Abstract
A rapid and accurate analytical method of orthophosphate was establishid by flow injection analysis based on solvent extraction system as follows: Twenty μl of sample solution was injected to molybdenum reagent stream (1 % ammonium molybdate in 0.8 N HCl, 0.8 ml/min). The aqueous phase carrier stream containing a sample and isobutylacetate stream (an organic phase carrier, 1.0 ml/min) are mixed by the segmentor. Phosphomolybdic acid, H3PO4(MoO3)12, is formod and extracted away from other substances into organic segments in the extraction tube (0.5 mm i.d. × 2 m). The stream of alternative aqueous and organic phase segments entered to the membrane phase separator {L. Nord, B. Karlberg: Anal. Chim. Acta, 118, 285(1980)}. The organic phase was sucked through the membrane and the complex in the phase was measured at 310 nm. In this method, sampling rate was 80 samples/h and the detection limit was 0.01 ppm (200 pg as P). The relative standard deviations (RSD) were 2.1 % and 1.8 % for 1.0 ppm and 10 ppm phosphate, respectively. It was found that this method was effective in determining orthophosphate in human seminal plasma and urine without deproteinization.
