ICP-MS

The analysis of metals using inductively coupled plasma–mass spectrometry (ICP-MS), ICP-atomic emission spectroscopy (ICP-AES), and atomic absorption can serve many purposes in environmental, health, and forensic studies. Yi He, a chemistry professor at John Jay College of Criminal Justice at The City University of New York, has been using these elemental analysis techniques for fingerprinting and provenance of counterfeit cigarettes and as an educational tool. Here, she discusses some of that work.

October’s AP column highlights a team of geochemists at the University of Houston who have been developing methods to streamline multi-element analysis for a more complete fingerprinting of oils by using one sample preparation method utilizing a single reaction chamber microwave digestion system and then analyzing these solutions for major, and minor elements by ICP-OES and low abundance trace elements by triple quadrupole (QQQ) ICP-MS. Results to date using this approach have shown that complete elemental recovery and removal of organic matrices can be achieved safely and that up to 57 elements can be determined in oils with good accuracy and precision. Removal of organic matrices during digestion not only helps to limit the formation of polyatomic spectral interferences, but improves instrument stability and reduces carbon build in the sample introduction and interface regions, which have traditionally plagued “dilute and shoot” methods.

Signal suppression caused by matrix effects has long presented challenges to analysts using inductively coupled plasma–atomic emission spectrometry (ICP-AES) and inductively coupled plasma–mass spectrometry (ICP-MS) techniques. In some cases, however, matrix effects enhance the signal, and thus benefit the analysis. Guillermo Grindlay of the University of Alicante, in Spain, has been studying signal enhancement by charge-transfer reactions resulting from the presence of carbon, sulfur, and phosphorus in the sample matrix. His aim is to better understand under what conditions these matrix effects occur and what mechanisms are involved, to assist analysts in managing interferences and improving the analytical figures of merit in their work. He recently spoke to us about his research.

To get better performance from inductively coupled plasma (ICP)-based methods, it is informative to study the properties of the ICP under different conditions. Annemie Bogaerts and Maryam Aghaei at the University of Antwerp, Belgium, are using computational modeling to examine how various properties of the ICP, such as gas flow path lines and velocity, temperature changes, and ionization effects, are affected by numerous factors, such as the gas flow rates of injector and auxiliary gas, applied power, and even the very presence of an MS sampler. They have also applied their models to study particle transport through the ICP. Using their developed model, it is now possible to predict optimum conditions for specific analyses. Bogaerts and Aghaei spoke to us about this work.

Titanium (Ti) is used in lightweight alloys, catalysts, cutting and grinding tools, and medical implants. Most Ti is refined into the white pigment titanium dioxide (TiO2), used in paint, paper, plastics and food, and in consumer products such as toothpaste and sunscreens. TiO2 is considered inert and safe, but TiO2 nanoparticles are much more reactive and bioavailable, so they may have adverse effects on human health and the environment. There is a need for analytical techniques and methods for accurate, low level analysis of Ti in environmental samples, biological tissues, and other samples. This application is difficult for conventional quadrupole ICP-MS because of the presence of matrix-based spectral interferences on the isotopes of Ti. In this paper, we show how the interferences can be removed using tandem ICP-MS (ICP-MS-MS). This allows sub-ng/L (ppt) detection limits to be achieved, and ensures that accuracy is maintained in the presence of complex sample matrices

Efficient and accurate measurement of mercury concentration is a challenge. A direct sample preparation method for reliable ICP-OES mercury measurement would be invaluable to chemical manufacturers, testing laboratories, and other industries. Historically, ICP-OES Hg measurements have been plagued by poor Hg detection limits, severe carryover effects, and sample instability. In this study, we present a method of sample preparation for ICP-OES mercury analysis in various reagent chemical compounds. This sample preparation method is straightforward and direct, allowing mercury analysis in a variety of reagent chemicals without digestion.

This paper describes the analysis of edible oils radial view ICP-OES. Information is provided regarding the most suitable wavelengths, background correction, and integration times. Results of a detection limit study are presented. The accuracy of the analytical method is validated using soybean, olive, and corn oil matrices.

Matrix effects-changes in analyte sensitivity induced by a high concentration of matrix elements-can reduce accuracy in inductively coupled plasma–mass spectrometry (ICP-MS). It has long been accepted, since the 1987 publication of a study by Tan and Horlick (1), that matrix effects are more severe for light analyte ions in the presence of heavy matrix ions. However, new studies by Shi Jiao and John Olesik in the Trace Element Research Laboratory (TERL) at The Ohio State University (Columbus, Ohio), carried out using current ICP-MS instruments, show that matrix effects are not strongly dependent on analyte ion mass. These study results have implications for understanding the fundamental causes of matrix effects in ICP-MS, and for the choice of internal standards. Jiao and Olesik spoke to Spectroscopy about this work.

Inductively coupled plasma–mass spectrometry (ICP-MS) is a powerful analytical technique. But like any other analytical techniques, there are challenges involved. We recently asked ICP-MS experts what unresolved problems exist-especially with samples in complex matrices-and how ICP-MS methods or technologies can be developed to attack them.

In honor of Spectroscopy's celebration of 30 years covering the latest developments in materials analysis, we asked a panel of experts to assess the current state of the art of inductively coupled plasma–mass spectrometry (ICP-MS) and to try to predict how the technology will develop in the future.

Low-level analysis of food matrices has placed a demand on manufacturers, testing laboratories, and instrumentation vendors worldwide. Stricter regulations, better analytical instrumentation, and greatly improved sample preparation (preanalytical) techniques have focused efforts to simplify and standardize these analyses. Often overlooked, the preanalytical step determines the quality of the resulting data and requires careful attention to a number of details, including sample size, digestion parameters, and the level of detection needed.

Multiple-collector inductively coupled plasma–mass spectrometry (MC-ICP-MS) has some specific advantages over traditional ICP-MS instruments.

A novel approach to handling samples with very high and variable levels of sample matrix is to use aerosol dilution, whereby the amount of sample aerosol that reaches the plasma is reduced by dilution with an additional argon gas stream.

This article compares several performance criteria such as full width at half maximum, background equivalent concentrations, limits of detection, purge requirements, and results for some substances for the "traditional" As lines at 188.979, 193.696, and 197.197 nm for the "new" line at 228.812 nm.

Rare earth elements (REEs) have become indispensable in many electronic, optical, magnetic, and catalytic applications because of their specific properties such as magnetism and phosphorescence, as well as their ability to both donate and accept electrons.

The California Department of Public Health has proposed to establish the first regulatory limit in the United States for hexavalent chromium (chromium-6) in drinking water. The proposed Maximum Contaminant Level (MCL) sets the limit for hexavalent chromium at 10 parts per billion. California, like those of other states and United States federal government, currently only regulates total chromium levels.

A new sodium peroxide fusion method is described, as well as the conditions for inductively coupled plasma–optical emission spectrometry, and a list of the accuracy and precision measurements for all prepared samples.

A critical review of the main developments in instrument technology, calibration, and sample preparation that have made it possible to determine low sulfur concentrations in fuels followed by a discussion of strategies to minimize spectral interferences related to sulfur determination by ICP-MS, such as collision–reaction cells, high-resolution mass analyzers, and the interference standard method.

A look at ICP–MS, ICP–OES, X-ray fluorescence spectroscopy, and laser-induced breakdown spectroscopy in the areas of research and development, marketing, application, and use of these techniques.

Conventional pneumatic nebulizer-spray chamber combinations for ICP spectrometry have a sample introduction efficiency of only 1-3%. A unique electrothermal vaporization device developed by Vassili Karanassios of the University of Waterloo uses field-portable rhenium filament coils with a very small vaporization chamber and increases the sample introduction efficiency to 100%.

The authors have been characterizing an electrothermal, near-torch vaporization (NTV) micro- and nano-sample introduction system for inductively coupled plasma (ICP) spectrometry.

Triple-quadrupole inductively coupled plasma–mass spectrometry (ICP-MS) can operate in MS-MS mode, which offers the potential to improve the removal of spectral interferences compared to conventional quadrupole ICP-MS with a collision–reaction cell, or high-resolution ICP-MS.

Spectroscopy recently spoke with Frank A. Kero, an analytical applications specialist with Biotage, about his research with ICP-MS.

This article highlights the benefits of using ion-molecule chemistry in a quadrupole-based collision–reaction cell to determine titanium levels in the presence of problematic polyatomic spectral interferences encountered in the analysis of human blood and serum samples from patients who have undergone artificial joint replacement surgery.