Chromium simultaneous analysis

However, an independent analysis of workroom levels of chromium in the three chromate production factories in the United Kingdom performed around 1950 indicated average levels for various phases in the process ranging from 0.0006 to 2.14 mg chromium(III)/m3 and from 0.002 to 0.88 mg chromium(VI)/m3 (Buckell and Harvey 1951). The importance of further follow-up of the cohort to confirm that the risk has declined with improvements in the working environment, of simultaneous analysis of such factors as age, duration of employment, and time since first exposure, and of examining smoking habits was emphasized (Davies et al. 1991). 

Conductivity detection performed with a contactless conductivity detector through the packed bed was shown to be a more versatile and sensitive method than indirect UV detection [77]. Chen et al. employed inductively couple plasma mass spectrometry (ICP MS) as a detection tool for the simultaneous analysis of various ionic species of arsenic, chromium, and selenium [79]. The separation was achieved on an OT CEC column prepared by bonding a macrocyclic polyamine medium on the walls of the capillary. 

The simultaneous analysis of aluminum and chromium from water was effected by heating samples with trifluoroacetylacetone in benzene at 55—60° for 20—25 minutes and shaking the organic layer with dilute sodium hydroxide High sensitivities were reached for both elements (Fig. 1.2). 

The method described by Heberling works very well with standards, but difficulties were reported with precolumn derivatization of chromium(lll) in real-world samples from the electroplating industry. While this method does not appear to be suited for the simultaneous analysis of chromium(III) and chromium(Vl), it is unmatched for trace analysis of chromium(VI) in pure chromium(lll) utilizing postcolumn derivatization with 1,5-DPC (no precolumn derivatization with PDCA). Based on an injection volume of 50 pL, it is possible to determine 20 pg/L chromium (VI) without any problem. Eluent pH should be kept neutral to ensure that all chromium(VI) exists in the chromate form. 

Figure 10.161 Simultaneous analysis of chro-mium(lll) and chromium(VI). Separator column lonPac AS7 eluent 40mmol/L MgSO -1-30 mmol/L HCIO4 flow rate 0.5 mL/ min detection photometry at 365 nm after postchromatographic oxidation of chromium...

The best ion chromatographic method for the simultaneous analysis of chro-mium(III) and chromium(VI) at present is based - according to Somerset [37] — on the ion-exchange separation of both species with post-chromatographic oxidation of chromium(III) to chromium(VI), which can then be detected photometrically at 365 nm. The oxidation is carried out with potassium peroxodisul-fate, using silver nitrate as a catalyst. Complete conversion is achieved within a short time by raising the reaction temperature to 80 °C. 

The analysis of vanadium steels is effected by the application of one of the foregoing methods. Blank determinations on a steel free from vanadium but otherwise of the same approximate composition are used as a control. Iron and molybdenum are removed from hydrochloric acid solution by Kothe s ether separation method 1 chromium, nickel, copper, etc., are then precipitated as hydroxides by caustic soda, the filtrate containing the vanadium as vanadate.2 The method is modified for the simultaneous estimation of both vanadium and chromium in a vanadium-chromium steel.3... 

The analysis of the five sampling points, each of which is occupied with four objects, demonstrates the very small differences in pollutant loading perpendicular to the direction of flow of the river (Fig. 8-4). Consideration of the optimum separation set, sulfate, ammonium, and chromium, results in a multivariate scaled separation measure of only 15.9. A significant difference in the simultaneous comparison exists for sampling points 2 and 5 only. 

This chapter discusses the advantages and limitations of the multielement analysis of biologically related samples using induction-coupled plasma optical emission. The sample categories covered include grains, feeds, fish, bovine liver, orchard leaves, and human kidney stones. These materials have been simultaneously analyzed for copper, nickel, vanadium, chromium, phosphorus, cobalt, lead, potassium, zinc, manganese, iron, strontium, sodium, aluminum, calcium, magnesium, silicon, boron, and beryllium, often with limited amounts of sample. 

An article entitled "Metallurgical Analysis might be expected to be broad in treatment, but actually it was a description of a method for the simultaneous specti ophotometric determination of chromium and manganese in steel. The reader will be left to guess what was included in two articles, one entitled "Chemical Affinity and the other "Experimental Results for Some Molecules. ... 

In sulfuric acid chromium baths, ion chromatography allows the simultaneous determination of the two main components sulfate and chromate, even if they are usually present in very different concentrations. This is illustrated in Fig. 8-33. In the analysis... 

A77. Nadkarni, R.A. and B.C. Haidar Simultaneous determination of chromium and zinc by neutron activation analysis Radiochem. Radioanal. Lett. 9 (1971) 233-240. 20A95. 

Figure 4.67. Manifolds designed for speciation analysis of Cr(VI) and Cr(III) by reversed FI A, both species being determined spectrophotometrically by a single detector, (a) Asynchronous merging zones mode for simultaneous determination of both species, (b) Sequential method for this speciation by use of a selecting valve for determination of Cr(VI) (channel 1) or overall chromium (channel 2). (From Ref. 968, by permission of Springer Verlag.)...

Ortiz, I., Galan, B., and Irabien, A. 1996. Kinetic analysis of the simultaneous nondispersive extraction and back-extraction of chromium(VI). Ind. Eng. Chem. Res. 35 1369-1377. 

FIGURE 1,6 Example of manifolds developed for flow injection speciation analysis, (a) Manifold of the reversed FIA system for speciation of chromium with pH measurements and spectrophotometric detection, q—peristaltic pumps, V—injection valves, L— reaction coil, M.E.—pH glass electrode. (Adapted from Ruz, J. et al. 1986. J. Autom. Ghent. 8 70-74.) (b) Manifold of branched FIA system for simultaneous biamperomet-ric determination of nitrate and nitrite. (Cd)Cu—reductive column with copperized cadmium, L—mixing coils. (Adapted from Trojanowicz, M., W. Matuszewski, and B. Szostek. 1992. Anal. Chim. Acta 261 391-398.) (c) Example signal recordings obtained in the FIA system shown in (b) 1-6—standard solutions, A-I—natural water samples. Concentration in standard solutions 1—0.075 2—0.050 3—0.025 mM nitrate and 4—7.5 5—5.0 6—2.5 pM nitrite. 

The instrumental conditions for the speciation analysis are shown in Table 18.3, and a plot of signal intensity versus time of the simultaneous separation of a 1 pg/L standard of arsenic, chromium, and selenium is shown in Figure 18.7. 

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