboratories participating to the proficiency program only use ready-to-use media. The internal quality assurance programs lead also to an increasing use of media quality controls. The impact of analytical methods on bacterial counts was assessed by grouping together the results obtained by participating laboratories during the 10 last testing schemes from 1999 to 2003. The identified significant factors influencing enumeration results are variable from one microflora to another. Some of them significantly influence many microflora: the plating method (spiral plating or not) is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, and staphylococci, the type of culture medium and the medium manufacturer is influential for aerobic micro-organisms, Enterobacteriaceae, coliforms, E. coli, anaerobic sulfito-reducing bacteria, staphylococci, and L. monocytogenes. Others are specific of some micro-organisms: the resuscitation broth for L. monocytogenes, the mode of medium preparation for staphylococci and the incubation temperature for C. perfringens. These effects lead generally to small differences of about 0.1log10 cfug−1, except for the enumeration of anaerobic sulfito-reducing bacteria, where the difference reaches 0.7log10 cfug−1. These results, although difficult to extrapolate to all actual situations, which associate numerous food constituents and physiological states of bacteria to detect or numerate, allow nevertheless the quantification of interlaboratory variations linked to the methods in use. The analysis of bacterial counts obtained by the laboratories participating to the RAEMA proficiency testing program allowed also to validate a formula to calculate the repeatability of bacterial counts and to estimate the between-laboratory uncertainties for the majority of micro-organisms enumerated in food microbiology. The repeatability uncertainty is only indirectly affected by the method in use but depends essentially on the number of counted colonies. On the other hand, the between-laboratory uncertainty varies with the enumeration method in use, this variability is relatively small for the enumerations calling for methods without colony confirmation, i.e. for the enumeration of aerobic micro-organisms, Enterobacteriaceae, ‘total’ and thermotolerant coliforms, β-glucuronidase-positive E. coli and coagulase-positive staphylococci with the technique using the rabbit-plasma fibrinogen agar. For these methods, the average between-laboratory standard deviation is 0.17log10 cfug−1. The between-laboratory uncertainty is, on the contrary, larger for more complex techniques. For the enumeration of coagulase-positive staphylococci with the Baird–Parker agar, the between-laboratory standard deviation is equal to 0.23log10 cfug−1, it is equal to 0.28log10 cfug−1 for the enumeration of L. monocytogenes, to 0.34log10 cfug−1 for the enumeration of C. perfringens, and to 0.47log10 cfug−1 for the enumeration of anaerobic sulfito-reducing bacteria. [Copyright &y& Elsevier]

Abstract: This article presents an overview of statistical methods used in validation and proficiency testing for qualitative testing in analytical chemistry, paying particular attention to interlaboratory study. A definition of “qualitative analysis” that allows a general treatment of a wide variety of different examples is used. We discuss the characterisation of qualitative method performance, and consider in detail methods for the analysis of false response rates. We review appropriate statistical methods for a variety of circumstances, including the application of logistic regression to interlaboratory and intralaboratory studies of method performance. Finally, we propose provisional recommendations for the design and statistical treatment of validation and proficiency studies. [Copyright &y& Elsevier]

Lead (Pb) and cadmium (Cd) are environmental pollutants, known to cause adverse health effects in humans even following long-term exposure to low doses. These metals, individually or in combination with other persistent environmental contaminants, have been claimed to have the potential to cause alterations in the function of the endocrine system. Human exposure to Pb and Cd is generally assessed by monitoring their concentrations in blood, taking into account the influence of various factors, such as age, gender, smoking habit, occupation, alcohol consumption, diet and air pollution. Following the phase-out of leaded gasoline in the European Union and improvements in food-packaging and contamination control, a decrease in blood Pb levels of the general population has been observed in several European countries and the USA. We report the preliminary results of a study, performed within the framework of the project “Human Exposure to Xenobiotics with potential Endocrine Activities: Evaluation of Reproductive and Developmental risks”. We measured the concentrations of Cd and Pb in the blood of a group of patients with endocrine/metabolic disorders. The analytical procedures, based on atomic absorption spectrometry, were validated according to the EURACHEM guidelines. The median values and ranges were 0.48 μg l−1 (0.20–1.73 μg l−1) and 21.8 μg l−1 (12.0–65.7 μg l−1) for Cd and Pb, respectively; the Cd levels were significantly higher in smokers. Overall, the concentrations of Cd and Pb found in our series of patients were comparable to levels currently expected in the general population. [Copyright &y& Elsevier]

In 1999 the Centre of Biomedical Research (CRB) in co-operation with the Italian interdisciplinary and intersociety Working Group on Markers of Myocardial Damage proposed a national external quality assurance scheme that was granted in accordance with the UK Clinical Pathology Accreditation Standards in 2001. The scheme, which stresses the importance of educational aspects in quality assurance, was scientifically designed to ensure that it would provide an objective assessment of participants' performance and promote quality improvements to meet the needs of participants. The present paper reports on the data collected in EQA cycles conducted to evaluate improvements in the performance of participants and in related methods. The findings obtained demonstrate that during the 4-year experience the scheme provided opportunities to improve the performance of laboratories and promoted an efficient, more satisfactory approach to analytical aspects. The number of unacceptable performances decreased from 11.6% to 5.6% for troponin I, from 19.5% to 9.0% for myoglobin and from 13.2% to 4.3% for creatine kinase myocardial isoenzyme (CK-MB). During cycles in 2001 and 2002, inter-variability (coefficient of variation, CV%) data for all markers appeared satisfactory and showed a significant improvement (lower than 10%), in particular for procedures automated on Dade Beh- ring Dimension and Beckman Access systems. How- ever, reference values/decisional limits declared by laboratories and those suggested by the manufacturers are not comparable, even within the same diagnostic system. The findings demonstrate that participation in EQA schemes provided an opportunity for participating laboratories to continuously improve the quality of their services. [ABSTRACT FROM AUTHOR]

• D-HFUF-SAL was effective in enumerating coliphage levels from 1 l water samples. • Average somatic and F + coliphage recoveries were 72 % and 52 %, respectively. • Somatic coliphage recovery in freshwater was slightly higher than F+ (p = 0.0134). • F + coliphage recovery was lower than somatic in marine waters (p ≤ 0.0001). • Spike titer method significantly affected F + coliphage recovery rates (p < 0.0001). Dead-end hollow fiber ultrafiltration combined with a single agar layer assay (D-HFUF-SAL) has potential use in the assessment of sanitary quality of recreational waters through enumeration of coliphage counts as measures of fecal contamination. However, information on applicability across a broad range of sites and water types is limited. Here, we tested the performance of D-HFUF-SAL on 49 marine and freshwater samples. Effect of method used to titer the spiking suspension (SAL versus double agar layer [DAL]) on percent recovery was also evaluated. Average somatic coliphage recovery (72 % ± 27) was significantly higher (p < 0.0001) compared to F+ (53 % ± 19). This was more pronounced for marine (p ≤ 0.0001) compared to freshwaters (p = 0.0134). Neither method affected somatic coliphage, but DAL (28 % ± 12) significantly (p < 0.0001) underestimated F + coliphage recoveries compared to SAL (53 % ± 19). Overall, results indicate that, while D-HFUF-SAL performed well over a wide variety of water types, F + coliphage recoveries were significantly reduced for marine waters suggesting that some components unique to this habitat may interfere with the assay performance. More importantly, our findings indicate that choice of spike titer method merits careful consideration since it may under-estimate method percent recovery. [ABSTRACT FROM AUTHOR]

• An analytical method for detection of 12 anthelmintics in fishery products was developed. • Analysis was carried out using liquid chromatography-tandem mass spectrometry. • The established method exhibited satisfactory validation parameters. • None of the market samples were tested positive for the monitored analytes. • The reported protocol could be used for xenobiotic quantification in aquaculture. Herein, an analytical method was developed for simultaneous determination of 12 anthelmintics (closantel, niclosamide, nitroxynil, rafoxanide, cymiazole, fluazuron, levamisole, morantel, praziquantel, pyrantel, thiophanate, and trichlorfon) in fishery products (eel, flatfish, and shrimp) using liquid-liquid extraction coupled with liquid chromatography-tandem mass spectrometry. A reversed-phase analytical column was then used to separate the analytes from various matrices. Linear matrix-matched calibration curves were generated with coefficients of determination ≥ 0.9935. Recovery rates at three spiking levels (5, 10, and 20 µg/kg) ranged between 61.58% and 119.37% with relative standard deviations ≤ 19.05%. Limits of detection were in the range of 0.3–1.6 μg/kg, whereas limits of quantification ranged between 1.0 and 5.0 μg/kg. The matrix effect was moderate with values ranging from −99.47% to 51.98%. Matrices procured from large markets tested negative for the 12 anthelmintics. The developed method proved amenable to real sample testing and can be used for simultaneous determination of target analytes in aquatic products. [ABSTRACT FROM AUTHOR]

Introduction : We aimed to determine the analytical capabilities of a commonly used faecal immunochemical test (FIT) to detect faecal haemoglobin (Hb) in symptomatic people attending primary care in the context of the English NICE DG30 guidance. Materials and Methods : Data obtained from independent verification studies and clinical testing of the HM-JACKarc FIT method in routine primary care practice were analysed to derive performance characteristics. Results : Detection capabilities for the FIT method were 0.5 µg/g (limit of blank), 1.3 µg/g (limit of detection) and 3.0 µg/g (limit of quantitation). Of 33 non-homogenized specimens, 31 (93.9%) analysed in triplicate were consistently categorized relative to 10 µg/g, compared to all 33 (100%) homogenized specimens. Imprecision was higher (median 27.8%, (range 20.5% to 48.6%)) in non-homogenized specimens than in homogenized specimens (10.2%, (7.0 to 13.5%)). Considerable variation was observed in sequential clinical specimens from individual patients but no positive or negative trend in specimen degradation was observed over time (p = 0.26). Discussion : The FIT immunoassay evaluated is capable of detecting faecal Hb at concentrations well below the DG30 threshold of 10 µg/g and is suitable for application in this context. The greatest practical challenge to FIT performance is reproducible sampling, the pre-analytical step associated with most variability. Further research should focus on reducing sampling variability, particularly as post-COVID-19 guidance recommends greater FIT utilization.