Quantitative analysis by on-line supercritical fluid extraction/Fourier transform infrared spectrometry

Abstract

A system Is described wherein the supercritical fluid extracts of compounds can be analyzed on-line by FT-IR without prior chromatographic separation. A 1-m-X 0.010-ln.-i.d. stainless steel transfer line was used between the extraction vessel/ system cryotrap and the high-pressure IR flow cell. Extraction can be directly conducted as static, dynamic, static-dynamic, or dynamlc-cryotrap with minor system alterations. Quantitation was performed by Integrating the area of the extract plug, plotted In terms of detector signal versus time. The system was perfected for the extraction and quantification of n-tetracosane (C24) from Cellte, but has subsequently been applied to more complex systems, such as flber/fabrlc finishing oils, with comparable success. The detection limit for C24 by on-line SFE/FT-IR was calculated to be 74 ng. The relative speed and reproducibility of the method make It a viable alternative to the liquid extraction/1R methods used In Industrial process analysis that require Increasingly EPA-regulated solvents.

Analysis of Fiber Finishes Using SFE Coupled to a Simple, Universal IR Flow Cell

“…We have reported dye diffusion rates in multiple layers of nylon fabrics [ 4,5,6 j and porous membranes [ 7, 8 j . We observed that surface concentration of dye in multiple layers increased with dyeing time. The increasing surface concentration was attributable to the resistance to dye transfer across the diffusional boundary layer.…”

“…The finishing oil content of the sample is then quantified using Beer's law, i.e., the linear relationship between the optical absorbance of the analyte versus the quantity of the analyte. This particular technique will be referred to as sFE on-line IR or simply SFE-IR [6]. The feasibility of SFE-IR for fiber finish analysis has been reported elsewhere [3,4,5,7].…”

Chemical species

“…Direct on-line supercritical fluid extraction-Fourier transforminfrared spectroscopy (SFE-FT-IR), without chromatographic separation, has been demonstrated for extraction and determination of nanogram quantities of hydrocarbons (Kirschner and Taylor, 1993). Quantitative analysis was performed by integrating signal area under the extracted plug.…”

Bioanalytical Applications Using Supercritical Fluid Techniques

“…From 1993, the range of detectors for SFE showed a rapid expansion. Infrared spectroscopy [72], spectrophotometry [73], spectrofluorimetry [74], thermal lens spectrometry [75], atomic absorption spectrometry [76], MS [77] and proton NMR [78] were all demonstrated in SFE using a windowed high-pressure flow cell for hybridization. FiguRe 4 shows the use of SFE and SFC in various analytical fields.…”