Robert J. Conzemius

Elemental partitioning in ash depositories and material balance for a coal burning facility by spark source mass spectrometry

Spark source mass spectrometry is shown to be an excellent analytical tool for determining enrichment factors and a useful tool for measuring material balances for a coal-burning facility. Measurements of enrichment and material balance are reported for 62 elements in two US coals obtained by using SSMS as the sole analytical technique. Copper was used as an internal reference. The halogens, Hg, S and Se were found to be lost to the stack. Systematic errors are noted in relative sensitivity coefficients for some of the elements, and between coal and ash samples.

An electrical detection system for a spark-source mass spectrograph.

An electrical detection system has been developed which can be used with the high-frequency spark-source mass spectrograph. Details of the system are discussed and examples are given illustrating its advantages (rapidity and precision). One distinct advantage of electrical detection is that a constant volume of sample material is used for each impurity determination. The system can also be used to assess sample inhomogeneities.

The partitioning of elements during physical cleaning of coals

Abstract The fate of 75 different elements was determined in coal samples before and after physical cleaning; in coarse coal wastes removed during cleaning; in process waters before and after the cleaning of coal; and in leachates of coal wastes. The results showed that the concentration of most elements simply followed the ash content of coal before and after cleaning. Germanium was significantly enriched and beryllium, molybdenum, uranium, iodine, cobalt and antimony were slightly enriched in cleaned coals. Sodium, sulfur, chlorine, calcium, iron, magnesium and potassium were observed in the process waters at concentrations above 100 mg/l with sodium at 860 mg/l being the highest concentration observed.

Determination of rare earths in selected rare earth matrices by spark source mass spectrometry

Three methods of preparing rare earth samples for mass spectrographic analysis are presented. Techniques for adding appropriate internal standards are described and relative sensitivity factors for rare earth impurities in rare earths, lanthanum, yttrium and scandium matrices are presented. Although indium has some value as an internal standard in rare earth samples, best analytical results are obtained when selected rare earths are used as internal standards.

The determination of trace elements in aqueous media without preconcentration using a cryogenic hollow-cathode ion source

The glow discharge in a hollow cathode containing 20–50 μl of an aqueous sample held at liquid-nitrogen temperature is used as a source of ions in a double-focussing mass spectrometer. The device was tested with nine solutions containing an aggregate of seventy elements. Seven elements (F, P, S, Sc, Mn, Ni, and Ta) could not be determined because of interferences. The remainder of the elements could be determined at various detection limits ranging from sub-ng ml−1 to μg ml−1. Mercury (32 pg) could be detected in 20 μl of water in the presence of Tl, Pb, Bi, Th, U, and Al.

Relative sensitivity coefficients for rare earths in spark-source mass spectrometry

Relative sensitivity coefficients have been computed for rare earth elements according to empirical models which have been proposed in the literature. Explanations concerning differences between the computed and observed values are based upon possible instrumental discrimination effects which negate some processes occurring in the ion source. Computations relating elemental physical constants to observed results in a semi-random manner are shown which support this contention.

Fast diffusion and electrotransport of iron in scandium

Abstract The diffusion and electrotransport properties of iron in α and β scandium were measured over the temperature range 970 to 1515 °C. The diffusion coefficients are of the order of 10−9 to 10−10 m2 s−1 in both phases. The effective valence Z ∗ is negative at all temperatures corresponding to solute migration in the direction of electron flow. The activation energy for diffusion of iron in α-Sc is 54 ± 6 kJ mol−1 and the diffusion constant is 1.5 × 10−7 m2 s−1. The solubility of iron in the α phase was determined to be between 0.01 and 0.025 at.% at 700 °C increasing to less than 0.043 at.% at 825 °C. The magnitude of the diffusivity of iron in scandium was found to be similar to that of iron in other rare earth metals.

Automatic control of the ion-illumination angle in a spark-source mass spectrometer

Automatic adjustment of only the spark-gap width in a spark-source mass spectrometer does not ensure that optimum conditions of electrode geometry are maintained with respect to the ion-optics system. A device has been developed which simultaneously maintains a constant gap width and also a more constant z-axis ion-illumination angle. This is the first development to utilize ion-optics parameters to adjust the sparking electrodes automatically. The system maintains the electrodes in an optimum configuration such that higher and more constant instrument sensitivity is maintained automatically. In addition, a significant improvement in the precision of instrumental response is demonstrated. It appears that relative isotopic abundances can be determined directly by the spark-source method which are comparable to those obtained in some cases by surface ionization or by electron bombardment. Results are given that support this contention.

Application of low-cost operational amplifiers to electrical detection in spark-source mass spectrometry

An electrical detection system for spark-source mass spectrometry has recently been developed. This brief addendum describes an improvement in the signal amplification and its conversion to digital output which has important implications in the future development of electrical detection.

A high resolution mass spectrometric measurement system for a vacuum fusion apparatus

Abstract A high resolution mass spectrometric read-out system for a vacuum fusion apparatus is described. Rapid analyses are possible and the rate at which various gases are evolved can be monitored. Gas mixture assays are accomplished by scanning the nominal mass 28 peak. Serial measurements of CO + , N 2 + and C 2 H 4 + are made. Thus detection and measurement of evolved hydrocarbons are possible. The results for silver and tin from a conventional vacuum fusion apparatus and the mass spectrometer apparatus are compared.