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ABSTRACT A method for High Performance Liquid Chromatography (HPLC) for the residue determination of pendimethalin herbicide in water and food samples was developed. The chromatographic analysis was carried out, on a C18 packed capillary column with gradient elution, 20 µl injection volume and ultraviolet detector at 240 nm. Samples were spiked with amount between 5µg g-1 and 15µg g-1 of herbicide and were isolated from samples by applying microwave assisted extraction (MAE) acetone, ethanol and water as extraction solvent. Percent recoveries were improved by optimizing solvent types, solvent volume and time. Calibration curve range determined by HPLC was 0.2-40µgm L-1. The interaction of different variables for maximum % recovery response was found to be in range from 91.22±0.01-99.32±0.01. Application of this procedure to the analysis of herbicide in water and vegetable samples showed the effectiveness of the methodology proposed.
Key words: MAE, pendimethalin, water, vegetable samples, HPLC.
INTRODUCTION The intensive use of herbicides and other classes of chemicals products, in agricultural practice has resulted in serious impacts on the environment, causing an increase in the level of herbicide residues in natural water, soil, and foodstuffs. Herbicide pendimethalin N-(1- ethylpropyl)-2, 6- dinitro-3-4 xylidine is dinitroaniline group-containing compound used as selective herbicide to control annual grasses and broad-leaved weeds in cultivation of corn, potato, rice, wheat, onion, tomato, soya bean, cabbage, and pepper (Andressa et al. 2011; Lin et al. 2007). Pendimethalin is available in markets as the preparation of Stomp 330E or mixed with other herbicide. Pendimethalin degrades slowly in aerobic soil and rapidly in anaerobic soil conditions.
Acting as a microtubule inhibitor, the dinitroaniline herbicide pendimethalin has been used in agricultural applications as a selective pre-emergence herbicide in various plant cultures. Field dissipation studies by (Kol, 2002) have revealed that pendimethalin is persistent, and its half life is 98 days at 30ºC. Pendimethalin is classified as a non-leaching compound (Kaleem, 2006) Toxicological report of pendimethalin by shows that pendimethalin causes liver and kidney damages and number of mutagenic effects (Dimitro et al., 2006). The methods available in the literature for determination of pendimethalin are mostly based on gas chromatography (Engebretson et al., 2001; Bruzzoniti et al., 2006; Shen et al., 2007; Arora et al., 2008; Zhang et al., 2008). The degradation products metabolism of pendimethalin...