Residue and decline study of 2-ethanoyldroxybenzoic acid in rice

A high performance liquid chromatographic (HPLC) method was established for the analysis of 2-ethanoyldroxybenzoic acid residue in rice and paddy field.The paddy water was extracted with acidic chloroform.For the paddy soil,rice culm and rice hull,samples were firstly extracted with acidity ethanol.For brown rice,it was first extracted with ethanol,followed by chloroform.The extracts were then cleaned-up on a Florisil column and detected by high performance liquid chromatography with an ultraviolet detector (UVD) on a ODS Hypersid column (4.0 mm×25 cm×10 μm).The calibration curve showed good linearity from 0.10 mg/L to 3.06 mg/L with the correlation coefficient more than 0.999 8.The average recoveries of this method were from 80.8% to 103.0% with the relative standard deviations of 0.74%－6.11% at the spiked levels of 0.1－1.0 mg /L(mg/kg).The limit of quantification was 0.10 mg/kg(or mg/L) for paddy water,paddy soil,rice culm,rice hull and brown rice.Results of field trial showed that the decline curves accorded with the first-order kinetic equation.The average degradation half-life of 2-ethanoyldroxybenzoic at high dosage(spraying for one time) was 2.44-2.66 d in paddy water,4.44-5.21 d in paddy soil,3.95-4.04 d in rice culm, respectively.The final residues showed that at the low dosage and high dosage (0.027 and 0.041 g/m2) (spraying for three times and four times),residues on brown rice were less than 0.042 mg/kg at harvest.0.10 mg/kg was recommended as maximum residue level (MRL) for 2-ethanoyldroxybenzoic in brown rice.