Temperature and pressure effects on the supercritical fluid extraction profiles of sulfonamides from a spiked matrix using CHF3 and CO2

The effect of temperature and pressure upon the extraction profiles of polar sulfonamides from sand using supercritical CO2, methanol-modified CO2, CHF3, and methanol-modified CHF3 was investigated. Increasing temperature showed less effect upon extraction rates at 450 atm than at 300 atm using pure CO2. No change in extraction rates was observed with increasing temperature using methanol-modified CO2, but recovery improved by increasing the pressure at constant temperature. Extraction rates were altered using pure CHF3 by increasing the temperature at 300 atm causing a distinct change in the extraction profile for sulfamethazine (SMZ) and sulfadimethoxine (SDM). However, at 450 atm increasing temperature served only to decrease recovery and did not greatly affect the extraction profile. Sulfaquinoxaline (SQX) achieved similar total recovery regardless of temperature at constant pressure, although extraction rates varied with temperature. Methanol-modified CHF3 exhibited no temperature dependence at 300 atm. However, decreased recovery was obtained at 450 atm and 40 °C compared to the higher temperatures.