Application Investigation Of Chromatographic Analysis Of Phosphorus-containing Amino Acid Herbicides

The phosphorus-containing amino acid herbicides have been widely used to control thegrowth of weed in agriculture, forestry, gardening. The use of the herbicides has brought greatbenefits for agriculture. However, it also results in the potential harm to the environment andhuman health, owing to its excessive and unconscionable use. Therefore, Many countriesformulate standards of maximun residue limits of the phosphorus-containing amino acidherbicides. Hence, there is vitally significant to determine the content of thephosphorus-containing amino acid herbicides.Capillary electrophoresis (CE) and high performance liquid chromatography (HPLC) areeffective separation technology, which are used in the determination of thephosphorus-containing amino acid herbicides. In this paper, several simple and sensitivemethods are developed for the determination of phosphorus-containing amino acid herbicides(glyphosate, glufosinate and aminomethylphosphonic acid) by capillary electrophoresis withlaser-induced fluorescence detection or high performance liquid chromatography withUltraviolet-visible and fluorescence detection. Our research has the following four parts:(1) A high performance liquid chromatography method coupled with Ultraviolet-visible (UV-Vis)and fluorescence detection (FLD) for the analysis of glufosinate and aminomethylphosphonicacid is presented. The best HPLC conditions for the separation of glufosinate andaminomethylphosphonic acid in environmental samples were achieved using a Agilent EclipseXDB-C18column and mobile phase at pH5.0which consisted of55%(v/v) methanol and20mmol/L phosphate buffer. The linear analyte concentration was obtained in the ranges20-2000nmol/L (R2=0.9906-0.9981). Using this method, we have successfully separated and determinedglufosinate and aminomethylphosphonic acid in water and soil samples with a recovery of92.1-99.7%and relative standard deviation from1.33to6.76%.(2) A rapid capillary electrophoresis method for glyphosate analysis after oxidation andderivatisation has been accomplished. The glyphosate was converted to glycine using sodiumhypochlorite. Subsequent fluorescent labeling was used6-Oxy-(N-succinimideacetat)-9-(2’-m-ethoxylcarbonyl) fluorescein (SAMF). Optimal separation was obtained with a backgroundelectrolyte of4.5×10-2mol/L phosphate buffer (pH5.0), applying a10kV voltage. The proposed method was successfully appied to the determination of glyphosate in theenvironmental samples (water, soil, maize) with a recovery of90.1-101%, providing goodresults in terms of accuracy and precision.(3) A capillary electrophoresis with laser-induced fluorescence detection method is describedfor the simultaneous determination of glufosinate and aminomethylphosphonic acid. Severalexperimental parameters such as the type and concentration of buffer solution, pH value,operating voltage, injection time were studied in order to find the optimum conditions for thetwo derivatives. The effect of different variables that affect and derivatization(time, temperature,pH, and SAMF concentration) was studied. Under optimum conditions, detection limits(signal-to-noise ratio of3) for glufosinate and aminomethylphosphonic acid were0.29and0.38nmol/L, respectively, with concentration ranges of2-200nmol/L. The validated method wastested for the analysis of both analytes in spiked water and soil with good success. The recoverywas92.8-102%. The method was simple, rapid, reliable and inexpensive.(4) A simple and effective capillary electrophoresis with laser-induced fluorescence detectionmethod (CE-LIF) combined with microwave-assisted derivatizing was developed fordetermining phosphorus-containing amino acid herbicides (glyphosate, glufosinate andaminomethylphosphonic acid).5-(4,6-dichlorotriazinyl) amino fluorescein (DTAF) andfluorescein isothiocyanate (FITC) were chosen as fluorescent derivatizing reagent. The amountof reagent, microwave power and derivatization time were optimized. Under optimizedconditions, The detection limits of this method were found to be0.18nmol/L for glyphosate,0.31nmol/L for glufosinate, and0.19nmol/L for aminomethylphosphonic acid. The newlyestablished approaches were successfully applied to the analysis of glyphosate, glufosinate, andaminophosphonic acid in spiked tap drinking water and soil samples.