Compatibilitty of the cyclone BC-112 with the measurement of endotoxins in bioaerosols : A study in laboratory conditions.

The BC-112 cyclone is an individual bioaerosol sampler constituted of a metallic main body (2 mm inlet), a first collection stage (1.5 ml collection tube) and a final collection stage (37 mm three pieces cassette). The sampler has been used for sampling airborne fungi, bacteria and viruses but its suitability for endotoxins sampling has not yet been demonstrated. A laboratory study has been carried out with E. coli experimental bioaérosols in order to find out in what extend the BC-112 cyclone could be used for sampling of airborne endotoxins. A first set of experiments allowed the validation of a protocol for the removal of endotoxins form contaminated BC-112 cyclones. A second set of has showed that the filter used in the final stage of the sampler had a significant (p<0.005) effect on the measured concentrations of airborne endotoxins. A last set of assays allowed a side by side comparison of the BC-112 cyclone (with PVC filter) and the closed-face cassette (with PVC filter) upon a wide range of concentrations. The results revealed a significant correlation (r=0.87; n=9; p=0.001) between the two methods with a BC-112 cyclone/cassette ratio from 0.65 to 1.42. The study has provided an efficient protocol for the decontamination of BC-112 cyclones and has shown that a PVC filter could be used as collecting medium in the final collection stage. It has also demonstrated that endotoxins deposits on inner cassette walls should be taken into account for accurate measurement with experimental bioaérosols. The BC-112 cyclone is suitable for the assessment of airborne endotoxins providing these protocol adaptations. A filed sampling campaign is required to assess the global efficiency of the BC-112 cyclone for endotoxins in real exposure conditions.