The trace elements of chlorpyrifos and malathion pesticides on guava fruit using laser induced breakdown spectroscopy

Abstract

Laser induced breakdown spectroscopy (LIBS) is an analytical technique used for identification of elements by analysing the emission line spectrum produced by a sample. LIBS is implemented as analytical technique for this study because it requires minimal sample preparation, fast result and non-destructive technique compared to other commercial detection techniques such as gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), Raman spectroscopy, and inductively coupled plasma (ICP) that need long experimental process, complicated sample preparation, and destructive to sample. In this research, LIBS technique was deployed for determination of presence pesticides on guava fruit. The experimental setup consists of Q-switched Nd:YAG laser operating at 1064 nm (139 mJ per pulse) and fiber optical cable was connected with HR4000 spectrometer in order to collect the atomic emission light. Different pesticide concentrations (1, 10, 100, and 1000 ppm) were prepared for calibration curve analysis in determination of limit of detection (LOD) and limit of quantification (LOQ). LIBS technique was able to detect the pesticide elements on guava sample such as phosphorus at wavelength of 253.56 nm and 255.33 nm. The different pesticide concentrations resulted to the proportional changes of pesticide element intensity such as phosphorus and carbon. LOD and LOQ were also measured with minimum value of 0.7 and 1.4 mg/L, respectively. Principal component analysis (PCA) implemented in the study was able to classify the group of pesticide at different concentrations with variance 95%. In conclusion, the combination of LIBS and PCA method has potential for detection of pesticides at different concentrations.