Estimation of measurement uncertainty for the quantification of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid and its glucuronide in urine using liquid chromatography-tandem mass spectrometry

Detection of Cannabinoids in Oral Fluid Specimens as the Preferred Biological Matrix for a Point-of-Care Biosensor Diagnostic Device

An increasing number of countries have started to decriminalize or legalize the consumption of cannabis for recreational and medical purposes. The active ingredients in cannabis, termed cannabinoids, affect multiple functions in the human body, including coordination, motor skills, memory, response time to external stimuli, and even judgment. Cannabinoids are a unique class of terpeno-phenolic compounds, with 120 molecules discovered so far. There are certain situations when people under the influence of cannabis may be a risk to themselves or the public safety. Over the past two decades, there has been a growing research interest in detecting cannabinoids from various biological matrices. There is a need to develop a rapid, accurate, and reliable method of detecting cannabinoids in oral fluid as it can reveal the recent intake in comparison with urine specimens, which only show a history of consumption. Significant improvements are continuously made in the analytical formats of various technologies, mainly concerning improving their sensitivity, miniaturization, and making them more user-friendly. Additionally, sample collection and pretreatment have been extensively studied, and specific devices for collecting oral fluid specimens have been perfected to allow rapid and effective sample collection. This review presents the recent findings regarding the use of oral fluid specimens as the preferred biological matrix for cannabinoid detection in a point-of-care biosensor diagnostic device. A critical review is presented, discussing the findings from a collection of review and research articles, as well as publicly available data from companies that manufacture oral fluid screening devices. Firstly, the various conventional methods used to detect cannabinoids in biological matrices are presented. Secondly, the detection of cannabinoids using point-of-care biosensors is discussed, emphasizing oral fluid specimens. This review presents the current pressing technological challenges and highlights the gaps where new technological solutions can be implemented.

Uncertainty Evaluation for the Quantification of Urinary Amphetamine and 4-Hydroxyamphetamine Using Liquid Chromatography-Tandem Mass Spectrometry: Comparison of the Guide to the Expression of Uncertainty in Measurement Approach and the Monte Carlo Method with R

Estimating the measurement uncertainty (MU) is becoming increasingly mandatory in analytical toxicology. This study evaluates the uncertainty in the quantitative determination of urinary amphetamine (AP) and 4-hydroxyamphetamine (4HA) using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method based on the dilute-and-shoot approach. Urine sample dilution, preparation of calibrators, calibration curve, and method repeatability were identified as the sources of uncertainty. To evaluate the MU, the Guide to the Expression of Uncertainty in Measurement (GUM) approach and the Monte Carlo method (MCM) were compared using the R programming language. The MCM afforded a smaller coverage interval for both AP (94.83, 104.74) and 4HA (10.52, 12.14) than that produced by the GUM (AP (92.06, 107.41) and 4HA (10.21, 12.45)). The GUM approach offers an underestimated coverage interval for Type A evaluation, whereas the MCM provides an exact coverage interval under an abnormal probability distribution of the measurand. The MCM is useful in complex settings where the measurand is combined with numerous distributions because it is generated from the uncertainties of input quantities based on the propagation of the distribution. Therefore, the MCM is more practical than the GUM for evaluating the MU of urinary AP and 4HA concentrations using LC-MS/MS.

Estimation of measurement uncertainty for the quantification of protein by ID-LC-MS/MS

The emergence of mass spectrometry (MS)-based methods to quantify proteins for clinical applications has led to the need for accurate and consistent measurements. To meet the clinical needs of MS-based protein results, it is important that the results are traceable to higher-order standards and methods and have defined uncertainty values. Therefore, we outline a comprehensive approach for the estimation of measurement uncertainty of a MS-based procedure for the quantification of a protein biomarker. Using a bottom-up approach, which is the model outlined in the "Guide to the Expression of Uncertainty of Measurement" (GUM), we evaluated the uncertainty components of a MS-based measurement procedure for a protein biomarker in a complex matrix. The cause-and-effect diagram of the procedure is used to identify each uncertainty component, and statistical equations are derived to determine the overall combined uncertainty. Evaluation of the uncertainty components not only enables the calculation of the measurement uncertainty but can also be used to determine if the procedure needs improvement. To demonstrate the use of the bottom-up approach, the overall combined uncertainty is estimated for the National Institute of Standards and Technology (NIST) candidate reference measurement procedure for albumin in human urine. The results of the uncertainty approach are applied to the determination of uncertainty for the certified value for albumin in candidate NIST Standard Reference Material® (SRM) 3666. This study provides a framework for measurement uncertainty estimation of a MS-based protein procedure by identifying the uncertainty components of the procedure to derive the overall combined uncertainty.

Statistical distributions commonly used in measurement uncertainty in laboratory medicine

Uncertainty is an inseparable part of all types of measurement. Recently, the International Organization for Standardization (ISO) released a new standard (ISO 20914) on how to calculate measurement uncertainty (MU) in laboratory medicine. This standard can be regarded as the beginning of a new era in laboratory medicine. Measurement uncertainty comprises various components and is used to calculate the total uncertainty. All components must be expressed in standard deviation (SD) and then combined. However, the characteristics of these components are not the same; some are expressed as SD, while others are expressed as a ± b, such as the purity of the reagents. All non-SD variables must be transformed into SD, which requires a detailed knowledge of common statistical distributions used in the calculation of MU. Here, the main statistical distributions used in MU calculation are briefly summarized.

Estimating Uncertainty in Wisconsin’s Evidential Breath Alcohol Measurements

Breath alcohol measurement accuracy and precision quantification is a critical component of impaired driving prosecution and is required for laboratory accreditation. The Chemical Testing Section of Wisconsin’s Department of Transportation conducted a bottom-up study to quantify uncertainty of breath alcohol measurements conducted on Intoximeter’s EC/IR II instrument. After an exercise in combined uncertainty source identification, individual input values were either reported from National Institute of Standards and Technology traceable reference materials or quantified using instrument data from 2014 to 2018. From input values, an expanded uncertainty value of 4.58 × 10-3 g/210L was found that encompasses all identified sources with a 95% confidence interval.

Measurement uncertainty and metrological traceability of whole blood cyclosporin A mass concentration results obtained by UHPLC-MS/MS

BACKGROUND

Traceable and accurate results of cyclosporine A (CsA) mass concentrations in whole blood are required to ensure the monitoring of immunosuppressive therapy in transplant recipients. Metrological traceability and measurement uncertainty can allow ensuring reliability and comparability of these results over time and space. In this study, we provide a practical and detailed example of how the traceability and uncertainty of mass concentration of CsA results, obtained using an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) procedure, can be described and estimated.

METHODS

Traceability was described mainly according to ISO 17511 and information obtained from certificates facilitated with the manufacturer's calibrators. Uncertainty estimation was performed using the bottom-up and top-down approaches. For the bottom-up approach, the most relevant sources of uncertainty were identified and later used to estimate the standard, combined and expanded uncertainties. For the top-down approach, expanded uncertainty was estimated directly using intralab quality control data mainly.

RESULTS

Mass concentration of CsA results was traceable to the manufacturer's product calibrators used to calibrate the UHPLC-MS/MS procedure. The expanded uncertainties estimated by the bottom-up and top-down approaches were 7.4% and 7.2%, respectively.

CONCLUSIONS

After performing the bottom-up and top-down approaches, we observed that their results were quite similar. This fact would confirm that the top-down approach could be sufficient for estimating uncertainty of CsA mass concentrations in whole blood results in clinical laboratories. Finally, we hope that this study can help and motivate clinical laboratories to describe metrological traceability and to perform measurement uncertainty studies based on the simpler top-down approach.

Evaluation of the measurement uncertainty: Some common mistakes with a focus on the uncertainty from linear calibration

The rational strategy in the evaluation of analytical measurement uncertainty is to combine the "whole method" performance data, such as precision and recovery, with the uncertainty contributions from sources not adequately covered by those data. This paper highlights some common mistakes in evaluating the uncertainty when pursuing that strategy, as revealed in current chromatographic literature. The list of the uncertainty components usually taken into account is discussed first and fallacies with the LOD- and recovery uncertainties are noted. Close attention is paid to the uncertainty arising from a linear calibration normally used. It is demonstrated that following a well-known formula for the standard deviation of an analytical result obtained from a straight line calibration leads to double counting the precision contribution to the uncertainty budget. Furthermore, the precision component itself is often estimated improperly, based on the number of replicates taken from the precision assessment experiment. As a result, the relative uncertainty from linear calibration is overestimated in the budget and may become the largest contribution to the combined uncertainty, which is clearly shown with an example calculation based on the literature data.

Rapid quantification of free and glucuronidated THCCOOH in urine using coated well plates and LC–MS/MS analysis

Aim: Generally, urine drug testing for cannabis abuse involves measuring total concentrations of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) obtained by enzymatic and/or alkaline hydrolysis of THCCOOH-glucuronide. As hydrolysis can be inconsistent and incomplete, direct measurement of the two metabolites is preferable. Methodology & results: We developed a high-throughput LC–MS/MS method for simultaneous quantification of free and glucuronidated THCCOOH in urine using coated 96-well plates for analyte extraction and column-switching chromatography. Excellent separation of the two analytes was achieved within 2.5 min, with linear ranges from 5 to 2000 μg/l for THCCOOH and from 10 to 4000 μg/l for THCCOOH-glucuronide. Conclusion: The method was successfully validated and applied to authentic urine samples from cannabis consumers, demonstrating its applicability for routine cannabinoid testing.