Application of LIBS to study the difference in elemental composition between organic and genetically modified plants

Abstract

Genetic modification includes the change in the genetic make-up of a plant in order to meet the requirements for food security, which is in contrast to organic plants that are grown naturally by the use of organic fertilizers and natural manure. The purpose of this research was to study the difference in elemental composition between organic and genetically modified plants. It is believed that change in genetic make-up results in change in elemental composition of a plant. Hence, analyzing and comparing the elemental composition between organic and genetically modified plants can be the key solution to solve the plants related diseases or the environment unfriendliness imposed by genetically modified plants, which can be due to the excess, deficiency or change in elemental expression. Many different techniques can be used for elemental analysis but in this case, laser induced breakdown spectroscopy (LIBS) was used because it is a non-invasive technique that permits concurrent multi-elemental examination in a single measurement, with little or no sample preparation needed. For accuracy, inductively coupled mass spectroscopy (ICP-MS) was used in order to verify and validate LIBS results. Using LIBS technique, one is able to differentiate the two categories according to the signature of their essential and trace elements and determine the effects of GMO to the environment and people. In this study, a solid maize sample was run under LIBS in a dark room to avoid light interference, which resulted in good results as compared to liquid and powder samples. A portion of the same sample was then digested using a Perkin-Elmer microwave digester and then ran under ICP-MS. The obtained results indicated that genetic modification does not add or reduce the expected nutrient elements but it changes the elemental concentration and intensities. LIBS detected six elements, which are Mn I, Fe I, Fe II, Cu II, K I and O I in all organic samples whilst Mn I, Fe I, Fe II, Cu II, K I, O I plus Ca II, C I, N II and CaI were detected in all genetically modified samples. ICP-MS detected all expected seventeen elements in both sample categories. This research thus proved that both techniques (LIBS and ICP-MS) are good when they are both used for the same analysis in order to avoid systematic errors. For future use, it is recommended to run LIBS experiments in the presence of Argon gas to avoid matrix effect and self-absorption.