title: Quantitative measurements of ammonium, hydrogenophosphate and Cu(II) by diffuse reflectance spectrometry.
abstract: Diffuse reflectance spectrometry is shown to be useful for the quantitative determination of small amounts of pollutants. The relation between sample concentration and reflectance is described by the Kubelka-Munk equation. The experiments were performed with a laboratory constructed diode array spectrophotometer. We can obtain the quantitative reflectance values of different precipitates like ammonium with Nessler's reagent, hydrogenophosphate with silver nitrate and a complex such as Cu(II) with dithiooxamide 'rubeanic acid' by forming a spot colour on filter paper. We have obtained for each reagent a calibration curve by plotting the relative intensity of reflectance versus the log of the mol (dm(3))(-1) concentration. The linearity was obtained for Cu(II) from 8x10(-4) to 2.5x10(-2) mol l(-1) with r(2)=0.9838 and from 10(-3) to 10(-1) mol l(-1) for polyphosphate with r(2)=0.9975 and from 5x10(-4) to 5x10(-2) mol l(-1) for ammonium with r(2)=0.9889. We can consider that for a direct measurement of the intensity of reflectance, it is possible to perform quantitative spot-test analysis.
authors.affiliation: Université de Savoie, ESIGEC LCIE Campus Scientifique, Savoie Technolac 73376 le bourget du lac-cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Ghauch
authors.forename: J
authors.initials: J
authors.lastname: Rima
authors.forename: A
authors.initials: A
authors.lastname: Charef
authors.forename: J
authors.initials: J
authors.lastname: Suptil
authors.forename: C
authors.initials: C
authors.lastname: Fachinger
authors.forename: M
authors.initials: M
authors.lastname: Martin-Bouyer