Abstract
The standard methods to determine either sulfur1)-4) or chlorine5) in oils routinely used in many laboratories are time-consuming and laborious. The presnet paper describes a rapid method involving the energy dispersive X-ray technique that determines simultineously sulfur and chlorine in the range up to 2wt% and 5wt%, respectively.
The results of pre-examination using samples prepared from base oils and additives listed in Table 2 indicated that there were marked interelemental effects (Fig. 3a and 3b) between sulfur and chlorine, and that chlorine X-ray line was interfered by the scattered X-ray from Rh-tube. These effects, however, were well compensated for by the mathematical correction proposed by Lucas-Tooth and Pyne (Eq. 2). Evaluation of the resulting working Eqs. (3) and (4) was made on the prepared samples and used cutting oils, and the results obtained are shown in Tables 5 and 6, respectively. It was recognized from these results in the tables that, when no element other than sulfur and chlorine was present in the sample, differences between the given and calculated concentrations were generally small as compared with the standard deviations of Table 4, and it was also recognized that 0.1wt% of either iron or calcium present homogeneously in the sample did not affect the observed values. However, when large quantity of iron particulates were added to the sample, they settled at the bottom of the sample holder, and the values of both elements observed became lower due to absorption; but, removing the particulates from the sample by filtration, their actual concentrations could be obtained. The working equations once established might be used for more than six months, since the apparatus used showed good date-to-date reproducibility (Table 3) and a monitoring sample was used for correcting the long-term drift of the apparatus. In the present method, the monitoring and test samples should be analyzed alternately for determining the relative intensities (Eq. 1).
