CALIBRATION OF THE THERMAL-DESORPTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY SYSTEM USING STANDARDS GENERATED IN THE PROCESS OF THERMAL-DECOMPOSITION OF CHEMICALLY-MODIFIED SILICA-GEL

A calibration method for the thermal desorption gas chromatographic-ma ss spectrometric (TD-GC-MS) determination of n-propanethiol based on a gas standard mixture generated in the process of thermal decompositio n of chemically modified silica gel is proposed. The experimental resu lts indicated that the total amount of n-propanethiol liberated from u nit mass of the gel did not depend on the total mass of the gel used. A calibration curve for the TD-GC-MS system for n-propanethiol, determ ined for the relationship between the mass of n-propanethiol and the m ass of the modified silica gel used, was found by a linear regression method and was characterized by a correlation coefficient r=0.99. This means that the amounts of liberated n-propanethiol are directly propo rtional to the mass of the modified gel used within the examined range of masses of silica gel samples. Consequently, the amount of the anal yte (n-propanethiol) can be determined on the basis of mass of silica gel used and hence the modified silica gel can be treated as a standar d of the liberated component (n-propanethiol in this case).