Human bone marrow as a tissue in post-mortem identification and determination of psychoactive Substances-Screening methodology.

The aim of this study was to apply a new instrumental approach to the analysis of human bone marrow for forensic purposes. A new screening method for the detection of more than 30 psychoactive drugs in bone marrow was developed and applied to case samples. The drugs used in this study belonged to the following groups: benzodiazepines (BZDs, n=16), tricyclic antidepressants (TCAs, n=5), selective serotonin reuptake inhibitors (SSRI, n=4), serotonin-norepinephrine reuptake inhibitors (n=1), anticonvulsants (n=1), imidazopyridines (n=1) and piperazines (n=3). The sample preparation procedure involved microwave-assisted extraction (MAE) and the experimental settings were optimized using the simplex method. Separation and detection was carried out using a UHPLC-TOF system. The method were validated using marrow samples, and further applied in the analysis of three case samples, in which diazepam, nordiazepam, citalopram, doxepin and paroxetine were successfully detected. Finally the presented method is a good example of an assay that could potentially find an application in forensic analysis.

A comparative study of various physicochemically modified capillaries used in CE technique for the three distinct analytical purposes.

The five different commercially offered capillaries, bare silica, one dynamically and three permanently coated, have been tested with respect to the three distinct bioanalytical issues: (i) achiral and chiral separation of small mass molecules, warfarin and its six isomeric hydroxy-derivatives; (ii) ultraselective separation of transferrin and albumin including differentiation between the diferric, two monoferric and iron-free forms of transferrin; and (iii) pioneering identification of albumin-induced shifts of acid dissociation constant by using CE instrumentation, revealed for warfarin and six hydroxywarfarins. As a result all of these pharmacologically and biochemically-relevant purposes have been reached, but using different capillaries. The dynamically coated silica capillary has allowed for the first time to separate warfarin from its six main hydroxy-metabolites by CE with high resolution. The bare silica capillary has performed well in cyclodextrin-assisted enantioseparation of these compounds. The neutral capillary has provided excellent resolution and performance in separation of proteins. The amine capillary, in turn, has occurred to be the best choice for identification of albumin-induced pKa shifts occurring in vivo, omitting capillary clogging and providing better sensitivity than the neutral capillary. This work reveals specific predispositions and shows that there is no universal capillary which may be applied to all issues.

Analytical aspects of achiral and cyclodextrin-mediated capillary electrophoresis of warfarin and its two main derivatives assisted by theoretical modeling.

Several distinct analytical issues have been addressed by performing capillary electrophoresis-based separations of the warfarin, 7-hydroxywarfarin and 10-hydroxywarfarin in an achiral and cyclodextrin-containing media. The measurements were conducted across a range of pH in order to find optimum conditions for achiral and chiral separations. The values of acid dissociation constant (pKa) have been determined and compared. Subsequently, after performing a series of mobility shift assays at different pH and cyclodextrin concentration, the pKa values ascribed to diastereomeric complexes with methyl-ß-cyclodextrin have been estimated. The significant pKa shifts upon complexation have been noticed for warfarin - up to 1.5 pH units, and only subtle for 10-hydroxywarfarin. A new approach that allows the estimation of association percentage based on the electrophoretic mobility curves has been also demonstrated. The complex mechanism of chiral separation has been found to be responsible for the observed migration profile, relying on a combined equilibrium between complexation/partition and protonation/deprotonation phenomena. The occurrence of the pKa-related migration order reversal has been demonstrated in achiral medium between warfarin and 7-hydroxywarfarin, and in chiral medium between enantiomers, causing a drop in enantioselectivity at specific pH. In parallel, the density functional theory-based calculations have been performed in order to obtain the structures of warfarin and its derivatives as well as to rationalize the shifts in pKa values.

Fast separation of warfarin and 7-hydroxywarfarin enantiomers by cyclodextrin-assisted capillary electrophoresis.

The enantioseparation of warfarin and its main metabolite has been achieved using several cyclodextrin types and buffers at different pH, including conditions that have not been attempted so far. Methyl-ß-cyclodextrin, highly sulfated-ß-cyclodextrin and highly sulfated-γ-cyclodextrin were the most efficient chiral selectors. The pH range, within which particular cyclodextrins support chiral separation, has been approximately determined for the first time. By shortening the effective capillary length to 10 cm, the time of analysis has been vastly reduced <2 min. Hence, baseline separations of warfarin and 7-hydroxywarfarin enantiomers have been achieved in times unreported for those species until now. The established conditions are promising for the further development of new highly selective and fast methods involving warfarin, its derivatives, as well as the same cyclodextrin types.