Kelly Ryan T, Page Jason S, Tang Keqi, Smith Richard D
Biological Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA.
Anal Chem. 2007 Jun 1;79(11):4192-8. doi: 10.1021/ac062417e. Epub 2007 May 2.
An array of emitters has been developed for increasing the sensitivity of electrospray ionization mass spectrometry (ESI-MS). The linear array consists of 19 chemically etched fused-silica capillaries arranged with 500 microm (center-to-center) spacing. The multiemitter device has a low dead volume to facilitate coupling to capillary liquid chromatography (LC) separations. The high aspect ratio of the emitters enables operation at flow rates as low as 20 nL/min/emitter, effectively extending the benefits of nanoelectrospray to higher flow rate analyses. To accommodate the larger ion current produced by the emitter array, a multicapillary inlet to the mass spectrometer was also constructed. The inlet, which matched the dimensions of the emitter array, preserved ion transmission efficiency. Standard reserpine solutions of varying concentration were electrosprayed at 1 microL/min using the multiemitter/multi-inlet combination, and the results were compared to those from a standard, single-emitter configuration. A 9-fold sensitivity enhancement was observed for the multiemitter relative to the single emitter. A bovine serum albumin tryptic digest was also analyzed, and a sensitivity increase ranging from 2.4- to 12.3-fold for the detected tryptic peptides resulted; the varying response was attributed to reduced ion suppression under the nanoESI conditions afforded by the emitter array. An equimolar mixture of leucine enkephalin and maltopentaose was studied to verify that ion suppression is indeed reduced for the multiplexed ESI (multi-ESI) array relative to a single emitter over a range of flow rates.
为提高电喷雾电离质谱（ESI-MS）的灵敏度，已开发出一种发射器阵列。线性阵列由19根化学蚀刻的熔融石英毛细管组成，毛细管中心距为500微米。这种多发射器装置的死体积小，便于与毛细管液相色谱（LC）分离联用。发射器的高纵横比使得其能够在低至20纳升/分钟/发射器的流速下运行，有效地将纳喷的优势扩展到更高流速的分析中。为了适应发射器阵列产生的更大离子流，还构建了一个进入质谱仪的多毛细管入口。该入口与发射器阵列的尺寸匹配，保持了离子传输效率。使用多发射器/多入口组合，以1微升/分钟的流速对不同浓度的利血平标准溶液进行电喷雾，并将结果与标准单发射器配置的结果进行比较。观察到多发射器相对于单发射器的灵敏度提高了9倍。还分析了牛血清白蛋白胰蛋白酶消化产物，检测到的胰蛋白酶肽的灵敏度提高了2.4至12.3倍；响应的差异归因于发射器阵列提供的纳喷条件下离子抑制的降低。研究了亮氨酸脑啡肽和麦芽五糖的等摩尔混合物，以验证在一系列流速下，相对于单发射器，多路复用电喷雾（多ESI）阵列的离子抑制确实降低。
