Development and Validation of an Analytical Method for Quantitation of Sulfolane in Rat and Mouse Plasma by GC-MS

Sulfolane is an industrial solvent commonly used for extraction of aromatic hydrocarbons in the oil refining process, as well in the purification of natural gas. Its wide use and high solubility in water has led to contamination of groundwater. The objective of this work was to develop and validate an analytical method to quantitate sulfolane in rodent plasma in support of the National Toxicology Program toxicology and toxicokinetic studies of sulfolane. The method uses extraction of plasma with ethyl acetate and analysis by gas chromatography-mass spectrometry with electron ionization. The method was validated in male Sprague Dawley (SD) rat plasma over the concentration range of 20-100,000 ng/mL. The method was linear (r ≥ 0.99), accurate (mean relative error (RE) ≤ ±5.1%) and precise (relative standard deviation (RSD) ≤ 2.9%). The absolute recovery was ≥74%. The limit of detection was 0.516 ng/mL. Standards as high as ~2.5 mg/mL could be successfully diluted into the calibration range (mean %RE ≤ ±4.5; %RSD ≤ 4.6). Extracted samples were stable for at least 3 days at ambient and refrigerated temperatures, and freeze/thaw stability in matrix was demonstrated after three cycles over 3 days (calculated concentrations within 90.8-102% of Day 0 concentrations). Sulfolane was stable in frozen plasma for at least 75 days at -80°C (calculated concentrations within 93.0-98.1% of Day 0 concentrations). Matrix evaluation was performed for sulfolane in female SD rat plasma and male and female B6C3F1 mouse plasma (mean %RE ≤ ±4.9; %RSD ≤ 3.3). These data demonstrate that the method is suitable for determination of sulfolane in rodent plasma.