Cadmium curves

Figure 6.13. (a) Apparatus Tor stripping analysis, (b) Curve A Current-voltage curve for anodic stripping of cadmium. Curve B Residual current curve for blank. Reprinted with permission and adapted from R. D. DeMars and 1. Shairf, Anal. Chem. 29,182S (1957). Copyright by the American Chemical Society... 

Fig. IV-21. Surface pressure versus area for monolayers of immiscible components a monolayer of pure cadmium arachidate (curve 1) and monolayers of mixed merocyanine dye, MC2, and cadmium arachidate of molar ratio r = 1 10 (curve 2) 1 5 (curve 3), 1 2 (curve 4), and pure MC2 (curve 5). The subphase is 2.5 x 0 M CdC, pH = 5.5 at 20°C. Curve 3a (O) was calculated from curves 1 and 5 using Eq. IV-44. (From Ref. [116].)...

Provide an SOP for the determination of cadmium in lake sediments by atomic absorption spectrophotometry using a normal calibration curve. 

A typical conventional polarogram for 0.003 M-cadmium sulphate in 1M potassium chloride in the presence of 0.001 per cent gelatin, and the corresponding derivative curve, are shown in Fig. 16.7 (/max is the maximum current recorded in the derivative mode). 

Determine the half-wave potential from the current-voltage curve as described in Section 16.6 the value in 1M potassium chloride should be about — 0.60 vs S.C.E. Measure the maximum height of the diffusion wave after correction has been made for the residual current this is the diffusion current Id, and is proportional to the total concentration of cadmium ions in the solution. 

FIGURE 3-7 Normal-pulse (curve A) and differential-pulse (curve B) polarograms for a mixture of 1 mg L-1 cadmium and lead ions. The electrolyte is 0.1 M HNOj. 

Cadmium crystallizes in the hep system. Its electronic structure is 5s24p2 and the melting point is 594 K. The first attempt to determine Ev=o of (0001) and (1010) Cd faces by C, curves was made by Abdullin... 

Fig. 15-11 Effects of strong complexation on metal ion toxicity, (a) Increasing concentration of NTA, a strong multi-dentate complexing agent, decreases the toxicity of Cd to grass shrimp. All systems have equal concentrations of total Cd. (b) When the results are replotted showing survival as a function of Cd concentration, the data for all concentrations of NTA collapse to a single curve. (Reprinted with permission from W. G. Sunda et al. (1978). Effect of chemical speciation on toxicity of cadmium to grass shrimp, Palaemonetes pugio importance of free cadmium ions. Environ. Sci. Technol. 12,409-413, American Chemical Society.)...

Using this equation, the flow of the reaction was followed by registering the frequency shift as a function of reaction time. Typical dependencies are shown in Figure 38 (Facci et al. 1994). As one can see, the curves tend to come to saturation (saturation time depends on film thickness). On the other hand, the plateau level in all cases corresponds well to the value resulting from simple calculation of the number of cadmium atoms available for the reaction in each sample. Numerical data of such estimates are presented in Table 8. The available amount of cadmium atoms was estimated in this case, taking into ac-... 

Calibration of the quartz oscillators was performed by consequent deposition of the cadmium arachidate layers (Facci et al. 1993). The dependence of the frequency shift on the number of deposited bilayers is shown in Figure 46. The analysis of the curve reveals a sensitivity of 1.482 pg/mm Hz for our transducer. 

Figure 1.4 shows a typical curve demonstrating the dependence of concentrations of copper, lead, and cadmium in the filtrate on the volume of seawater sampled. Metal levels become constant after 1-1.51 of sample have been filtered, and it can be concluded that at this point, contamination of the sample by the filtration equipment is negligible. 

Pruszkowska et al. [135] described a simple and direct method for the determination of cadmium in coastal water utilizing a platform graphite furnace and Zeeman background correction. The furnace conditions are summarised in Table 5.1. These workers obtained a detection limit of 0.013 pg/1 in 12 pi samples, or about 0.16 pg cadmium in the coastal seawater sample. The characteristic integrated amount was 0.35 pg cadmium per 0.0044 A s. A matrix modifier containing di-ammonium hydrogen phosphate and nitric acid was used. Concentrations of cadmium in coastal seawater were calculated directly from a calibration curve. Standards contained sodium chloride and the same matrix modifier as the samples. No interference from the matrix was observed. 

Electrothermal atomic absorption spectrophotometry with Zeeman background correction was used by Zhang et al. [141] for the determination of cadmium in seawater. Citric acid was used as an organic matrix modifier and was found to be more effective than EDTA or ascorbic acid. The organic matrix modifier reduced the interferences from salts and other trace metals and gave a linear calibration curve for cadmium at concentrations < 1.6 pg/1. The method has a limit of detection of 0.019 pg/1 of cadmium and recoveries of 95-105% at the 0.2 pg of cadmium level. 

Stein et al. [673] have described a simplified, sensitive, and rapid method for determining low concentrations of cadmium, lead, and chromium in estuarine waters. To minimise matrix interferences, nitric acid and ammonium nitrate are added for cadmium and lead only nitric acid is added for chromium. Then 10,20, or 50 pi of the sample or standard (the amount depending on the sensitivity required) is injected into a heated graphite atomiser, and specific atomic absorbance is measured. Analyte concentrations are calculated from calibration curves for standard solutions in demineralised water for chromium, or an artificial seawater medium for lead and cadmium. 

Figure 5.23 shows typical stripping curves for cadmium, lead, and zinc obtained from a 25 ml seawater sample. The sample was analysed as previously described. The concentrations found were 7.1 pg/1 (Pb11), 0.2 ig/l (Cn), and 4.1 xg/l(Znn). 

Figure 4. Recompression effects on PhDA2-8 jc-A curves over a subphase containing both cadmium chloride and potassium bicarbonate. The subphase temperature 5.0°C and the compression rate was 7.5 (A2/molecule)/min. For recompiession the blade was stopped at each of the following the surface pressures ...

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