Department of Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States.
Center for Wireless Integrated MicroSensing and Systems , University of Michigan , Ann Arbor , Michigan 48109 , United States.
Anal Chem. 2019 Apr 2;91(7):4747-4754. doi: 10.1021/acs.analchem.9b00263. Epub 2019 Mar 19.
We describe a belt-mountable prototype instrument containing a gas chromatographic microsystem (μGC) and demonstrate its capability for near-real-time recognition and quantification of volatile organic compounds (VOCs) in moderately complex mixtures at concentrations encountered in industrial workplace environments. The μGC comprises three discrete, Si/Pyrex microfabricated chips: a dual-adsorbent micropreconcentrator-focuser for VOC capture and injection; a wall-coated microcolumn with thin-metal heaters and temperature sensors for temperature-programmed separations; and an array of four microchemiresistors with thiolate-monolayer-protected-Au-nanoparticle interface films for detection and recognition-discrimination. The battery-powered μGC prototype (20 × 15 × 9 cm, ∼2.1 kg sans battery) has on-board microcontrollers and can autonomously analyze the components of a given VOC mixture several times per hour. Calibration curves bracketing the Threshold Limit Value (TLV) of each VOC yielded detection limits of 16-600 parts-per-billion for air samples of 5-10 mL, well below respective TLVs. A 2:1 injection split improved the resolution of early eluting compounds by up to 63%. Responses and response patterns were stable for 5 days. Use of retention-time windows facilitated the chemometric recognition and discrimination of the components of a 21-VOC mixture sampled and analyzed in 3.5 min. Results from a "mock" field test, in which personal exposures to time-varying concentrations of a mixture of five VOCs were measured autonomously, agreed closely with those from a reference GC. Thus, reliable, near-real-time determinations of worker exposures to multiple VOCs with this wearable μGC prototype appear feasible.
我们描述了一种可佩戴在腰带上的原型仪器，其中包含一个气相色谱微系统（μGC），并展示了其在浓度适中的复杂混合物中对挥发性有机化合物（VOC）进行实时识别和定量的能力，这些浓度在工业工作场所环境中遇到。μGC 由三个离散的 Si/Pyrex 微加工芯片组成：一个用于 VOC 捕获和注入的双吸附剂微预浓缩-聚焦器；一个带有薄金属加热器和温度传感器的壁涂覆微柱，用于程序升温分离；以及一个带有硫醇单层保护金纳米粒子界面膜的四个微化学电阻器阵列，用于检测和识别-区分。这款电池供电的 μGC 原型机（20×15×9 厘米，不含电池约 2.1 公斤）具有板载微控制器，可自主分析每小时给定 VOC 混合物的成分数次。校准曲线涵盖每个 VOC 的阈限值（TLV），空气中 5-10 毫升样本的检测限为 16-600 部分/十亿，远低于各自的 TLV。2:1 注射分裂将早期洗脱化合物的分辨率提高了高达 63%。响应和响应模式在 5 天内保持稳定。使用保留时间窗口有助于对 21-VOC 混合物的成分进行化学计量识别和区分，该混合物在 3.5 分钟内被采样和分析。在“模拟”现场测试中，自主测量个人对五种 VOC 混合物的时间变化浓度的暴露情况，结果与参考 GC 非常吻合。因此，使用这种可穿戴 μGC 原型机可靠地实时确定工人对多种 VOC 的暴露情况似乎是可行的。
