Instrumentation atomic emission spectroscopy

Because light emitted from inductively coupled plasma torches is characteristic of the elements present, the torches were originally introduced for instruments that optically measured the frequencies and intensities of the emitted light and used them, rather than ions, to estimate the amounts and types of elements present (inductively coupled plasma atomic emission spectroscopy. 

Instrumental Quantitative Analysis. Methods such as x-ray spectroscopy, oaes, and naa do not necessarily require pretreatment of samples to soluble forms. Only reUable and verified standards are needed. Other instmmental methods that can be used to determine a wide range of chromium concentrations are atomic absorption spectroscopy (aas), flame photometry, icap-aes, and direct current plasma—atomic emission spectroscopy (dcp-aes). These methods caimot distinguish the oxidation states of chromium, and speciation at trace levels usually requires a previous wet-chemical separation. However, the instmmental methods are preferred over (3)-diphenylcarbazide for trace chromium concentrations, because of the difficulty of oxidizing very small quantities of Cr(III). 

The metal content analysis of the samples was effected by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES Varian Liberty II Instrument) after microwaves assisted mineralisation in hydrofluoric/hydrochloric acid mixture. Ultraviolet and visible diffuse reflectance spectroscopy (UV-Vis DRS) was carried out in the 200-900 nm range with a Lambda 40 Perkin Elmer spectrophotometer with a BaS04 reflection sphere. HF was used as a reference. Data processing was carried out with Microcal Origin 7.1 software. 

When the problem has been defined and needed background information has been studied, it is time to consider which analytical methods will provide the data you need to solve the problem. In selecting techniques, you can refer back to the other chapters in this book. For example, if you want to measure the three heavy metals (Co, Fe, and Ni) that were suspect in the Bulging Drum Problem, you might immediately think of atomic absorption or inductively coupled plasma atomic emission spectroscopies and reread Chapter 8 of this book. How would you choose between them Which would be more accurate More precise Does your lab have both instruments Are they both in working order What if you have neither of them What sample preparation would be needed ... 

Measurements of the intensity and wavelength of radiation that is either absorbed or emitted provide the basis for sensitive methods of detection and quantitation. Absorption spectroscopy is most frequently used in the quantitation of molecules but is also an important technique in the quantitation of some atoms. Emission spectroscopy covers several techniques that involve the emission of radiation by either atoms or molecules but vary in the manner in which the emission is induced. Photometry is the measurement of the intensity of radiation and is probably the most commonly used technique in biochemistry. In order to use photometric instruments correctly and to be able to develop and modify spectroscopic techniques it is necessary to understand the principles of the interaction of radiation with matter. 

Atomic emission spectroscopy is one of the oldest instrumental techniques used for chemical analysis. It is used to study the transitions between electronic energy levels in atoms or ions. These energy differences are usually in the visible region (400-700 nm) of the electromagnetic spectrum, but if the energy difference is larger, then the transitions may lie in the ultraviolet region. 

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. 

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. 

Figure 1.2 shows the basic instrumentation necessary for each technique. At this stage, we shall define the component where the atoms are produced and viewed as the atom cell. Much of what follows will explain what we mean by this term. In atomic emission spectroscopy, the atoms are excited in the atom cell also, but for atomic absorption and atomic fluorescence spectroscopy, an external light source is used to excite the ground-state atoms. In atomic absorption spectroscopy, the source is viewed directly and the attenuation of radiation measured. In atomic fluorescence spectroscopy, the source is not viewed directly, but the re-emittance of radiation is measured. 

The inductively coupled plasma13 shown at the beginning of the chapter is twice as hot as a combustion flame (Figure 21-11). The high temperature, stability, and relatively inert Ar environment in the plasma eliminate much of the interference encountered with flames. Simultaneous multielement analysis, described in Section 21 1. is routine for inductively coupled plasma atomic emission spectroscopy, which has replaced flame atomic absorption. The plasma instrument costs more to purchase and operate than a flame instrument. 

X-ray fluorescence, mass spectroscopy, emission spectrography, and ion-conductive plasma—atomic emission spectroscopy (icp—aes) are used in specialized laboratories equipped for handling radioisotopes with these instruments. 

Judging from the degree of apparent interest and the number of papers published in the field of elemental TOF-MS over the last 3-4 years, it appears that this marriage is one full of promise for the future of elemental analysis. Perhaps the primary reason for such a trend is the need for a truly simultaneous mass spectrometer capable of extending capabilities beyond current instrumentation. The fields of ICP and GD atomic emission spectroscopy have been revolutionized by the incorporation of simultaneous array detectors. This revolution is just now beginning in the mass spectrometry field. 

In particular, we demonstrate the usefulness and compatibility of two multi-element methods of analysis instrumental neutron activation analysis (INNA) and inductively coupled plasma-atomic emission spectroscopy (ICP). 

Solution pH was measured with a Ross combination electrode and Orion model 601A pH meter. Specific conductance was measured with a Yellow Springs Instruments model 32 conductance meter and cell. Cations were determined by inductively coupled atomic-emission spectroscopy. Sulfate and chloride were determined by ion chromatography. Bicarbonate was determined by titration with H2SO4 to pH 4.5. 

Inductively coupled plasma (ICP) emission techniques can be used to measure selenium concentrations in air. ICP techniques offer multielement capabilities, but instrumentation is costly and background interference can be a problem (Koirtyohann and Morris 1986). The NIOSH-recommended method for determining selenium in air is inductively coupled argon plasma atomic emission spectroscopy (NIOSH... 

The tests utilized to measure these contaminants and degradation by-products include infrared (IR) spectroscopy, electronic particle counting (PC), Karl Fischer titration (KFT), atomic emission spectroscopy (AES) and X-ray fluorescence (XRF) spectroscopy. These methods are available in the form of off-line or at-line benchtop instruments and online/in-line sensors. Most off-line instruments are automated to provide several hundred analyses per day by a single technician. At-line instruments and sensors permit immediate results and diagnostic capabilities. Online sensors can be integrated into machinery control systems to provide real-time monitoring capability. 

The instrumentation used for atomic emission spectroscopy (AES) consists of an atomization cell, a spectrometer/detector and a read-out device. In its simplest form, flame photometry (FP), the atomization cell consists of a flame (e.g. 

Turning initially to multidetection, and here first to simultaneous usage, an obvious application is to combine the gradient FIA techniques with the use of detectors that provide several signals at several values of the instrumental variables, which indeed gives FIA a doubly dynamic character. In these techniques, which have already been mentioned in Section 2.4, advantage can be taken by multidetectors, such as the fast-scan vol-tammetric detectors [288] or by inductively coupled plasma atomic emission spectroscopy [808] or by diode array detectors [1017, 1075, 1382]. Combined with the advantages offered by chemometrics, these multidetection procedures may in fact be extended to multideterminations. 

The samples collected during the first visit were digested in a mixture of HNO3 and HCIO4 in an aluminium block. The instrumental analysis was performed by inductively coupled plasma atomic emission spectroscopy (ICP/AES), Seiko SPS 1500 VR for Cu, Fe, Mn and Zn at the College of Agriculture, Kyoto University. 

The analytical application of atomic-absorption or atomic-emission spectroscopy generally involves obtaining the sample in an appropriate solution for measurement and calibrating the instrument properly. Commonly used methods for different materials are described below. Frequently, a releasing agent will have to be added, or a solvent extraction will be required to concentrate the element and increase the sensitivity. Standards should be treated in a similar manner. 

Sodium and potassium in serum are determined in the clinical laboratory by atomic-emission spectroscopy, using an instrument designed specifically for this purpose [5]. Two filter monochromators isolate the sodium and potassium emission lines. A lithium internal standard is used, and the ratios of the Na/Li and K/Li signals are read out on two separate meters. The internal standard compensates for minor fluctuations in flame temperature, aspiration rate, and so forth. A cool flame, such as air-propane, is used to minimize ionization. Typically, the serum sample and standards are diluted 1 200 with a 100 ppm Li solution and aspirated directly. The instrument can be adjusted to read directly in meq/1 for sodium and potassium by adjusting the gain while aspirating appropriate standards. 

Inconspicuous instrumental, environmental, or chemical effects often cause a loss of instrument response. In atomic emission spectroscopy, for example, sensitivity is affected by such instrumental factors as flame temperature, aspiration rate, and slit width. In amperometric measurements, diffusion currents vary with temperature, and a significant loss in sensitivity may occur with a drop in sample temperature. In ion-selective electrode measurements, sensitivity may be affected by chemical effects, such as changes in ionic strength or pH. 

Atomic Emission Spectroscopy, Another commonly automated spectroscopic method is atomic emission spectroscopy (flame photometry). Because sample processing is less elaborate—usually only a dilution—atomic emission spectroscopy was the first to be adapted to the modern methods of data read-out and processing. Instruments were available in 1964 that gave simultaneous numerical read-out of the concentrations of Na and K in directly reportable units. 

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