Sample introduction into a direct current plasma by filament vaporization

Miscellaneous · Sun Jan 01 00:00:00 EST 1989

OSTI ID:7201070

Buckley, B T

This dissertation describes sample introduction into a direct current plasma by a tungsten filament vaporizer. The filament heater was designed to resistively heat a 0.1 mm diameter tungsten wire quickly and efficiently. The heating system is under microprocessor control for precise power application to the filament. The cell volume is small, less than 4 mL, and the accessibility of the primary emission zone allowed placement of the filament less than 5 cm from the confluence point of the plasma. The first study describes some of the fundamental design considerations, as well as performance of the interface. The absolute mass detection limits for Ca, Fe, Al, and Cu are 80, 2,000, 90, and 200 fg respectively. The blackbody emission temperature of the filament was measured. The initial heating rate was 50,000{degree}C/s. Observations are reported for optimization of operating parameters, as well as how to locate the region of maximum analyte emission intensity. Finally, the application of this technique to the analysis of a biological sample, swine blood, is reported. The second study examines the sources of noise and their components. Noise is grouped into additive and multiplicative noise occurring in three frequency ranges. The largest contribution, greater than 90%, was shot to shot multiplicative variations in sample vaporization and excitation. The third study examines the effect of addition of concomitant substances to the analyte. The substances were added both as metal salts to the aqueous analyte solution and as dopant gases to the carrier gas. Measured transport efficiencies ranged from 60 to 103% for manganese under various concomitant conditions. A 1% doping of the carrier gas with hydrogen caused significant enhancement of the emission signal of three metals, Fe, Al, and Ca. Enhancement correlated with volatility of the reduced form of the element.

• Research Organization: North Carolina State Univ., Raleigh, NC (United States)
• OSTI ID: 7201070
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
METALS
QUANTITATIVE CHEMICAL ANALYSIS
ALUMINIUM
CALCIUM
COPPER
EXPERIMENTAL DATA
FLASH HEATING
IRON
PLASMA
SAMPLE PREPARATION
ALKALINE EARTH METALS
CHEMICAL ANALYSIS
DATA
ELEMENTS
HEATING
INFORMATION
NUMERICAL DATA
TRANSITION ELEMENTS
400102* - Chemical & Spectral Procedures