Patent ID: 11885780
Assignee: QUEST DIAGNOSTICS INVESTMENTS INCORPORATED
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for determining the amount of chromogranin A (CgA) in a sample, said method comprising:
(a) purifying CgA in the sample;
(b) ionizing CgA to produce one or more ion(s) of CgA detectable by mass spectrometry;
(c) determining the amount of the ion(s) from step (b) by mass spectrometry, comprising measuring the amount of a precursor ion having a mass-to-charge ratio of 729.6±0.5, wherein the amount of ions is related to the amount of CgA in the sample, wherein the limit of quantitation of the method is less than or equal to 50 ng/mL, and
(d) correlating the amount of CgA in the sample to the amount of the precursor ion measured in step (c).