Application of Photoelectrochemical Biosensor to Determination of Butachlor

The electrode of ITO/Gr/CH₃NH₃PbI₃/CS/GOx was prepared. The obtained electrode was immersed into 5.0 mL of 0.1 mol·L^-1 PBS (pH 7.0), and butachlor solution was added. After keeping for 10 min, the electrode was taken out and immersed into 0.1 mol·L^-1 PBS (pH 7.0) containing 0.8 mmol·L^-1 gluocose, and the photoelectric current (I) was measured. A blank test was done in the same way as mentioned above but in absence of butachlor, and the photoelectric current (I₀) was measured. Inhibition rate of photoelectric current by butachlor was calculated from (I₀-I)/I₀×100. The results showed that inhibition rate was linear with the concentration of butachlor in the range of 0.02-10.0 nmol·L^-1, and the detection limit (3S/N) was 0.005 nmol·L^-1. The method was applied to determination of butachlor in spiked blank samples of vegetables and fruits, giving measured values consistent with those obtained by gas chromatography-mass spectrometry, and RSDs (n=6) between 1.8% and 4.7%. Recovery obtained by standard addition method were in the range of 93.3%-102%.