On-line coupling of subcritical water extraction with high-performance liquid chromatography via solid-phase trapping

• Published in: Journal of Chromatography A Vol. 873; no. 2; pp. 175 - 184
• Main Authors: Li, Bin, Yang, Yu, Gan, Youxin, Eaton, Clinton D, He, Ping, Jones, Aaryn D
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 24.03.2000; Elsevier
• Subjects: Analytical chemistry; Aniline Compounds - analysis; Aniline Compounds - chemistry; Caffeine; Caffeine - analysis; Chemistry; Chloroanilines; Chlorophenols; Chlorophenols - analysis; Chromatographic methods and physical methods associated with chromatography; Chromatography, High Pressure Liquid - methods; Exact sciences and technology; Nitrotoluenes; Other chromatographic methods; Polychlorinated biphenyls; Polychlorinated Biphenyls - analysis; Sensitivity and Specificity; Subcritical water; Toluene - analogs & derivatives; Toluene - analysis; Water; Solid-phase trapping; Subcritical water; Extraction methods; Nitrotoluenes; Polychlorinated biphenyls; Chloroanilines; Chlorophenols; Caffeine; Trace analysis; Water; Chemical analysis; On line; Liquid liquid extraction; Halophenols; Coupled method; Benzene derivatives; HPLC chromatography; Experimental study; Solvent extraction; Polychlorobiphenyl; Pollutant; Ultraviolet detector; Sample preparation; Organochlorine compounds; Chlorine Organic compounds; Chlorocarbon; Explosives; Subcriticality; Quantitative analysis
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(99)01322-9

Although ambient water is very polar and cannot dissolve many organic species, water at elevated temperatures behaves like a polar organic solvent. Thus, subcritical water has been proven to be an effective extraction fluid for several classes of organic compounds. While solvent trapping was used to collect the extracted analytes in most of previous subcritical water extractions, sorbent trapping has also been developed for subcritical water extraction. In this study, an on-line system for subcritical water extraction and high-performance liquid chromatography (HPLC) was built and tested. A sorbent trap was used as the interface between subcritical water extraction and HPLC. Several shut-off valves have been utilized to switch the system from one mode to another (e.g., from the extraction mode to HPLC mode). The coupling technique of subcritical water extraction and HPLC eliminates the liquid–liquid extraction used in solvent trapping subcritical water extraction and provides higher sensitivity. Compared to the off-line system reported in an earlier work, the operation of this on-line system is even easier. Some peak broadening occurred after the coupling the water extraction with HPLC for the analytes studied. The performance of this on-line system was evaluated by the extraction and determination of caffeine, nitrotoluenes, polychlorinated biphenyls, chlorophenols and anilines.