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

Abstract

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.

Postmortem tissue distribution of morphine and its metabolites in a series of heroin‐related deaths

“…These results in vitreous when compared to femoral blood are in agreement with a previous study (R 2 = 0.26; n = 40, 61 as are the results of femoral blood to cardiac blood (R 2 = 0.76) and psoas muscle (R 2 = 0.75) 16 but do not agree with the results of two other studies that showed significant correlations between femoral blood and vitreous concentrations (R 2 = 0.87; p < 0.01, n = 69 62 ), (R 2 = 0.72; p < 0.001, n = 52 60 ), and (R 2 = 0.79; p > 0.001, n = 45 16 ). The differing sets of results obtained by the various groups and this study show that although correlations may exist for populations due to differences such as individual tolerance, individual metabolism, survival time after the administration of the drug, and also postmortem redistribution, 63,64 in the absence of a femoral blood sample in a case other samples should not be used to attempt to determine the femoral blood concentration.…”

Salvia Divinorum : Toxicological Aspects and Analysis in Human Biological Specimens

“…The main drawback of this specimen is the low volume that can be collected during a forensic autopsy (at best about 5 ml). A large number of compounds can be detected in this specimen, being of great interest in forensic toxicology, as has been demonstrated by many authors [63]. Actually, this specimen can be useful in forensic toxicology for SA analysis as a complementary sample to blood and/or urine when considering intake of SD, even though the studies of SA disposition regarding vitreous humor are limited to a publication [24].…”

“…Nevertheless, in forensic toxicology a diversity of biological matrices are used in addition to blood and urine. A large number of studies have been published describing the relevance of the developed methodologies for the analysis of drugs of abuse in various biological specimens, highlighting some review articles [60][61][62][63]. In this review, on the basis of reports published between 2004 and 2015 describing the analysis of SA in human biological specimens, different analytical methodologies in conventional and unconventional matrices (blood, plasma, urine, vitreous humor, pericardial fluid, sweat, oral fluid and hair), with special attention to its advantages and disadvantages, are introduced [15,[24][25][26][54][55][56].…”

“…This is the matrix with less endogenous interfering compounds, and toxicological analysis does not require complex preparation. Substances that are highly protein bound would not have a significant concentration in vitreous humor, and compounds not highly protein bound would be expected to have significant concentrations in this matrix [63,64]. The absence of significant metabolic activity in the eye suggests that the concentration of the drug found in vitreous humor correlates well with the corresponding concentration in blood.…”

SEM (EDX) is an indispensable tool for the characterization of subcutaneous, preperitoneal and visceral adipose tissue of obese patients

“…The conventional methods for determining the composition of fats are gas and liquid chromatography [21][22][23][24][25]. However, it is clear that new alternative analytical procedures for the analysis of the adipose are very much desired [26][27][28][29][30][31][32].…”