subject: The Many Applications Of Ion Analysis [print this page] Ion analysis has been developed for the sensitive detection of ions in gasses and liquids, but can also be used for the determination of ion make up of solids. The surface of solids can be analyzed via a probe that ionizes the surface molecules and draws the resulting gasses into an ion detector, such as a mass spectrophotometer. This method is excellent for quantifying atomic elements found in metals, maintaining purity to aid in the smelting process in foundries.
The system used is a spark generation mass spectrophotometer/ion-mobility detector. A sample of the processed metal is cleaned of debris by using a lathe to turn the surface to be analyzed smooth. The sample, or ingot, is placed on the analyzer and an ionizing probe is brought to within microns of the surface. An electrical charge is passed through the probe onto the metal surface, causing a discharge of ionized gas. This gas is drawn into the mass spectrophotometer that analyzes and separates ions into their respective elements. This gives the foundry lab technician a view of what needs to be adjusted in the mixing cauldron before final pouring.
Another system for ion analysis is used for liquids using ion-specific electrodes. This system utilizes special metals in the fabrication of the electrodes and an electrolyte solution to draw specific ions into the detection area. A thin membrane that is semi-permeable, which allows only those ions to be detected, is used to filter out the liquid's interfering substances. A buffer solution is used to reduce ions for the detection process, as it is qualitative as well as quantitative.
This system is used in clinical as well as biological research laboratories. It is used mainly for the metabolite functions in biological processes in humans and nature, and is vital for the monitoring of human body chemistry in hospitals all over the world.
Ion analysis can also be accomplished using ion exchange chromatography, a system that uses columns to separate substances in a matrix. The principle is as follows: The sample is drawn with a buffered solution into the column during the "mobile phase", and when it reaches the column, it becomes the "stationary phase". The column is usually filled with either gel or some type of fiber that is covalently charged opposite of what ions need separation. The ions are then retained in this phase as the fluid is drawn through the system. In most chromatography systems, ultraviolet or visible light at specific wavelengths are used to detect, through light absorption, the ions in a quantitative and qualitative manner.
This is an excellent system for protein separation and amino acid grouping. Biochemists use this sensitive system for metabolic function tests, as well as determining biological changes in nature. Research laboratories use this system for many metabolic studies, and for classification of proteins being studied for medical or biological applications. Pharmaceutical companies use sensitive systems like ion chromatography analysis to determine the functions of drugs before using them in experimental trials.
Many manufacturers of ion exchange chromatography instruments attest to their functionality and reliability, so perusing each manufacturer's process and record of accomplishment is encouraged to those who need to make an informed decision. Whatever system is decided upon, reliability and sensitivity is a plus, as ion exchange chromatography is the most used system for protein separation and amino acid detection.
