Assessing the Sensitivity and Efficiency of Laser-Induced Breakdown Spectroscopy (LIBS) for High-Concentration...

Area of Science:

• Analytical Chemistry
• Food Science
• Spectroscopy

Background:

• Cocoa is a significant global commodity, but heavy metal contamination, especially cadmium (Cd), poses risks.
• Accurate and rapid quantification of Cd in cocoa powder is crucial for food safety and quality control.
• Traditional methods for elemental analysis can be time-consuming and require complex sample preparation.

Purpose of the Study:

• To demonstrate the efficacy of laser-induced breakdown spectroscopy (LIBS) for fast Cd quantification in cocoa powder.
• To develop and validate a robust sample preparation protocol for challenging food matrices like cocoa powder.
• To assess the accuracy and sensitivity of LIBS for Cd detection in a complex food matrix.

Main Methods:

• A mechanical mixing and pelletization protocol was developed to overcome cocoa powder's physical limitations.
• Laser-induced breakdown spectroscopy (LIBS) was employed for elemental analysis, utilizing specific Cd atomic emission lines.
• A specialized algorithm for background subtraction and plasma characterization were implemented for accurate quantification.

Main Results:

• LIBS successfully quantified cadmium in cocoa powder across concentrations ranging from 70 to 5000 ppm.
• Quantification results for double-blinded unknown samples showed good agreement with normalized standard deviations of 9.73% and 5.88%.
• The method achieved low limits of detection for Cd, specifically 0.4 and 0.08 μg/g for the two analyzed lines.

Conclusions:

• LIBS is a rapid, versatile, and accurate analytical tool for cadmium detection and quantification in complex food matrices like cocoa.
• The developed sample preparation method ensures sample uniformity, crucial for reliable spectroscopic analysis.
• LIBS holds significant potential for field-based and industrial monitoring of heavy metal contamination in food products.