Use of Buffers in Spectrophotometric Determination of NPhosphonomethylglycine by the Ninhydrin Colour Reaction
| Autor: | Lami A. Nnamonu, Nnadozie N. Nkpa |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | IOSR Journal of Environmental Science, Toxicology and Food Technology. 1:06-10 |
| ISSN: | 2319-2402 2319-2399 |
| DOI: | 10.9790/2402-0110610 |
| Popis: | The aim of this work was to develop a spectrophotometric method of glyphosate assay that is consistent and reproducible over a wide range of concentrations. The use of two buffer systems 4M CH3COOLi pH 5.2/Hydrindantin/DMSO and 0.2M sodium citrate buffer pH 5.0/Ascorbic acid/DMSO which have not been used before for ninhydrin quantification of glyphosate is hereby reported. The absorbance of the resulting purple derivative was measured at 570 nm with molar absorptivity of 5.799×10 4 and 1.975×10 4 L mol −1 cm −1 . Linear relationships between concentration and absorbance were observed over Beer's law range from 0.3 to 4.5μg/ml. For the citrate system, R 2 =0.982, SD = 0.3744, N= 9 and P < 0.0001; while R 2 =0.984, SD = 1.0956, N= 8 and P < 0.0001 for the acetate system. The citrate buffer/ascorbic acid system was employed successfully in adsorption studies of glyphosate unto kaolin and starch. Limits of detection and quantification were 0.6159 and 0.699 μg/ml respectively for citrate buffer and 1.802 and 5.5465 μg/ml respectively for the lithium acetate buffer system. The method was applied to quantification of glyphosate adsorption to kaolin and starch, where the citrate buffer gave R 2 values of 0.803 (Freundlich) and 0.964 (Langmuir) for kaolin. |
| Databáze: | OpenAIRE |
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