After noting the advantages and disadvantages of using the liver as an alternative to blood when measuring the presence and concentration of opioids in a decedent, this report describes the findings and methodology of a study that assessed remedies for one of the disadvantages, i.e., the need for effective clean-up or sample preparation before analysis of the liver.
Disadvantages to using liver as an alternate specimen are the protein, fat, phospholipid matrix, and potential putrification products that compose the liver. With the increase in the use of opioids to treat pain and subsequent increase in compliance testing of the individuals using these medications, newer sample-preparation techniques have been developed and marketed. The use of these techniques for difficult matrices such as liver has occurred with limited understanding of the effects that liver has on the analysis of the drugs of interest. Traditional techniques involve solid-phase extraction (SPE), liquid-liquid extraction (LLE), and filtration. These techniques have limited published, peer-reviewed data regarding use with tissue matrices such as liver. In order for these techniques to be used effectively for liver analysis, matrix effects and absolute recovery must be evaluated before method validation can be initiated in determining how effective these techniques are in cleaning up sample matrix, or at least a better understanding of the effect of the matrix on the analysis. Time was the most important issue observed in this study. Liver tissue homogenates were stable for about 3 weeks when stored in the refrigerator. Liver homogenates were stable for two freeze-thaw cycles, but not for a third cycle. A recommendation for preparing quality-control materials is to prepare the materials aliquot into single-use containers and store frozen until needed for analysis. 4 tables and 28 references