The axial view presents a longer viewing channel with more light, which increases sensitivity.” “The longer the path length, the greater the sensitivity. Erica Cahoon, PerkinElmer’s global ICP-OES product manager. The difference is a Beer’s Law phenomenon, notes Dr. The radial view provides the highest upper linear range, whereas axial reduces the plasma background, offering a tenfold improvement in detection limit. Light from the ICP may be viewed radially (perpendicular to the plasma orientation) or axially (along the plasma axis). The high temperature completely atomizes sample elements and minimizes chemical interference. Inductively coupled plasma optical emission spectroscopy (ICP-OES) measures light emitted from elements in an argon plasma that reaches 10,000 K. “Flame AA can’t quantify the gaseous elements and the halogens,” says Heidi Grecsek, global AA portfolio director at PerkinElmer. On the downside, furnace AA analysis times are longer, and the list of potential elemental analytes is shorter than for flame AA-about 40 elements versus about 70. All the atomized sample is available to the light path passing through the tube, so sensitivity and detection limits are greatly improved over those of flame AA. In graphite furnace AA, the sample is introduced into a graphite tube, cleared of solvent and matrix, and completely atomized. Related Article: AA Spectroscopy: Sensitive, Quantitative Metal Analysis Sample introduction for flame AA occurs through a high-temperature burner-nebulizer, which represents the method’s major limitation: only a fraction of the sample is heated, leading to low sensitivity. Every element detected requires a different light source, although sources may be combined for multiple-element detection. Light sources are either hollow cathode or electrodeless discharge lamps. The more atoms present, the higher the absorption. Flame OE is less expensive and easier to operate.Ītomic absorption occurs when an atom in the ground state absorbs light energy and transitions to a higher energy level. ICP-OE spectroscopy has the advantage in speed, lower detection limits, fewer interferences, and the ability to analyze multiple elements within the same sample. ICP OE is more widely used than flame OE is. As its name implies, flame OE uses a flame to excite atoms, whereas ICP employs a much higher-temperature plasma, resulting in more efficient excitation. Optical emission (OE) spectroscopy comes in two forms: flame OE and the more popular inductively coupled plasma (ICP) OE. Flame AA is the most common type, with graphite furnace AA and cold vapor AA following. The two principal forms of atomic spectroscopy are based on emission and absorption.īased on the absorption of optical radiation by gas-state atoms, atomic absorption (AA) spectroscopy measures analyte concentrations down to parts per billion. Many industries use atomic spectroscopy to quantify elements, particularly but not exclusively metals, in pharmaceuticals, wastewater streams, consumer products, foods, and other products.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |