Ostman Pekka, Jäntti Sirkku, Grigoras Kestas, Saarela Ville, Ketola Raimo A, Franssila Sami, Kotiaho Tapio, Kostiainen Risto
Division of Pharmaceutical Chemistry, Faculty of Pharmacy, P.O. Box 56, FI-00014, University of Helsinki, Finland.
Lab Chip. 2006 Jul;6(7):948-53. doi: 10.1039/b601290f. Epub 2006 Apr 27.
A miniaturized nebulizer chip for capillary liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (capillary LC-microchip APCI-MS) is presented. The APCI chip consists of two wafers, a silicon wafer and a Pyrex glass wafer. The silicon wafer has a DRIE etched through-wafer nebulizer gas inlet, an edge capillary insertion channel, a stopper, a vaporizer channel and a nozzle. The platinum heater electrode and pads for electrical connection were patterned on to the Pyrex glass wafer. The two wafers were joined by anodic bonding, creating a microchip version of an APCI-source. The sample inlet capillary from an LC column is directly connected to the vaporizer channel of the APCI chip. The etched nozzle in the microchip forms a narrow sample plume, which is ionized by an external corona needle, and the formed ions are analyzed by a mass spectrometer. The nebulizer chip enables for the first time the use of low flow rate separation techniques with APCI-MS. The performance of capillary LC-microchip APCI-MS was tested with selected neurosteroids. The capillary LC-microchip APCI-MS provides quantitative repeatability and good linearity. The limits of detection (LOD) with a signal-to-noise ratio (S/N) of 3 in MS/MS mode for the selected neurosteroids were 20-1000 fmol (10-500 nmol l(-1)). LODs (S/N = 3) with commercial macro APCI with the same compounds using the same MS were about 10 times higher. Fast heat transfer allows the use of the optimized temperature for each compound during an LC run. The microchip APCI-source provides a convenient and easy method to combine capillary LC to any API-MS equipped with an APCI source. The advantages and potentials of the microchip APCI also make it a very attractive interface in microfluidic APCI-MS.
本文介绍了一种用于毛细管液相色谱-大气压化学电离质谱联用（毛细管LC-微芯片APCI-MS）的小型化雾化器芯片。该APCI芯片由两片晶圆组成，一片硅晶圆和一片派热克斯玻璃晶圆。硅晶圆上有一个通过深反应离子刻蚀制成的贯穿晶圆的雾化器气体入口、一个边缘毛细管插入通道、一个塞子、一个汽化器通道和一个喷嘴。铂加热电极和用于电连接的焊盘被制作在派热克斯玻璃晶圆上。两片晶圆通过阳极键合连接在一起，形成了一个APCI源的微芯片版本。来自LC柱的样品入口毛细管直接连接到APCI芯片的汽化器通道。微芯片中蚀刻的喷嘴形成一个狭窄的样品羽流，该羽流被外部电晕针电离，形成的离子由质谱仪进行分析。该雾化器芯片首次实现了将低流速分离技术与APCI-MS联用。使用选定的神经甾体对毛细管LC-微芯片APCI-MS的性能进行了测试。毛细管LC-微芯片APCI-MS具有定量重复性和良好的线性。在MS/MS模式下，选定神经甾体的信噪比（S/N）为3时的检测限（LOD）为20 - 1000 fmol（10 - 500 nmol l(-1)）。使用相同质谱仪对相同化合物采用商用大型APCI时的LOD（S/N = 3）约高10倍。快速的热传递允许在LC运行期间针对每种化合物使用优化的温度。微芯片APCI源提供了一种方便且简单的方法，可将毛细管LC与任何配备APCI源的API-MS联用。微芯片APCI的优势和潜力也使其成为微流控APCI-MS中极具吸引力的接口。
