Evaluation of new cellulose-based chiral stationary phases Sepapak-2 and Sepapak-4 for the enantiomeric separation of pesticides by nano liquid chromatography and capillary electrochromatography.
Two novel polysaccharide-based chiral stationary phases (CSPs), known as Sepapak-2 (cellulose tris(3-chloro-4-methylphenylcarbamate)) and Sepapak-4 (cellulose tris(4-chloro-3-methylphenylcarbamate)), have been evaluated in this work for the chiral separation of a group of 16 pesticides including herbicides, insecticides and fungicides. The optimization of the mobile phase employed in nano-liquid chromatography (nano-LC) enabled the chiral separation of seven pesticides on Sepapak-2 and of nine pesticides on Sepapak-4. Due to the fact that Sepapak-4 gave better results, this column was selected to compare nano-LC and capillary electrochromatography (CEC) under the same conditions that consisted in the use of a 90/9/1 (v/v/v) ACN/H₂O/ammonium formate (pH 2.5) background electrolyte (BGE). As expected, both the efficiency and the chiral resolution obtained in CEC experiments were higher than in nano-LC for all the analyzed compounds. The analytical characteristics of the CEC developed methodology were evaluated in terms of linearity, LODs, LOQs, precision, selectivity, and accuracy allowing its application to the quantitation of metalaxyl and its enantiomeric impurity in a commercial fungicide product marketed as enantiomerically pure (metalaxyl-M) and in soil and tap water samples after solid phase extraction (SPE). The determined amount of metalaxyl-M was found to be a 26% above the labeled content and it contained an enantiomeric impurity of a 3.7% of S-metalaxyl was determined.
Department of Analytical Chemistry, Faculty of Chemistry, University of Alcalá, Alcalá de Henares, Madrid, Spain.
Virginia
V
Pérez-Fernández
Elena
E
Dominguez-Vega
Bezhan
B
Chankvetadze
Antonio L
AL
Crego
Maria Ángeles
MÁ
García
Maria Luisa
ML
Marina
D000097:Acetonitriles; D053801:Capillary Electrochromatography / Q000379:methods*; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D005561:Formates; D000432:Methanol; D036103:Nanotechnology / Q000379:methods; D010575:Pesticides / Q000032:analysis* / Q000737:chemistry; D048448:Phenylcarbamates / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013237:Stereoisomerism
D000097:Acetonitriles; D005561:Formates; D010575:Pesticides; D048448:Phenylcarbamates; C538979:cellulose tris(3-chloro-4-methylphenylcarbamate); C552444:cellulose tris(4-chloro-3-methylphenylcarbamate); C030544:formic acid; D002482:Cellulose; D000432:Methanol; C032159:acetonitrile