Solution nebulization device (ultrasonic nebulizer) for inductively coupled plasma spectrometry and alternate plasma source (low-pressure inductively coupled plasma) for mass spectrometry.

摘要

Ultrasonic nebulizers (USNs) are useful analytical tools for liquid sample analysis in plasma spectrometry. It provides better sensitivity and detection limits as a result of its high nebulization efficiency. This work deals with the design and construction of ultrasonic nebulizers for sample introduction into the inductively coupled plasma (ICP). A direct air-cooled USN has been developed and evaluated for use in inductively coupled plasma atomic emission spectrometry (ICP-AES) using multielement solutions in 2% nitric acid. Pertinent figures of merit such as signal-to-background, sensitivity detection limit and linear dynamic range has been obtained for the USN and compared to those of the pneumatic and glass frit nebulizers. Response times were also compared and stability & reproducibility tests were conducted. In addition, the performance of the USN was evaluated for solutions with high salt content (i.e. synthetic ocean water). Another USN employing an indirect water-cooling method for the transducer was designed and evaluated for analysis of non-aqueous solutions by inductively coupled plasma mass spectrometry (ICP-MS).;A low pressure inductively coupled plasma (LP-ICP) has been developed and characterized as an alternate ion source for mass spectrometry. The advantages provided by the LP-ICP include (1) low gas consumption which makes the use of high purity gases more affordable, (2) low power requirements, (3) easy ignition, (4) elimination of interferences due to atmospheric entrainment, (5) plasma gas flexibility, and (6) adaptability to existing instrumentation. Of particular importance is the generation of a low pressure He ICP. Helium plasmas are better ionization sources due to He's high ionization energy. However, the generation of a stable He-plasma at atmospheric pressure is not an easy task. By generating the He ICP under low pressure conditions, a stable plasma can be obtained. The performance of the LP-He ICP-MS has been evaluated for the analysis of gaseous samples in the form of gas chromatographic (GC) eluates which resulted in detection limits in the low pg range for the halogenated (bromine and chlorine) test compounds. In addition, a low pressure air ICP has also been used for the detection of halogen (iodine)-containing GC eluates. Detection of supercritical fluid chromatography products (ferrocene and ferrocene derivatives) using the LP-He ICP-MS has been attempted. An investigation on the feasibility of liquid sample analysis via solution nebulization into the LP-He ICP-MS has also been conducted.