“…The chromatograms (not shown) of the same sample mixture on P-C 18 and P-C 8 are similar to that shown in Figure B. Although the analysis time of the sample components on H-C 18 is somewhat longer, the column allowed a good separation of the solutes on a shorter column at a lower carrier gas flow rate and column head pressure compared to bidentate alkylsilane- and cyclic siloxane-modified silica columns. , Also, butane was eluted much faster (3 min or less) on the present columns than Porapak N and Spherosil (∼13 min), Carbopack and Carbosieve (∼4 min), and nonporous glass beads loaded with heteropoly compounds (∼14 min) − under isothermal conditions. 7 Separation of a 10-component mixture of C 1 −C 4 saturated and unsaturated hydrocarbons on (A) H-C 18 and (B) M-C 18 columns.…”
Section: Resultssupporting
confidence: 58%
“…Although the analysis time of the sample components on H-C 18 is somewhat longer, the column allowed a good separation of the solutes on a shorter column at a lower carrier gas flow rate and column head pressure compared to bidentate alkylsilane-and cyclic siloxane-modified silica columns. 4,6 Also, butane was eluted much faster (3 min or less) on the present columns than Porapak N and Spherosil (∼13 min), 18 Carbopack and Carbosieve (∼4 min), 19 and nonporous glass beads loaded with heteropoly compounds (∼14 min) [20][21][22] under isothermal conditions.…”
Cyclic siloxane-based silica columns of high retention capacity for light hydrocarbons were prepared by incorporation of octyl and octadecyl groups on the siloxane skeleton. Spectroscopic studies revealed the presence of the alkyl groups on the silica surface, which results in high surface coverage of the packing materials. The retention characteristics of the columns are significantly higher than those of cyclic siloxane phases due to their high surface coverage and better solute-stationary phase interactions. In agreement with previous data for micropacked columns, the H vs ū curves, on passing through the optimum region, remained substantially constant at high linear gas velocities, indicating their usefulness for fast analysis of light hydrocarbons at high flow rates without any appreciable loss in column performance. Presumably due to greater availability of the bonded alkyl groups for interactions, a 10-component mixture of C(1)-C(4) saturated and unsaturated hydrocarbons was sufficiently separated on the hexamethylcyclotrisiloxane-octadecylsilyl phase compared to the conventional octadecyldimethylsilyl phase, irrespective of the high carbon content of the latter.
“…The chromatograms (not shown) of the same sample mixture on P-C 18 and P-C 8 are similar to that shown in Figure B. Although the analysis time of the sample components on H-C 18 is somewhat longer, the column allowed a good separation of the solutes on a shorter column at a lower carrier gas flow rate and column head pressure compared to bidentate alkylsilane- and cyclic siloxane-modified silica columns. , Also, butane was eluted much faster (3 min or less) on the present columns than Porapak N and Spherosil (∼13 min), Carbopack and Carbosieve (∼4 min), and nonporous glass beads loaded with heteropoly compounds (∼14 min) − under isothermal conditions. 7 Separation of a 10-component mixture of C 1 −C 4 saturated and unsaturated hydrocarbons on (A) H-C 18 and (B) M-C 18 columns.…”
Section: Resultssupporting
confidence: 58%
“…Although the analysis time of the sample components on H-C 18 is somewhat longer, the column allowed a good separation of the solutes on a shorter column at a lower carrier gas flow rate and column head pressure compared to bidentate alkylsilane-and cyclic siloxane-modified silica columns. 4,6 Also, butane was eluted much faster (3 min or less) on the present columns than Porapak N and Spherosil (∼13 min), 18 Carbopack and Carbosieve (∼4 min), 19 and nonporous glass beads loaded with heteropoly compounds (∼14 min) [20][21][22] under isothermal conditions.…”
Cyclic siloxane-based silica columns of high retention capacity for light hydrocarbons were prepared by incorporation of octyl and octadecyl groups on the siloxane skeleton. Spectroscopic studies revealed the presence of the alkyl groups on the silica surface, which results in high surface coverage of the packing materials. The retention characteristics of the columns are significantly higher than those of cyclic siloxane phases due to their high surface coverage and better solute-stationary phase interactions. In agreement with previous data for micropacked columns, the H vs ū curves, on passing through the optimum region, remained substantially constant at high linear gas velocities, indicating their usefulness for fast analysis of light hydrocarbons at high flow rates without any appreciable loss in column performance. Presumably due to greater availability of the bonded alkyl groups for interactions, a 10-component mixture of C(1)-C(4) saturated and unsaturated hydrocarbons was sufficiently separated on the hexamethylcyclotrisiloxane-octadecylsilyl phase compared to the conventional octadecyldimethylsilyl phase, irrespective of the high carbon content of the latter.
“…2,7,12,13 In recent years methods reported in the literature have used solid adsorbent preconcentration followed by thermal desorption and gas chromatography for the analysis of volatile organic compounds in air. Examples include trace levels of formaldehyde, 14 lower-molecular-weight hydrocarbons, 15,16 the chemicalwarfare agent mustard gas, 17 volatile hydrocarbons in indoor air, 18 dimethyl sulfoxide and dimethyl sulfone in air, 19 or polycyclic aromatic hydrocarbons. 20 Recently, a multistage solid adsorbent trapping system has also been developed for analysis of ppt-level volatile organic trace gases (especially halocarbons).…”
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