title: Cavitation of liquid flow in electrospray mass spectrometry especially for addition of internal calibrant in 'accurate mass' measurements.
abstract: 'Accurate mass' measurements in electrospray mass spectrometry are becoming more prevalent with the increasing availability of mass spectrometers with sufficient resolution. A reference compound is ideally admitted separately but almost simultaneously with the analyte and this is achieved by use of a 'dual sprayer' or voltage switching between reference and sample sprayers. This paper describes a novel third method, relying on cavitation (segmentation) of the liquid stream containing the reference compound, allowing the sample to ionise independently from the sample, thus preventing interference. The technique may also find application in kinetic experiments, such as protein folding studies. A high-performance liquid chromatography (HPLC) injector was also used to provide a reference compound, producing Gaussian-shaped profiles of varying ion intensity, thus allowing easier selection of a desirable measurement point where the intensities of the reference and analyte were similar.
authors.affiliation: MRC Bioanalytical Science Group, Department of Biological Sciences, Birkbeck College, University of London, Malet Street, London WC1E 7HX, UK. g.lord@sbc.bbk.ac.uk
authors.forename: Gwyn A
authors.initials: GA
authors.lastname: Lord
authors.forename: Chang-Kee
authors.initials: CK
authors.lastname: Lim
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D004743:Enkephalin, Leucine / Q000737:chemistry; D004867:Equipment Design; D008970:Molecular Weight; D016011:Normal Distribution; D004364:Pharmaceutical Preparations / Q000737:chemistry; D012015:Reference Standards; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D004364:Pharmaceutical Preparations; D004743:Enkephalin, Leucine