Rapid assay of neopterin and biopterin in urine by wooden-tip electrospray ionization mass spectrometry

A rapid and sensitive method based on wooden-tip electrospray ionization mass spectrometry (WT-ESI-MS) has been established for the quantitative detection of neopterin and biopterin in urine with only little sample preparation required. The limits of detection (LODs) for the analyses of neopterin and biopterin were determined to be 30 ng mL(-1) and 50 ng mL(-1) (S/N >= 3), respectively. Acceptable relative standard deviation (RSD) values (6.3-9.5%) and recovery values (90-133.6%) were obtained for direct measurements of neopterin and biopterin in raw urine. Moreover, neopterin and biopterin were directly detected from 9 clinical urine samples by WT-ESI-MS. A single sample analysis was completed within a few minutes, indicating that the present WT-ESI-MS method is a promising strategy for the rapid analysis of clinical samples.