Correction of iron interface in the spectrophotometric flow injection catalytic determination of molybdenum in plants.
Iron interference in the spectrophotometric catalytic determination of molybdenum based on the iodide-hydrogen peroxide reaction can be corrected by using sulphosalicylic acid as masking and color-forming reagent. The catalytic influence of iron ions is circumvented to the extent of about 90% and correction of any remaining iron ions is possible by monitoring the colored iron(III)-salicylate complex at 490 nm. In this way, iron is also determined. With the proposed system, molybdenum can be determined in plant and food digests within the 0-100 mug Mo 1(-1) range in the presence of up to 25 mg Fe 1(-1), at a sampling rate of about 50 determinations h(-1). The relative standard deviation of 10 consecutive measurements was estimated as < 2%. Results for samples were comparable with those obtained by graphite furnace atomic absorption spectrometry. In addition, recoveries within the range 94-100% were calculated.
Carrilho
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EN
Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, P.O. Box 96, 13400-970 Piracicaba, São Paulo, Brazil.
Krug
F J
FJ
Zagatto
E A
EA