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A Study Of Whisker Walled Open Tubular Columns Coated With Inorganic Salts Or Liquid Stationary Phases For Gas Chromatographic Investigations

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Description: The present investigation was undertaken to obtain a means of coating the inorganic salts manganese (II) chloride and cobalt (II) chloride directly on the inner walls of glass capillary columns and to study the characteristics of these columns in comparison to earlier results with conventional packed columns containing these adsorbents. The whisker growth technique was employed as a means of securing the inorganic salts to the glass capillary tubing. This technique, in addition to he necessary roughening, provided the advantage of approximately ten times more wall area per column length than a smooth glass capillary of equal dimension, allowing for increased adsorbent-adsorbate interaction. A thorough investigation of the whisker technique was carried out to obtain reproducible results where the whisker growth was evenly and totally distributed throughout the entire length of a 100 meter column. Both the static and dynamic coating methods were employed. The dynamic method was preferred since the static method required a prohibitively long coating time. Several parameters such as column internal diameter, column length and concentration of the inorganic salts on the column were studied. Columns of 25-50 meters in length and 0.25 mm I.D. provided the best results. A 1 mg/m coating of the inorganic salts was determined as the maximum amount that could be successfully coated in an 0.25 mm I.D. column. Evidence for a porous surface was indicated from the observation that retention increased with increasing salt concentration. Several aromatic hydrocarbons substituted with the (pi)-electron withdrawing and donating groups were employed to study the selectivity of manganese (II) chloride and cobalt (II) chloride toward (pi)-electron density. Halogen-substituted aromatic compounds were less retained and, therefore, eluted earlier than n-alkyl substituted aromatic compounds of similar boiling points due to the decrease in (pi)-electron density. In contrast, methoxybenzene, which experiences (pi)-electron donation from the methoxy group, was retained longer than an n-alkyl substituted aromatic compound of similar boiling point. Other specific interactions were observed with variations in the number and position of alkyl substitutions.
Language: English
Format: Degree Work