Journal of Tea Science Research. 2015, Vol. 5, No. 9, 1-7
6
4.4.2 Clean up
The extract was evaporated to dryness on a rotary
vacuum evaporator and the residue was dissolved in
10 ml hexane and again transferred to 125 ml
separating funnel. The round bottom flask was
rinsed with 5 ml portions of hexane and the rinses
were added to the separating funnel. About 30 ml
acetonitrile–saturated with hexane was added to it
and the acetonitrile layer was drained into a 250 ml
round bottom flask containing anhydrous sodium
sulphate. The acetonitrile extract was evaporated to
dryness at 60°C. The concentrated residue was
dissolved in 5 ml hexane and cleaned up by
adsorption column chromatography using
10 g of 5% deactivated florisil and 150 ml of 6%
diethyl ether in hexane as eluting solvent. Prior
to elution, the column was washed with 50 ml of
hexane to remove the co-extractives. The collected
elution was concentrated at about 60°C to dryness
and dissolved with 10 ml of hexane and injected into
GLC as per the standard operating conditions
(AOAC, 2005).
4.4.3 Preparation of acetonitrile saturated with
hexane
Three portions of acetonitrile were combined
with one portion of hexane in a 125 ml separating
funnel, gently shaken and then the lower part of
acetonitrile layer was collected. This is called
acetonitrile saturated with hexane.
4.4.4 Bifenthrin residues in tea brew
2 g of made tea was infused in 100 ml of boiling
water (ISO 3103 -1990). After 6 minutes of brewing,
the water extract was filtered, cooled and partitioned
with 100 ml of hexane. The organic phase was
passed through anhydrous sodium sulfate. The
extract was concentrated by evaporating in a rotary
vacuum evaporator and dissolved with 10 ml hexane
and analysed for the residues of bifenthrin. The
spent leaves were dried between the folds of
filter paper and residues were extracted following
the method described above for black tea.
Authors Contributions
SS conducted the field trials, sample preparation,
residue analysis and interpreted the results. NM
approved the protocol and drafted the manuscript.
Acknowledgements
The authors are grateful to the National Tea
Research Foundation (NTRF), C/o. Tea Board, Govt.
of India for the financial assistance for this work.
References
Agnihothrudu V. and Muraleedharan N., 1990, Pesticide residues in tea,
Planters’ Chronicle, 85: 125-127.
AOAC 2005, Official Method 998.01. Synthetic pyrethroids in agricultural
products, Official methods Analysis, AOAC International, (18
th
Eds),
Maryland, USA.
Awasthi M.D. and Prakash N.B., 1997, Persistence of chlorpyrifos in
soil under different moisture regimes, Pesticide Science, 50: 1-4.
Bisen J.S. and Ghosh Hajra N., 2000, Residues and persistence of certain
insecticides in Darjeeling tea, Journal of Plantation Crops, 28(2):
123-131.
Chen Z.M. and Wan H., 1988, Factors affecting residues of pesticides in
Tea. Pesticide Science, 23: 109-118.
Chen Z.M. and Wan H., 1997, Degradation of pesticides on plant surfaces
and its prediction. A case study on tea plant, Environmental
Monitoring and Assessment, 44: 305-313.
Gu X.Z., Zhang G.Y., Chen L., Dai R.L. and Yu Y.C., 2008, Persistence
and dissipation of synthetic pyrethroid pesticides in red soils from
the Yangtze River Delta area, Environmental Geochemistry and
Health, 30: 67–77.
ISO 3103 (1990); IS 6400 (1993), Indian Standard, Method for preparation
of tea infusion for sensory evaluation (I rev.), Bureau of Indian
Standards, Manak Bhavan, New Delhi.
Jaggi S., Sood C., Kumar V., Ravindranath S.D. and Shanker A., 2001,
Leaching of pesticides in tea brew, Journal of Agricultural and Food
Chemistry, 49: 5479-5483.
Kumar V., Tewary D.K., Ravindranath S.D. and Shanker A., 2004,
Investigation in tea on fate of fenazaquin residue and its transfer in
brew, Food and Chemical Toxicology, 42: 423–428.
Manikandan K.N., Muraleedharan N. and Selvasundaram R., 2001,
Residues of deltamethrin in black CTC tea, Bulletin of UPASI Tea
Research Foundation, 54: 88-92.
Manikandan K.N., Muraleedharan N. and Selvasundaram R., 2005,
Degradation of quinalphos during the processing of black CTC tea,
Journal of Plantation Crops, 33(2): 146-148.
Manikandan K.N., Smitha S., Seenivasan S., Muraleedharan N. and
Selvasundaram R., 2006, Fenazaquin residues in tea and its persistence
in south Indian climatic conditions, Journal of Plantation Crops, 34(3):
410-413.
Nagayama T., Maki T., Kan K., Iida M., Tamura Y. and Nishima T., 1996,
Residues of organophosphorus pesticides in commercial tea and their
leaching into tea, Nippon Noyaku Gakkaishi, 14: 39-45.
Rajukkannu K., Blasubramanian M. and Vasudevan P., 1981, Residues of
dicofol and tetradifon in tea leaves, Journal of Plantation Crops, 9(2):
124-125.
Ripley B.D., Ritcey G.M., Harris C.R., Denomme M.A. and Brown P.D.,
2001, Pyrethroid insecticide residues on vegetable crops, Pest
Management Science, 57: 683-687.
