[Determination of HVA and VMA in urine using high performance liquid chromatography-tandem mass spectrometry]. 
To establish a method for the determination of homovanillic acid (HVA) and vanil mandelic acid (VMA) in urine, using high performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) detection.  A 200 μl volume of urine sample added with 20 μl chlorzoxazone internal standard was mixed in a centrifuge tube, then added 100μL methanol (containing 1% acetic acid) , vortex mixed and centrifuged at 13 000 rpm for 1 min.  A 10 μl volume of the above supernatant solution was injected into HPLC/MS/MS system for quantitative analysis.  With internal standard method, the calibration curves of HVA and VMA were linear in the range of 20~10 000 ng/ml and 20~7 500 ng/ml, with correlation coefficient of 0.995 6 and 0.997 0, respectively.  The LOQ of HVA and VMA was 4.69 ng/ml and 2.33 ng/ml, respectively.  The method recoveries were in the range of 85.72%~117.95% for HVA, and 95.82%~113.78% for VMA.  This method is simple, rapid and characterized with acceptable sensitivity and accuracy to meet the requirements for the analysis of homovanillic acid and vanilla mandelic acid.