Abstract: A sprayer assembly for an ion source is disclosed. The sprayer includes a capillary having an outlet, a sheath for the capillary, and an elastic member. The sheath can move relative to the capillary between a first position in which the sheath covers the outlet of the capillary and a second position in which the outlet of the capillary is exposed. When the sheath moves from the first position to or towards the second position, the elastic member provides a restoring force that acts to restore the position of the sheath to or towards the first position.

Abstract: A sprayer assembly for an ion source is disclosed. The sprayer includes a capillary having an outlet, a sheath for the capillary, and an elastic member. The sheath can move relative to the capillary between a first position in which the sheath covers the outlet of the capillary and a second position in which the outlet of the capillary is exposed. When the sheath moves from the first position to or towards the second position, the elastic member provides a restoring force that acts to restore the position of the sheath to or towards the first position.

Abstract: A sprayer assembly for an ion source is disclosed. The sprayer includes a capillary having an outlet, a sheath for the capillary, and an elastic member. The sheath can move relative to the capillary between a first position in which the sheath covers the outlet of the capillary and a second position in which the outlet of the capillary is exposed. When the sheath moves from the first position to or towards the second position, the elastic member provides a restoring force that acts to restore the position of the sheath to or towards the first position.

Abstract: A method for assaying an analyte in a bodily fluid from a subject includes collecting a sample of the bodily fluid comprising an analyte of interest from a subject. A sample with the bodily fluid comprising the analyte of interest suitable for analysis by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF) is then prepared. Mass spectrometry is then performed to determine mass-to-charge ratios and ion abundances of the bodily fluid or its components. The mass-to-charge ratio values and the ion abundance of each of these ratios are then analyzed using calibration standards to interpret a resulting mass spectrum and to provide quantitative information.

Abstract: In various aspects, provided are methods for identification of the presence of modified peptides using at least in part mass spectrometric signals from metastable ions that are formed in the field free region of the analyzer. For example, in various embodiments where the modified peptides are phosphopeptides, such metastable ions can appear approximately 95 u lower than the precursor ion m/z value from which they were formed when the peptide contains a phosphate group. In various embodiments, detection of such metastable ions in a MALDI-TOF mass spectrum can identify the modified peptide. In various aspects, provided are methods for identification of the presence of modified peptides using at least in part MS/MS data from two or more of modified peptides, de-modified peptides and non-modified peptides by comparing the sequence and/or site of modification information for two or more of these three forms of a peptide.