Development of Multi-ESI-Sprayer, Multi-Atmospheric-Pressure-inlet Mass Spectrometry and Its Application to Accurate Mass Measurement Using Time-of-Flight Mass Spectrometry

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• 作者：Longfei Jiang and Mehdi Moini
• 刊名：Analytical Chemistry
• 出版年：2000
• 出版时间：January 1, 2000
• 年：2000
• 卷：72
• 期：1
• 页码：20 - 24
• 全文大小：103K
• 年卷期：v.72,no.1(January 1, 2000)
• ISSN：1520-6882

文摘

The atmospheric pressure sampling nozzle (orifice, heatedcapillary, or inlet) of a high mass accuracy time-of-flightmass spectrometer (TOF-MS) was modified by replacingits single nozzle with multiple atmospheric pressurenozzles. This allowed multiple streams of liquids to beintroduced into the MS in parallel (an electrosprayer foreach nozzle), with minimum analyte interactions betweenthe streams. The chemical contents of all liquid streamswere analyzed concurrently using a single mass spectrometer. To obtain a higher mass accuracy by providinginternal reference on each scan (acquisition) and toevaluate the suitability of TOF-MS for molecular-formulaconfirmation, a dual-ESI-sprayer, dual-nozzle version ofthis design was used. The accurate masses of tens oforganic compounds in the mass range of 200-3000 Dawere measured, and the results were compared with thoseobtained using dual-sprayer, single-nozzle TOF-MS. Asignificant improvement in mass accuracy was observedwhen the former technique was used. Comparison between the mass accuracy using dual-ESI-sprayer, dual-nozzle TOF-MS and that obtained using a double-focusingmass spectrometer operating under chemical ionization(CI) and fast atom bombardment (FAB) shows the suitability of the technique for elemental-composition confirmation. Approximately 85% of samples analyzed had masserrors of less than 5 ppm, and the other 15% had masserrors less than 8 ppm. Using a high-performance liquidchromatography (HPLC) as a device for introduction ofone liquid stream (sample) and a syringe pump as adevice for introduction of the second liquid stream (reference standard), the accurate mass of a tryptic digest ofcytochrome c was measured. The range of mass errorswas from -6.1 ppm to +3.6 ppm, a significant improvement over our previously reported mass accuracy for thisdigest using single-nozzle TOF-MS. The interactions between analytes in the liquid streams also were investigatedusing a variety of sample-introduction and nozzle-designcombinations, including single-ESI-sprayer, single-nozzle;dual-ESI-sprayer, single-nozzle; dual-ESI-sprayer, Y-shaped inlet; and dual-ESI-sprayer, dual-inlet. The resultsdemonstrated that the dual-ESI-sprayer, dual-inlet designprovides reference peaks on every acquisition with minimum analyte-reference interaction and, therefore, higherconsistent mass accuracy.