We compared results of the stannous chloride and vanadate methods for estimating serum inorganic phosphorus on the "SMA 12/60" (Technicon). The technically simpler vanadate method gave better linearity and reproducibility, with virtually no carry-over or baseline drift; the reagents were stable, and it was most important to ensure that the concentration of sulfuric acid in the recipient and sample streams was identical. Instability in the stannous chloride method was due to precipitation in the stannous chloride-hydrazine working solution.
No takes yet. Share an insight, caveat, or question.
Davies et al. (1973) studied this question.