Soil Sample Preparation Methods to Optimize a Laser-Induced Breakdown Spectroscopy Signal

Laser-Induced Breakdown Spectroscopy (LIBS) is an atomic emission spectroscopy technique used to analyze the elemental composition of materials, including heavy metals. A high-powered laser ablates a sample's surface and forms a plasma that emits characteristic spectra. Because LIBs can provide rapid results, one application is evaluating the safe redevelopment of brownfields, previously developed urban areas. When using LIBS to analyze soil, the sample's natural heterogeneity and moisture content can influence its ability to withstand data collection. In many cases, the laser pulse will cause the soil samples to disintegrate completely. Because of its composition of organic matter and particles of varying sizes, soil requires a preparation method that improves its uniformity and preserves its integrity during laser exposure. This study compares how different preparation techniques affect the sample's ability to withstand laser ablation while maintaining consistent emission characteristics. Preparation techniques include heating, drying, grinding, layering, and adding binders, such as KBr, at varying ratios. By varying these conditions, the samples can better withstand multiple laser blasts, allowing for greater data collection and an improved signal-to-noise ratio (SNR). This study is part of YREP, a larger initiative that engages high school students in meaningful environmental research and encourages them to address community challenges through scientific inquiry.