Biochemical Techniques and Instrumentation

2.6.3.1.Carrier gas

Most commonly used carrier gases include nitrogen, hydrogen, helium, argon and carbon dioxide. They must be chemically inert and of high purity. The carrier gas system often contains a molecular sieve to remove water and other impurities. They should have a constant flow rate. The faster the flow rate, the lower will be the retention time. The flow rate of the carrier gas is generally set at 55 ml/min. The choice of carrier gas is dependent upon the type of detector. eg. FID uses helium gas.