Quantitative trace elemental analysis by laser-induced breakdown spectroscopy with dried droplet pretreatment

• Published in: Journal of analytical atomic spectrometry Vol. 35; no. 1; pp. 2224 - 223
• Main Authors: Liu, Yuanchao, Hsieh, Yi-Kong, Chu, Yanwu, Ahmed, Irfan, Hu, Zhenlin, Khan, Muhammad Shehzad, Zhang, Siyu, Manno, Francis A. M, Manno, Sinai H. C, Lian, Meng, Wang, Chu-Fang, Guo, Lianbo, Lau, Condon
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 09.10.2020
• Subjects: Analytical chemistry; Atomic properties; Droplets; Filter paper; Inductively coupled plasma mass spectrometry; Laser ablation; Laser induced breakdown spectroscopy; Lasers; Linearity; Mass spectrometry; Pretreatment; Pulsed lasers; Regression analysis; Regression coefficients; Trace elements
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/d0ja00164c

Quantitative trace element analysis is crucial to a range of industries, including food, natural and man-made materials, and biomedicine. For this purpose, we here developed laser-induced breakdown spectroscopy (LIBS) with dried droplet sample pretreatment. This novel method is quantitative and especially suited to analyzing small solid samples with trace concentrations of low atomic number elements. The dried droplet pretreatment involves acid digesting the sample and allowing a droplet to dry on filter paper free of the analytes. LIBS was then performed on the dried droplet using pulsed laser ablation and spectroscopic detection from 200-1000 nm with 0.1 nm resolution. A standard addition approach was employed to quantify LIBS signals by adding known amounts of analytes into the droplets. The method was demonstrated by measuring sodium, potassium and calcium in four selected samples. All the standard addition calibration curves showed good linearity, with all regression coefficients >0.981 and relative standard deviation <5.6%. Meanwhile, the limit of detection ranges from 0.57 to 14.5 mg kg −1 and the limit of quantification ranges from 1.9 to 48 mg kg −1 . For validation, all samples were also analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The relative error of LIBS compared to ICP-MS was low, <6.3% for all samples. Altogether, LIBS with dried droplet pretreatment is a promising new technique for quantitative trace element analysis of small solids. A dried droplet pre-treatment method for small solid samples containing trace elements, involving acid digestion of the sample followed by drying of a droplet on filter paper free of the analytes and quantitative elemental analysis by LIBS.