The extraction of analytes from aqueous solution using supercritical fluids

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5650801

Hedrick, J L

Supercritical fluid extraction (SFE) of analytes from aqueous solution has not received much attention. The design of a system for the extraction of analytes from aqueous solution has been explored in this thesis. Several related areas (injection techniques for supercritical fluid chromatography and on-line SFE) were also developed. The injection port of a supercritical fluid chromatograph was modified to provide more reproducible sample introduction. On-line SFE/SFC was explored as a possible configuration for the extraction of analytes from aqueous solution. Solvent elimination injection (SEI) was developed for SFC. The difference in vapor pressure between the analytes and solvent allowed for the solvent to evaporate and be transported from the system while the analytes were collected on various traps. After evaporation of the injection solvent the analytes were flushed onto a chromatographic column. SEI allowed for the reproducible injection of larger volumes of sample (solvent and analyte) into the system. SEI allowed for different hardware configurations to be tested without performing an actual supercritical fluid extraction. An off-line solid phase trapping system for SFE was developed. The system trapped the analytes from the SFE effluent onto a solid phase extraction cartridge. The cartridge could be rinsed to elute the analytes. Trapping was found to allow for faster extraction rates than liquid trapping. A system which allowed for the extraction of moderate volumes (3-5 mL) of aqueous solution was developed. A test solution of phenols was used to evaluate the system. The extractability of the phenols was a function of pressure of the system and the chemical nature of the phenol. A decrease in extractability of the phenols took place at pressures greater than 250 atm. The distribution coefficient of phenol increased steadily through 400 atm, probably because of a decrease in surface area of the supercritical fluid passing through the aqueous solution.

• Research Organization: Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)
• OSTI ID: 5650801
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical & Spectral Procedures
400105* -- Separation Procedures
AQUEOUS SOLUTIONS
AROMATICS
CHROMATOGRAPHY
DESIGN
DISPERSIONS
EXTRACTION
HYDROXY COMPOUNDS
INJECTION
INTAKE
MIXTURES
ORGANIC COMPOUNDS
PHENOLS
SEPARATION PROCESSES
SOLUTIONS
SUPERCRITICAL FLUID CHROMATOGRAPHY