Method for urinary neopterin measurements by HPLC.

In the June 2004 issue of the Journal, Drs. Ribeiro de Castro and coworkers described a new method to determine neopterin concentrations in urine by HPLC and UV-absorption detection [de Castro MR, Di Marco GS, Arita DY, Teixeira LC, Pereira AB, Casarini DE. Urinary neopterin quantification by reverse-phase high-performance liquid chromatography with ultraviolet detection. J Biochem Biophys Methods 2004;59:275-83 ]. Although simple and rapid, unfortunately this report does not consider any possible analytical complications known from the biochemistry of neopterin. The major problem with this method is that the authors did not at all consider possible interferences with related compounds.