The effect of sodium fluoride preservative and storage temperature on the stability of 6-acetylmorphine in horse blood, sheep vitreous and deer muscle

Alternative matrices in forensic toxicology: a critical review

Purpose

The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.

Methods

The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).

Results

This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.

Conclusions

Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.

Stability of Ketoprofen Methylester in Plasma of Different Species

BACKGROUND

Pharmacokinetic and pharmacodynamic assessment of ester-containing drugs can be impacted by hydrolysis of the drugs in plasma samples post blood collection. The impact is different in the plasma of different species.

OBJECTIVE

This study evaluated the stability of a prodrug, ketoprofen methylester (KME), in commercially purchased and freshly collected plasma of mouse, rat, dog, cat, pig, sheep, cattle and horse.

METHODS

KME hydrolysis was determined following its incubation in commercially purchased and freshly collected plasma of those species. Different esterase inhibitors were evaluated for prevention of the hydrolysis in rat, dog and pig plasma.

RESULTS

KME was rapidly hydrolyzed in both commercially purchased and freshly collected plasma of mouse, rat, and horse. The hydrolysis was initially quick and then limited in cat plasma. KME hydrolysis was minimum in commercially purchased plasma of dog, pig, sheep and cattle but substantial in freshly collected plasma of those species. Different esterase inhibitors showed different effects on the stability of KME in rat, dog and pig plasma.

CONCLUSION

These results indicate that plasma of different species has different hydrolytic activities to estercontaining drugs. The activities in commercially purchased and freshly collected plasma may be different and species-dependent. Esterase inhibitors have different effects on preventing hydrolysis of the ester-containing drugs in the plasma of different species.

Inferences and Legal Considerations Following a Blood Collection Tube Recall

In mid-2019, medical, forensic and legal communities were notified that a certain shipment of evacuated blood sampling tubes were recalled by the manufacturer. This recall order described that the preservative sodium fluoride (100 mg) and anticoagulant potassium oxalate (20 mg) were missing from a small batch of 10-mL evacuated tubes. This gave cause for concern for possible implications in criminal justice (e.g., in drink-driving offenses) when blood-alcohol concentrations are interpreted. In reality, the lack of an anticoagulant would have been immediately obvious during sample preparation, owing to the formation of a large clot in the tube when received. Certain impairing drugs (e.g., cocaine and 6-acetylmorphine) are unstable in blood and tend to degrade without an enzyme inhibitor, such as sodium fluoride, present. In reviewing available literature related to current practices and the stability of ethanol in stored blood samples, there does not appear to be a clear consensus regarding the amount of sodium fluoride preservative necessary, if any at all, when blood is taken from living subjects under sterile conditions for typical forensic ethanol analysis.

Pitfalls in drug testing by hyphenated low- and high-resolution mass spectrometry

This paper reviews various pitfalls observed during developing, validation, application, and interpretation of drug testing approaches using GC-MS and low- and high-resolution LC-MS. They include sampling and storage of body samples, sample adulteration and contamination, analyte stability, sample preparation without or with cleavage of conjugates, extraction, derivatization, internal standardization, false negative and positive results by GC-MS or LC-MS screening and/or confirmation procedures including artifact formation, ion suppression or enhancement by electrospray ionization, and finally pitfalls in data interpretation. Conclusions and prospects close the Tutorial.

Stability studies in biological fluids during post-analysis custody. Opiate compounds derived from heroin consumption

In Forensic Toxicology, the evidences have to be maintained under custody for, at least, one year. Depending on the conditions and duration of storage, drug concentrations might have changed considerably since the first analysis. The aim of this study is to evaluate in vitro stability of opiate compounds, derived from heroin consumption, 6-acetylmorphine (6-MAM), morphine (MOR) and codeine (COD), in blood and urine, during post-analysis custody. Parameters evaluated were: time of custody, temperature, addition of preservative (blood) and pH (urine). Blood and urine samples were spiked with the three analytes to give a final concentration of 1000 ng/mL. The prepared samples were divided into 2 groups and stored at two temperatures (4 °C and -20 °C). Each one of these groups was subsequently divided in other two groups: with and without preservative (1%NaF) for blood, and pH 4 and 8 in the case of urine. 6-MAM, MOR and COD were analyzed by GCMS after SPE and derivatization with BSTFA. Analyses were performed in triplicate every two weeks for a year. In blood samples 6-MAM is the only compound that degrades. The best storage conditions were at -20 °C with NaF, with 6-MAM recoveries, after one year of custody, of 47.1 ± 1.5%; while in the other conditions 6-MAM disappeared after 215 days (at 4 °C with NaF), 45 days (at -20 °C without NaF) and 15 days (at 4 °C without preservative). COD does not degrade, with recoveries higher than 90%, in all of the conditions. They ranged from 89.7 ± 3.6% in samples maintained at -20 °C without NaF to 95.9 ± 2.0% in those maintained at 4 °C with NaF. MOR recoveries were lower than those of COD. They ranged from 66.9 ± 3.6%, in frozen samples added with NaF, to 78.6 ± 0.5% in refrigerated samples without preservative. In urine samples the three compounds were stable in all the studied conditions, with the exception of 6-MAM in samples at pH 8 and stored at 4 °C. In these conditions, 6-MAM disappeared after 135 days of custody; while recoveries in the other conditions ranged from 93.7 ± 6.4%, at 4 °C and pH 4, to 85.1 ± 2.0% at -20 °C and pH 8. MOR and COD recoveries were similar in the four conditions. In the case of MOR, they ranged from 82.1 ± 1.2% at 4 °C and pH 4 to 89.5 ± 6.0% at -20 °C and pH 8. As far as COD is concerned, recoveries ranged from 111.6 ± 5.8% at 4 °C and pH 8 to 102.6 ± 1.2% at 4 °C and pH 4. In conclusion, the study showed that the most labile opiate compound is 6-MAM. Its stability mainly depends on urine pH or the addition of preservative, in blood samples. The best storage conditions for samples from heroin consumers are in the freezer, at -20 °C. In addition, blood samples must be added with 1%NaF and urine samples must be buffered at pH 4.

Vitreous humor analysis for the detection of xenobiotics in forensic toxicology: a review

Vitreous humor (VH) is a gelatinous substance contained in the posterior chamber of the eye, playing a mechanical role in the eyeball. It has been the subject of numerous studies in various forensic applications, primarily for the assessment of postmortem interval and for postmortem chemical analysis. Since most of the xenobiotics present in the bloodstream are detected in VH after crossing the selective blood-retinal barrier, VH is an alternative matrix useful for forensic toxicology. VH analysis offers particular advantages over other biological matrices: it is less prone to postmortem redistribution, is easy to collect, has relatively few interfering compounds for the analytical process, and shows sample stability over time after death. The present study is an overview of VH physiology, drug transport and elimination. Collection, storage, analytical techniques and interpretation of results from qualitative and quantitative points of view are dealt with. The distribution of xenobiotics in VH samples is thus discussed and illustrated by a table reporting the concentrations of 106 drugs from more than 300 case reports. For this purpose, a survey was conducted of publications found in the MEDLINE database from 1969 through April 30, 2015.

'Lingering' opiate deaths? Concentration of opiates in medulla and femoral blood

'Lingering death' cases occur when the circumstances of death indicate an opiate overdose, but measured opiate blood levels are only in the therapeutic range; death results from cardiac and respiratory depression. This study examined the relative concentration of opiates in femoral blood and in the medulla oblongata (sites for cardiac and respiratory control) from 41 cases to determine whether a difference in opiate concentration might explain lingering deaths. Opiates from blood and medulla were analyzed using GC-EI-MS in selective ion monitoring mode. Results were correlated with gross and microscopic findings of the lungs and with cause and manner of death. Opiate concentrations for morphine, codeine and 6-acetylmorphine (6-AM) were higher in the medulla than in blood. The brain: blood ratio for the analytes demonstrated an increasing ratio from morphine, to codeine, to 6-AM (1.42, 2.48 and 4.86), which corresponds to the relative lipophilicity of these analytes. The average right and left lung weights were 762 and 668 g, respectively. Histologic examination showed edema, and/or polarizable microemboli, acute bronchopneumonia and acute bronchitis. The preferential distribution of opiates to medulla suggests that lingering opiate deaths may be explained, at least in part, because of higher relative concentrations of drug in brain, compared with femoral blood.

Toxicology Analysis for Pathologists: A Review of the Available Techniques and Technologies, Including Recommendations for Best Practice

The success of the forensic postmortem investigation that is suspected to involve drugs or poisons depends on the toxicologist and pathologist/medical examiner working closely together as a team. The pathologist relies on the experience and analytical skills of the toxicology laboratory to provide answers concerning the possible presence of drugs in autopsy specimens; however, in order that this may be successful, the toxicologist relies on the pathologist to provide appropriate specimens for analysis. The role of the forensic toxicologist is to then identify drugs or toxins in the human body tissues and to offer an interpretation as to whether or not their presence may be a contributory factor to the death.

This review will consider the scope of toxicology analysis in relation to forensic investigations, outline the processes undertaken in the forensic laboratory and offer guidance to assist the medical examiner who may wish to employ near-body drug screening. The review will also demonstrate the importance of specimen collection at autopsy and relate this to the techniques available in the forensic toxicology laboratory; recommendations for appropriate specimen preservation and storage will also be discussed. The pathologist and toxicologist must work closely as a team to ensure that poisoning is not missed.