Premium
Separation and determination of homologues of linear alkylbenzenesulfonates by nonaqueous capillary zone electrophoresis using alkylammonium salts in ethanol
Author(s) -
HerreroMartínez José Manuel,
SimóAlfonso Ernesto F.,
RamisRamos Guillermo
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200106)22:10<2017::aid-elps2017>3.0.co;2-c
Subject(s) - chemistry , capillary electrophoresis , acetic acid , chromatography , resolution (logic) , electrolyte , repeatability , electrophoresis , detection limit , analytical chemistry (journal) , ethanol , organic chemistry , electrode , artificial intelligence , computer science
The separation of linear alkylbenzene sulfonates (LAS) by nonaqueous capillary electrophoresis (NACE) using negative polarity, and a buffer containing acetic acid and an alkylamine in nonaqueous ethanol, has been investigated. Several primary, secondary, and tertiary alkylamines with alkyl chains of different length were compared. The solutes travelled against the electroosmotic flow (EOF), and at the same time were braked by association with the alkylamine molecules or with the alkylammonium ions. The best resolution between adjacent LAS homologues ( R ∼ 2.1), partial isomer resolution in two peaks, and at the same time an excellent repeatability, was obtained with a small dipentylamine excess over the acetic acid. When the buffer concentration increased, resolution between the homologues increased slightly ( R ∼ 2.4), and a different isomer group was partially separated. A background electrolyte (BGE) containing 10 m M acetic acid and 20 m M dipentylamine to separate and quantify the homologues within 25 min is recommended. The isomer peak profile with up to three peaks can be estimated using this buffer and another one with 80 m M acetic acid and 90 m M dipentylamine. The former BGE was used to determine LAS in liquid and powder laundry detergents. The detection limit for the determination of total LAS in these products was 2.5 νg mL –1 , and the peak area and migration time interday repeatabilities were below 4.3 and 2.8%, respectively.