Development a HPLC Method for Simultaneous
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Journal of Pharmaceutical and Health Sciences 2012;1(4), 79-87. Original Article Development a HPLC method for simultaneous determination of Open Access Azinphose methyl, Diazinon, Phosalone and Chlorpyrifos residues in fruit Maliheh Soodi1*, Atefeh Garshasbi2, Soheil Eskandari3 1 Department of Toxicology, School of Medical Sciences, Tarbiat Modares University, Tehran ,Iran 2 Department of Analytical Chemistry, Islamic Azad University-Shahr-e-Ray Branch, Tehran, Iran 3 Food and Drug Research Center, Tehran, Iran Abstract A high-performance liquid chromatography with ultraviolet detection (HPLC/UV) method which was used solid-phase extraction for cleanup, was developed for the determination of Azinphos methyl ,Phosalone, Diazinon and Chlorpyrifos residues in fruits. A full factorial experimental design was used for development of HPLC condition and evaluation of effect of three factors (pH of mobile phase, percent of acetonitril in mobile phase and flow rate) on the retention time and resolution of peaks. The samples were extracted with Hexan/Aceton(50/50) and then is loaded onto a C18 end-caped SPE cartridge for further clean up. For SPE condition optimization, several solvents (acetonitril, dichloromethane, ethyl acetate and hexane) were tested as eluent and the best recovery was found with hexane. The optimum HPLC condition was achieved with acetonitril: water (60:40) as mobile phase, flow rate 1 ml/min, on C8 column. The standard calibration curves were linear between 0.05-1μg/ml for Azinphos methyl and 0.1-2 μg/ml for others.Archive The hexan:acetone extraction followed of by the SID C18 end-cap SPE cleanup provided recoveries of >70% for all of pesticides and removing the greatest number of sample matrix interferences. Keywords: Azynphos methyl, Phosalone, Diazinon, Chlorpyrifos, Organophosphate pesticide, HPLC *Corresponding author: Maliheh Soodi, PhD., Department of Toxicology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Tel: +98 21 82884549 Fax: +98 21 82884555 E-mail address: [email protected] www.SID.ir Soodi et al. HPLC method is suitability of this technique 1. Introduction for precise analyzing of polar and thermally labile compounds. In some studies, pesticide Pesticides are chemical agents used to control compounds with a wide range of polarity and reduce pest populations. Published are simultaneously measured (Fernandes reports represent that the total amount of et al.,2011). Derivatization is not required pesticides used in agriculture is increasing. through this approach. Clean up procedure Unfortunately these compounds were using SPE cartridges is compatible with HPLC improperly used without attention to currency and also HPLC methods are more simple and period of pesticide by farmers. As a result of robust than GC methods (Picó et al.,2012; the large quantities and inappropriate use of Jedrzejczuk et al., 2001). the pesticides, they are present in all areas of Azinphose methyl, Diazinon, Phosalone and the natural environment and food commodity Chlorpyrifos are commonly used organophos- (Tadeo et al.,2008; Ecobichon 2001). phate pesticides in fruit gardens ,and the aim Organophosphate pesticides have been of this study was the development of a HPLC widely used as insecticide in agriculture for method to determine the residues of these last decades. Because of relatively rapid compound in fruits. decomposition of these compounds, then short half life in the environment, they were replaced organochlorine pesticide and todays extensive- ly were used in agriculture. As a consequence, 2.Materials and Methods residues of these substances can be found in food, and raises significant concerns about Chemicals potential risk for human health (Damalas et Azinphos methyl, Phosalen, Diazinon and al.,2011) . Several Studies have shown that chlorpryphs reference standards, purity > human exposure to these compounds can have 99%, AccuStandard® .Methanol, Acetonitrl, adverse health effects like suppressing of Hexan, Ethyl acetate, Methylen chloride, were the immune system, cancer and neurological analytical grade and were purchased from disorder (Damalas et al.,2011; Jaga et al.,2005; Merck. Kamel et al.,2005). Therefore, control and measurement of the Instrumentation pesticide residues on fruit crops is an essential The chromatography was performed on a measure and requires a simple and affordable Thermo Scientific Dionex UltiMate 3000 method of analysis. HPLC system, which comprised online Chromatography-based methods are frequent- degasser, autosampler, column oven, and ly applied for theArchive determination of pesticide UV detector.of ThisSID system was controlled by residues in various matrices. Gas chromatog- Cromoleon software 6.8. An RP column raphy is the conventional method for the (Prontosil 120,C8 ACE-EPS, 5μm, 25 × 0.46 detection and quantification of organophos- cm ) was used. phate pesticides (Hennion et al.,1997; Picó et al.,2012) . However, number of studies Preparation of Standard solutions used high-performance liquid chromatog- Individual stock standards solutions of each raphy (HPLC) technique for analyzing compound were prepared by weighing the the organophosphate residues in food is powder and dissolution in 10 mL of Acetonitril increasing (Picó et al.,2012; Jedrzejczuk et al., to prepare 1000 μg/ml stock solution then this 2001; Ravelo-Pérez et al.,2006, Fernandes et stock solution was diluted by acetonitril to al.,2011) .The major advantage of the use of prepare 100 μg/ml working standard . Next, 80 J Pharm Health Sci Volume 1 Issue 4 Autumnwww.SID.ir 2012 simultaneous determination of organophosphate pesticide pesticide mixture solutions were prepared by dryness on a vacuum rotary evaporator, The adequate dilution of the corresponding stock obtained residue was re-dissolved in 5 mL of solution with acetonitril. The concentration of hexan and 1 ml of this extract was loaded on standard solutions were 0.1, 0.2, 0.4, 0.8, 1.6 SPE cartridge for further clean up. and 2 μg/ml for Diazinon , Chlorpryphos and Phosalen, and 0.05, 0.1, 0.2, 0.4, 0.8 and 1 μg/ Clean up ml for Azinphos methyl. The C18 SPE cartridge (CHROMBOND®, end-capped) was used for clean up the extracts. Extraction The SPE sorbent was conditioned with 3 ml The chopped fresh fruits were blended in Methanol followed by 3 ml water and then a blender and 20 gr of well blended fruits loaded with1 ml of extract. Different solvents were weighed in two 250 mL glass bottles including Hexan, Acetonitrl, Dichloro methan fitted with screw caps. One of these weighed and Ethyl acetate) were tried as eluent to obtain samples was used as blank sample and another the optimum recovery for elution .Finally, the one was used as spiked sample. The spiked eluate was saved and evaporated to dryness sample was prepared by adding proper amount under a gentle nitrogen stream then residue of stock solution of pesticides, in which final was re-dissolved in 2 ml mobile phase and concentrations of 0.25 μg/ml for Azinphos injected to the HPLC. methyl and 0.5 μg/ml for Diazinon , Chlorpry- phos and Phosalen were achieved. The spiked HPLC method development samples were left standing for 1 h before The mixed standard solution of pesticides was beginning the extraction step. Two samples used for the optimization of HPLC conditions. were extracted as described by Talebi([Talebi, The eluate was monitored by UV absorbance 2006). Briefly, Solvent (acetone:hexane, at 235 nm. The preliminary experiment 50:50 v/v) in the amount of 150 mL was conducted with C18 column as stationary added and agitated for 20 min using a shaker. phase and water/acetonitril mixture with The sample was filtered, and the resultant varying percent as mobile phase .But these liquid was transferred into a separatory funnel conditions were not resulted in good separation containing 50 mL of sodium chloride solution of pesticide peaks, even with changing percent (20 g/l).The solution was shaken vigorously of acetonitrl in mobile phase and flow rate and left on the lab bench for layers to separate. (figure 1), therefore the experiments were The upper layer was separated, and the lower conducted by C8 column. layer was re-extracted with 25 mL of hexane. Experimental design method was used for The combined hexaneArchive extract evaporated to estimation of of optimumSID HPLC condition. a Figure 1. Chromatogram of the mixed standard solution of pesticides on C18 column ©2012 Soodi et al.; licensee to Islamic Azad University-Pharmaceutical Sciences Branch www.SID.ir81 Soodi et al. 23 full factorial design was proposed for In this method each factor was tested in two assessing effect of three major factors ( pH of levels , 2.5 and 7 for pH, 50 and 70 for percent mobile phase , percent of acetonitril in mobile of acetonitril in mobile phase and 0.7 and 1.3 phase and flow rate ) on the retention times for flow rate, and each condition was repeated and resolution of pesticide peaks , and for three times, then the total 24 experiments estimating the best value for these factors in were performed (Table 1). Design Expert® which the pesticide were eluted in minimum 6.01 software (Stat- Ease Inc.) was used for retention time and optimum peak resolution. planning and interpreting of this design. Table 1. Assignment of factors and levels of the factorial design Archive of SID 3. Results and discussion According to model that software was prepared were not affected by changing of pH of mobile between factors and responses , the pH factor phase (p value > 0.05 with ANOVA analysis), did not any significant effect on responses and but two other factors significantly affect the the retention time of peaks and peak resolution responses.(Table 2). The retention time of 82 J Pharm Health Sci Volume 1 Issue 4 Autumnwww.SID.ir 2012 simultaneous determination of organophosphate pesticide Table 2. Results of experiments Each result represents Mean ± SD of three replicate for each condition R1: resolution of Azinphos methyl and Diazinon peaks R2: resolution of Diazinon and Phosalon peaks R3: resolution of PhosalonArchive and Clorpiryfos peaks of SID peaks and peak resolution were significantly the software.