Linearity assessment: deviation from linearity and residual of linear regression approaches.

In this computer simulation study, we examine four different statistical approaches of linearity assessment, including two variants of deviation from linearity (individual (IDL) and averaged (AD)), along with detection capabilities of residuals of linear regression (individual and averaged). From the results of the simulation, the following broad suggestions are provided to laboratory practitioners when performing linearity assessment. A high imprecision can challenge linearity investigations by producing a high false positive rate or low power of detection. Therefore, the imprecision of the measurement procedure should be considered when interpreting linearity assessment results. In the presence of high imprecision, the results of linearity assessment should be interpreted with caution. Different linearity assessment approaches examined in this study performed well under different analytical scenarios. For optimal outcomes, a considered and tailored study design should be implemented. With the exception of specific scenarios, both ADL and IDL methods were suboptimal for the assessment of linearity compared. When imprecision is low (3 %), averaged residual of linear regression with triplicate measurements and a non-linearity acceptance limit of 5 % produces <5 % false positive rates and a high power for detection of non-linearity of >70 % across different types and degrees of non-linearity. Detection of departures from linearity are difficult to identify in practice and enhanced methods of detection need development.

Verification of bile acid determination method and establishing reference intervals for biochemical and haematological parameters in third-trimester pregnant women.

OBJECTIVES: The aims of this study were to verify the bile acids (BA) method and to establish reference intervals (RIs) for bile acids (BA) and biochemical and haematological parameters in Croatian pregnant women. METHODS: BA spectrophotometric method verification was performed on Siemens Atellica Solution CH 930 automated analyser using Sentinel reagent. Stability, precision, trueness, linearity, and RIs, as well as lipemia interference were tested according to CLSI guidelines. BA, biochemical, and haematological parameters were measured in serum (BA, biochemical) and whole blood (haematological) samples of fasting healthy third-trimester pregnant women from Croatia (n=121). The establishment of the RIs was done a priori according to the CLSI EP28-A3C:2010 guideline. Selected reference individuals' data were analysed using parametric, non-parametric, and robust methods. RESULTS: Stability study showed that BA are stable in serum samples for 2 days at 20 °C, 14 days at 4-8 °C, and 22 days at -20 °C. The precision study and adult RIs verification met the criteria. Linearity was verified for the concentration range of 3.5-172.1 µmol/L whereas the lipemia interference test showed a positive bias (%) in BA concentration. The determined reference limits generally exhibited better precision for haematological parameters, being lower than the upper recommended value 0.2, unlike biochemical parameters. Haematological parameters showed notable differences between pregnant and non-pregnant women, while many biochemical parameters' RIs remained similar. Only ALT and GGT showed lower non-comparable RI upper limits in the population pregnant women. CONCLUSIONS: Spectrophotometric BA method showed satisfactory performance and all examined parameters were within the set criteria. Moreover, RIs for key biochemical and haematological parameters, including BAs, have been established for the first time in the population of Croatian pregnant women.

Using analytical performance specifications in a medical laboratory.

Analytical performance specifications (APS) are used for the quantitative assessment of assay analytical performance, with the aim of providing information appropriate for clinical care of patients. One of the major locations where APS are used is in the routine clinical laboratory. These may be used to assess and monitor assays in a range of settings including method selection, method verification or validation, external quality assurance, internal quality control and assessment of measurement uncertainty. The aspects of assays that may be assessed include imprecision, bias, selectivity, sample type, analyte stability and interferences. This paper reviews the practical use of APS in a routine clinical laboratory, using the laboratory I supervise as an example.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for Laboratory Evaluation and Analytical Performance Characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript.The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

Monitoring and environmental risk assessment of agricultural fungicide and insecticides in water, sediment from Kumkale Plain, Çanakkale-Turkey.

This study was conducted to assess pesticide residues in 34 water and sediment samples taken from Kumkale Plain of Çanakkale-Turkey. Residue analyses were performed with the use of Quick-Easy-Cheap-Efficient-Rugged-Safe (QuEChERS)-liquid chromatography/tandem mass spectrometry (LC-MS/MS) procedure. For method verification, blank sediment and water samples were spiked at two limits of quantification (LOQ) levels of the pesticides. Overall recovery was 81.66% for sediment and 91.50% for water samples. In sediment samples, chlorpyrifos-M had the highest concentration, pyridaben was encountered in the majority of the samples (15 samples) and the highest number of pesticides (35) was seen in sample no. s13. In water samples, methoxyfenozide had the greatest concentration, metalaxyl was encountered in the highest number of samples (three samples) and the highest number of pesticide (8) was seen in sample no.w13. Sample no. s13 and w13 were taken from around the fountain basin. Pyraclostrobin and chlorantraniliprole residues exceeded the national limits set for water. In terms of hazard quotient (HQ), pesticides in sediment and waters were found to be safe. Despite the safe nature of pesticide on samples, greater attention has been paid on toxicity of the residues. It was concluded that authorities should put strict regulations on agrochemicals to reduce health risks of these chemicals.

Determination of fungicide residues in soil using QuEChERS coupled with LC-MS/MS, and environmental risk assessment.

Fungicide residues of soil samples taken from Batak Plain of Çanakkale province of Türkiye were assessed. Fungicide residue analyses were performed with the use of QuEChERS method and LC-MS/MS device. Blank samples were spiked at two different limit of quantification (LOQ) levels for method verification. Overall recovery was identified as 85.69% with an RSD of 12.36% (n=360; SD=10.59). A total of 110 soil samples were taken in November 2020. Present analyses revealed that 59.09% of samples contained fungicide residues at different concentrations. Propiconazole had the highest concentration (1736.06 µg/kg) in one sample, taken from the edge of the field where pesticide wastes were found and 26 fungicides were found at different concentrations in the same sample. Azoxystrobin was encountered in majority of the samples (29 samples). The most frequent fungicides were ordered as; boscalid and tebuconazole (22 samples) > metalaxyl (17 samples) > fluopyram (15 samples). Thirteen triazole fungicides were found in soil samples, mostly at moderately hazardous level (Class II). Risk assessments revealed that hazard levels of fungicides for adults and children were low with a hazard quotient (HQ) and hazard index (HI) of <1. Despite the safe nature of fungicides in soil samples, the greatest HQ values were identified for propiconazole (326.52E-08 for adults and 2449.00E-08 for children). The sum of hazard quotients for all fungicides was 86.31E-08 8 for adult and 647.35E-08 for children. In terms of soil pollution, it is important for farmers to apply fungicides with low HQ levels.

Method Verification of the Caretium XC-A30 Automated Erythrocyte Sedimentation Rate Analyser for Erythrocyte Sedimentation Rate.

Background: The erythrocyte sedimentation rate (ESR) analyser is widely used in haematological testing. In addition to the Westergren method, new automatic methods for ESR measurements have been developed. We aimed to study the reliability, precision, accuracy and stability of the Caretium XC-A30 automated ESR analyser. Methods: Ethylenediamine tetraacetic acid (EDTA)-treated blood samples were analysed via the Caretium XC-A30 automated ESR analyser and the Westergren method to compare accuracy. Precision was assessed using control samples and patient samples were classified into three groups-low, medium and high-according to their rates of sedimentation. Moreover, a stability test was performed. Results: The correlation coefficient of the results of the Caretium XC-A30 and Westergren analyses was 0.97. The correlation coefficient of ESR values obtained from the two methods assessed in the low, medium and high groups were r = 0.80, r = 0.68 and r = 0.74, respectively. The coefficient of variation of within-run (%CVw) and between-run (%CVb), with replicates performed with commercial controls samples, were 7.54% and 8.04% for the normal control and 4.68% and 3.50% for abnormal control, respectively. The %CVw obtained with patient samples in the low, medium and high groups were 10.68%, 13.13% and 4.45%, respectively. The Caretium XC-A30 measurements were stable for up to 24 h when samples were stored at 4 °C. Conclusion: The Caretium XC-A30 ESR analyser proved to be a suitable instrument for routine analysis of ESR.

Investigation of pesticide residues in peach and nectarine sampled from Çanakkale, Turkey, and consumer dietary risk assessment.

The present study was conducted to investigate pesticide residues on peach and nectarine. For method verification, samples were spiked at 0.1, 1.0, and 10.0 times of maximum residue limit (MRL) for each pesticide. The Quick-Easy-Cheap-Efficient-Rugged-Safe (QuEChERS)-liquid chromatography/tandem mass spectrometry detection revealed that limit of quantifications (LOQs) of pesticides were below the MRL. The overall recovery was 113.51% with relative standard deviation (RSD) of 17.33% for peach and 113.61% with RSD of 11.44% for nectarine. These figures were within the Directorate-General for Health and Food Safety (SANTE) recovery limits (60-140%) and the values specified for the repeatability (RSD ≤ 20%). Samples were collected from 5 different stands at Çanakkale open markets for 12 weeks. None of the residues was not ≥ MRL in any samples. Maximum levels of 567.80 and 322.10 µg/kg boscalid were detected in peach and nectarine, respectively, corresponding approximately 1/10 and 1/15 of the MRL. Maximum levels for tebuconazole were about 1/12 and 1/10 of the MRL for peach (47.53 µg/kg) and nectarine (56.90 µg/kg), respectively. Chlorpyrifos residues of all samples were below LOQ. According to our findings and the World Health Organisation Guideline, chronic exposure levels of pesticides were low and there is no risk to human health in terms of 3 pesticides.

Practical approach to method verification in plasma and validation in cerebrospinal fluid under accreditation using a flexible scope in molecular virology: setting up the HIV, HBV and HCV Aptima™ Quant Dx assays.

Background Our laboratory obtained the ISO 15189 accreditation for the plasmatic HIV-1, HBV and HCV viral load (VL) using the m2000 RealTime™ system, which was recently changed for the platform Panther®. Here, we discuss a strategy for performing method validation/verification very quickly. Methods We performed the mandatory (repeatability, internal quality assessment [IQA], measurement uncertainty [MU]) and optional technical verifications for CE/IVD assays using the flexible scope range A. We also performed the mandatory assays for the validation of HIV-1 VL in the cerebrospinal fluid (CSF) using the flexible scope range B. The change was checked by following up on the turnaround time (TAT). Results The coefficient of variation (CV%) for repeatability and IQA complied with the limit of 0.25 log. The MU results ranged from 0.04 to 0.25 log copies or IU/mL. The comparisons of methods showed excellent correlations (R2 = 0.96 for the three parameters) but a delayed centrifugation on HCV VL showed variations of up to 2 log IU/mL. An excellent linearity for HIV-1 in the CSF was obtained from 1.5 to 5 log copies/mL with R2 = 0.99. The TAT increased (84%-98%) in routine usage. Conclusions The three Aptima assays are well suited for routine laboratory use and can be integrated within less than 2 weeks in accordance with flexible scope range A. Our data allows us to confidently perform HIV-1 VL in CSF following flexible scope range B. Finally, we provide an organizational guide for flexible scope management in molecular virology within a short time frame.

Precision matters: Repeatability and reproducibility of total PSA and homocysteine measurements in Alinity i-system.

Background: The precision of test measurements is critical in clinical diagnostics, especially for biomarkers like total PSA and homocysteine, which are essential to disease assessment. Using the CMIA approach, this study investigates the repeatability and reproducibility of these biomarkers on the Abbott Alinity system. Methods: The present study was conducted in the clinical chemistry laboratory at Mohammed VI University Hospital of Oujda. The evaluation of the Alinity i-system's analytical performance for total PSA and homocysteine focused on assessing repeatability and intermediate precision. The assessment followed the protocols and guidelines established by the French Accreditation Committee (COFRAC). Results: Our analysis yielded favorable findings regarding the performance of the Alinity assays. The coefficients of variation for both the within-run and between-run precision were less than 5.89% and 4.29%, respectively. These findings produce acceptable outcomes compared to the manufacturer's claims and the SFBC database. Our study underscores the tests' precision, affirming the CMIA method's reliability in measuring total PSA and homocysteine levels. Conclusions: The assessment of the Alinity i-system for total PSA and homocysteine showed significant analytical performance. Our findings have implications for laboratory personnel, researchers, and physicians supporting a continuous diagnostic accuracy improvement culture.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

Less is more: Validating a single method for comprehensive rh-insulin analysis.

The objective of this current study is to establish a single method for potency and related proteins analysis of human insulin formulations using reverse-phase high performance liquid (RP-HPLC) chromatography technique which was validated and verified for the potency analysis in insulin formulations. Chromatographic separation was achieved using an octadecylsilane (C-18) stationary phase and a mobile phase composed of 55% (v/v) buffer (0.2 M sodium sulfate in water, {pH 2.3}) and 45% (v/v) acetonitrile. Detection was performed by UV detector at 214 nm with a flow rate of 1 ml/min and an injection volume of 20 µL, at 40°C. Currently there are separate methods available in Indian Pharmacopoeia for analysis of Potency and Related proteins in human insulin. We have validated a single method where quantitation of potency and related proteins can be performed in the same run. The method validation exhibited linearity over the concentration range of 0.08-4.5 mg/ml (r2=0.999) with limit of detection of 0.094 mg/ml The accuracy of the method was 99-102.8%. Thus, it is proposed that both potency and related proteins in insulin formulations can be precisely evaluated using a single run thus saving the time and cost for quality analysis of insulin preparations both at manufacturing and regulatory laboratories which in turn will increase the market availability of such standard quality insulin preparations for public health use.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the Laboratory Evaluation and Analytical Performance Characteristics (LEAP) checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for Laboratory Evaluation and Analytical Performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

On-site verification of the CBEU method using UriSelect4 chromogenic medium at the National Institute of Hygiene (INH) of Lomé.

PURPOSE: The Cytobacteriological Examination of Urine (CBEU) is one of the most requested microbiological analyses in the medical bacteriology laboratory. According to the ISO 15189 standard, Medical Biology Laboratory (MBL) must validate the techniques before their use. It is in this perspective that, within the Medical Bacteriology Laboratory of the INH of Lome, we have carried out the on-site verification of the CBEU method using UriSelect4 chromogenic medium at the INH of Lomé. MATERIAL AND METHODS: The biological material was composed of reference bacterial strains and clinical bacterial strains isolated at INH. Failure Modes Effects and Criticality Analysis (FMECA) with 5 â€‹M model was used to perform risk analysis and performances as repeatability, intermediate fidelity/reproducibility, sensitivity and inter-operator variability were evaluated using references strains and different operators. "Comité Français d'Accréditation" (COFRAC) SH GTA 04 was used as reference. Single-factor ANOVA was used to analyze the data. RESULTS: Operating procedures, Patients preparation, Samples and Preparation of culture media were identified as main critical points with a criticality index of 8, 9, 9 and 12 respectively. The use of uriselect4 to perform ECBU was shown to be repeatable and reproducible. The sensibility of Uriselect4 to detect urinary infection was 100% with negligible inter-operator variability. CONCLUSION: This study performed on-site verification of Uriselect4 at the bacteriology lab of INH of Lome and identified some critical points to master. The overall performance criteria from COFRAC SH GTA 04 were conform.

A Reliable Method for Determining the Degree of Orientation of Fibrous Foods Using Laser Transmission and Computer Vision.

The degree of organised alignment of fibre structures, referred to as the degree of orientation, significantly influences the textural properties and consumer acceptance of fibrous foods. To develop a new method to quantitatively characterise the fibre structure of such foods, a laser transmission imaging system is constructed to capture the laser beam spot on a sample, and the resulting image undergoes a series of image processing steps that use computer vision to translate the light and dark variations of the original images into distinct ellipses. The results show that the degree of orientation can be reasonably calculated from the ellipse obtained by fitting the outermost isopixel points. To validate the reliability of the newly developed method, we determine the degree of orientation of typical fibrous foods (extruded beef jerky, pork jerky, chicken jerky, and duck jerky). The ranking of the measured orientation agrees with the results of pseudocolour maps and micrographs, confirming the ability of the method to distinguish different fibrous foods. Furthermore, the relatively small coefficients of variation and the strong positive correlation between the degree of organisation and the degree of orientation confirm the reliability of this newly developed method.

Performance evaluation of the XT MicroSlide assay pairs on the Vitros XT 7600 compared to VITROS single microslide assays on Vitros 5600.

Objectives: Pediatric hospitals are always challenged by specimen volumes and thus any innovation in this realm is very welcome. With the introduction of Microslide assay pairs, we aimed to evaluate the analytical performance of the Vitros XT MicroSlide assay pairs on the Vitros XT 7600 compared to single MicroSlides. Design: Performance characteristics included within-run precision, analytical measurable range, method comparison, and interference verification. We compared six XT MicroSlide pairs on the Vitros XT 7600 with twelve corresponding single slide assays on the Vitros 5600 system. Results: The XT MicroSlides on Vitros XT 7600 demonstrated excellent precision, equivalent analytical measurable range, and strong method correlation with single slide assays on Vitros 5600 for most of the assays tested. Within-run CVs of the analytes ranged between 0.32% and 2.93% with between-run CV of less than 8.8% and linearity for all analytes was within the manufacturer's specified range. Interference studies showed comparable effects of hemolysis, lipemia, and bilirubin on both instruments. Conclusions: The XT MicroSlides are comparable to the single MicroSlide assays with improved efficiency, turnaround times and lower sample volumes.

Verification of quantitative analytical methods in medical laboratories.

BACKGROUND: Globally, all medical laboratories seeking accreditation should meet international quality standards to perform certain specific tests. Quality management program provides disciplines targeted to ensure that quality standards have been implemented by a laboratory in order to generate correct results. The hallmark of the accreditation process is method verification and quality assurance. Before introducing a new method in your laboratory, it is important to assess certain performance characteristics that reflect the concept of method verification. METHODS: In this review, we illustrated how to verify the performance characteristics of a new method according to the recent guidelines. It includes an assessment of precision, trueness, analytical sensitivity, detection limits, analytical specificity, interference, measuring range, linearity, and measurement uncertainty. CONCLUSIONS: Although the presence of several updated guidelines used to determine the performance characteristics of new methods in clinical chemistry laboratories, the real practice raised several concerns with the application of these guidelines which in need for further consideration in the upcoming updates of these guidelines.