Clenbuterol is a well-established β2-agonist, which is prohibited in sports and strictly regulated for use in the livestock industry During the last few years clenbuterol-positive results in doping controls and in samples from residents or travellers from a high-risk country were suspected to be related the illegal use of clenbuterol for fattening A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to detect low clenbuterol residues in hair with a detection limit of 002 pg/mg A sub-therapeutic application study and a field study with volunteers, who have a high risk of contamination, were performed For the application study, a total dosage of 30 µg clenbuterol was applied to 20 healthy volunteers on 5 subsequent days One month after the beginning of the application, clenbuterol was detected in the proximal hair segment (0-1 cm) in concentrations between 043 and 476 pg/mg For the second part, samples of 66 Mexican soccer players were analyzed In 89% of these volunteers, clenbuterol was detectable in their hair at concentrations between 002 and 190 pg/mg A comparison of both parts showed no statistical difference between sub-therapeutic application and contamination In contrast, discrimination to a typical abuse of clenbuterol is apparently possible Due to these findings results of real doping control samples can be evaluated Copyright © 2014 John Wiley & Sons, Ltd

Statistical significance of hair analysis of clenbuterol to discriminate therapeutic use from contamination

Amphetamines, cannabinoids, cocaine, opiates, methadone, and benzodiazepines in authentic hair samples with drug concentrations around the medical and psychological assessment (MPA) guidelines cut-offs were screened by LUCIO-direct ELISA kits. Following confirmation of all positive and a significant number of negatively screened samples with gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods accredited for forensic purposes. Receiver operating characteristics (ROC) were plotted and the area under the curve (AUC) and overall misclassification rate (OMR) were calculated and compared to those obtained for the same drug classes in urine. While fulfilling the validation criteria of the German forensic guidelines, for almost all screening tests in hair and urine the AUC were greater than 0.8, indicating good to excellent performance. Moreover the AUC calculated for the detection of drugs in hair did not differ significantly to the AUC calculated for the detection of the same drug classes in urine, thus showing a comparable screening performance to the well accepted, previously published application of the same ELISAs for the detection of drugs at unconventionally low cut-offs in urine. For the first time, the validation of the immunoassay tests for the complete 6-drug panel MPA profile in hair and urine using a large population of authentic hair and urine samples with drug concentrations around MPA cut-offs, lower than conventional clinical or workplace drug testing guidelines cut-offs as well as those suggested by the Society of hair testing (SoHT) is presented.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/dta.1644

Utility of ELISA screening for the monitoring of abstinence from illegal and legal drugs in hair and urine

Phosphatidylethanol (PEth) is a direct biomarker for alcohol consumption consisting of a fraction of different ethanol-modified, homologue phospholipids. The aim of this study was to validate an ultra-high-performance liquid chromatography-tandem mass spectrometry method to quantitate six different homologues of PEth (16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2, and 18:1/18:1) from dried blood spots (DBSs). DBSs were prepared volumetrically (20 μL of whole blood) and extracted with 1 mL of methanol (0.02 ng/μL internal standards). PEth homologues were separated on a BEH C18 column (2.1 × 150 mm, 1.7 μm) using methanol and ammonium acetate buffer (25 mM) in a 7 min isocratic run. Multiple reaction monitoring mode was used for the detection of PEth and the internal standards. Calibrators (10-1000 ng/mL) and quality controls (40, 400, and 700 ng/mL) were prepared from spiked whole blood; external control samples were obtained from proficiency testing schemes. After a comprehensive validation of the method, quantitative patterns of the different homologues were investigated in PEth positive samples (n = 57) from patients in a transplant setting. Satisfactory chromatographic separation, sensitive detection, and reliable quantification of the PEth homologues in DBSs can be achieved using the liquid chromatography-tandem mass spectrometry (LC/MS/MS) procedure. Validation results, including accuracy, linearity, recovery, matrix effects, and in-process stability, complied with international standards, and the analytical performance of the procedure was not affected by the hematocrit of the blood samples. Different quantitative patterns of the investigated PEth homologues were observed in authentic samples from liver transplant patients. This method will enable the study of the kinetics of six PEth homologues simultaneously and investigate the meaning of the homologues' distribution in individuals.

Analysis of six different homologues of phosphatidylethanol from dried blood spots using liquid chromatography-tandem mass spectrometry.

Methadone and buprenorphine are commonly used as oral substitutes in opiate maintenance programs to treat persons who are dependent on heroin During these programs, patients are not allowed to continue using illicit drugs Abstinence can easily be monitored by urine tests with immunochemical methods It is well known that the intravenous abuse of heroin substitutes like methadone or buprenorphine has become common as well The methadone-prescribing physician has no opportunity to check whether the opiate maintenance treatment patient takes his substitution medicines orally as intended or continues with his intravenous misuse now substituting the methadone instead of injecting heroin In Germany, substitutes are available as liquids and tablets that contain carbohydrates as adjuvants Sucrose is used to increase viscosity in liquids, while lactose is needed for pressing tablets (eg, Methaddict w and Subutex w ) In case of oral ingestion, disaccharides are broken down into monosaccharides by disaccharidases in the small intestine These monosaccharides are absorbed into the blood stream by special monosaccharide transporters Disaccharidases do not exist in blood, thus sucrose and lactose are not split if substitute medicines are injected intravenously Our assumption, therefore, was that they are excreted unchanged in urine We investigated a method for the detection of disaccharides in urine as markers of intravenous abuse of substitutes Urine samples of 26 intravenous substitute abusers showed all positive results for lactose (769%) and/or sucrose (731%) The method is assumed to be useful to detect intravenous abuse of substitutes

Disaccharides in urine samples as markers of intravenous abuse of methadone and buprenorphine.

Most of the daily work of forensic toxicologists deals with fatal cases resulting from overdoses of licit and illicit drugs. However, another reason for fatalities in patients suffering from epilepsy can be undetectable or subtherapeutic levels of antiepileptic drugs. Some studies have shown a correlation between “sudden unexpected death in epilepsy” (SUDEP) and the ineffective treatment of epilepsy. Low levels of antiepileptic drugs may be a risk factor for SUDEP. The death of a psychiatric patient also suffering from epilepsy inspired the investigation. Subsequent to the death of the patient, the doctor was accused of providing inadequate therapy for epilepsy. The patient was to be treated with valproic acid. We developed and validated a simple method of determining valproic acid levels by gas chromatography–mass spectrometry for serum, but a transfer of the method from serum to postmortem whole blood failed. The method had to be modified and revalidated for postmortem whole blood specimens. A stability study of valproic acid in postmortem blood was conducted, showing a decline of valproic acid levels by 85 % after storage at room temperature for 28 days. During the storage time, the blood samples showed changes in consistency. Depending on the stage of decomposition, it is necessary to perform a determination by standard addition with an equilibration time of 4 h before extraction to achieve reliable results. For a proper interpretation of quantitative results, it is necessary to keep the postmortem decline of valproic acid concentrations in mind.

Quantitative determination of valproic acid in postmortem blood samples--evidence of strong matrix dependency and instability.

The special requirements for the validation of forensic-toxicological analysis were constituted by the working group ‘quality assurance’ of the GTFCh. For the easy execution of all necessary calculations the Excel program Valistat was developed. The following features were supported by the first version: ! examination of working range and calibration model ! examination for systematic and accidental errors ! calculation of analytical limits (DIN 32645) ! calculation of recovery (extraction yield) According to the revised guidelines of the German Society of Toxicology and Forensic Chemistry (GTFCh) new special calculations can be performed by means of the second program version: ! processed sample stability ! evaluation of beta expectation intervals ! determination of matrix effects ! new alternative methods for the determination of the LOD and LOQ

/pdf/valistat-software-for-method-validation-in-forensic-11q5bzvmtc.pdf

VALISTAT - Software for Method Validation in Forensic Toxicology

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Georg Schmitt

Author Tools

Chat about Author

Papers

VALISTAT - Software for Method Validation in Forensic Toxicology