Design and performance of a high resolution electrospray ion source for a magnetic sector mass spectrometer with a heated capillary inlet

Combining capillary with radio-frequency-only quadrupole as an interface for a home-made time-of-flight mass spectrometer

A heated capillary tube combined with a radio-frequency-only quadrupole has been coupled with a home- made, high-resolution orthogonal-injection, time-of-flight mass spectrometer to improve ion transmission from the atmospheric pressure to the low--pressure regions. With an electrospray ion source, the performance of the interface on the intensity of spectra was investigated. For electrospray ionization, the ion intensity detected on the time-of- flight mass spectrometer was seen to increase three-fold compared with an orifice interface. It has been shown that the enhanced ion inlet designs can not only increase the ion translation efficiency, but also improve the detection limits of the mass spectrometer. Coupling atmospheric pressure matrix-assisted laser desorption/ionization with the improved interface resulted in an instrument detection limit as low as 2.5 fmol.

Analysis of peptides, proteins, protein digests, and whole human blood by capillary electrophoresis/electrospray ionization-mass spectrometry using an in-capillary electrode sheathless interface

An in-capillary electrode sheathless interface was applied to the capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS) analysis of mixtures of small peptides, proteins, and tryptic digests of proteins. The effects of different experimental parameters on the performance of this CE/ESI-MS interface were studied. The distance of the in-capillary electrode from the CE outlet and the length of the electrode inside the capillary had no significant effects on the CE separation and ESI behavior under the experimental conditions used. However, significant enhancement of the sensitivity resulted from the use of narrower CE capillaries. Using a quadrupole mass spectrometer, an aminopropylsilane-coated capillary, and a wide scan mass-to-charge ratio range of 500-1400, detection limits of approximately 4, 1, and 0.6 fmol for cytochrome c and myoglobin were achieved for 75-, 50-, and 30-micron inner diameter capillaries, respectively. Approximately one order of magnitude lower detection limits were achieved under the multiple-ion monitoring mode. The application of the in-capillary electrode sheathless interface to real-world samples was demonstrated by CE/ESI-MS analysis of a human blood sample.

Advances in instrumentation in liquid chromatography-mass spectrometry and related liquid-introduction techniques

In the past few years, the instrumental developments in the field of combined liquid chromatography-mass spectrometry (LC-MS) and related liquid-introduction techniques has been extremely fast. Soon after the demonstration of the ability to obtain multiply-charged ions from proteins by electrospray ionization, a major impetus was given to the field. Numerous LC-MS systems based on atmospheric-pressure ionization sources have now been described. This paper reviews these instrumental developments with reference to currently available commercial LC-MS systems. Not only low and high flow-rate electrospray on quadrupole instrument is discussed, but also electrospray on ion-trap, double-focusing sector, time-of-flight, and Fourier-transform ion-cyclotron resonance instruments are reviewed.