Spark Source Mass Spectrography Research Articles

Spark-Source Mass Spectra of Several Aromatic Hydrocarbons Using a Spinning Electrode

The purpose of this investigation was to evaluate the application of a spark-source mass spectrograph equipped with a spinning-electrode system for the study of various high molecular-weight materials derived from coal. Eight structural types having molecular weights from 178 to 252 corresponding to those substances previously seen in an electron-impact mass spectrum of the coal-tar pitch were affirmed by this technique. Easily interpreted mass spectra of phenanthrene, anthracene, and chrysene were obtained by the spinning-electrode system. Mass spectra obtained from synthetic mixtures of anthracene and chrysene demonstrated that the technique is applicable for semiquanitative analysis.

Determination of boron in boronated graphite crystals using a spark source mass spectrograph

Determination of boron in boronated graphite crystals using a spark source mass spectrograph

The analysis of titanium dioxide pigments by spark-source mass spectrography

Graphite, silver and gold powders have been investigated as conducting media in the analysis of titanium dioxide pigments for trace elements by solid-source mass spectrography. It is concluded that graphite and silver are satisfactory, and that by using both these electrode systems the only elements that cannot be determined are sodium and copper.It has been shown that by using niobium in low concentration as an internal standard, quantitative analysis is possible; the coefficient of variation of the results being approximately 15 per cent. Sensitivity factors for 44 elements relative to niobium in a graphite matrix, and 3 elements relative to niobium in a silver matrix, have been determined. The results of the determination of 27 elements commonly present in titanium dioxide pigments are given. The total time for a quantitative analysis is approximately 3 hours, and it is possible to analyse up to 8 samples in a working day of 8 hours.

Geochemical analysis by spark source mass spectrography

The application of spark source mass spectrography to geological materials is described. The instrument employed is the A.E.I. M.S. 7 model. Powdered samples are briquetted with graphite containing Lu as the internal standard. The sample is sparked at 25 kV in a high vacuum (10 −7 torr). The ion beam is brought to focus by electrical and magnetic fields and the mass spectra from B-U are recorded on a 10 in. Ilford Q-2 plate. Densities are read on a microphotometer and converted to intensities by the self-calibration method. The principles underlying the selection of internal standards are listed. Data for the standards G-1, and W-1 are given. Satisfactory agreement is obtained with other values. Data for about 45 elements are currently obtained with the technique. A new procedure for tabulating results based on geochemical association, is described.

Mass Spectrographic Analyses of Non conducting Ceramics

Powdered or densified nonconductive ceramic materials analyzed by spark source mass spectrography based on use of conducting probe

A modified recording technique for improvement of detection limits in spark-source mass spectrography

A method to improve the limits of detection in spark-source mass spectrography is described. This improvement is achieved by prevention of secondary emission fogging by removal of selected portions of the photographic plate.

Isotope Dilution Analyses by Spark Source Mass Spectrography.

Isotope Dilution Analyses by Spark Source Mass Spectrography.

Geochemical Application of Spark Source Mass Spectrography

Geochemical Application of Spark Source Mass Spectrography

Relative Sensitivities of Elements in a Spark-Source Mass Spectrograph

Abstract The relative sensitivities of eleven elements in a spark-source mass spectrograph have been determined for monatomic singly-charged positive ions detected with Ilford Q2 plates. The results show that the elements have approximately the same sensitivities to within a factor of 3 in spite of large differences in both physical and chemical properties among them, and that the sensitivity of each element is constant in value within an uncertainty factor of 1.5, independent of changes in the bulk concentration of the element. Relative ion production rates have also been determined from the above sensitivities; they are in reasonable agreement with published values determined by electrical detection. From repeated measurements of the relative intensities of various ions, it has been suggested that relative ion yields from a spark ion source are not always constant for different elements. On the basis of these investigations, a discussion has been made of the general applicability of the sensitivity as the analytical constant in the quantitative mass spectrography of solids. Five different formulas have been used to express the “density” of mass lines, and exposures have been determined with an integrated monitor current. By trying several isotopic analyses, the calibration methods have been shown to be useful for mass spectrography.

Geologic age determination by direct lead isotope analysis

A commercial spark source mass spectrograph was used for the examination of lead isotope ratios in uranium bearing minerals. The ratio Pb/sup 206//Pb/sup 207/ was evaluated and related to geologic age. Results of some of the measurements are tabulated and compared with some of the accepted values from the literature. Advantages and disadvantages of the method are discussed. (P.C.H.)

Some New Upper Limits of Isotopic Abundance by Mass Spectrometry

Using a spark source mass spectrograph, a search has been made for undiscovered naturally occurring isotopes of low abundance None was found, although the spark source instrument permitted examination of elements that have not been analyzed in this context for many years. The ability of the instrument to ionize all elements and the ease with which the rarer isotopes may be seen allowed upper limits of <0 000001 atom % to be placed on some isotopes. Be, P, Mn, Co, As, Rh, Au, and Bi were confirmed as monoisotopic.