Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Heraklion, 70013, Greece.
Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, Voutes Campus, Heraklion, 70013, Greece.
Anal Chim Acta. 2021 Sep 22;1179:338830. doi: 10.1016/j.aca.2021.338830. Epub 2021 Jul 6.
Microfluidics coupled on-line with ICP-MS detection can be combined with powerful quantitation procedures that take advantage of internal standardization and standard additions, such as the recently introduced Standard Dilution Analysis (SDA). Although so far used at mL min flow rates, here we demonstrate that SDA can be conveniently employed with a microfluidic chip-based ICP-MS system to improve determination accuracy for various sample types, including water, biological and cell digest samples, analyzed at μL min flow rates. The efficient coupling of a microfluidic chip to ICP-MS was accomplished using a combination of commercially available components, including a pneumatic high-efficiency nebulizer and a spray chamber designed to allow for the addition of a laminar flow makeup gas. The addition of the makeup gas was crucial in order to avoid detrimental suction effects that can disrupt the operation of the microfluidic chip and cause signal instability, while it still allowed for the highly sensitive detection of metal isotopes by using ICP-MS. All mixing and dilution operations of the sample with the two calibration solutions required for SDA were performed in an automated and highly reproducible fashion on the microfluidic chip with the assistance of an external distributor valve. High average recoveries (97.4-100.1%) and low average relative standard deviations (2.9-4.8%) were achieved for the determined elements (Cd, Co, Pb, Cr) across several spiked matrices and certified reference materials, whereas only 140 μL of sample is required for SDA in triplicate or 40 μL for a single analysis. Hence, accuracy, precision, limited sample consumption, and the elimination of the need for manual sample dilution and mixing manipulations are some of the advantages of this newly developed chip-based microfluidic SDA ICP-MS technique.
微流控与 ICP-MS 在线联用，可以与强大的定量程序相结合，利用内标和标准加入法，如最近引入的标准稀释分析（SDA）。尽管目前在 mL min 流速下使用，但我们在此证明，SDA 可以方便地与基于微流控芯片的 ICP-MS 系统结合使用，以提高各种样品类型（包括水、生物和细胞消化样品）的测定准确性，流速为 μL min。通过组合使用商业上可获得的组件，包括气动高效雾化器和喷雾室，实现了微流控芯片与 ICP-MS 的有效耦合，该喷雾室旨在允许加入层流补充气体。添加补充气体对于避免有害的抽吸效应至关重要，抽吸效应会破坏微流控芯片的运行并导致信号不稳定，同时仍然允许使用 ICP-MS 对金属同位素进行高灵敏度检测。SDA 所需的两种校准溶液与样品的所有混合和稀释操作都在微流控芯片上以自动化和高度重现的方式完成，借助外部分配阀。对于几种加标基质和认证参考材料，所测定元素（Cd、Co、Pb、Cr）的平均回收率（97.4-100.1%）高，平均相对标准偏差（2.9-4.8%）低，而 SDA 一式三份或单次分析仅需 140 μL 样品。因此，准确性、精密度、有限的样品消耗以及消除手动样品稀释和混合操作的需求是这种新开发的基于芯片的微流控 SDA ICP-MS 技术的一些优势。
