The study of an appropriate method for some Carbamates insecticide residue analysis in fruits using high performance liquid choromatography/photo diode array detector (Thai)

Abstract

In this study, an appropriate sample preparation and analysis method for Carbamate residue in fruits
using high performance liquid chromatography with a photodiode array detector are demonstrated. The studied Carbamates include methomyl, carbofuran, carbaryl and methiocarb, while the studied fruits were grape, roseapple, jujube, cantaloupe and watermelon. The appropriate sample preparation method was extraction by mixture of solvent, dichloromethane:petroleum ether:acetone (1:1:1, v/v), evaporation under nitrogen stream, dissolved in 1 ml dichloromethane, cleaning up using aminopropyl cartridge, eluted with 1% methanol in dichloromethane, evaporation to dryness in nitrogen stream, and dissolved in 1 ml of acetonitrile:water; 20:80, v/v. The optimum condition for analysis of the target pesticides using C
18 column HPLC/PDA was as followed; gradient elution of acetonitrile and water at a flow-rate of 0.8 ml/min. At the initial state, the ratio of acetonitrile:water was 20:80 for 30 min, the ratio was changed to 55:45 and at 35-45 min to 20:80. The range of percentage recoveries obtained from the proposed method for grape, roseapple, jujube and cantaloupe fortified with 0.1 μ g/g of each pesticide were 82.00-102.00, 77.54-104.38, 92.48-104.82
and 99.60-122.75, respectively, while that of water melon (fortified with 0.02 and 0.04 μg/g ) was 48.87-111.33. The limit of detection (3 SDb/S) and limit of quantitation(10 SDb/S) varied from 0.0046-0.0215 and 0.0150-0.0717 mgL^-1, respectively. Twenty six fruit samples were collected from the Train station and Barnglumpoo market,Tesco Lotus and Big-C supermarket, in maung district of Khon Kaen during February 2003 to March 2003 and analysed using the proposed method. All of the target analytes were not found in water melon, jujube and cantaloup, while methomyl was found in 7 from 11 samples of grape (63.64%), and carbaryl in 1 from 11 sampls of grape (9.09%), methomyl in 1 from 8 samples of roseapple (12.5%) The content of methomyl found was 0.0439 to 1.8109 μg/g and carbaryl was 0.0212 to 0.023μg/g. The quantities of methomyl and carbaryl found did not exceeded the allowed quantities according to thestandard regulation of the ministry of public health.