ABSTRACT
For environmental analyses, a high-performance and powerful preconcentration system exceeding 1 x 10(7)-fold was developed that was composed of a blue cotton method (solid extraction method)/homogeneous liquid-liquid extraction method/on-line concentration method for capillary electrophoresis (CE). This system was named the "triplex concentration system" and it was achieved by finding a new phase-separation phenomenon (homogeneous liquid-liquid extraction) from a water-miscible organic solvent. Parts per trillion levels of polycyclic aromatic hydrocarbons (PAHs) were used as model analytical targets in this study. With the proposed method, 20-L levels of environmental water could be preconcentrated up to 1 x 10(7)-fold within a maximum of 1 h. The parts per trillion levels of PAHs were easily determined even using UV/CE, which has a serious sensitivity problem, and the detection limit of benzo[a]pyrene was 3.60 ppt. This system was also used as a practical monitoring method for the Miyata River (in Japan).
ABSTRACT
A powerful preconcentration method for nonylphenol (NP) has been developed for liquid-chromatography by combining the use of cellulose cotton (solid-phase extraction) with homogeneous liquid-liquid extraction. A 100 ml of sample solution was preconcentrated using cotton, and the eluate obtained (acetonitrile; 5 ml) was further preconcentrated to 50 microl within 10 min using a homogeneous liquid-liquid extraction method (volume ratio, 2,000-fold; 100 ml--> 50 microl). The sample concentration increases from preconcentration was 1,599-fold, and NP was extracted into the sedimented phase at 80%. The proposed method was applied to high performance liquid chromatography with fluorescence detection (FL/HPLC); the lowest determination limit obtained was 1.0 x 10(-9) mol l(-1).
