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.

中文翻译：

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干滴预处理通过激光诱导击穿光谱法进行痕量元素分析

痕量元素定量分析对食品，天然和人造材料以及生物医学等一系列行业至关重要。为此，我们在这里开发了采用干滴样品预处理的激光诱导击穿光谱（LIBS）。这种新颖的方法是定量的，尤其适合分析痕量低原子序数元素的小型固体样品。干燥的液滴预处理包括酸消化样品，并允许液滴在不含分析物的滤纸上干燥。然后，使用脉冲激光烧蚀和200–1000 nm的光谱检测器以0.1 nm的分辨率对干燥的液滴进行LIBS。通过将已知量的分析物添加到液滴中，采用标准添加方法对LIBS信号进行定量。通过测量钠证明了该方法，四个选定样本中的钾和钙。所有标准加法校正曲线均显示出良好的线性，所有回归系数均> 0.981，相对标准偏差<5.6％。同时，检出限为0.57至14.5 mg kg^-1，定量极限范围为1.9至48 mg kg ^-1。为了验证，还通过电感耦合等离子体质谱法（ICP-MS）分析了所有样品。与ICP-MS相比，LIBS的相对误差很低，所有样品均<6.3％。总之，采用干滴预处理的LIBS是一种用于定量分析小固体的有前途的新技术。