Choi Han-Bum, Moon Seung-Hyun, Kim Hyang, Guthikonda Nagaraju, Ham Kyung-Sik, Han Song-Hee, Nam Sang-Ho, Lee Yong-Hoon
Department of Chemistry, Mokpo National University, Jeonnam, Muan-gun 58554, Republic of Korea.
Plasma Spectroscopy Analysis Center, Mokpo National University, Jeonnam, Muan-gun 58554, Republic of Korea.
Sensors (Basel). 2023 Nov 20;23(22):9280. doi: 10.3390/s23229280.
Salt, one of the most commonly consumed food additives worldwide, is produced in many countries. The chemical composition of edible salts is essential information for quality assessment and origin distinction. In this work, a simple laser-induced breakdown spectroscopy instrument was assembled with a diode-pumped solid-state laser and a miniature spectrometer. Its performances in analyzing Mg and Ca in six popular edible sea salts consumed in South Korea and classification of the products were investigated. Each salt was dissolved in water and a tiny amount of the solution was dropped and dried on the hydrophilicity-enhanced silicon wafer substrate, providing homogeneous distribution of salt crystals. Strong Mg II and Ca II emissions were chosen for both quantification and classification. Calibration curves could be constructed with limits-of-detection of 87 mg/kg for Mg and 45 mg/kg for Ca. Also, the Mg II and Ca II emission peak intensities were used in a -nearest neighbors model providing 98.6% classification accuracy. In both quantification and classification, intensity normalization using a Na I emission line as a reference signal was effective. A concept of interclass distance was introduced, and the increase in the classification accuracy due to the intensity normalization was rationalized based on it. Our methodology will be useful for analyzing major mineral nutrients in various food materials in liquid phase or soluble in water, including salts.
盐是全球消费最为普遍的食品添加剂之一，许多国家都有生产。食用盐的化学成分是质量评估和产地区分的重要信息。在这项工作中，我们用二极管泵浦固体激光器和微型光谱仪组装了一台简单的激光诱导击穿光谱仪。研究了其对韩国消费的六种常见食用海盐中镁和钙的分析性能以及产品分类情况。每种盐都溶解于水，取少量溶液滴加在亲水性增强的硅片基底上并干燥，使盐晶体均匀分布。选择强镁II和钙II发射线进行定量和分类。可以构建校准曲线，镁的检测限为87 mg/kg，钙的检测限为45 mg/kg。此外，镁II和钙II发射峰强度用于最近邻模型，分类准确率达98.6%。在定量和分类中，以钠I发射线作为参考信号进行强度归一化是有效的。引入了类间距离的概念，并据此解释了强度归一化导致分类准确率提高的原因。我们的方法将有助于分析包括盐在内的各种液相或可溶于水的食品原料中的主要矿物质营养成分。
