Analysis of salicylic acid in willow barks and branches by an electrochemical method

An electrochemical method for measuring free salicylic acid (SA) was optimized and used to detect its content in barks and branches of thirteen Salix species. We utilized square wave voltammetry method in combination with pencil lead, the detection limit of which was 1.7 ng/ml of salicylic acid. The highest contents of free SA were observed in the bark of S. laponum (3.0 mg/g fr wt) and in the branches of S. purpurea, cv. Nana (2.1 mg/g fr wt) and S. planifolia (2.2 mg/g fr wt). The technique utilized for determination of SA in willow tissues has a much broader dynamic range and lower limit of detection in comparison to both linear sweep and cyclic voltammetry because of its efficient discrimination of capacitance current.