Spectrometers for Elemental Spectrochemical Analysis, Part IV: Inductively Coupled Plasma Optical Emission Spectrometers

摘要

In this tutorial, we discuss inductively coupled plasma (ICP) spectrometers. The basic modules of spectrometer systems already have been discussed in Part I of this series (1). Here, we focus on the ICP excitation and sample introduction system. A discussion of some optical configurations used in ICP is included. The plasma excitation spectrometer is a relative newcomer, invented in the 1960s, although commercially available units were not sold until the late 1970s. The term "plasma" here describes what is commonly referred to as the "fourth state of matter;" that is, a very hot, ionized gas. Plasma sources are typically used for the analysis of liquids, finding their primary application in environmental monitoring and other areas where samples may be readily available in liquid form. Although there are different ways to produce these plasmas, by far the most common is the inductively coupled plasma (ICP). In ICP-optical emission spectroscopy (OES), the energy from the high-temperature argon plasma (5000-10,000 K) excites the sample atoms. Generally, the sample must be in liquid form.