Patent ID: 11860141
Assignee: QUEST DIAGNOSTICS INVESTMENTS INCORPORATED
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for determining an amount of guanidinoacetate (GAA), creatine, and creatinine in a single human urine sample comprising:
(a) purifying underivatized GAA, creatine, and creatinine in the single human urine sample;
(b) ionizing GAA, creatine, and creatinine in the human sample to produce one or more ion(s) of GAA, creatine, and creatinine, wherein said ionization comprises electrospray ionization (ESI);
(c) determining an amount of the ion(s) from step (b) by mass spectrometry, wherein a fragment ion with the mass/charge ratio of 72.1±0.5 is used to determine the amount of GAA ions;
wherein the amount of the GAA, creatine, and creatinine ion(s) is related to the amount of GAA, creatine, and creatinine in the single human urine sample.