DLLME-spectrophotometric determination of glyphosate residue in legumes

A new separation and pre-concentration method for spectrophotometric determination of glyphosate herbicide was developed. Glyphosate was converted into dithiocarbamic acid with CS₂, followed by copper in the presence of ammonia to promote complex formation. This complex was collected in a CH₂Cl₂ organic drop and absorbance measured at 435nm. The analytical parameters, such as the amount of NH₃, Cu(II) and CS₂, type of extraction solutions, and the ratio of dispersive and organic liquids were optimized. The calibration curve was linear in the range 0.5-10mgl^-1. The limits of detection and quantification were calculated from 3s to 10s criterions as 0.21mgl^-1 and 0.70mgl^-1, respectively. The developed method was applied to legume samples with the satisfactory recovery values of 98±4-102±3%.