The evaluation of novel microwave-induced plasma sources and the inductively-coupled plasma for element specific detection for capillary supercritical fluid chromatography and ion chromatography

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:7110086

Forbes, K A

This dissertation involved two aspects of the development of plasma atomic emission detectors for chromatography. Four novel microwave cavities/devices were investigated to establish the positive features and limitations of each. The enhanced Beenakker cavity (EBC) was determined to be easiest to operate and tune. An annular helium plasma was produced in a concentric torch in the EBC, and 5 ppm phosphorus was detected in aqueous solutions introduced into the 85 W plasma by means of an ultrasonic nebulizer/desolvator. The annular plasma produces more efficient analyte excitation than a filament type of plasma, and had minimal contact with the torch walls, resulting in much lower silicon emission. Gaseous and supercritical fluid carbon dioxide were introduced into the helium plasmas in the EBC and the stripline cavity. The molecular background increased significantly due to CO and CO{sup +} systems, however, the increase in C{sub 2} molecular bands was not significant. A large analytically useful window exists in the background spectrum of the plasmas in the EBC and SLC with CO{sub 2} added from a capillary supercritical fluid chromatograph (SFC). The inductively coupled plasma (ICP) was interfaced to a capillary SFC. The argon plasma was optimized for Si(I) 251.6 nm emission to detect separated organosilicon compounds selectively. The linear dynamic concentration range for octamethylcyclotetra-siloxane was 10{sup 2}, with a detection limit of 5.8 ng Si injected. The relative standard deviations of the peak heights for repetitive injections were typically 1-5%. The effects of the CO{sub 2} pressure on the plasma stability and sensitivity, and upon the spectral background are presented. An ICP was also used as an element specific detector for ion chromatography. An analytical method is presented for the determination of Didronel (1-hydroxyethylidene-l,l-disodium diphosphonate, HEDP), in standard solutions and tablet dosage formulations.

• Research Organization: Massachusetts Univ., Amherst, MA (United States)
• OSTI ID: 7110086
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
CHEMICAL ANALYSIS
CHROMATOGRAPHY
DATA
DESIGN
EMISSION SPECTROSCOPY
EXPERIMENTAL DATA
HEATING
INFORMATION
LIQUID COLUMN CHROMATOGRAPHY
MEASURING INSTRUMENTS
MICROWAVE HEATING
MONITORS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PARAMETRIC ANALYSIS
PLASMA
QUANTITATIVE CHEMICAL ANALYSIS
SENSITIVITY
SEPARATION PROCESSES
SPECTROSCOPY
SUPERCRITICAL FLUID CHROMATOGRAPHY