Abstract
A rapid method is described for preparation of support - bonded Carbowax 20M columns packing using a conventional furnace to heat the packing. Solvent extraction of the stationary phase removes the non-immobilized poly(ethylene glycol) (PEG) from the support and the difference between final and initial weight provides the total percent extracted and, consequently, the total percent immobilized. Treatment of the packing material at 250 °C for 10 h. reveals that the immobilization reduces the material activity and increases the plates number (N) and resolution (Rs) while the retention factor (k) is decreased. Thus, separations with this treated column are faster and display higher efficiency.
Highlights
Carbowax® poly(ethylene glycol) (PEG) 20M is widely used in gas chromatography (GC) because of its unique selectivity, which allows resolution of polar compounds having similar boiling points
In the thermogravimetric simulation these packings were heated under N2 and weighted several times using a special ampoule adapted for Gas Chromatography
Thermal stability is determined by thermogravimetric simulation (Figure 4)
Summary
Carbowax® PEG 20M is widely used in gas chromatography (GC) because of its unique selectivity, which allows resolution of polar compounds having similar boiling points. Immobilization of the stationary phase is generally achieved by bonding the polymer chain to the support This immobilization process is initiated by free radicals which are produced by heat[1,2,3,4,5], chemical initiators such as azocompounds[6,7,8], peroxides[9,10,11,12,13] or ozone[14,15], and ionizing radiation such as electrons[16], gamma radiation[17,18] and low-temperature plasmas[19]. 20% Carbowax 20M (Merck) on ChromosorbW/AW (80-100 mesh, Merck) was prepared by evaporation[20] of solvent This material was placed in borosilicate glass ampoules which were sealed under N2 and heated at different temperatures (200, 250, 300, 350 and 400 oC) for 5 and 10 h. In the thermogravimetric simulation these packings were heated under N2 and weighted several times using a special ampoule adapted for Gas Chromatography
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