On-line standard additions with direct injection nebulization for inductively coupled plasma mass spectrometry

Multiple-channel Concentric Grid Nebulizer for Online Standard Addition in Inductively Coupled Plasma Optical Emission Spectrometry

A multiple channel-type concentric grid nebulizer (m-CGrid) was developed for realizing efficient online standard addition in inductively coupled plasma optical emission spectrometry (ICP-OES) without premixing of liquids before nebulization. The m-CGrid can nebulize two independent liquids without premixing due to a unique structure, having two independent liquid-flow capillaries inside a single nozzle and a grid screen (over 350 mesh per inch) placed on the hole of the nozzle. The grid acts as both a flow damper and sieve; two liquids are well-mixed with a gas flow in a small space just before the grid screen, and the mixture breaks up into small droplets by passing through the grid. The m-CGrid nebulizer provides almost the same or better spray performance compared with a conventional nebulizer, such as Meinhard nebulizer; the primary aerosols were much finer (D50: 2.9 and 3.1 μm for two channels) than those generated with Meinhard nebulizer type C (D50: 19.5 μm). The signal intensities in ICP-OES obtained with two liquid channels were almost the same and were 2- to 3-fold higher than that obtained with the Meinhard nebulizer for 23 elements. The performance of m-CGrid in an online standard addition was demonstrated in the analysis of NIST SRM1577b bovine liver and NIES No. 3 Chrorella. The analytical results were in good agreement with their certified values.

Matrix effects in inductively coupled plasma mass spectrometry: a review

Fundamental research on non-spectroscopic interferences, also known as matrix effects, in inductively coupled plasma (ICP) mass spectrometry with sample introduction using nebulization is critically and exclusively examined in this review, starting with fundamental processes that may be a source of matrix effects during sample introduction, ion generation in the ICP, ion extraction through the interface, and ion transport through the ion optics to the detector. Various methods for attenuating matrix effects are then reviewed and illustrated with some examples. Instead of exhaustively reviewing the literature, representative references are used to comprehensively describe the main issues, several of which are also common to ICP optical emission spectrometry.

A new continuous calibration method for inductively coupled plasma spectrometry

A new calibration method was developed and applied to inductively coupled plasma atomic emission spectrometry. External calibration was performed as follows. A container was filled with a given volume of deionized (V(p)) water. Then a concentrated standard was introduced at a controlled rate (Q(e)) into the tank by means of a peristaltic pump. The resulting solution was stirred throughout the experiment. Simultaneously, the solution inside the tank was pumped from the vessel to the plasma at a given rate (Q(s)). The signal was continuously recorded. The variation of the concentration of the solution leaving the tank with time was determined by applying a basic equation of stirred tanks. The representation of the emission intensity versus the time and the further conversion of the time scale into a concentration scale gave rise to the calibration line. The best results in terms of linearity were achieved for V(p)=15 cm3, Q(e)=0.6-0.75 ml min(-1) and Q(s)=1-1.2 ml min(-1). Graphs with more than 40 standards were obtained within about 10 min. The results found were not statistically different from those afforded by the conventional calibration method. In addition, the new method was faster and supplied better linearity and precision than the conventional one. Another advantage of the stirred tank was that procedures such as dynamic calibration and standard additions could be easily and quickly applied, thus shortening the analysis time. A complete analysis following these procedures based on the measurement of 30 standards took about 5 min. Several synthetic as well as certified samples (i.e., bovine liver, mussel tissue and powdered milk) were analyzed with the stirred tank by applying four different calibration methodologies (i.e., external calibration, internal calibration, standard additions and a combination of internal standardization and standard additions), with the combination of internal standardization and standard additions being the method that provided the best results. The element concentrations obtained were not significantly different from the actual or certified values.

Capillary electrophoresis-inductively coupled plasma-mass spectrometry: an attractive complementary technique for elemental speciation analysis

Some basic and practical aspects of interfacing capillary electrophoresis to inductively coupled plasma-mass spectrometry (CE-ICP-MS) are reviewed in this article with emphasis on the use of this hyphenated technique for elemental speciation analysis. The principles behind the techniques of both CE and ICP-MS are introduced. The interfacing of CE to ICP-MS is discussed including several devices and nebulizers reported in literature. A brief account of their advantages and limitations is given. The various CE-ICP-MS applications for elemental speciation analysis are also reviewed. Some issues concerning the future of CE-ICP-MS for the elemental speciation analyses are discussed.

Elements in environmental and occupational medicine

Occupational and environmental medicine traditionally dealt with elements, particularly with heavy metals. The interest was justified by the wide exposure in the workplace and in the general environment and by the evidence of their specific biological and toxicological effects. During the last 2 decades of 20th century the availability of indicators of exposure or of internal dose has substantially increased thanks to improvement in AAS-ETAAS techniques and to the entrance of ICP-MS into the field of biological monitoring. There are now more and more demands for controlling pre-analytical and analytical factors, for analysing biological matrices in addition to blood and urine and for setting up methods for elements not yet extensively studied in respect to their possible biological or toxicological role. Finally, deeper knowledge has to be reached in order to evaluate the significance of elements and, possibly, of their species in biological fluids at current doses and in order to face their effects, especially those in the first portion of the dose-response curve, which is going to be the main field of interest of occupational and environmental toxicology for the next few years.

The development of iodine based impinger solutions for the efficient capture of Hg0 using direct injection nebulization-inductively coupled plasma mass spectrometry analysis

Inductively coupled plasma mass spectrometry (ICP/MS) with direct injection nebulization (DIN) was used to evaluate novel impinger solution compositions capable of capturing elemental mercury (Hg0) in EPA Method 5 type sampling. An iodine based impinger solution proved to be very efficient for Hg0 capture and was amenable to direct analysis by DIN-ICP/MS. Hg0 capture efficiency using aqueous iodine (I3-) was comparable to Hg0 capture using acidified potassium permanganate impinger solutions which were analyzed by cold vapor atomic absorption spectrometry (CVAAS), with greater than 98% capture of Hg0 in the first oxidizing impinger. Using DIN-ICP/MS, it was demonstrated for the first time that iodine can be generated just prior to impinger sampling for efficiently oxidizing Hg0 and retaining it in solution as HgI4(2-). Due to the increased interest in Hg speciation from combustion sources and the potential for using DIN-ICP/MS for multiple metals analyses, an impinger sampling train for gaseous Hg speciation and multiple metals analyses using DIN-ICP/MS analyses is presented. The unique feature of such a sampling train is that each impinger solution in the series is amenable to direct analysis by DIN-ICP/MS. A bituminous coal was combusted in a bench scale coal system, and gaseous Hg species (oxidized and elemental) were determined using the proposed impinger train. The DIN-ICP/MS instrumental detection limit was 0.003 ppb, and MDLs ranged from 0.007 to 0.116 microg/L (ppb) in a variety of impinger solutions used for Hg capture.