Validation of a Diffusive Sampler for Determination of Occupational Exposure to Halogenated Anesthetic Gases

Abstract

P-737 Introduction: Anesthetic gases such as desflurane, sevoflurane, isoflurane, enflurane and halothane are used on a daily bases in operating theatres. Waste anesthetic gases may have a negative effect on the members of the operating team as well as on the personnel in the resuscitation rooms. There is a need for an easy and convenient procedure for measuring the personal exposure to these gases. SKC 575–002 is a diffusive sampler filled with Anasorb 747. This sampler is widely used in the sampling of volatile gases, but has not been validated experimentally for use with halogenated anesthetic gases. The calculated uptake rates, recommended by SKC Inc., are based on geometry and physical characters. Our aim was to validate the sampler at various conditions. Methods: We validated the samplers in a laboratory dynamic system with standard atmospheres (4–140 mg/m3) of the compounds. Parameters tested were desorption efficiency, concentration, relative humidity, back-diffusion (clean air for 7.5 h after 0.5h of exposure), as well as storage stability for up to 8 weeks. Uptake rates were achieved by comparing with an active sampling approach (Gilian pumps (n=2–4)), providing independent controls for each sampling trial lasting for 1, 4 or 8 hours. Analysis and detection were performed using a gas chromatograph-flame ionization detector (GC/FID). Analysis of variance was used to evaluate influence of time, concentration, dose and relative humidity. Results: The desorption efficiencies ranged from 100 to 108% for all targets compounds. The uptake rates ranged from 11 to 15 mL/min and the levels were lower than those reported by SKC Inc. There were statistically significant effects of relatively humidity for all compounds (approx 10% lower uptake rates at 25% RH as compared with 60% RH). We also found significant effects (10–20%) of time and concentration for all substances with lower uptake rates at higher concentrations and longer sampling times. All samplers were run in replicates (n=5–8) and the relative standard deviations (RSD) were mostly low (<10%). The effects on back-diffusion or losses due to storage up to 8 weeks were insignificant. Discussion and Conclusions: Effects on uptake rates of sampling time, concentration and relative humidity were moderate. The samplers SKC 575–002 with Anasorb 747 could be used for personal monitoring of occupational exposure to halogenated anesthetic gases. Specific uptake rates, taken time and concentration into account, could be used or alternatively the lowest uptake rate found to ensure that levels are not underestimated.