The use of nitrous oxide for supercritical fluid extraction of pharmaceutical compounds from animal feed

Abstract

Abstract Supercritical fluid extraction (SFE) coupled “off‐line” with HPLC analysis has been applied to pharmaceutical analysis: two different matrixes (rodent and dog feed) were spiked with compounds under investigation in pharmacological studies in order to study the supercritical extraction of such matrixes prior to further analysis and quantification of the compounds of interest. The fluid flow‐rate in the SFE system was governed by the geometric characteristics (internal diameter and length) of the linear fused silica capillaries. The changes in fluid flow‐rate, between experiments, for each new restrictor, required the introduction of the term Total Gaseous Fluid Volume (TGFV), which enabled a series of extraction results to be compared. The comparative behavior of nitrous oxide and carbon dioxide as supercritical extraction fluids was investigated. Results obtained using pure supercritical fluids with high solvating power (density 0.79 g ml −1 ) and fluids modified with a polar liquid solvent (methanol and acetonitrile) are discussed.