Instrument for Evaluating Phase Behavior of Mixtures for Supercritical Fluid Experiments

Page, Steven H.; Morrison, Janet F.; Christensen, Richard G.; Choquette, Steven J.

doi:10.1021/ac00093a003

Cited by 5 publications

(3 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During the static extraction step of the SFE method reported here, the extraction vessel contains a complex ternary fluid mixture consisting of carbon dioxide, water, and triethylamine. The fluid phase behavior of mixtures of CO 2 with TEA and water was studied previously by monitoring the scattered or transmitted laser light signal through a 1 mL high-pressure view cell under the same SF conditions and fluid mixture ratios used for the SFE method reported here. These studies demonstrated that while the CO 2 /TEA mixture exists as a single phase, the CO 2 /water and CO 2 /TEA/water mixtures exhibit phase separation under the static conditions employed (110 °C, 40.5 MPa, 100 μL of modifier or modifier mixture added to view cell).…”

Section: Resultsmentioning

confidence: 99%

Matrix and Modifier Effects in the Supercritical Fluid Extraction of Cocaine and Benzoylecgonine from Human Hair

et al. 1998

Self Cite

View full text Add to dashboard Cite

The supercritical fluid extraction (SFE) behavior of cocaine and its major metabolite benzoylecgonine (BZE) was investigated and found to be highly dependent upon the chemical nature of the matrix and the manner in which the target drug analytes are incorporated into or on the matrix. The recovery of cocaine from Teflon wool, filter paper, drug-fortified hair, and drug user hair was studied using a variety of CO2/modifier mixtures. Incorporation of a triethylamine (TEA)/water modifier mixture provided dramatic improvements in the recovery of cocaine from interactive matrixes. The results suggest that the SF extractability of cocaine is not limited by analyte solubility; rather, desorption of cocaine from hair binding sites is a rate-limiting step in the SFE process. A displacement SFE mechanism is hypothesized in which TEA (as the triethylammonium cation) competes with cocaine for negatively charged hair binding sites. The dependence of extractability on hair/drug binding interactions allows the differentiation of cocaine present at different discrete sites in hair based on differences in SFE behavior. These findings suggest the potential for distinguishing exogenous (i.e., environmental) from endogenous (i.e., physiological) sources of drugs in hair. In contrast to the results observed for cocaine, SFE recoveries of BZE were poor from all matrixes and under all conditions studied. Its increased polarity, the presence of an additional binding site, and the possibility of multiple charged states suggest that poor BZE recoveries may be due to both poor analyte solubility and failure to desorb the analyte from hair binding sites under the conditions employed.

show abstract

Section: Resultsmentioning

confidence: 99%

Matrix and Modifier Effects in the Supercritical Fluid Extraction of Cocaine and Benzoylecgonine from Human Hair

et al. 1998

Self Cite

View full text Add to dashboard Cite

show abstract

“…The method was modified to include a variable-volume view cell with a stirrer to enable a rapid equilibration of the cell contents, and used to study phase behaviour in CO 2 -propylene carbonate mixture [192] and in pure CO 2 and CO 2 -methanol mixture [193]. Subsequently, a view cell enabling the use of either scattered or transmitted light was employed to evaluate the phase behaviour in mixtures of CO 2 or chlorodifluoromethane with methanol, water, and triethylamine [194].…”

Section: Phase Behaviour Of Binary Mobile Phase Fluidsmentioning

confidence: 99%

Determination of thermodynamic properties by supercritical fluid chromatography

Roth

2004

Journal of Chromatography A

View full text Add to dashboard Cite

“…The cylindrical geometry of the cell was also unfavorable. A more robust flow cell was constructed by a straightforward alteration of a stainless steel cross, using thick sapphire windows seated in two of the cross connectors, placed at an angle of 90° or 180° for sampling scattered or transmitted light, respectively. This view cell was used to investigate phase changes in multicomponent mixtures of CO 2 or chlorodifluoromethane with methanol, triethylamine, and water.…”

mentioning

confidence: 99%

Screening of Polycyclic Aromatic Hydrocarbons in Soil by On-Line Fiber-Optic-Interfaced Supercritical Fluid Extraction Spectrofluorometry

1996

View full text Add to dashboard Cite

Instrument for Evaluating Phase Behavior of Mixtures for Supercritical Fluid Experiments

Cited by 5 publications

References 33 publications

Matrix and Modifier Effects in the Supercritical Fluid Extraction of Cocaine and Benzoylecgonine from Human Hair

Matrix and Modifier Effects in the Supercritical Fluid Extraction of Cocaine and Benzoylecgonine from Human Hair

Determination of thermodynamic properties by supercritical fluid chromatography

Screening of Polycyclic Aromatic Hydrocarbons in Soil by On-Line Fiber-Optic-Interfaced Supercritical Fluid Extraction Spectrofluorometry

Contact Info

Product

Resources

About