Supercritical CHF3 and methanol-modified CHF3 were compared with supercritical CO2 and methanol-modified CO2 for the extraction of sulfonamides from a spiked sand sample. In addition, a fortified nonfat milk powder, fortified egg yolk, and fortified beef liver were studied. The results showed CHF3 has higher solvating power and selectivity for extraction of two of the three sulfonamides than CO2. Extraction efficiencies of sulfamethazine and sulfadimethoxine using pure CHF3 were more than 45% higher from spiked sand samples and over 200% higher from fortified beef liver samples than pure CO2.

A chemiluminescent nitrogen detector was optimized for packed-column supercritical fluid chromatography. Methanol modifier concentrations of 15% or less, an ozone flow of 5.8 mL/min, and a decompressed CO(2) flow between 240 and 310 mL/min were found to exhibit a maximum sensitivity of 5 ng for sulfamethazine (1 ng of N). The addition of a membrane drier to the "optimized" system further decreased the minimum detectable quantity (MDQ) to 0.5 ng (0.1 ng of N). In addition, by using a microbore column (2 mm i.d.) instead of an analytical scale column, the postcolumn decompressed flow split could be eliminated, further reducing the MDQ to 0.125 ng of sulfamethazine (0.025 ng of N).