A Validated Method for the Quantitation of 1,1-Difluoroethane Using a Gas in Equilibrium Method of Calibration

Abstract

1,1-Difluoroethane (DFE), also known as Freon 152A, is a member of a class of compounds known as halogenated hydrocarbons. A number of these compounds have gained notoriety because of their ability to induce rapid onset of intoxication after inhalation exposure. Abuse of DFE has necessitated development of methods for its detection and quantitation in postmortem and human performance specimens. Furthermore, methodologies applicable to research studies are required as there have been limited toxicokinetic and toxicodynamic reports published on DFE. This paper describes a method for the quantitation of DFE using a gas chromatography-flame-ionization headspace technique that employs solventless standards for calibration. Two calibration curves using 0.5 mL whole blood calibrators which ranged from A: 0.225-1.350 to B: 9.0-180.0 mg/L were developed. These were evaluated for linearity (0.9992 and 0.9995), limit of detection of 0.018 mg/L, limit of quantitation of 0.099 mg/L (recovery 111.9%, CV 9.92%), and upper limit of linearity of 27,000.0 mg/L. Combined curve recovery results of a 98.0 mg/L DFE control that was prepared using an alternate technique was 102.2% with CV of 3.09%. No matrix interference was observed in DFE enriched blood, urine or brain specimens nor did analysis of variance detect any significant differences (alpha = 0.01) in the area under the curve of blood, urine or brain specimens at three identical DFE concentrations. The method is suitable for use in forensic laboratories because validation was performed on instrumentation routinely used in forensic labs and due to the ease with which the calibration range can be adjusted. Perhaps more importantly it is also useful for research oriented studies because the removal of solvent from standard preparation eliminates the possibility for solvent induced changes to the gas/liquid partitioning of DFE or chromatographic interference due to the presence of solvent in specimens.

Sudden death involving inhalation of 1,1-difluoroethane (HFC-152a) with spray cleaner: Three case reports

“…The tissue distribution of HFC152a depends on its concentration, solubility and tissue blood circulation because hydrocarbon gases are readily absorbed into the blood. The blood concentration of HFC-152a in this report was within the range of past studies with results between 40.3 and 141.1 mg/l [1][2][3], while the interpretation requires careful approach due to the uncontrolled loss of volatile gas and the difference of sampling and storage condition [13]. HFC-152a was also detected in the urine and gastric content.…”

Forensic Science

“…1,3-Propanediol was determined in body fluids by GC-FID (371). A method for the quantitation of 1,1-difluoroethane using HS-GC-FID has been described (372). Helium was detected in an asphyxial suicide victim by GC/MS (373).…”