Search

A kinetic spectrophotometric method for determining residues of insecticide diflubenzuron 1(4-chlorphenyl)-3-(2,6-diflubenzoyl)urea (DFB) has been developed and validated. Kinetic method was based on the inhibitory effect of DFB on the oxidation reaction of sulfanilic acid (SA) by hydrogen peroxide in the presence of Co2+ ions in a phosphate buffer, which was monitored at 370 nm. DFB can be measured in the concentration interval 0.102 – 3.40 μg mL-1 and 3.40 – 23.80 μg mL-1. The detection and quantification limits of the method were calculated according to the 3σ criteria and found to be 0.077 μg mL-1 and 0.254 μg Ml-1, respectively. The relative standard deviations for five replicate determinations of 0.102, 1.70 and 3.40 μg mL-1 DFB were 2.08, 1.22 and 1.21 %, respectively, for the first concentration interval, and the recovery percentage values were from 94.12 to 97.35 %. HPLC method was used as a parallel method to verify results of the kinetic method. The kinetic method was successfully applied to determine diflubenzuron concentrations in spiked water and baby food samples after solid phase extraction of the samples. The F and t values at 95% confidence level are lower than the theoretical ones, confirming agreement of the developed and the HPLC method. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172061]

The objective of this paper was to develop and apply the kinetic-spectrophotometric method for the determination of the pesticide dicamba in infant baby foods available in Serbia. The method is based on the inhibition effect of dicamba on the oxidation of sulfanilic acid (SA) by hydrogen peroxide in universal buffer (pH = 9.66) in the presence of Co2+ ion. The reaction was monitored spectrophotometrically at 368 nm. The HPLC method was used as a comparative method to verify the results of the kinetic method. Under the experimental conditions proposed, dicamba showed a linear dynamic range of 0.31 to 3.10 µg mL-1, and from 3.10 to 31.00 µg mL-1 with standard deviation from 1.77 to 4.55 %. Limit of detection and a limit of quantification are 0.101 μg mL-1 and 0.306 μg mL-1, respectively. The kinetic method was efficiently applied for dicamba determination in baby food samples after solid phase extraction. This method is highly sensitive, simple, easy to operate, and requires cheap reagents. It can be successfully used for routine analysis of dicamba in baby food. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pesticides are potentially toxic to humans and can produce both acute and chronic health effects, depending on the quantity and the ways in which a person is exposed. Exposure to pesticides can cause serious health problems. Infants and young children are particularly sensitive to these contaminants because their brains and organ systems are not fully developed. For this reason, it is important to determine the quantities of pesticides in baby food. RESULTS: The aim of this study was to develop a kinetic‐spectrophotometric method for atrazine determination and to apply it to determine pesticide in baby‐food samples, using solid‐phase extraction (SPE) followed by the kinetic‐spectrophotometric method and the high‐performance liquid chromatography (HPLC) method. This method is based on the inhibition effect of atrazine (the oxidation of sulfanilic acid (SA) by hydrogen peroxide in the alkaline medium in the presence of the Co2+ ion). Under the experimental conditions used, atrazine showed a linear dynamic range of 0.5 to 5.0 μg mL−1, and from 5.0 to 70.00 μg mL−1 with relative standard deviations (RSD) from 1.91% to 9.41%. The limit of detection and the limit of quantification were 0.074 and 0.225 μg mL−1, respectively. The kinetic method was successfully applied to determine the atrazine concentration in spiked samples after SPE of samples. High‐performance liquid chromatography was used to verify the results. CONCLUSION: The proposed method is highly sensitive, simple, easy, requires cheap reagents, and leads to good recovery levels. It is linear, precise, and accurate. It can be used successfully for the routine analysis of atrazine in infant formulae and cereal‐based food samples. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]