Microwave assisted extraction of ketamine and its metabolites from skeletal tissues

Abstract

The use of Microwave Assisted Extraction (MAE) to extract ketamine and its metabolites from decomposed bone tissue is described. Wistar rats received 75 mg kg À1 (i.p.) ketamine (n ¼ 12) or remained drug-free (controls, n ¼ 4). Following euthanasia, rats were allowed to decompose to skeleton outdoors. Bones (vertebrae, rib, pelvi, femora, tibiae, humeri and scapulae) were collected and pooled. Analyte stability to MAE in methanol or acetone-hexane mixture (1 : 1, v/v) in a closed vessel microwave system was assessed, and acetone-hexane was chosen as the MAE solvent. Bone samples underwent MAE, and extracts were assayed using microplate solid phase extraction (MPSPE) in a mixed-mode configuration and gas chromatography-mass spectrometry. Drug levels, expressed as mass normalized response ratios, were used to characterize extraction time and the effect of MAE solvent volume on the extraction time and relative recovery for each analyte. Extraction time varied slightly with solvent volume, while relative analyte recovery did not differ significantly. Recovery was at least 90% of maximal value within the first 5 min for all samples examined and maximum recovery occurred within 20 minutes. MAE in combination with MPSPE offers a substantial improvement in analytical throughput for toxicological analysis of skeletal remains.

Analysis of dextromethorphan and dextrorphan in decomposed skeletal tissues by microwave assisted extraction, microplate solid‐phase extraction and gas chromatography‐ mass spectrometry (MAE‐MPSPE‐GCMS)

“…All analyte levels reported in this work are expressed as mass‐normalized response ratios (RR/m), as has been done in various other published studies . The response ratio (RR) is the ratio of analyte peak area to that of the internal standard.…”

“…other published studies. [4,[7][8][9][10][11] The response ratio (RR) is the ratio of analyte peak area to that of the internal standard. Normalization of RR to the mass of bone sampled (i.e., RR/m) accounts variation in the mass of bone sampled.…”

“…These values should be regarded as estimates as analyte recovery from the solid bone matrix cannot be accurately measured or calibrated for, using techniques conventional to forensic toxicology, as described above and elsewhere. [4,[7][8][9][10][11]…”

“…Toxicological analysis of bone has been the subject of renewed interest in recent years. [1][2][3][4][5][6][7][8][9][10] The results of studies since 2000 done with both human tissues derived from forensic casework [1][2][3] and animal tissues derived from studies involving controlled drug exposure and post-mortem conditions [4][5][6][7][8][9][10][11][12] have shown that detection of a wide variety of drugs and metabolites is possible, but there remains uncertainty with respect to the interpretive value of quantitative measurements in bone, due to poor correlation of drug levels in bone and those in corresponding blood samples. Furthermore, the use of bone as a substrate for toxicological analysis may be expected to occur primarily in cases involving extensive decomposition, where few or no other conventional sample types are available.…”

Optimization of ultrasonic frequency for the improvement of extraction yields of bufadienolides from the Chinese medicine ChanSu by using a novel ultrasonic system

“…ChanSu is widely used as a local anesthetic agent and cardiotonic in China and other countries and it is responsible for the characteristic structural feature of the bufadienolides, which is a doubly unsaturated six membered lactone ring on position 17 of C-24 steroids. Existing extraction techniques are well proven, widely accepted and available for obtaining higher extraction yields, 16,17 but they are oen viewed as laborious and complex, requiring timeconsuming treatment of the samples. 10 Among these techniques, UAE was proven to signicantly shorten the extraction time, lower the consumption of solvent and enhance extraction yields in many natural products.…”