29. Chemicals
29.1 Argon, Air, and Hydrogen Cylinders, 99.999 % pure. Argon is used to overpressurize the headspace and to carry the substances contained in the injection loop through the stationary phase to the detectors.
29.2 Three Gas Mixtures, prepared with a precision of about 0.5 % used to establish a three-point calibration curve for each substance. The concentrations of these mixtures should be chosen in order to fully cover the expected concentration range of field samples, which depends on the type of equipment monitored.
