# Emerging Trends in Pharmacotoxicological and Forensic Sample Treatment Procedures
## 3 Main Solid Matrices for Forensic Purposes
### Liver Tissue  
Sometimes in the liver, many toxic substances are present in higher concentrations than in other matrices. This type of specimen is favored when blood is unavailable due to exsanguination.  
[PERSON] et al. used a liver sample for quantitative analysis of fentanyl and its analogs, assessing the correlation between the liver, brain, and blood. Homogenized liver tissue was buffered with sodium phosphate, vortexed, and then centrifuged. The extraction step was performed using positive pressure solid-phase United Chemical Technologies Clean Screen mixed mode columns. After conditioning, the supernatant obtained from the sample was added to the columns, and then the analytes were eluted with dichloromethane:isopropanol:ammonium hydroxide (78:20:2, _v:v:v_) and evaporated. Before the analysis in UHPLC-MS/MS, the dried sample was reconstituted with 50 mL of 0.1% formic acid in water [59]. [PERSON] et al. investigated the distribution of zolpidem in body fluid and organ tissue. In this study, a portion of the liver was homogenized and applied to the Extrelut NT column. After waiting for 1 h, elution was carried out with 20 mL of ethyl acetate:chlorobutane (4:1, _v:v_). The extract was dried and reconstituted with the same mixture prior to analysis [60]. [PERSON] et al. proposed an interesting method for the determination of cocaine in the human liver obtained from overdose victims. They have validated an efficient method for extraction of analytes from the liver using solid-liquid extraction with low-temperature partitioning (SLE-LTP) by evaluating the influence of different variables such as pH of extract, volume, and composition of extraction solvent and sorbent material. This technique allows researchers to obtain relatively pure extracts that can be directly analyzed and are based on low steps (Figure 1). After evaluating the extraction parameters, they decided to continue using physiological pH (7.4) and 8 mL of pure acetonitrile without the addition of sorbent material (primary secondary amines, PSA) and NaCl [61].  
To reduce the pretreatment procedures and consumption of organic solvent, [PERSON] et al. have developed an analytical method for quantifying barbitures in postmortem liver samples using three-phase hallow fiber-liquid phase microextraction (HF-LPME) and GC-MS. This technique is very efficient for cleaning up the sample and eliminating the potential interference problems and allows researchers to overcome the difficulties of classic solid-phase extraction with homogenates tissue because some particles in the sample can block the pores of the cartridge. Briefly, after homogenization of the sample, 0.8 mL of hydrochloric acid (0.1 M) was added. 9 cm of hollow fiber was then used for the extraction, and the fiber lumen was filled with the acceptor phase (25 mL of a NaOH aqueous solution pH 13) and immersed in the sample solution with a U-configuration. The extraction was conducted for 5 min in an ultrasonic bath. Successively, the extraction phase was withdrawn and dried before the analysis [62].