A Cost-Effective Spectrophotometric Method Based on Enzymatic Analysis of Jackfruit Latex Peroxidase for the Determination of Carbaryl and Its Metabolite 1-Napthol Residues in Organic and Chemical-Free Vegetables

Abstract

Carbaryl is a member of the carbamate family and commonly used as an insecticide. A cost-effective and reliable method to determine carbaryl and its metabolite 1-naphthol was developed based on alkaline hydrolysis of carbaryl into 1-naphthol followed by enzymatic reaction with peroxidase, extracted from jackfruit latex in the presence of 4-aminoantipyrine and hydrogen peroxide under pH 6.0. The reaction product was pre-concentrated using ultrasound-assisted cloud-point extraction (UA-CPE) of Triton X-114 as surfactant prior to spectrophotometry at 500 nm. UA-CPE of jackfruit latex peroxidase achieved a calibration curve of carbaryl standard between 0.025 and 0.20 mg L−1 with r2 > 0.99. Detection and quantification limits were 9 and 24 μg L−1, respectively. Intra- and inter-day assay %RSDs were 5.15% (n = 7) and 7.24% (n = 4), respectively. An UA-QuEChERS technique was employed to ameliorate extraction performance of sample preparation. Recoveries between 81.9 and 102.4% were achieved. The proposed method was applied to determine carbaryl residues in organic and chemical-free vegetable samples. HPLC with UV detection was also performed for comparison and confirmation of measurements obtained by the proposed method.