Long-term storage of authentic postmortem forensic blood samples at -20°C: measured concentrations of benzodiazepines, central stimulants, opioids and certain medicinal drugs before and after storage for 16-18 years.

The long-term stability of benzodiazepines, opioids, central stimulants and medicinal drugs in authentic postmortem blood samples was studied. All together, 73 samples were reanalyzed after storage at -20°C for 16-18 years. At reanalysis samples containing diazepam, nordiazepam and flunitrazepam demonstrated only small changes during long-term storage when mean and median drug concentrations were compared, while clonazepam concentrations tended to decrease. Samples containing amphetamine, morphine, codeine and 'acidic' medicinal drugs as paracetamol and meprobamate also showed small changes over 16-18 years in mean and median drug concentrations at a group level. For many drugs, however, single samples could demonstrate marked concentration changes, both increases and decreases during storage. For 'alkaline' medicinal drugs, concentration losses were observed in most cases.

Long-term stability of GHB in post-mortem samples and samples from living persons, stored at -20°C, using fluoride preservatives.

PURPOSE: Reanalyses are frequently requested in forensic toxicology, and knowledge of the stability of drugs in biological samples is of major importance for the interpretation of the toxicological findings. Currently, the literature on stability of gammahydroxybutyrate (GHB) in blood samples from living subjects and in post-mortem blood is limited. The purpose of this study was to evaluate the long-term stability of GHB in both blood samples from persons suspected of drug use and post-mortem blood samples. METHODS: A total of 59 reanalyses were performed in whole blood samples, 27 samples from living subjects and 32 samples taken at autopsies. The samples were stored in the freezer between 0.4 and 7.2 years at -20°C in vials containing preservatives. Analyses were performed by GC-FID, and cut-off level was 10.3 mg/L. The concentrations in 22 of the samples were below cut-off. RESULTS: The mean change in concentration between initial analysis and reanalysis was -0.8% for the positive samples from living persons and -7.1% for the positive post-mortem samples. Changes ranged from -32.4% to 21.0% for samples from living and from -30.4% to 34.4% for post-mortem samples. All negative samples were still negative at the time of reanalysis. CONCLUSION: Reanalysis of these forensic whole blood samples stored several years at -20°C with fluoride preservation did not exhibit changes in GHB concentrations of practical significance for the interpretation of toxicological findings.

Comparison of the stability of stock solutions of drugs of abuse and other drugs stored in a freezer, refrigerator, and at ambient temperature for up to one year.

The aim of this study was to evaluate the stability of stock solutions of a variety of illegal and medicinal drugs, important in forensic analysis, when stored refrigerated or at ambient temperature compared to solutions stored in a freezer. Stock solutions in methanol, acetonitrile, or a mixture of acetonitrile/methanol were transferred to autosampler vials and analyzed after storage for one month, three months, six months, and one year at ambient temperature, in a refrigerator, and in a freezer. Some of the compounds investigated, such as morphine and amitriptyline, showed to be stable for at least one year when stored at ambient temperature, but others, such as prometazine and olanzapine, nearly vanished when stored at ambient temperature for one month.

Comparison of ethanol and other drugs of abuse concentrations in whole blood stored in venoject glass and plastic and venosafe plastic evacuated tubes.

The aim of this study was to evaluate the stability of blood concentrations of a variety of illegal and medicinal drugs that are important for forensic analyses when spiked and stored in Vacutainer or Venosafe evacuated plastic collection tubes compared to Vacutainer evacuated glass tubes. Tubes were filled with spiked whole blood and analyzed after storage for one week at ambient temperature and at -20 degrees C, respectively. Freeze-and-thaw stability was included in the study. No significant difference between storage in glass or plastic tubes was noted for any compound investigated.

[On-site testing for drug abuse in urine]. / Bruk av hurtigtester for påvisning av rusmidler i urin.

BACKGROUND: There is an increasing interest in on-site testing for drugs of abuse. METHODS: Based upon our own experience and published literature, we have reviewed advantages and disadvantages of such tests. On-site testing is also evaluated in relation to the recommendations for urinary testing of drugs of abuse from the Norwegian Health Authorities. RESULTS: The most significant advantage with on-site testing is provision of rapid results, usually within 5-10 minutes. Disadvantages are the risks of false positive and false negative results, the fact that numerous drugs cannot be tested for, and the limited possibilities to detect manipulation. According to Norwegian regulations, on-site testing can be used for medical purposes, but cannot be used as the only method if a positive result may cause sanctions such as e.g. exclusion from school, job dismissal or loss of parental rights. There are also special requirements for the organization of such testing. INTERPRETATION: Before starting on-site testing for drugs of abuse, it should be considered if such testing is allowed or discouraged in the specific case. It is mandatory to know how the specific test works and to have routines for follow-up of positive test results.

Headspace gas chromatographic determination of ethanol: the use of factorial design to study effects of blood storage and headspace conditions on ethanol stability and acetaldehyde formation in whole blood and plasma.

Our headspace gas chromatographic flame ionization detection (HS-GC-FID) method for ethanol determination showed slightly, but consistently, low ethanol concentrations in whole blood (blood) in proficiency testing programs (QC-samples). Ethanol and acetaldehyde were determined using HS-GC-FID with capillary columns, headspace equilibration temperature (HS-T degrees ) of 70 degrees C and 20 min equilibration time (HS-EqT). Full factorial designs were used to study the variables HS-T degrees (50 degrees -70 degrees C), HS-EqT (15-25 min), ethanol concentration (0.20-1.20 g/kg) and storage at room temperature (0-6 days) with three sample-sets; plasma, hemolyzed blood and non-hemolyzed blood. A decrease in the ethanol concentration in blood was seen as a nearly equivalent increase in the acetaldehyde concentration. This effect was not observed in plasma, indicating chemical oxidation of ethanol to acetaldehyde in the presence of red blood cells. The variables showed different magnitude of effects in hemolyzed and non-hemolyzed blood. A decrease in ethanol concentration was seen even after a few days of storage and also when changing the HS-T degrees from 50 to 70 degrees C. The formation of acetaldehyde was dependent on all the variables and combinations of these (interactions) and HS-T degrees was involved in all the significant interaction effects. Favorable instrumental conditions were found to be HS-T degrees of 50 degrees C and HS-EqT of 15-25 min. The ethanol concentrations obtained for the range 0.04-2.5 g/kg after analyzing authentic forensic blood samples with a HS-T degrees of 50 degrees C were statistically significantly higher than at 70 degrees C (+0.0154 g/kg, p < 0.0001, n = 180). In conclusion, chemical oxidation of ethanol to acetaldehyde in the presence of red blood cells has been shown to contribute to lowered ethanol concentrations in blood samples. Storage conditions before analysis and the headspace equilibration temperature during analysis were important for the determination of blood ethanol concentrations.

An automated alcohol dehydrogenase method for ethanol quantification in urine and whole blood.

In a previous work, an automated alcohol dehydrogenase method for the quantification of ethanol in whole blood (blood) specimens was presented. In the present work the application of the method to urine specimens has been investigated. Also, method robustness to routine analysis of urine and blood specimens during a period of eight months is shown. The limits of detection and quantification for urine were 0.0012 g/dL and 0.0042 g/dL, respectively. Relative standard deviations for the repeatability and within-laboratory reproducibility were in the ranges 1.4-4.1% and 1.8-4.6%, respectively. The method was compared with two headspace gas chromatography-flame ionization detection methods using authentic forensic urine specimens (n = 305) and blood specimens (n = 3186). Passing-Bablok regression for the concentration range 0.01-0.48 g/dL (urine) and 0.002-0.40 g/dL (blood) showed a statistically significant difference, for urine y = 0.9313 (0.9250 - 0.9377)x + 0.0038 (0.0029-0.0044) and for blood y = 0.9493 (0.9491 - 0.9495)x + 0.0032 (0.00318-0.00323), at 95% confidence level. The results of the external quality control specimens were in accordance with the reported theoretical concentrations.

Fast quantification of ethanol in whole blood specimens by the enzymatic alcohol dehydrogenase method. Optimization by experimental design.

A sensitive, fast, simple, and high-throughput enzymatic method for the quantification of ethanol in whole blood (blood) on Hitachi 917 is presented. Alcohol dehydrogenase (ADH) oxidizes ethanol to acetaldehyde using the coenzyme nicotinamide adenine dinucleotide (NAD), which is concurrently reduced to form NADH. Method development was performed with the aid of factorial design, varying pH, and concentrations of NAD+ and ADH. The linear range increased and reaction end point decreased with increasing NAD+ concentration and pH. The method was linear in the concentration range 0.0024-0.4220 g/dL. The limits of detection and quantification were 0.0007 g/dL and 0.0024 g/dL, respectively. Relative standard deviations for the repeatability and within-laboratory reproducibility were in the ranges 0.7-5.7% and 1.6-8.9%, respectively. The correlation coefficient when compared with headspace gas chromatography-flame ionization detection methods was 0.9903. Analysis of authentic positive blood specimens gave results that were slightly lower than those of the reference method.