Abstract
The technique described here permits rapid and accurate determinations of carbon and hydrogen contents for volatile liquid petroleum samples, e.g., gasoline.
Glass1) or aluminum2) capillary tube has been used as a sampling device for volatile samples to prevent their losses, but the use of either of them with the Hewlett-Packard 185B CHN Analyzer was found difficult for low boiling samples because they tend to vaporize and burn at the time of capillary tube sealing (Table 1).
A volumetric sampling system by micro syringe and a combustion furnace of Dohrmann MOTS-10 microcoulometric titration system were successfully used. Some low boiling samples with boiling points in the range from 27.9 to 144.4°C were introduced into the combustion furnace without any vaporization and burning by use of micro syringe. Water and carbon dioxide produced by combustion of the samples were collected in separate absorption tube and weighed, and their carbon and hydrogen contents determined (Table 2); moreover, no effects of sulfur, nitrogen and chlorine contained in the samples were observed (Table 3).
The standard deviations of n-pentane and gasoline were 0.74%, 0.65% for carbon and 0.14%, 0.13% for hydrogen, respectively. Furthermore, the difference between the theoretical and observed values of carbon and hydrogen contents for n-pentane could be regarded as insignificant (Table 4).
Several gasoline samples were determined by this method, and some of their results were compared with the gas chromatographic results (Table 5).
