Analysis of Carbaryl Pesticide Residues in Environmental Samples with Spectrophotometry

A facile,rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in itsformulations,water and grain(rice and wheat)samples with newly synthesised reagent.The proposed method wasbased on the alkaline hydrolysis of carbaryl pesticide and thus resulted 1-naphthol was coupled with diazotised4,4'-methylene-bis-m-nitroaniline in basic medium(pH 9)to give red colored product having λ_(max)480 nm for dia-zonium method(DM)or 1-naphthol reacts with 4,4'-methylene-bis-m-nitroaniline in the presence of oxidising agentpotassium dichromate(K_2Cr_2O_7)to give red colored product having λ_(max)510 nm for oxidation method(OM).Theformation of colored derivatives with the coupling agent is instantaneous and stable for 48 h(DM)and 32 h(OM)respectively.Beer's law was obeyed in the concentration range of 0.2—10.0 μg·mL~(-1)for DM and 0.2—0,150μg·mL~(-1)for OM.The proposed methods are sensitive,easy to operate and permitted for the determination of car-baryl with detection limits of 0.028 μg·mL~(-1)for DM and 0.024 μg·mL~(-1)for OM respectively.The experimentalresults indicate that the procedure can eliminate the fundamental interferences caused by other pesticides andnon-target ions,which made the methods more sensitive and selective.The method was applicable to the determina-tion of carbaryl residue in water and food grain samples up to μg level.

Analysis of Carbaryl Pesticide Residues in Environmental Samples with Spectrophotometry

A facile, rapid and sensitive spectrophotometric method was developed for the determination of carbaryl in its formulations, water and grain (rice and wheat) samples with newly synthesised reagent. The proposed method was based on the alkaline hydrolysis of carbaryl pesticide and thus resulted 1‐naphthol was coupled with diazotised 4,4′‐methylene‐bis‐m‐nitroaniline in basic medium (pH 9) to give red colored product having λ_max 480 nm for diazonium method (DM) or 1‐naphthol reacts with 4,4′‐methylene‐bis‐m‐nitroaniline in the presence of oxidising agent potassium dichromate (K₂Cr₂O₇) to give red colored product having λ_max 510 nm for oxidation method (OM). The formation of colored derivatives with the coupling agent is instantaneous and stable for 48 h (DM) and 32 h (OM) respectively. Beer's law was obeyed in the concentration range of 0.2–10.0 µg·mL^?1 for DM and 0.2–0.150 µg·mL^?1 for OM. The proposed methods are sensitive, easy to operate and permitted for the determination of carbaryl with detection limits of 0.028 µg·mL^?1 for DM and 0.024 µg·mL^?1 for OM respectively. The experimental results indicate that the procedure can eliminate the fundamental interferences caused by other pesticides and non‐target ions, which made the methods more sensitive and selective. The method was applicable to the determination of carbaryl residue in water and food grain samples up to µg level.