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Effect of NaOH on large‐volume sample stacking of haloacetic acids in capillary zone electrophoresis with a low‐pH buffer
Author(s) -
Tu Chuanhong,
Zhu Lingyan,
Ang Chay Hoon,
Lee Hian Kee
Publication year - 2003
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/elps.200305460
Subject(s) - haloacetic acids , capillary electrophoresis , chromatography , chemistry , capillary action , stacking , electrolyte , volume (thermodynamics) , extraction (chemistry) , analytical chemistry (journal) , matrix (chemical analysis) , solvent , sample preparation , tap water , dissolution , materials science , physics , chlorine , organic chemistry , electrode , quantum mechanics , composite material , environmental engineering , engineering
Large‐volume sample stacking (LVSS) is an effective on‐capillary sample concentration method in capillary zone electrophoresis, which can be applied to the sample in a low‐conductivity matrix. NaOH solution is commonly used to back‐extract acidic compounds from organic solvent in sample pretreatment. The effect of NaOH as sample matrix on LVSS of haloacetic acids was investigated in this study. It was found that the presence of NaOH in sample did not compromise, but rather help the sample stacking performance if a low pH background electrolyte (BGE) was used. The sensitivity enhancement factor was higher than the case when sample was dissolved in pure water or diluted BGE. Compared with conventional injection (0.4% capillary volume), 97–120‐fold sensitivity enhancement in terms of peak height was obtained without deterioration of separation with an injection amount equal to 20% of the capillary volume. This method was applied to determine haloacetic acids in tap water by combination with liquid‐liquid extraction and back‐extraction into NaOH solution. Limits of detection at sub‐ppb levels were obtained for real samples with direct UV detection.