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Direct Sensitive Spectrophotometric Determination of Glyphosate by Using Ninhydrin as a Chromogenic Reagent in Formulations and Environmental Water Samples
Author(s) -
Bhaskara Besagarahally L.,
Nagaraja Padmarajaiah
Publication year - 2006
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200690240
Subject(s) - chemistry , ninhydrin , molar absorptivity , reagent , chromatography , glyphosate , chromogenic , aqueous solution , absorption (acoustics) , spectrophotometry , relative standard deviation , glycine , nuclear chemistry , analytical chemistry (journal) , detection limit , organic chemistry , agronomy , biochemistry , physics , acoustics , optics , biology , amino acid
A simple, sensitive, and rapid spectrophotometric method for the assay of glyphosate (= N ‐(phosphonomethyl)glycine) in various formulations ( Roundup, Excel Mera 71 ) and environmental water samples is described. The method is based on the reaction of glyphosate with ninhydrin in presence of sodium molybdate in neutral aqueous medium at 100° to give a Ruhemann 's purple product having the VIS absorption maximum at 570 nm ( Scheme, Fig. 1 ). The product is stable for 10 h. Beer 's law is obeyed in the concentration range of 0.1–3.5 μg ml −1 . The molar absorptivity and Sandell 's sensitivity are 3.2816 ⋅ 10 4 l mol −1 cm −1 and 5.2 ng cm −2 , respectively ( Table 1 ). The method is highly reproducible, as confirmed by the relative‐standard‐deviation (r.s.d.) values (1.70%; Table 2 ). Recovery studies establish that this method is accurate ( Table 5 ) and can be successfully employed for the determination of glyphosate.