Detection of chlorpyrifos pesticide in apple surface by surface-enhanced Raman spectroscopy

Abstract

Abstract. Apple is one of the highly consumed fruit items. It is also one of the major carriers of pesticide to human health. This has created a great need for precise detection of pesticide residue in apple fruit. Traditional methods cannot meet current industrial desire of rapid and non-destructive detection of pesticide residue in fruits. Optical methods have recently gained importance in the evaluation of food quality because of their rapid and non-destructive nature. This research focuses on development of Raman spectral instrument for rapid detection of commercially available organophosphorous (chlorpyrifos) pesticide in apple surface by surface enhancement technology. Silver colloid was used for surface-enhanced Raman Spectroscopy (SERS) measurement. Apple samples after contamination with different concentrations of chlorpyrifos pesticide were applied to surface enhancement experiment to detect trace amount of pesticide residue. The surface enhancement was coated at several points in the surface of intact apple and laid to nearly dry at laboratory temperature before collecting Raman spectral signals. The noise signals and fluorescence background were removed by Savitzky-Golay filter and 8th order polynomial fitting respectively. Results show that the SERS can be used to detect chlorpyrifos pesticide in apple surface below 1 mg/kg which is lower than maximum permitted residue limit in apple by Chinese government. The result is promising for detection of pesticide residue rapidly and non-destructively. It is potential to be used for rapid and non-destructive detection of pesticide residues in different fruits and vegetables for industrial application.