Element analyzer

AT the path length, and P (A) the mass absorption coefficient at wavelength A. Between absorption edges, P (A) is proportional to Z A and is nearly independent of physical or chemical state. An absorption measurement on each side of an absorption edge is required for each element analyzed. X-ray absorption is especially useful in determining heavy elements in mixed materials of lower Z, such as lead in gasoline and uranium in aqueous solution. 

The evaluation of metrological characteristics of the technique, perfonued with minerals of different composition, showed that technique developed for reliability and precision satisfies the requirements offered for quantitative determinations, category II. The detection limits are acceptable for solving the problems posed and amount to 0.1 - 0.4 wt. %, depending on the element analyzed. 

All the ealeulations for every analytieal line use its own AC-10 virtual unified sample material eontaining 10% of ehemieal element analyzed. In praetiee, instead of AC-10 speeimen, one ean use eertified sample material named Benehmark Referenee Material (BRM). One must know eomplete ehemieal eontent of BRM. Having measured analytieal line intensity of the speeimen, one ean determine the intensity from AC-10 by eorreetion system. Anyone eertified sample material ean be used as BRM for a few elements. Quantitative eomposition of BRM does not depend on the range of varying ehemieal elements eontent in samples analyzed substantially faeilitating a seleetion and ehange of these BRM. 

Nuclear Data for Elements Analyzed by Neutron Activation . ... 

C and 5 N values were determined by mass spectrometry (MM 903, VG Isogas), equipped with a CN elemental analyzer (Roboprep CN, Europa Scientific). As control for sample purity, C N ratios from the elemental analyser were compared with C N ratios as calculated from the amino acid profile of the same sample. 

The elemental analysis of a compound is usually determined by a laboratory that specializes in this technique. A chemist who has prepared a new compound sends a sample to the laboratory for analysis. The laboratory charges a fee that depends on the type and number of elements analyzed. The results are returned to the chemist as a listing of mass percent composition. The chemist must then figure out which chemical formula matches this composition. If a chemist has reason to expect a particular chemical formula, the observed percentages can be matched against the calculated percentages for the expected formula. This process is illustrated in Example 3-13. 

Elemental analysis of the oils was carried out as follows carbon and hydrogen by micro combustion using a Perkin-Elmer 240 Elemental Analyzer sulphur by X-ray fluorescence using a Telsec Lab X-100 apparatus nitrogen by chemiluminescence using a Dohrmann DN-10 apparatus. 

Multi-Element Analytical Scheme The 76 elements analyzed include 39 elements originally analyzed in the RGNR Projects, and 37 new elements. The analytical scheme is based largely on ICPMS, ICPAES and XRF, supplemented with other techniques (Table 1). The lower levels of detection of all elements are less than their crustal abundances (Table 2). 

The data listed in Table 1 factually reflect abundances of chemical elements in various kinds of geological media of rocks, soils, sediments and in the continental crust of China, because the samples have a good representativity for various media and elements analyzed by high-quality analytical methods under strict quality... 

CF-IRMS provides reliable data on micromoles or even nanomoles of sample without the need for cryogenic concentration because more of the sample enters the ion source than in DI-IRMS. CF-IRMS instruments accept solid, liquid, or gaseous samples such as leaves, soil, algae, or soil gas, and process 100-125 samples per day. Automated sample preparation and analysis takes 3-10 min per sample. The performance of CF-IRMS systems is largely determined by the sample preparation technology. A variety of inlet and preparation systems is available, including GC combustion (GC/C), elemental analyzer, trace gas pre-concentrator and other. The novel... 

Sample blanks are prepared using exactly the same methodology as the samples, but they do not contain any sample. However, they will have the same amounts of reagents and internal standard, and therefore can be used to determine the levels of introduced contamination. Repeated analyses of the sample blank (typically ten) are used to calculate the limits of detection for each element analyzed (see below). 

The detection limits for elements analyzed by ICP-mass spectrometry (ICP-MS) are significantly lower in most cases than the detection limits for other atomic techniques. See Table 10.1. See Workplace Scene 10.3. 

Many hollow cathode lamps are needed because each element, since it must be contained in the cathode, requires a different lamp. Some lamps, however, are multielement. The element analyzed must be contained in the cathode so that its line spectrum will be generated and absorbed by the same in the flame. 

Elemental Analyzer CHN-O-Rapid. Operating Instructions, W. C. Heraeus GmbH, Hanau, Germany, 1986. 

In the method, a weighed portion of a sample of coke dried at 110°C (230°F) and crushed to pass a No. 200-mesh sieve, mixed with stearic acid, and then milled and compressed into a smooth pellet. The pellet is irradiated with an x-ray beam and the characteristic x-rays of the elements analyzed are excited, separated, and detected by the spectrometer. The measured x-ray intensities are converted to elemental concentration by using a cahbration equation derived from the analysis of the standard materials. The K spectral lines are used for aU the elements determined by this test method. This test method is also apphcable to the determination of additional elements provided that appropriate standards are available for use and comparison. 

In the other study. X-ray fluorescence spectroscopy was used to analyze trace element concentrations by observing dusts on 37 ram diameter cellulose acetate filters (20). Twenty-three elutriator and twenty-three area samples from 10 different bales of cotton were analyzed. The average fraction of total dust accounted for by the elements analyzed was 14.4% amd 7.6% for vertical elutriator and area samples, respectively. Although the variation in absolute quantity of atn element was high, the relative abundance of an element was consistent for measurements within a bale. Averaged over all the samples analyzed, calcium was the most abundant element detected (3.6%), followed by silicon (2.9%), potassium (2.7%), iron (1.1%), aluminum (1.1%), sulfur (1.0%), chlorine (0.8%) and phosphorous (0.6%). Other elements detected in smaller aunounts included titanium, manganese, nickel, copper, zinc, bromine, rubidium, strontium, barium, mercury amd lead. 

The classical off-line procedures for sample preparations are time consuming and analytical precision depends on the skill of the investigator. With on-line techniques, using a combination of an elemental analyzer directly coupled to the mass spectrometer many problems of the off-hne preparation can be overcome and minimized. Differences in both techniques are summarized in Table 1.5. 

The development of this technique has proceeded along several independent paths with two principal lines being elemental analyzer-IRMS and capillary gas chromatography-IRMS. In elemental analyzers, samples are combusted to CO2, N2, SO2, and H2O, which are either chemically trapped or separated on GC columns. The advantages of these techniques are an automated preparation with low costs per sample and a large sample through-put. 

Commercial combustion elemental analyzers perform a flash combustion, converting samples to CO2, H2O, N2, and SO2 simultaneously. These different gases are then chemically trapped, converted, or separated on GC columns and measured in a continuous flow mass spectrometer. This technique allows the determination... 

For the extraction of sulfates and total sulfur a suitable acid and reducing agent, such as tin(II)-phosphoric acid (the Kiba solution of Sasaki et al. 1979) is needed. The direct thermal reduction of sulfate to SO2 has been described by Holt and Engelkemeier (1970) and Coleman and Moore (1978). Ueda and Sakai (1984) described a method in which sulfate and sulfide disseminated in rocks are converted to SO2 and H2S simultaneously, but analyzed separately. With the introduction of on-line combustion methods (Giesemann et al. 1994), multistep off-line preparations can be reduced to one single preparation step, namely the combustion in an elemental analyzer. Sample preparations have become less dependent on possibly fractionating wet-chemical extraction steps and less time-consuming. 

Giesemann A, Jager HA, Norman AL, Krouse HR, Brand WA (1994) On-line sulphur isotope determination using an elemental analyzer coupled to a mass spectrometer. Anal Chem 66 2816-2819... 

This metho dology was previously successfully used for express on-line analyses of phosphate ores. The commercial TRACER 2100 Laser Element Analyzer, a laser-induced breakdown spectroscopy instrument, was utilized for rapid analyses of phosphate ores at the mine site (Rosenwasser et al. 2001). Excellent calibrations were achieved for P and Mg with correlation coefficients significantly above 0.98. The instrument demonstrated strong potential of the LIBS for use in on-site, real-time or grading. LIBS apparatus was developed for ap-... 

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