Preparation Of Two Azo Probes And Their Application In The Detection Of Micro Copper And Avermectins

Azo molecular probes have been widely used in the detection of heavy metals and pesticide residues in food in recent years due to their special molecular structure.In order to detect the total amount of copper in mushroom and the residue of Avermectin in apple,a method for the determination of copper in mushroom by ultraviolet-visible spectroscopy was established using a newly synthesized azo molecule 3,5-dicarboxylic acid-4'-hydroxyazobenzene as a chromogenic reagent.In addition,a new fluorescence spectrometric method for the determination of avermectin residues was developed using azo 1,3,5-tris(5'-p-phenoxyazo)benzene-1,3-dicarboxylic acid as fluorescence probe.Two azo probes,3,5-dicarboxylic acid-4'-hydroxyazobenzene and 1,3,5-tris(5'-p-phenoxyazo)benzene-1,3-dicarboxylic acid,were synthesized by one-pot method.The composition and structure were determined by IR,UV Vis,1H-NMR and ESI.The ultraviolet-visible spectra of 3,5-dicarboxylic acid-4'-hydroxyazobenzene and its colour reaction with copper(?)were studied.On the basis of optimizing the determination conditions,a single-wavelength and dual-wavelength methods for the determination of Trace Copper in mushroom by ultraviolet spectrophotometry were established.The results of single-wavelength method showed that the mass concentration of copper(?)obeyed Bill's law in the range of 0.21-2.5 ?g·mL-1 with 320 nm as detection wavelength.Copper and chromogenic agent formed 1:1 complex.The recovery of standard addition was 97.0-101.3%and RSD was 0.93-1.50%.The detection limit is 0.064 ?g·mL-1.The results of dual-wavelength method showed that the mass concentration of copper(?)obeys Beer's law in the range of 0.19-3.6 g· mL-1 with 380 nm as the determination wavelength and 342 nm as the reference wavelength.The recovery of standard addition is 99.5-100.4%and RSD is 0.30-1.00%.The detection limit is 0.059 ?g·mL-1.The copper content in mushroom determined by the two methods was 5.95±0.49 and 5.80±0.05 mg·100g-1 respectively,which were similar to ICP test results of 5.89±0.09 mg·100g-1.Based on the fluorescence spectra of probe 1,3,5-tris(5'-p-phenoxyazo)benzene-1,3-dicarboxylic acid and avermectin added into apples,the conditions for determination of avermectin residues in apples were optimized.The optimum conditions were as follows:the concentration of fluorescent probe was 6.0×10-6 mol·L-1,the amount of buffer solution was 0.80 mL,and the luminescence intensity at 420 nm was quantitatively determined.The linear range was 4.4×10-3?6.0×10.2 ?g·mL-1.The detection limit is 1.3×10-3 ?g·mL-1,the quantitative limit is 4.4×10-3 ?g·mL-1,the recovery is 98.8?103.1%,and RSD is 0.29?2.20%.The ultraviolet-visible spectrophotometry for the determination of copper in mushroom and the fluorescence spectrophotometry for the determination of avermectin residues in apple were established.Because of its simple operation,low cost,high precision and accuracy,it is expected to be applied to the detection of heavy metals in food and pesticide residues.