Estimation of Abamectin Residues Present in Tea: High-Performance Liquid Chromatography Technique

A simple, reliable, and sensitive method was based on high-performance liquid chromatography (HPLC) was developed and validated for the estimation of abamectin residues present in tea. The abamectin residues extracted with acetone-water mixture (70？:？30, v/v) and derivatised with 1-methylimidazole (1-MIM) and trifluoroacetic anhydride (TFAA) were estimated by HPLC using fluorescence detector (FLD). The technique was validated in terms of linearity, precision, recovery, specificity, limit of detection (LOD), and limit of quantification (LOQ). A good linear relationship ( ) was absorbed in the abamectin concentration range from 0.01 to 1.0？μg mL？1. The limit of detection and limit of quantification of the method were 0.01 and 0.02？μg？g？1, respectively. The average recoveries of the pesticide from black tea and dried green leaves ranged from 83.3 to 103.8% and 83.8 to 98.0%, respectively. 1. Introduction Tea, one of the oldest and most popular beverages in the world, is obtained from the tender leaves of the plant Camellia sinensis (L).O. Kuntze. South India, a major contributor to the global production of tea, continues to be the leader in national tea production contributing about 25% in toto and has the largest domestic market [1]. In order to improve the productivity and protect the tea plants from the harmful pests like mite, the acaricides are being applied on the canopy and/or tea bushes being with chemical spray. As a result, residue level of the acaricide present in the consumable tea is of considerable importance. Therefore, development of a highly reliable method is critical for the estimation of the acaricide residues present in tea. Abamectin, which belongs to the macrocyclic lactone class of avermectins, is composed of at least 80% of avermectin B1a and less than 20% of avermectin B1b (Figure 1), is produced by the actinomycetes (Streptomyces avermitilis) [2]. Because of its high toxicity to agricultural pests abamectin is widely used to control insects and mites in tea, vegetables, and fruits [3]. Abamectin present in various biological matrices including animal tissues, serum, fruits, and vegetables can be successfully determined by high-performance liquid chromatography (HPLC) in the reverse phase mode, coupled with different detectors, namely, ultraviolet detection (UVD), fluorescence detection (FLD), and mass spectrometry (MS) [3–5]. However, there is no report in the literature on the methodology for the determination of abamectin residues present in tea. Since the concentration of abamectin residues is very low, the UVD is less