Food and Chemical Toxicology 44 (2006) 596–600 www.elsevier.com/locate/foodchemtox Investigation in tea on fate of fenazaquin residue and its transfer in brew q Vipin Kumar, Dhananjay Kumar Tewary, Srigiripuram Desikachar Ravindranath, Adarsh Shanker * Institute of Himalayan Bioresource Technology, Council of Scientific and Industrial Research, Palampur 176 061, HP, India Abstract Fenazaquin is a non-systemic acaricide/insecticide used widely in controlling mites and other related pests in fruits, vegetables and tea. The objective of this research was to investigate the disappearance trend in tea of fenazaquin residue level and its transfer in brew. Fenaz- aquin was applied on a tea crop at two rates, 125 and 250 g AI/ha in wet and dry seasons under field conditions. Samples (green shoots, made tea and its brew) were analyzed for fenazaquin and quantification was by high performance liquid chromatography using a UV detector. The residue dissipated faster in the wet season than in the dry season. Seven days after the treatment (normal round of plucking) the residues observed in the green shoots at the two rates were 2.17, 3.07 mg/kg and 2.04, 2.84 mg/kg in the wet and dry seasons, respec- tively. However, the degradation rale in both seasons followed first-order kinetics. Half-lives in green shoots were in range 1.43–1.70 and 2.10–2.21 days and in made tea 1.59–1.73 and 1.87–1.94 days for wet and dry seasons, respectively. During processing of green shoots to made tea considerable loss (42–70%) of residue was observed. The transfer of residue from made tea brew was in the range 3–22%. In brew residue were below 0.02 mg/l after 5 days of application at both the rates in either of the seasons. The estimated intake with brew (normal consumption of 10 cup/day/adult) thus would be below the acceptable daily intake for fenazaquin (0.005 mg/kg-body weight). To avoid health hazards due to the toxic effect of residues in brew, a waiting period for plucking the tea shoots after fenazaquin appli- cation of more than 5 days for both the seasons at recommended rate (125 g AI/ha) may be suggested and considered quite safe. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Fenazaquin; Residue; Tea; Brew; Transfer 1. Introduction case with most large-scale agricultural ventures, the chem- ical control of pests dominates the tea growing environ- The tea crop is subject to attack from a wide range of ment as the single most widely used pest control strategy insects and mite pests which besides causing crop loss dete- in almost all tea growing countries. One of the major disad- riorate the quality of the processed tea. As has been the vantages of pesticide use is that residue may remain in tea and may be transferred in infusion (brew) in amounts above maximum residue limits (MRLs). This could pose Abbreviations: AI, Active ingredient; ADI, Acceptable daily intake; health hazards to consumers. This problem is being viewed EC, Emulsion concentrate; FAO, Food and Agriculture Organization; HPLC, High performance liquid chromatography; MRL, Maximum res- seriously by international organizations (US EPA, Codex idue limit; ND, Not detected; US EPA, Environmental Protection Agency Alimenterious Commission, WHO and FAO of the United or United States; WHO, World Health Organization. Nations). In the past few years there has been a continuous q DOI of original article: 10.1016/j.fct.2003.10.004, 10.1016/j.fct.2005. search for acaricide/insecticides with broad spectrum activ- 10.009. q ity and minimum residual problems. IHBT Communication No. 0326. * Corresponding author. Tel.: +91 1894 230454; fax: +91 1894 230433. Fenazaquin (IUPAC name: 4-tert-butylphenethyl qui- E-mail address: [email protected] (A. Shanker). nazolin-4-yl ether), is a white to tan crystalline solid, 0278-6915/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2005.10.010 V. Kumar et al. / Food and Chemical Toxicology 44 (2006) 596–600 597 the laboratory each time at 0 (1 h after spraying), 1, 3, 5, 7, 9, 11, 14 and 21 H2 CH C 3 days after the treatment. H2C CH3 CH O 3 2.2. Reagent and apparatus N 2.2.1. Analytical standards and working solutions An analytical standard of fenazaquin (active substance) and its com- N mercial grade formulation (MagisterÒ 10EC) were supplied by De-Nocil Crop Protection Ltd., India. A standard stock solution (1000 mg/l) was Fig. 1. Structure of fenazaquin. prepared in acetonitrile and the solutions required for preparing a stan- dard curve (0, 0.1, 0.2, 0.4, 0.8 and 1.0 lg/ml) were prepared from the standard stock solution by serial dilutions. All the solvents and chemicals belonging to the quinazoline group (Fig. 1) of pesticides, used were of Analytical Grade from E. Merck. for which the acceptable daily intake (ADI) was established at the level of 0.005 mg/kg body weight/day (Dow Elanco, 2.2.2. Apparatus 1993). It is marketed mainly in two formulation types, A high performance liquid chromatograph, LaChrom–Merck, equip- ped with a LiChrospherÒ 100 C18 (reverse phase) endcapped (5 lm) 200 g/l aqueous suspension concentrate and 100 g/l emul- column and a UV detector was used. The mobile phase was acetonitrile– sion concentrate under various trade names, e.g. Magister, water (80:20v/v) with 1 ml/min flow rate. The column oven was kept at Matador, Totem, Demitam and Magus. Fenazaquin is a 30 °C. The best detection was attained at wavelength of 218 nm. The broad spectrum, non-systemic acaricidal compound, effec- volume of the injection was 10 ll. tive in controlling phytophagus mites infesting a variety of crops namely fruits and vegetables (Solomon et al., 2.2.3. Florisil column Glass columns (30 cm · 1.1 cm i.d.) with Teflon stopcocks were packed 1993) and tea (Shanker et al., 2001). It acts as an electron from the bottom with a glass wool plug and 2.5 cm of Merck brand transport inhibitor, acting at Complex I of the mitochon- activated Florisil (60–100 mesh) between the layers of anhydrous sodium drial respiratory chain (Hollingworth et al., 1992). This sulfate. specific acaricide/insecticide has generally no effect on ben- eficial insects including predaceous mites (Hollingworth 2.3. Tea leaves and infusion et al., 1992) and thus offers a desirable reason for its use in developing new strategies of integrated pest management The untreated control and treated green leaves from the field were processed in the laboratory’s mini manufacturing unit using conventional in tea. an orthodox tea manufacturing process. The manufacturing process, in Residue levels of many pesticides in tea and in its infu- brief, involved withering of shoots at ambient temperature for 15–20 h; sion have been reported (Chen et al., 1987; Chen and rolling (twisting and rupturing the tissue to express the juice) using a piezy Wan, 1988; Muraleedharan, 1994; Bhattacharya et al., roller for about 30 min with pressure followed by fermentation (oxidation) 1995; Jaggi et al., 2001). Residual studies of fenazaquin for 1–2 h at 25–30 °C and 95% r.h. and finally drying in a tea dryer using hot air at 100 ± 5 °C to a final moisture content of 2–3%. The made tea on some food commodities are available (Dow Elanco, was further subjected to an infusion process wherein 5 g of manufactured 1993). However, no studies have been found in the litera- tea was infused in 150 ml of boiling water. After 3 min of brewing, the ture on the dissipation in tea of fenazaquin residue and water extract was filtered through a (2-lm sieve) stainless steel filter, its transfer in brew from made tea (processed dry tea cooled and examined for residue transfer from made tea. The matrices leaves). The present study was therefore, undertaken to used for residue determination were the green shoots, made tea, the infusion prepared and the spent leaves left in the stainless steel filter. generate data in wet and dry seasons in tea on the persis- tence of fenazaquin (MagisterÒ) residue and its transfer from made tea to infusion in hot water. This would help 2.4. Extraction to establish adequate monitoring of the residue of this 2.4.1. Green leaves and made tea newly introduced acaricide/insecticides and its judicious Samples of green tea leaves (25 g) and made tea (10 g) were extracted incorporation in pest management strategies in tea fields. with 150 and 100 ml of dichloromethane, respectively by mechanical shaking for 2 h. Extracts were filtered through a Whatman No. 1 filter 2. Materials and methods paper containing 2 g of anhydrous sodium sulfate (impregnated with dichloromethane). 2.1. Field trials 2.4.2. Infusion and spent leaves Two field trials (wet and dry season) were carried out at the IHBT tea After removing the spent leaves, infusion was cooled to room tem- experimental farm at Banuri, Palampur (32°N · 76°E), India. A random perature and transferred to a separating funnel (500 ml). The pesticide was block design was used, each block containing 100 bushes (10 · 10) of partitioned (extracted) into 100 ml dichloromethane twice. The organic Camellia sinensis (L.) O. Kurtze. Each block was separated from one layer was separated and collected in a 250-ml beaker. The spent leaves another by leaving two untreated rows as guard rows to prevent pesticide were dried between the folds of filter paper and residues were extracted from spill over.