Enantiomeric separation of FMOC-amino acids by nano-LC and CEC using a new chiral stationary phase, cellulose tris(3-chloro-4-methylphenylcarbamate).

A novel polysaccharide-based chiral stationary phase (CSP), cellulose tris(3-chloro-4-methylphenylcarbamate), also known as Sepapak-2 or Lux Cellulose-2, has been evaluated for the enantiomeric separation of FMOC derivatives of amino acids. After mobile-phase optimization in nano liquid chromatography (nano-LC) the column enabled the enantiomeric separation of 19 out of 23 amino acids tested, indicating the high chiral recognition power of this new CSP. Subsequently, a comparison of the driving force employed (pressure or voltage) was carried out comparing nano-LC and CEC under the same conditions. Better peak efficiencies and resolution were observed by using CEC experiments, which enabled the chiral discrimination of 20 out of 23 amino acids tested. Finally, in order to show the potential of this new CSP, the determination of the content and the enantiomeric purity of the non-protein amino acid citrulline in food supplements was performed. For that purpose, the method was optimized, evaluated and applied to different commercial samples.

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.