Special Issues-10-01-2007

Multiline analysis, which consists of using several lines per element to detect positive or negative bias caused by spectral interferences, is an ideal way to use all the information emitted by the plasma and collected by a charge-coupled device detector. However, method development and validation become more complex. Dedicated software has been developed to overcome it, and analysis of geological samples will illustrate their benefit in achieving high reliability of results.

The multielement analysis of water is one of the major applications for inductively coupled plasma-optical emission spectroscopy (ICP-OES). This report describes the analysis of metals and trace elements in drinking water in terms of sensitivity, precision, and accuracy. Instrument parameters and line selection are described. Excellent recoveries were found for the standard reference material (SRM) NIST SRM 1640.

Two of the most significant areas of advancement in inductively coupled plasma-mass spectrometry (ICP-MS) with respect to clinical applications have been the evolution of the sample introduction system and the interface of liquid chromatography (LC). The complexity of the sample matrix creates challenges for a number of components involved with the introduction of ions into the mass spectrometer, including the nebulizer, spray chamber, torch, and interface cones. The development of LC-ICP-MS methods enables analysts to quantitate not only the total metal content but the form of the metal as well, a distinction that in many cases is crucial. Although the refinement of reaction and collision cell technology has been important for this application, much has been written elsewhere and it will not be addressed here.

Bottled water has become increasingly popular over the past several years for convenience and safety. In some areas where publicly supplied tap water is contaminated or contains bacteria, this assumption is valid. However, in areas with clean tap water, the presence of bottled water can be controversial because it might be less clean than the local tap. This article discusses the analysis of inorganic contaminants in bottled water, including regulated contaminants and bromate. Detection limit considerations and speed of analysis also are discussed.

One of the promises of array detector inductively coupled plasma (ICP) systems has been the ability to measure all elements in an unknown sample. Sometimes referred to as elemental fingerprinting, this capability can be extremely powerful for quality control (QC) and forensic applications. To take advantage of this capability, the ICP system employed must provide full wavelength coverage as well as the spectral data handling tools needed to do the "fingerprinting." This article will demonstrate some of the elemental fingerprinting capabilities of ICP.

The spectrometric techniques of inductively coupled plasma–optical emission spectrometry (ICP-OES) and inductively coupled plasma–mass spectrometry (ICP-MS) are compared for their applicability to regulatory water analyses, bearing in mind recent method approval changes. ICP-OES is found to be at its limit for confident detection of several elements for drinking water analysis, but is still suitable for many environmental water quality measurements. ICP-MS is the closest there is to a universally applicable technique for water analysis.