Analytical Characteristics of Multicapillary Gas Chromatographic Columns with 25 µm Capillaries

Straight multicapillary columns (MCCs) with 40 µm capillaries are used in portable gas analyzers. In order to increase the efficiency and speed of gas chromatographic separation, straight MCCs with a diameter of 25 μm and a length of 200–250 mm with an OV-5 stationary phase (film thickness, 0.1–0.2 μm) were fabricated and their main chromatographic characteristics were determined. It was shown that the maximum specific efficiency of the MCCs was 25 600 theoretical plates/m and the separation rate reached 630 theoretical plates/s, which significantly exceed the corresponding values for 40 μm MCCs. The test MCCs retained high separation efficiency in wide ranges of carrier gas flow rates: 30–170 cm³/min for argon and nitrogen and 120–420 cm³/min for helium. However, as compared to the 40 µm columns, approximately twice the pressure was required to ensure the same flow of a carrier gas through the 25 µm MCCs. A decrease in the diameter of MCC channels from 40 to 25 µm made it possible to shorten the column length by about 1/3 with the retention of the column efficiency.