Time-weighted average sampling of volatile and semi-volatile airborne organic compounds by the solid-phase microextraction device

The ultimate goal of the chemist is to perform sample preparation, and anal ysis, if possible at the place where a sample is located rather than moving the sample to laboratory, as is common practice in many cases at the prese nt time. This approach eliminates errors and time associated with sample tr ansport and storage and therefore it would result in more accurate, precise and faster analytical data. In addition to portability, two other importan t features of ideal field sample preparation technique are elimination of s olvent use and integration with a sampling step. A method is developed whic h addresses these requirements for the determination of time-weighted avera ge concentration of gas phase compounds using a solid-phase microextraction device. Quantification of target analytes in air using this method can be carried out without external calibration. The volatile and semi-volatile or ganic compounds in air diffuse into the fiber coating which is retracted a known distance into its needle housing during the sampling period. The coat ings used are poly(dimethylsiloxane) and poly(dimethylsiloxane)-divinylbenz ene. The sampling rate at which gas phase analytes load onto the fiber is d etermined for a wide range of hydrocarbons, There is a good agreement betwe en the theoretical and experimental sampling rates. Sampling time ranges fr om 1 min to 24 h depending on the coating used and its retraction distance. Effect of the flow-rate on the uptake rate by the fiber is studied. The me thod is tested in the field and compared with National Institute of Occupat ional Health and Safety Method 1550. Goad agreement between the results is obtained. (C) 2000 Elsevier Science B.V. All rights resented.