The described method of arsenic determination based on the differential pulse cathodic dissolution stripping voltammetry of As(III) in the presence of Cu²⁺ ions (Anal. Chem. 55, 304 (1983)) was modified for any sample types in contrast to the original procedure which was suitable practically only for very pure matrices such as drinking water. The present method is appropriate, e.g., for arsenic determination in food, ashes, and agriculture products. Due to inexpensive instrumentation, the method is easily accessible to laboratories engaged in this area.