Sodium hydrogen citrate sesquihydrate is suitable reagent to investigate the mediatorless laccase cathodes as half-cell electrode under galvanostatic load by using a two-compartment set up. It may be used in the extraction of organ/tissue sample using QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction methods. It is suitable for use in the analysis of multiclass pesticides by multiresidue method based on the sample preparation by modified QuEChERS and detection by GC coupled to single quadruple mass spectrometery.