CWA Sensitivity Testing

The preferred method for analyzing vapor concentration is described in ERDEC s report 476 (March 1998). This method uses manual sample collection such that the sample enters directly into the preconcentrator tube of the MINICAMS. This avoids sample loss through the sampling line to achieve the most accurate measurement. The collected sample is then thermally desorbed into the GC column for separation and quantification using appropriate peak detectors. 

Other thermal desorption-GC devices could be used in a similar fashion. Systems like the Agilent Dynatherm-GC-FPD/MS will also produce similar results. This type of instrument can be used when a MINICAMS is not available. Analysis times, however, will be substantially longer than required by the described MINICAMS method. 

The system to be used must be calibrated using standards made from materials of known concentration, such as the Chemical Agent Standard Analytical Reference Materiel (CASARM), if available. The caUbration curve for the instrument is developed through varying the amount of the substance injected. GC output from the vapor sample collected is then correlated with the calibration curve to derive the exact vapor concentration by dividing the amount determined over the volume (sampling rate x time) of the sample collected. 

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