Optimization of Determination Conditions of Capsaicin in Capsicum by Cyclic Voltammetry

To find a new electrochemical method for rapid and accurate determination of capsaicin,the cyclic voltammetry with improved electrode was selected to measure the accuracy and feasibility of the detection method by the detection of limits(LODs),spike recovery and relative standard deviation(RSD). The suitable conditions for the determination of capsaicin were investigated by single factors and its optimization test,and the actual samples were used to test. The results showed that,the suitable conditions for the determination of capsaicin were β-cyclodextrin modified carbon paste electrode as working electrode,bottom solution with pH11,buffer system of Britton-Robison buffer solution,ionic strength regulator KCl with strength of 0.10 mol/L,voltage scanning rate of 100 mV/s,measurement temperature of about 20℃,constant result within 30 min(RSD ≤ 0.1%)and determination within 48 h with was good stability(RSD ≤ 1.8%). In addition,vitamin C,capsicum pigment and soluble sugar in the sample of pepper did not interfere with the measurement. The LODs was 0.3817 μg/mL(1.25 μmol/L)under suitable conditions,and the capsaicin concentration(c_cp)was excellently correlated with peak current(i_pk)from 1.0×10^-4 mmol/L to 1.0 mmol/L with linear line of i_pk=3.1046c_cp+1.0025(R²=0.9946). The determination of capsaicin content in two batches of 10 pepper samples showed that the measured capsaicin content was consistent by the HPLC and the literature report,and the recovery was 100.70%~109.89%(average 103.71%),the RSD was 1.1%~4.9%. This method was the potential of automatic,intelligent and quick online detection. It could be used as a quantitative analysis method for capsaicin contents.