ICP atomization

The extension of inductively coupled plasma (ICP) atomic emission spectrometry to seawater analysis has been slow for two major reasons. The first is that the concentrations of almost all trace metals of interest are 1 xg/l or less, below detection limits attainable with conventional pneumatic nebulisation. The second is that the seawater matrix, with some 3.5% dissolved solids, is not compatible with most of the sample introduction systems used with ICP. Thus direct multielemental trace analysis of seawater by ICP-AES is impractical, at least with pneumatic nebulisation. In view of this, a number of alternative strategies can be considered ... 

ICP is an emission technique, which means that it does not use a light source. The light measured is the light emitted by the atoms and monoatomic ions in the atomizer. The ICP atomizer is an extremely hot plasma, which is a high-temperature ionized gas composed of electrons and positive ions confined by a magnetic held. The extremely high temperature means that the atoms and monoatomic ions undergo sufficient excitation (and de-excitation) such that relatively intense emission spectra result. The sample is drawn in with a vacuum mechanism that will be described. The intensity of an emission line is measured and related to concentration. 

Several methods have been used to determine the number and position of metal atoms affixed to the protein surface. The number of metal atoms is commonly determined by atomic absorption analysis [16] or by inductively coupled plasma (ICP) atomic emission analysis [15]. Under favorable circumstances, the metal ratios in modified derivatives can be determined by UV-vis... 

The amount of polymer adsorbed on each sample was measured by pressure filtration through a 0.1 m filter, followed by analysis of the filtrate for residual polymer by gel permeation chromatography with refractive index determination. Particle zeta potentials were measured by taking a small sample of the solids from the centrifuge and re-suspending them in the supernatant prior to analysis in a Malvern Instruments Zetasizer . The concentration of all other types of ions in the supernatant was analysed by ICP atomic emission spectroscopy. 

Gadolinium may be measured in an acidic solution by flame or furnace atomic absorption or ICP atomic emission spectropbotometry. Also, gadolinium may be identified nondestructively and rapidly by x-ray fluorescence methods. It also may be measured by neutron activation analysis, and by various spectrophotometric techniques. The element shows sharp absorption bands in ultraviolet region at 270-280 nm. Other lanthanides also produce bands in this region however, those are low intensity minor bands. 

Elemental composition H 2.49%, Se 97.51%. The gas may be analyzed by GC using a TCD, FID or a flame photometric detector. The compound may be identified by GC/MS the molecular ions have masses 82 and 80. The compound may be absorbed in water and the solution analyzed for elemental selenium by flame or furnace atomic absorption—or by ICP atomic emission spectrophotometry. 

Iron metal can be analyzed by x-ray spectroscopy, flame- and furnace atomic absorption, and ICP atomic emission spectroscopy at trace concentration levels. Other instrumental techniques include ICP-mass spectrometry for extreme low detection level and neutron activation analysis. 

All sodium compounds impart a golden yellow color to flame. Sodium can be identified spectroscopically by characteristic line spectra. Trace sodium may be measured quantitatively by flame atomic absorption or flame emission photometric method. The element may be measured at 589 nm using an air-acetylene flame. If using an ICP-atomic emission spectrophotometer, sodium may be measured at 589.00 or 589.59nm. Metallic sodium may be analyzed quantitatively by treating with ethanol and measuring the volume of hydrogen liberated. 

A hand-auger drill was used to obtain samples at 30 cm depth intervals down to 5.0 m. At these depths the fly ash is unsaturated in both sites. Porewater samples were extracted from the fly ash samples by centrifugation, following the method of Edmunds Bath (1976) and analysed by inductively coupled plasma spectrometry (ICP), atomic absorption spectrometry (AAS), and ion chromatography. Because the porewaters were obtained by centrifuge extraction, the... 

Discuss in detail the origins and effects of interferences in ICP atomic emission and ICP mass spectrometry, and describe how they may be minimized or eliminated in practice. Explain why some of these interferences are common to both methods. Illustrate your answer with suitable examples where appropriate. 

First the responses Rq are measured for the sample. Thereafter K is determined by fitting the changes in the concentrations of the analytes in the sample, brought about by the standard additions, to the changes in the responses. Once all elements in the calibration matrix, K, have been determined, the concentration vector of the analytes in the sample is calculated. The method has been successfully applied to absorption spectrophotometry , anodic stripping voltametry and ICP-atomic emission spectrophotometry Attractive features of the method are that automation is very easy and automatic drift compensation is possible . A drawback is that all interferents should be known and be corrected for. 

C. Schierle and M. Otto, Comparison of a neural network with multiple linear regression for quantitative analysis in ICP-atomic emission spectroscopy, Fresenius J. Anal. Chem., 344(4-5), 1992, 190-194. 

I venture to say that the majority of practical chemometrics applications in analytical chemistry are in the area of instrument specialization. The need to improve specificity of an analyzer depends on both the analytical technology and the application. For example, chemometrics is often applied to near-infrared (NIR) spectroscopy, due to the fact that the information in NIR spectra is generally non-specific for most applications. Chemometrics may not be critical for most ICP atomic emission or mass spectrometry applications because these techniques provide sufficient selectivity for most applications. On the other hand, there are some NIR applications that do not require chemometrics (e.g. many water analysis applications), and some ICP and mass spectrometry applications are likely where chemometrics is needed to provide sufficient selectivity. 

There is also a standard test method for determination of major and minor elements in coal ash by inductively coupled plasma (ICP)-atomic emission spectrometry (ASTM D-6349). In the test method, the sample to be analyzed is ashed under standard conditions and ignited to constant weight. The ash is fused with a fluxing agent followed by dissolution of the melt in dilute acid solution. Alternatively, the ash is digested in a mixture of hydrofluoric, nitric, and hydrochloric acids. The solution is analyzed by (ICP)-atomic emission spectrometry for the elements. The basis of the method is the measurement of atomic emissions. Aqueous solutions of the samples are nebulized, and a portion of the aerosol that is produced is transported to the plasma torch, where excitation and emission occurs. Characteristic line emission spectra are produced by a radio-frequency inductively coupled plasma. A grating monochromator system is used to separate the emission lines, and the intensities of the lines are monitored by photomultiplier tube or photodiode array detection. The photocurrents from the detector... 

Coal contains several elements whose individual concentrations are generally less than 0.01%. These elements are commonly and collectively referred to as trace elements. These elements occur primarily as part of the mineral matter in coal. Hence, there is another standard test method for determination of major and minor elements in coal ash by ICP-atomic emission spectrometry, inductively coupled plasma mass spectrometry, and graphite furnace atomic absorption spectrometry (ASTM D-6357). The test methods pertain to the determination of antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, molybdenum, nickel, vanadium, and zinc (as well as other trace elements) in coal ash. 

Hoffmann and Lieser [112] used XFS to determine a range of elements in leaves and grass and compared this technique with neutron activation analysis, AAS, ICP-atomic emission spectrometry, polarography and voltammetry. 

Thus, the conductivity of any aqueous sample may be precisely calculated, as we see in the above two examples, if we know the concentrations of the metal ions and the anions in the sample. The presence of such metal ions and the anions and their concentrations may be simultaneously measured by ICP atomic emission spectrophotometer and ion chromatograph, respectively. 

The most important analytical techniques which are used in multielement trace analysis are ICP-MS, atomic absorption spectrometry (AAS) and ICP atomic emission spectrometry (AES). NAA is applied as reference method in order to establish certibed values. The regular atomic spectrometry update on clinical and biological materials, foods and beverages (ASU review) gives an overview of the recent developments in elemental analysis of food and beverages [81]. 

L. Racz, L. Papp, B. Prokai, Zs. Kovacs, Trace element determination in cultivated mushrooms an investigation of manganese, nickel and cadmium intake in cultivated mushrooms using ICP atomic emission, Microchem. J., 54 (1996), 444-451. 

An ICP-MS instrument will not tolerate dissolved solids at concentrations that can be run with an ICP-atomic emission spectrometer. In addition to increasing the probability of interelement (isobaric) interferences and signal suppression, high levels of dissolved solids condense on the sample-cone orifice. This deposition degrades the sensitivity and stability of the analytical signal. Typically, a maximum of 0.1% dissolved solids is recommended for continuous nebulization with a pneumatic... 

Fuishiro, M., Kubota, M. and Ishida, R. (1984) A study of designs of cross flow nebulisers for ICP atomic emission spectrometry, Spectrochimica Acta, Part B, 39, pp617-620. 

CETAC Technologies. Ultrasonic Nebulisation of Liquid Samples for Analytical ICP Atomic Spectroscopy, South Shields CETAC. 

Aziz, A., Broekaert, J.A.C. and Leis, F. (1982) Analysis of microamounts of biological samples by evaporation in a graphite furnace and ICP atomic emission spectroscopy, Spectrochimica Acta, Part B, 37, pp369-379. 

Figure 28-8 Viewing geometries for ICP sources, (a) Radial geometry used in ICP atomic emission spectrometers (b) axial geometry used in ICP mass spectrometers and in several ICP atomic emission spectrometers.

Figure 28-14 Block diagram of a typical ICP atomic emission Sample ...

A block diagram of a typical ICP-MS instrument is shown in Figure 28-20. Ions formed in the plasma are introduced into the mass analyzer, where they are sorted according to mass-to-charge ratio and detected. Solution samples are introduced into the plasma through a nebulizer, as in ICP atomic emission. Solids are either dissolved in solution or introduced directly by laser ablation methods. Gases can be introduced directly. 

Why are monochromators of a higher resolution found in ICP atomic emission spectrometers than in flame atomic absorption spectrometers ... 

Discuss the differences that result in ICP atomic emission and ICP-MS when the plasma is viewed axially rather than radially. 

With an ICP atomic emission spectrometer, for the spectral background intensity at 250 nm a signal of 104 digits is obtained with a 10 V A/D convertor and 12 bit resolution (4096), thus representing a voltage of 0.254 V. When a capacitor with 1.11 x 10 8 F and a measurement time of 10 s are used, this corresponds to a... 

These two-dimensional detectors [63] are ideally suited for coupling with an echelle spectrometer, which is state of the art in modem spectrometers for ICP atomic emission spectrometry as well as for atomic absorption spectrometers. As for CCDs the sensitivity is high and along with the signal-to-noise ratios achievable, they have become real alternatives to photomultipliers for optical atomic spectrometry (Table 3) and will replace them more and more. 

Fig. 38. Experimentally obtained ICP atomic emission spectral scan for a solution containing 10 mg/L Fe and spectral scan obtained by stripping the experimental spectral scan for a solution of 500 mg/L Zr...

Fig. 90. ICP atomic emission spectra for a 10 g/L Zr solution with and without 2 mg/L Fe in the vicinity of the Fe II 234.349 nm (a) and Fe II 239.562 nm (b) lines obtained with the IMAGE approach. (Reprinted with permission from Ref. [342].)...

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