液态奶中镁元素原位在线检测方法研究

Research on In-situ Online Detection Method of Magnesium in Liquid Milk

镁元素是牛奶中的重要营养组分之一,其含量检测的前处理步骤繁琐。该文提出了一种超声喷雾激光诱导击穿光谱(US-LIBS)检测方法,通过将超声雾化和极短焦激光诱导击穿光谱技术有机结合,巧妙避免了液态奶的等离子体猝灭效应。使用US-LIBS方法无需对液态奶样品进行任何前处理,即可在秒级时间内完成液态奶中镁元素的在线原位检测。为进一步提升镁元素的检测精度,实验通过构建重加权特征光谱算法(RCSA),从复杂、变动的基质干扰中准确提取镁元素的光谱信息。计算结果表明,经RCSA处理后,实际液态奶样品中镁元素的检出限和线性系数(r^(2))分别为0.3 mg/kg和0.97,可有效满足液态奶中镁元素的检测需求。因此,US-LIBS为乳制品智能制造提供了一种强大的在线分析工具,并有望进一步拓展至其它液态体系中微量元素的原位在线检测。

Magnesium(Mg)represents one of the important nutritional components in milk.However,its detection methods require cumbersome sample pretreatment,which is inadequate for the high-throughput online analysis of trace elements.In this regard,this work developed a novel methodology that was named as ultrasonic spraying laser-induced breakdown spectroscopy(US-LIBS).In the US-LIBS,the techniques of ultrasonic spraying and ultra-short focus laser-induced breakdown spectroscopy were combined to avoid the plasma quenching,thus enhancing the stability and intensity of the signal greatly.Benefiting from the instantaneous phase transition technology,US-LIBS can achieve in situ analysis of trace elements in milk samples within seconds without any pretreatment of the milk samples.This enables the intelligent assessment of dairy product quality and safety in an efficient way.In order to improve the detection accuracy of US-LIBS,the algorithm of reweighted-characteristic spectrum algorithm(RCSA)was also developed to extract the spectral bands of Mg element from the complicated and fluctuant matrix interference.Moreover,the RCSA algorithm utilizes its flexible weighting distribution to guarantee the integrity of spectral information,thus preventing the loss of crucial information bands.As a result,the RCSA algorithm exhibits a notably superior quantitative accuracy and reliability than those of other variable selection algorithms.In the validation samples,the limit of detection and r^(2)of Mg were 0.3 mg/kg and 0.97,respectively.The results reveal that the US-LIBS is a promising online analysis tool for smart manufacturing of dairy products,which may well extend to any other liquid systems as well.