Simultaneous determination of guanidinoacetate, creatine and creatinine by liquid chromatography-tandem mass spectrometry: a diagnostic tool for creatine deficiency syndromes in body fluids and a perspective use on cultured fibroblasts

LC-MS/MS measurements of urinary guanidinoacetic acid and creatine: Method optimization by deleting derivatization step

“…Measurement of such molecules, not held on conventional columns, requires usually an esterification step with butanol. This method, although reliable and with an analytical performance provided, is long and laborious due to the derivatization step [16]. To get round this problem we used ion pairing method.…”