An evaluation of triple quadrupole ms/ms for on-line analyses of trace sulfur compounds from oil shale processing

In order to effectively reduce sulfur gas content from shale processing to environmentally acceptable levels, H2S, COS, S02 and CH3SH plus trace sulfur compounds must be removed. Of these, the trace sulfur compounds have not been well characterized but should be known to ppm levels In order to optimize gas clean-up procedures. Most techniques for analysis of trace sulfur components In oil shale gases have limitations. The applications we describe using triple quadrupole mass spectrometric techniques (TQMS) appears to have overcome many problems of trace sulfur analysis. Basically a TQMS produces a mass spectrum of a mass spectrum and Is, therefore, highly sensitive, selective and specific. Tests on a Finnlgan TQMS at the University of Florida and on a totally computerized TQMS designed at LLNL using pure standards, mixed gas standards and Fisher assay gas grab samples show that we can quantitatively as well as qualitatively detect the following components: methyl mercaptan = <1 ppm; ethyl mercaptan = 3 ppm; n-propyl mercaptan = <1 ppm; isopropyl mercaptan = 4 ppm; carbonyl sulfide - 1 ppm; carbon disulfide = 4 ppm; didimethyl disulfide = <1 ppm; thiophene = <1 ppm; and 2 or 3 methyl thiophene = <1 ppm. For a rapidly changing gas stream, timing studies on the LLNL TQMS show that analytical results for 10 sulfur compounds (1000 readings on each parent and key daughter Ions) can be acquired and quantitatively calculated in approximately 30 seconds. For kinetics studies, data on selected daughters for 10 compounds can be acquired In a total of 540 milliseconds.