Simultaneous Determination Of Carbaryl Research Articles

Simultaneous chemiluminescent determination of carbaryl and 1-naphthol in soils using a flow-injection system

ABSTRACTA flow-injection method coupled with the luminol chemiluminescence (CL) detection was developed for the simultaneous determination of carbaryl and 1-naphthol in soils. The method is based on the inhibition of luminol oxidation by the presence of 1-naphthol with the consequent reduction in the CL intensity. The conversion of carbaryl into 1-naphthol was made by the alkaline hydrolysis with NaOH. Under the optimised conditions, the method permits the determination of carbaryl and 1-naphthol over the range 25–400 ng mL−1 with high determination coefficient using both peak area and height, and high sample throughput (40 h−1). The detection limits applying the International Unión of Pure and Applied Chemistry (IUPAC) criteria were 65 ng g−1 and 123.5 ng g−1 for peak height and area, respectively. A simple extraction procedure employing chloroform as the solvent and sonication was effective for the complete extraction of the analytes present in soils. The method was validated by the analysis of spiked samples, with recoveries between 88.7 and 103.1%. The Flow Injection-Chemiluminescence (FI-CL) method has proven to be simple, fast and accurate for the quantification of carbaryl and its main degradation product in soils.

Simultaneous Determination of Carbaryl and 1-Naphthol by First-Derivative Synchronous Non-Protected Room Temperature Phosphorescence

The applicability of non-protected room temperature phosphorescence (NP-RTP) in real samples was demonstrated in the present work. In this methodology, only two reagents, potassium iodide and sodium sulfite, were used to obtain phosphorescent signals. Overlapping of the phosphorescence spectra was resolved by using first-derivative synchronous phosphorimetry. The synchronous first-derivative spectra of carbaryl and 1-naphthol in the mixture were completely separated by changing the synchronous wavelength interval; with 240 nm the first-derivative spectra of carbaryl were recorded, while with 200 nm those of 1-naphthol appeared. The intensities in the spectra were proportional to the concentration of carbaryl and 1-naphthol. The calibration graphs were linear up to at least 1.1 x 10(-5) mol L(-1) for carbaryl and 1.3 x 10(-5) mol L(-1) for 1-naphthol, and the correlation coefficients were 0.9971 and 0.9932, respectively. Carbaryl and 1-naphthol were successfully determined by the proposed method in a hydrolyzed sample of a commercial formulation.

Simultaneous Determination of Carbaryl, Chlorpyrifos, and Its Metabolite 3,5,6-Trichloro-2-pyridinol (TCP) by Derivative Spectrophotometry. Direct Determination of the Degradation Grade of a Pesticide Formulation by Measurement of TCP

The degradation grade (DG) of a commercial pesticide formulation composed of carbaryl and chlorpyrifos has been directly determined by taking the first-derivative signal at 339 nm originated by 3,5,6-trichloro-2-pyridinol (TCP), which is the major breakdown product of chlorpyrifos. Detection and determination limits of 1.3×10 -6 and 4.4×10 -6 M, respectively, have been determined by using a commercial undegraded formulation (previously 1:50 diluted). Simultaneous determination of carbaryl, chlorpyrifos, and TCP can be performed in commercial formulations up to DG values of 25%

Simultaneous determination of carbaryl and azinphos-methyl in water by first-derivative synchronous spectrofluorimetry

A method is proposed for the simultaneous determination of the pesticides carbaryl (CBL) and azinphos-methyl (AZM) in water by first-derivative synchronous spectrofluorimetry. It is based on the alkaline hydrolysis of both pesticides to their metabolites 1-naphthol (from CBL) and anthranilic acid (from AZM). The constant wavelength difference chosen to optimize the determination is Δλ=λem−λex=103 nm. CBL is measured at 302/405 nm and AZM at 333/436 nm. The calibration graphs are linear between 2.0 and 500.0 ng/ml for CBL and between 1.2 and 500.0 ng/ml for AZM with detection limits of 0.62 ng/ml and 0.35 ng/ml, respectively. The precision of the method (RSD) is 2.4% at the 80.0 ng/ml level for CBL and 2.5% at the 80.0 ng/ml level for AZM. The method is applied to the determination of both analytes in samples of natural waters.