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Automated Modification of the Molybdenum Blue Colorimetric Method for Phosphorus Determination in Soil Extracts
- Hurtado, Maria Dolores, Carmona, Sergio, Delgado, Antonio
- Communications in soil science and plant analysis 2008 v.39 no.15-16 pp. 2250-2257
- soil solution, extracts, phosphorus, soil analysis, colorimetry, soil fertility, molybdenum, automation, flow injection analysis, detection limit
- A flow injection analysis (FIA) method capable of automation for molybdate reactive phosphorus (P) determination in soil extracts is described. Results obtained using this method in three soil extracts [calcium chloride (CaCl2), Olsen, and Mehlich I] were the same as those provided by the manual molybdate blue colorimetric method. Linear range extending to 2 mg P L-1, detection limits ranging from 6 to 26 μg L-1 depending on the soil extract, and accurate recoveries from P-spiked samples were achieved. The sensitivity of the system was around 0.3 absorbance units per mg P L-1, and the sampling frequency was 72 samples h-1, higher than those described for most of the flow injection methods.