Recent chromatographic and electrophoretic based methods for determining drugs of abuse in urine and oral fluid: A review from 2018 to June 2021

Urine and oral fluid are important biological matrices used for forensic and toxicological analyses. These two complementary matrices can be used to provide information about recent and long-term drug consumption. Several analytical methods have been developed in recent years to determine different drugs of abuse in these biological samples. Most of them are based on chromatographic and related techniques, such as liquid chromatography or gas chromatography and capillary electrophoresis. Moreover, as these biological matrices can contain various compounds that may interfere with the analytes of interest, a sample pre-treatment is usually necessary. Different pre-treatment strategies have been carried out, including solid-phase extraction and liquid-liquid extraction, among others. The present review aims to provide a comprehensive overview and a discussion of the latest trends and the most used strategies for determining drugs of abuse in urine and oral fluid samples using chromatographic and electrophoretic techniques between 2018 and June 2021.