The need for drug monitoring during chemical and toxicological studies of psychotropic and potent drugs is very high. A new technique for determining phenazepam in blood using cards for collecting and transporting biological material has been developed. The proposed technique is based on optimal blood sample preparation by direct extraction with methanol from the card and includes research conditions by high-performance liquid chromatography with a mass detector on a solid-phase column with a temperature regime of 30 °C and the use of two phases in a gradient mode. When using the proposed sample preparation, it is possible to detect phenazepam and 3-hydroxyphenazepam in minimal concentrations with retention times of 7.1 and 6.8 min, respectively, in the absence of a cold corridor of 2-4°C and equipment for storing and transporting biomaterial samples. © 2025 Elsevier B.V., All rights reserved.