GC-MS Determination of CS₂ in Indoor Air with Separation by Adsorption on Activated Carbon

A dynamic dilution instrument, with its gas outlet connected with an activated carbon adsorption tube, was used for sampling of air and separation of CS₂ from air by adsorption on activated carbon. An aliquot of 2 μL of CS₂ standard reserve solution (absolute mass of CS₂<4 μg) was introduced into the instrument and the air sample was collected under the optimum conditions (i.e., with flow-rate of 1 000 mL·min^-1 and time of 10 min in sweeping). At the end of sweeping time, the adsorption tube was dis-connected and transferred to be thermo-desorption device in which the CS₂ adsorbed on activated carbon was desorbed under the working condition of the desorption device and transferred to gas chromatograph to be separated on DB-5 chromatographic column (60 m×0.25 mm, 0.25 μm) under the mode of programed temperature elevation in the range between 50℃ to 250℃. Finally, CS₂ separated by GC was determined by MS. Standard curve was prepared with standard solution of CS₂ and analyzed by the same procedure described above. Linearity range of CS₂ was found between 0.010 mg·L^-1 to 2.0 mg·L^-1 with detection limit (3s) of 0.007 μg or 0.7 μg·m^-3 when 10 L of air sample were collected. Recovery was tested by the standard addition method giving value of recovery in the range of 105%-110%. Values of RSD (n=6) were found all less than 4%. To test for time of keeping of the CS₂ adsorbed on activated carbon in the adsorption tube, 9 portions of 2 μL of CS₂ standard reserve solution were taken and treated in the same way in the dynamic dilution instrument separately and 9 adsorption tubes with adsorbed CS₂ were obtained and their contents of CS₂ were determined by GC-MS after keeping for different times. It was shown that the concentration of CS₂ in the adsorption tubes were kept stable at least for 72 h, and in further, the contents of CS₂ determined in adsorption tubes kept under room temperature (23℃) and under low temperature (-18℃) showed no significant difference.