The (non)sense of routinely analysing beta-hydroxybutyric acid in forensic toxicology casework.

Beta-hydroxybutyric acid (BHB) is a ketone body which is generated from fatty acids as an alternative energy source when glucose is not available. Determination of this compound may be relevant in the forensic laboratory as ketoacidosis - an elevated level of ketone bodies - may contribute to the cause of death. In this study, we aimed at determining the relevance of routinely implementing BHB analysis in the forensic toxicological laboratory, as BHB analysis typically requires an additional workload.

Dried blood spot analysis of gabapentin as a valid alternative for serum: a bridging study.

We evaluated the applicability of a validated GC-MS method for the determination of gabapentin in dried blood spots (DBS). Important for the acceptance of DBS sampling as an alternative sampling strategy is the possibility to base solid conclusions on the quantification. Therefore, bridging studies -studies in which the correlation between both DBS and a reference matrix (e.

Microwave-assisted on-spot derivatization for gas chromatography-mass spectrometry based determination of polar low molecular weight compounds in dried blood spots.

Dried blood spot (DBS) sampling and analysis is increasingly being applied in bioanalysis. Although the use of DBS has many advantages, it is also associated with some challenges. E.

Quantification of EtG in hair, EtG and EtS in urine and PEth species in capillary dried blood spots to assess the alcohol consumption in driver's licence regranting cases.

Background: In Belgium, the analysis of indirect biomarkers such as carbohydrate deficient transferrin (CDT%), gamma-glutamyltransferase (GGT), aspartate aminotransferase/alanine aminotransferase (AST/ALT) and mean corpuscular volume (MCV), is currently used to monitor the alcohol consumption in cases of fitness to drive assessment. We evaluated the use of direct ethanol markers for this purpose, exclusively determined in matrices obtained via non- or minimally invasive sampling.

Methods: Three validated quantitative methods (ethylglucuronide (EtG) in hair and urine, ethylsulfate (EtS) in urine, and phosphatidylethanol species (PEth 16:0/18:1, PEth 18:1/18:1 and PEth 16:0/16:0) in capillary dried blood spots (C-DBS)) were used.

Alternative sampling strategies for the assessment of alcohol intake of living persons.

Monitoring of alcohol consumption by living persons takes place in various contexts, amongst which workplace drug testing, driving under the influence of alcohol, driving licence regranting programs, alcohol withdrawal treatment, diagnosis of acute intoxication or fetal alcohol ingestion. The matrices that are mostly used today include blood, breath and urine. The aim of this review is to present alternative sampling strategies that allow monitoring of the alcohol consumption in living subjects.

Quantification of phosphatidylethanol 16:0/18:1, 18:1/18:1, and 16:0/16:0 in venous blood and venous and capillary dried blood spots from patients in alcohol withdrawal and control volunteers.

Phosphatidylethanol species (PEths) are promising biomarkers of alcohol consumption. Here, we report on the set-up, validation, and application of a novel UHPLC-ESI-MS/MS method for the quantification of PEth 16:0/18:1, PEth 18:1/18:1, and PEth 16:0/16:0 in whole blood (30 μL) and in venous (V, 30 μL) or capillary (C, 3 punches (3 mm)) dried blood spots (DBS). The methods were linear from 10 (LLOQ) to 2000 ng/mL for PEth 16:0/18:1, from 10 (LLOQ) to 1940 ng/mL for PEth 18:1/18:1, and from 19 (LLOQ) to 3872 ng/mL for PEth 16:0/16:0.

Degradation and interconversion of plant pteridines during sample preparation and ultra-high performance liquid chromatography-tandem mass spectrometry.

The degradation and interconversion of a selected set of pterins (dihydroneopterin, hydroxymethyldihydropterin, dihydroxanthopterin, neopterin, hydroxymethylpterin, xanthopterin, 6-formylpterin, 6-carboxypterin and pterin), spiked to charcoal-treated potato and Arabidopsis thaliana matrix was investigated, together with their relative recovery in potato and A. thaliana. As a result, a matrix-specific procedure for the ultra-high performance liquid chromatography-tandem mass spectrometry based determination of 6 aromatic pterins (neopterin, hydroxymethylpterin, xanthopterin, 6-formylpterin, 6-carboxypterin and pterin) is proposed: 1.

An optimized and validated SPE-LC-MS/MS method for the determination of caffeine and paraxanthine in hair.

Caffeine is the probe drug of choice to assess the phenotype of the drug metabolizing enzyme CYP1A2. Typically, molar concentration ratios of paraxanthine, caffeine's major metabolite, to its precursor are determined in plasma following administration of a caffeine test dose. The aim of this study was to develop and validate an LC-MS/MS method for the determination of caffeine and paraxanthine in hair.

Improving folate (vitamin B9) stability in biofortified rice through metabolic engineering.

Biofortification of staple crops could help to alleviate micronutrient deficiencies in humans. We show that folates in stored rice grains are unstable, which reduces the potential benefits of folate biofortification. We obtain folate concentrations that are up to 150 fold higher than those of wild-type rice by complexing folate to folate-binding proteins to improve folate stability, thereby enabling long-term storage of biofortified high-folate rice grains.

Are capillary DBS applicable for therapeutic drug monitoring of common antipsychotics? A proof of concept.

Aim: DBS sampling has been proposed as an alternative for venous blood collection in therapeutic drug monitoring (TDM) of antipsychotics. For implementation in routine practice, a comparison between capillary and venous blood concentrations is mandatory.

Results: A DBS method for quantification of antipsychotics was clinically validated.

Alternative Sampling Strategies for Cytochrome P450 Phenotyping.

Interindividual variability in the expression and function of drug metabolizing cytochrome P (CYP) 450 enzymes, determined by a combination of genetic, non-genetic and environmental parameters, is a major source of variable drug response. Phenotyping by administration of a selective enzyme substrate, followed by the determination of a specific phenotyping metric, is an appropriate approach to assess the in vivo activity of CYP450 enzymes as it takes into account all influencing factors. A phenotyping protocol should be as simple and convenient as possible.

Does volumetric absorptive microsampling eliminate the hematocrit bias for caffeine and paraxanthine in dried blood samples? A comparative study.

Volumetric absorptive microsampling (VAMS) is a novel sampling technique that allows the straightforward collection of an accurate volume of blood (approximately 10μL) from a drop or pool of blood by dipping an absorbent polymeric tip into it. The resulting blood microsample is dried and analyzed as a whole. The aim of this study was to evaluate the potential of VAMS to overcome the hematocrit bias, an important issue in the analysis of dried blood microsamples.

Application of the characteristic function to evaluate and compare analytical variability in an external quality assessment scheme for serum ethanol.

Background: As a cornerstone of quality management in the laboratory, External Quality Assessment (EQA) schemes are used to assess laboratory and analytical method performance. The characteristic function is used to describe the relation between the target concentration and the EQA standard deviation, which is an essential part of the evaluation process. The characteristic function is also used to compare the variability of different analytical methods.

A validated ultra-high-performance liquid chromatography-tandem mass spectrometry method for the selective analysis of free and total folate in plasma and red blood cells.

A stable isotope dilution LC-MS/MS method is the method of choice for the selective quantitative determination of several folate species in clinical samples. By implementing an integrated approach to determine both the plasma and red blood cell (RBC) folate status, the use of consumables and time remains limited. Starting from a single 300μl whole blood sample, the folate status in plasma and RBCs can be determined after separating plasma and RBCs and sequential washing of the latter with isotonic buffer, followed by reproducible lysis using an ammonium-based buffer.

Paraxanthine/Caffeine Concentration Ratios in Hair: An Alternative for Plasma-Based Phenotyping of Cytochrome P450 1A2?

Background And Objective: Although metabolite-to-parent drug concentration ratios in hair have been suggested as a possible tool to study the metabolism of drugs in a non-invasive way, no studies are available that evaluated this in a systematic way. Cytochrome P450 (CYP) 1A2 is a drug-metabolizing enzyme characterized by large inter-individual differences in its activity. The standard approach for CYP1A2 phenotyping is to determine the paraxanthine/caffeine ratio in plasma at a fixed timepoint after intake of a dose of the CYP1A2 substrate caffeine.

Do capillary dried blood spot concentrations of gamma-hydroxybutyric acid mirror those in venous blood? A comparative study.

Gamma-hydroxybutyric acid (GHB) is a well-known illicit club and date-rape drug. Dried blood spot (DBS) sampling is a promising alternative for classical venous sampling in cases of (suspected) GHB intoxication since it allows rapid sampling, which is of interest for the extensively metabolized GHB. However, there is limited data if -and how- capillary DBS concentrations correlate with venous concentrations.

Folates from metabolically engineered rice: a long-term study in rats.

Scope: The biological impact of folates from folate rice, a metabolically engineered (biofortified) rice line, rich in folates, was investigated. Its consumption may be helpful to fight folate deficiency. Our objective was to investigate the potential of folate rice to supply the organism with folates and evaluate its biological effectiveness using a rat model.

Spot them in the spot: analysis of abused substances using dried blood spots.

Dried blood spot (DBS) sampling and DBS analysis have increasingly received attention during recent years. Furthermore, a substantial number of DBS methods has recently become available in clinical, forensic and occupational toxicology. In this review, we provide an overview of the different DBS-based methods that have been developed for detecting (markers of) abused substances.

Impact of the grinding process on the quantification of ethyl glucuronide in hair using a validated UPLC-ESI-MS-MS method.

The Society of Hair Testing (SoHT) has provided cutoffs for the quantification of ethyl glucuronide (EtG) in hair to indicate occasional or chronic/excessive alcohol consumption. Although several sensitive methods have been reported, past proficiency test results show a lack of reproducibility. An ultra-performance liquid chromatographic mass spectrometric method (LLOQ of 10 pg EtG/mg hair) has been validated according to the international guidelines, including the successful participation in five proficiency tests.

Potassium-based algorithm allows correction for the hematocrit bias in quantitative analysis of caffeine and its major metabolite in dried blood spots.

Although dried blood spot (DBS) sampling is increasingly receiving interest as a potential alternative to traditional blood sampling, the impact of hematocrit (Hct) on DBS results is limiting its final breakthrough in routine bioanalysis. To predict the Hct of a given DBS, potassium (K(+)) proved to be a reliable marker. The aim of this study was to evaluate whether application of an algorithm, based upon predicted Hct or K(+) concentrations as such, allowed correction for the Hct bias.