No abstract

Tea is the most commonly consumed beverage in the world. Tea infusion is prepared by pouring boiling hot water over cured leaves of the Camellia sinensis plant. Such a beverage should be free from toxic chemicals. Studies on the monitoring of pesticide residues in tea of South India had been carried. Tea samples collected from different districts of South India were analysed for the residues of certain pesticide such as dicofol, ethion, quinalphos, hexaconazole, fenpropathrin, fenvalerate and propargite. These pesticides are commonly used for the control of pests and diseases in tea. The results of study indicated that among 468 samples examined, only one sample contained hexaconazole residue that exceeded the maximum residue limit (MRL). Though the residues of ethion, quinalphos, hexaconazole, dicofol, propargite and fenpropathrin were most commonly found, only one sample exceeded the MRL.

The knowledge of nutrient aspects of organic fertilisers is of much relevance in assessing their availability and long-term effect to the soil and crop and in formulating sound fertiliser recommendation. Around 619 organic fertiliser samples under different categories, which were received by the analytical laboratory of UPASI Tea Research Institute, Valparai, were examined for their nutrient status. The trend in the number of samples received every year for the past 5 years showed that there is a gradual, steady and linear increase in the number of samples received by the laboratory which, in turn, authenticates the increase in the production and utilisation of organic fertilisers in agricultural sector. This also reveals the awareness of organic farming among farmers in recent times. The organic fertilisers received by the laboratory were categorised into different groups based on their nomenclature. The number of samples received each year under different categories varies to a larger extent. The nutritional status was unpredictable based on the nomenclature of the sample received. In addition to this frequency distribution, the nutritional values analysed are discussed in this paper. Correlation matrix was worked out between all the parameters estimated. It is evident that if maintenance of proper carbon-to-nitrogen ratio and moisture content is ascertained in the finished product, one can guarantee the quality of the organic fertiliser in terms of nutrient content.

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 ( 2 > 0.99) was absorbed in the abamectin concentration range from 0.01 to 1.0 g mL −1 . The limit of detection and limit of quantification of the method were 0.01 and 0.02 g 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.