Determination of residues of karbutilate and its major metabolites in water, soil, and grass by high-pressure liquid chromatography

Abstract

A high-pressure liquid chromatographic (HPLC) method was developed for the determination of residues of karbutilate (3-[ [(dimethylamino)carbonyl]amino]phenyl(l,l-dimethylethyl)carbamate), its hydrolysis product N'-(3-hydroxyphenyl)-N,N-dimethylurea and its demethylated metabolites monomethyl karbutilate (3-[ [ (methylamino)carbonyl)]amino]phenyl (1,l-dimethylethy1)carbamate) and demethyl karbutilate (3-[ (aminocarbonyl)amino]phenyl (1,l-dimethylethyl)carbamate), in water, soil, and grass. Recoveries of karbutilate and its degradation products from water ranged from 89 to 103%. The lower limit of sensitivity of the method is 0.01 ppm for karbutilate and N'-(3-hydroxyphenyl)-N,N-dimethylurea and 0.02 ppm for monomethyl karbutilate. The recovery of karbutilate and its carbamate metabolites from soil ranged from 84 to 95%. For residues in grass, the carbamates are converted to the corresponding phenols, which are analyzed by HPLC. The recovery of karbutilate and its carbamate metabolites from grass ranged from 80 to 87 7%. The lower limit of sensitivity of the method for residues in soil and grass is 0.1 ppm for karbutilate and 0.2 ppm for monomethyl karbutilate and demethyl karbutilate.

Photo-induced chemiluminometric determination of Karbutilate in a continuous-flow Multicommutation assembly

“…The suitable oxidant was established by testing some strong oxidant systems (oxidative reagent plus medium for the oxidation), namely 7 × 10 −4 mol l −1 potassium permanganate or 6 × 10 −3 mol l −1 Ce(IV) (both of them in 2.0 mol l −1 H 2 SO 4 ); 6 × 10 −3 mol l −1 Fe(CN) 6 3− in 1.5 mol l −1 NaOH; the higher outputs were obtained with the systems (medium for photodegradation-oxidant) NaOH-KMnO 4 and H 2 O 2 -Fe(CN) 6 3− . Two different systems resulted in higher outputs, namely (a) potassium permanganate in pyrophosphoric acid medium (other mineral acids were tested too) with photodegradation in NaOH 0.001 mol l −1 ; (b) hexacyanoferrate (III) in alkaline medium with the photodegradation in basic medium and 0.05% of hydrogen peroxide.…”

“…Other used pesticides tested were Fenobucarb (99.5%) and Isoprocarb (98.3%) obtained from the same manufacturer. Chemicals such as strong inorganic acids and alkalis, buffers, oxidants as KMnO 4 , Ce(NH 4 ) 2 (NO 3 ) 6 , H 2 O 2 , tensoactives and sensitizers (Triton X-100, N,N-dimethylformamide and Na 2 B 4 O 7 ·10H 2 O) were from Panreac, Spain; ␤-cyclodextrine (Fluka, Buchs, Switzerland) NH 3 , Na 2 HPO 4 , NH 4 Cl, FeSO 4 , FeNO 3 ·9H 2 O and sodium acetate from Probus; H 2 O 2 , ethanol and acetonitrile from Prolabo and Merck; KH 2 PO 4 , NaOH, HCl and acetic acid from J.T. Baker; sodium dodecyl sulphate and hexadecylpiridinium chloride from Fluka.…”

“…A paper dealing with the Karbutilate determination extracted different carbamic herbicides with methanol and the filtered resulting solution was analysed with the aid of HPLC at 40 • C by using acetonitrile as mobile phase and UV-vis detection [5]. The determination of Karbutilate residues on water, soil and grass matrices was also performed with the aid of HPLC methodology [6] with photometric detection at 254 nm; the method tested the separation of mixtures of Karbutilate and some of its degradation products (from hydrolysis and demethylation processes); a previous extraction with the water-methanol mixture was also required for solid samples, and according to authors the CG determination was not possible due to the thermal instability of Karbutilate. Some papers are dealing with the separation and determination of carbamate pesticides by liquid chromatography; one of them proposed the mass spectrometry as post-column detector for separation and detection of carbamate pesticides [7], and a summarized study of the fluid-chromatography parameters on the same group pesticides has been also published [8].…”