Versus atomic absorption

It is an advantage of electroanalysis and its apparatus that the financial investment is low in comparison, for instance, with the more instrumental spectrometric methods real disadvantages are the need to have the analyte in solution and to be familiar with the various techniques and their electrochemistry it is to be regretted that the knowledge of chemistry and the skill needed often deter workers from applying electroanalysis when this offers possibilies competitive with more instrumental methods (cf., stripping voltammetry versus atomic absorption spectrometry). 

Arsine itself and methyl arsines have different responses in colorimetric versus atomic absorption methods of analysis. The colorimetric AgDDC method is much more respon-... 

Benier, P. M., and Howell, J. (1994).Tutorial review. Advanced electroanalytical techniques versus atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry in environmental analysis. Hnii/yst (London) 119(2), 219. 

There are available also several kits for the assay of calcium, in 10 or 20 microliter samples by chelate formation colorimetrically or fluorimetrically. (Pierce Chem. Co., Rockford, 111.). These are read either with the spectrophotometer or by spectrofluorometry. In our experience, while these systems can be used for approximate results, the plot of concentration versus reading curves are rather flat and only an approximation of the values can be obtained. This may be very important late at night or at times when the atomic absorption machine is down, but if the atomic absorption instrument is available it should be used in preference to these procedures. 

A hanging mercury drop electrodeposition technique has been used [297] for a carbon filament flameless atomic absorption spectrometric method for the determination of copper in seawater. In this method, copper is transferred to the mercury drop in a simple three-electrode cell (including a counterelectrode) by electrolysis for 30 min at -0.35 V versus the SCE. After electrolysis, the drop is rinsed and transferred directly to a prepositioned water-cooled carbon-filament atomiser, and the mercury is volatilised by heating the filament to 425 °C. Copper is then atomised and determined by atomic absorption. The detection limit is 0.2 pg copper per litre simulated seawater. 

In analytical spectrometry there are many types of calibration curves which are set up by measuring spectrometric reference solutions. The measurements yield a curve of absorbance versus concentration, and the points between the data of the reference solutions are interpolated by fitting a suitable curve, which normally follows the Beer-Lambert law and which gives rise to a straight line through the origin of the coordinate system. The measurement conditions and the results of the calibration curve evaluations in the case of chromium and lead measurements by electrothermal atomic absorption spectrometry are presented in Table 1. 

Procedure Concomitantly determine the absorbance of each Standard Preparation and of the Sample Preparation at 422.7 nm, with a suitable atomic absorption spectrophotometer, following the operating parameters as recommended by the manufacturer of the instrument. Plot the absorbance of the Standard Preparations versus concentration of calcium, in micrograms per milliliter, and from the curve so obtained determine the concentration, C, in micrograms per milliliter, of calcium in the Sample Preparation. Calculate the quantity, in milligrams, of calcium in the sample taken by the formula... 

Procedure Concomitantly determine the absorbance values of the Test Solutions at the potassium emission line at 766.7 nm with a suitable atomic absorption spectrophotometer equipped with an air-acetylene flame, using water as the blank. Plot the absorbance values of the Test Solutions versus their contents of potassium, in micrograms per milliliter draw the straight line best fitting the three points and extrapolate the line until it intersects with the concentration axis. From the intercept, determine the amount, in micrograms, of potassium in each milliliter of Test Solution A. Calculate the percent potassium in the portion of sample taken by multiplying the concentration, in micrograms per milliliter, of potassium found in Test Solution A by 0.2. 

Procedure Concomitantly determine the absorbance values of the Test Solutions at the sodium emission line at 589.0 nm with a suitable atomic absorption spectrophotometer equipped with an air-acetylene flame, using water as the blank. Plot the absorbance values of the Test Solutions versus... 

Procedure Use a suitable atomic absorption spectrophotometer equipped with a sodium hollow-cathode lamp and an oxidizing air-acetylene flame. After using the Blank Solution to zero the instrument, concomitantly determine the absorbances of the Standard Solutions and the Test Solution at the sodium emission line of 589 nm. Plot the absorbances of the Standard Solutions versus concentration, in micrograms per milliliter, of sodium, and draw the straight line that best fits the plotted points. From the graph so obtained, determine the concentration, C, in micrograms per milliliter, of sodium in the Test Solution. Calculate the percentage of sodium in the portion of potassium lactate taken by the formula... 

Set a suitable atomic absorption spectrophotometer to a wavelength of 309.3 nm. Adjust the instmment to zero absorbance against water. Prepare and read the absorbance of four aqueous solutions containing 5, 10, 20, and 50 xg/mL of aluminum, in the form of the chloride, and plot the standard curve as absorbance versus concentration of aluminum. 

The display of signal versus time curves in real time is very important for the development of analytical procedures. In atomic absorption spectrometry with electrothermal atomization this is now indispensable and is an integral part of the development of an analytical procedure to be applied for a given analytical task. It is of further importance during the optimization of the plasma working parameters in ICP-AES and is certainly very useful for the optimization of the spectrometer with respect to drift and as a result of changes in any of the working parameters. 

Atomic absorption spectrophotometry is identical in principle to absorption spectrophotometry described in the previous chapter. The absorption follows Beer s law. That is, the absorbance is directly proportional to the pathlength in the flame and to the concentration of atomic vapor in the flame. Both of these variables are difficult to determine, but the pathlength can be held constant and the concentration of atomic vapor is directly proportional to the concentration of the analyte in the solution being aspirated. The procedure used is to prepare a calibration curve of concentration in the solution versus absorbance. 

Determination of Lead in Drinking Water Using Graphite Furnace Atomic Absorption Spectroscopy (GFAA) External Standard Versus Internal Standard Caubration Mode... 

FIGURE 9-16. Concentration of manganese in g/ml versus peak height in mm. [From W. G. Schrenk, in Flame Emission and Atomic Absorption Spectroscopy, Vol. 2, Edited by J. A. Dean and T. C. Rains, Marcel Dekker, New York (1971), Chapter 12. Used by permission of Marcel Dekker Inc.]... 

De Schrijver, I., Aramendia, M., Resano, M., Dumoulin, A., Vanhaecke, F (2008) Novel strategies for rapid trace element analysis of polyamide by graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry. Dissolution in an organic solvent versus direct solid sampling approaches. /. Anal. At. Spectrom., 23, 500-507. 

The assessment of the concentration of labile iron in parkinsonian and control SN was made by atomic absorption after eliminating all molecules that could be bound to large molecules, such as ferritin, and thus were bigger than 10 kDa. The concentration of the labile iron in PD SN was found to be significantly higher than in controi (I35 lOngg versus 76 5 ngg wet tissue) [30]. It is important to emphasize that these iron concentrations are about 2000 times smaller than the total iron concentration and could not be detected by Mossbauer spectroscopy. 

As in other more mature trace element techniques such as atomic absorption (AA) and inductively coupled plasma optical emission spectrometry (ICP-OES), quantitative analysis in ICP-MS is the fundamental tool used to determine analyte concentrations in unknown samples. In this mode of operation, the instrument is calibrated by measuring the intensity for all elements of interest in a number of known calibration standards that represent a range of concentrations likely to be encountered in your unknown samples. When the full range of calibration standards and blank have been run, the software creates a calibration curve of the measured intensity versus concentration for each element in the standard solutions. Once calibration data are acquired, the unknown samples are analyzed by plotting the intensity of the elements... 

The signal in an atomic absorption instrument is the measured reduction in the light intensity from /q to /. In modern instruments, the logarithm is automatically calculated so that the output of the instrument is the absorbance. Absorbance is a unitless number that varies typically between 0.001 and 2, but the number is usually referred to as absorbance units. The AAS calibration curve is a plot of A versus c with a slope of ab. It is best to work at concentrations that give signals in the middle of the absorbance range. 

FIGURE 12 Influence of line shape on calibration parameters for atomic absorption spectrometry. (A) Comparison of atomic line widths for a hollow cathode lamp versus the atomic absorption line width observed in atmospheric pressure atom cells. (B) The slope and linear dynamic range of the calibration changes from I to N as the emission line width of the hollow cathode lamp becomes broader. 

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