ASTM E260 Standard Practice for Packed Column Gas Chromatography
12. Use of the Gas Chromatographic Packed Column
12.1 Certain precautions and preventive maintenance are necessary to obtain the best column performance. Some of these points have been made before and will be referred to in this section. Further precautions will also be discussed.
12.2 Carrier Gas Purity - Trace, or adventitious, oxygen and water in the carrier gas can produce degradation of liquid phases on the support. Purification of the carrier gas and necessary precautions are discussed in 7.6.
12.3 The Injection Port - The injection port is often a source of trouble. The temperature can be either too low or too high. See 6.3. Another problem is a leaking septum. See 6.3.4.
12.4 Column Care:
12.4.1 Never heat a gas chromatographic column with air in it. When any column is first placed in a gas chromatograph, flush any air (oxygen) out of it by flushing with carrier gas at normal flow rates for 15 to 30 min. at ambient temperatures. Then heat the column to the desired operating temperature. Always cool the column to room temperature before removing it from the gas chromatograph. If the column is to be used again, cap the ends with metal caps to prevent diffusion of air (oxygen) into the column during storage. Contact of the stationary phase with oxygen when hot or for prolonged periods of time at room temperature cause degradation of the stationary phase. This is particularly the case with polyglycols and polyester type phases and to a lesser extent cyanosilicones. Other phases are affected to a varying degree.
12.4.2 After long periods of use, column performance may degrade as shown by peak broadening, tailing, or gradual merging of adjacent peaks. Often the problem lies in the front end of the column. The injection port temperature might have been too high and destroyed the initial section of the liquid phase on the column packing. Residues or decomposition products might have built up on the glass wool plug. These problems can be remedied by repacking the first few inches of a glass column, or cutting off the first few inches of a metal column. Use fresh silanized glass wool to close the end of the column in both cases.
