National Institute for Occupational Safety and Health

“ A straight line baseline should be attained at the highest sensitivity likely to be used. Select one of the following sampling modes: a. Spot sample. Draw air sample into the gas sampling loop of the GC with the on-board sampling pump, if supplied. Alternatively, inject an aliquot of air to be sampled into the GC with a gas-tight syringe. NOTE: A large contributor to random error in the method is imprecision of replicate injections. To improve precision: (1) use a gas sampling loop for injections, if available; (2) make at least three replicate determinations per sample ”

“ A six-inch strip chart recorder was used to obtain peak height data from the portable GC. A limitation in the use of this type of portable GC (e.g., packed column, room temperature isothermal) is the limited ability to separate the analyte from any interferences present. In the evaluation of this method, a six-foot DC 200 column was used. Its ability to separate the TCE peak from other contaminants was not evaluated. ”