The determination of minerals in cocoa powder using laser-induced breakdown spectroscopy

Abstract

Laser-Induced Breakdown Spectroscopy (LIBS) is one of the elemental identification techniques with high power energy source that is simple and has a wide range of detection. In this study, the LIBS system used to identify the minerals in six randomly chosen cocoa powder samples. The detection only occurs in ultraviolet (UV) range of 200 nm – 700nm. The samples were formed into pellets with 1cm thickness and 1 cm diameter using a hydraulic press. The Q-switched Nd: YAG pulsed laser with 1064nm fundamental wavelength along with a spectrometer, lenses, and mirror were set up for the system. Each sample was shot 10 times to get 10 spectra and then plotted average spectra. The peaks are identified by comparing their wavelengths with the Atomic Spectra Database (ASD) issued by the National Institute of Standards and Technology (NIST). The detected minerals were Mg I, Mg II, Ca I, Ca II, K I, N II also Na I with different intensities for each sample. Mg, I was detected at 284.75nm, 383.42nm, and 517.92nm while Mg II was detected at 279.18nm. Besides that, Ca I was detected at 422.29nm while Ca II were detected at 392.98nm and 396.47nm. K I was detected at nm while N II was detected at 500.05nm also Na I was detected at 588.45nm.