In soil laboratory testing, the acid 1-amino-2-naphthol-4-sulfonic (ANS) is used as reducing agent to determine P by UV/Visible spectrometry. However, there are risks to laboratory technician healthy and an alternative is the use of ascorbic acid (AA). But, changes in the analytical protocol may induce variations in results, been necessary to standardize and calibrate. The objective of this studsy was to evaluate the ANS and AA in extracts of Mehlich-1 and 3 in ranges 15, 30, 45, 60 and 120min of reaction. There was no difference in P concentration determined by both reducers when compared within each extractor. Ascorbic acid can substitute the ANS solution for P determination and the suggested reaction interval for colorimetric quantification is between 30 and 60min for both substances.
soil test; reducing agents; Mehlich-1; Mehlich- 3
