Division of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 University of Helsinki, Finland.
Anal Chim Acta. 2010 Mar 10;662(2):163-9. doi: 10.1016/j.aca.2010.01.005. Epub 2010 Jan 11.
A new integrated microchip for liquid chromatography-mass spectrometry (LC-MS) is presented. The chip is made from bonded silicon and glass wafers with structures for a packed LC column channel, a micropillar frit, a channel for optional optical detection, and a heated vaporizer section etched in silicon and platinum heater elements on the glass cover. LC eluent is vaporized and mixed with nebulizer gas in the vaporizer section and the vapor is sprayed out from the chip. Nonpolar and polar analytes can be efficiently ionized in the gas phase by atmospheric pressure photoionization (APPI) as demonstrated with polycyclic aromatic hydrocarbons (PAHs) and selective androgen receptor modulators (SARMs). This is not achievable with present LC-MS chips, since they are based on electrospray ionization, which is not able to ionize nonpolar compounds efficiently. The preliminary quantitative performance of the new chip was evaluated in terms of limit of detection (down to 5 ng mL(-1)), linearity (r>0.999), and repeatability of signal response (RSD=2.6-4.0%) and retention time (RSD=0.3-0.5%) using APPI for ionization and PAHs as standard compounds. Determination of fluorescent compounds is demonstrated by using laser-induced fluorescence (LIF) for detection in the optical detection channel before the vaporizer section.
一种新的用于液相色谱-质谱（LC-MS）的集成微芯片被提出。该芯片由键合硅和玻璃晶圆制成，具有填充 LC 柱通道、微柱 frit、可选光学检测通道以及在硅中刻蚀的加热汽化器部分和玻璃盖上的铂加热器元件的结构。LC 洗脱液在汽化器部分中被蒸发并与雾化器气体混合，然后从芯片中喷出蒸汽。非极性和极性分析物可以通过大气压光电离（APPI）在气相中有效地离子化，这一点通过多环芳烃（PAHs）和选择性雄激素受体调节剂（SARMs）得到了证明。这是目前的 LC-MS 芯片无法实现的，因为它们基于电喷雾电离，而电喷雾电离不能有效地离子化非极性化合物。使用 APPI 进行电离和以 PAHs 作为标准化合物，对新芯片的初步定量性能进行了评估，包括检测限（低至 5ngmL(-1)）、线性（r>0.999）以及信号响应重复性（RSD=2.6-4.0%）和保留时间（RSD=0.3-0.5%）。在汽化器部分之前的光学检测通道中使用激光诱导荧光（LIF）进行检测，证明了对荧光化合物的测定。
