ABSTRACT
Objective To establish a liquid chromatography-tandem mass spectrometry ( LC-MS/MS) method for the quantification of creatinine-correctedsarcosine in urine for the prostate cancer diagnosis and treatment.Methods It performed the method establishment and evaluation in this study.Random unrine samples were collected from 36 subjects with prostate cancer, 15 subjects with benign prostatic hyperplasia and 76 healthy people receiving medical examination.Urine samples mixed with [ 2 H3 ]-labeled sarcosine were treated by precolumn derivation using dansyl chloride, then analyzed by LC-MS/MSsystem in multiple reaction monitor ( MRM) mode.Sarcosine and creatinine were quantified by the isotope internal standard method and the standard curve was employed with a series of calibration.The limit of detection, precision and recovery were also evaluated in this study.The results of this methodology were compared with those of the enzymatic method.Results Sarcosine could be distinguished against its isomers completely. The linear equation of sarcosine was Y=2.045 6X+0.068 9, R2 =0.994.The limit of detection and limit of quantity were 8 ng/ml and 25 ng/ml respectively.The intraassay and interassay coefficients of variation were both below 6%.The recovery ratio of sarcosine ranged from 96.8%to 105.1%.The results from the ID-LC-MS method correlated with those from enzymatic method (R2 =0.815, P <0.01).Compared to enzymatic method, the average bias of sarcosine was -37.1%.Conclusions It established a LC-MS method for urinary sarcosine quantification with good specificity, sensitivity and repeatability.This method can provide a reliable platform for the diagnosis of prostate cancer.