Standard Flame Photometer

F = An optical filter to allow the transmission of only one strong-line of the element, 

H = A Null detector to record the intensity of the element under study and the internal-standard (Lithium), 

J2 = Lines due to the Internal Standard Lithium , and Kj K2 = Photocells to convert light-energy to electrical impulse. 

The use of an internal standard flame photometer not only eliminates the visible effects of momentary fluctuations in the flame characteristics produced by variations in either the oxidant or under full pressures, but also the errors caused due to differences in surface tension and in viscosity are minimised to a great extent. 

In short, an internal-standard flame photometer provides a direct and simultaneous result with respect to the ratio of intensities. 

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The layout of an internal standard flame photometer is illustrated in Figure 25.3. 

Commercial Hquid sodium alumiaates are normally analyzed for total alumiaa and for sodium oxide by titration with ethylene diaminetetraacetic acid [60-00-4] (EDTA) or hydrochloric acid. Further analysis iacludes the determiaation of soluble alumiaa, soluble siHca, total iasoluble material, sodium oxide content, and carbon dioxide. Aluminum and sodium can also be determiaed by emission spectroscopy. The total iasoluble material is determiaed by weighing the ignited residue after extraction of the soluble material with sodium hydroxide. The sodium oxide content is determiaed ia a flame photometer by comparison to proper standards. Carbon dioxide is usually determiaed by the amount evolved, as ia the Underwood method. 

Sodium and potassium were determined using Jenway PFP-7 model flame photometer and sodium or potassium chloride to prepare the standards. Calcium, iron,... 

Procedure. Switch on and set up the flame photometer according to the manufacturer s instructions. The standards (including a 50% sulphuric acid blank) and sample solutions in 50% sulphuric acid obtained from the Kjeidahi digest... 

Dissolution was carried out with the paddle method according to USP XXI, using a Prolabo dissolution tester. The dissolution medium was 1000 ml of distilled water at 37 0.5°C and 50 rev min-1. At appropriate time intervals, 5 ml of sample was withdrawn and an equal volume of medium was added to maintain a constant volume. Sample were filtered, diluted with lithium carbonate solution as an internal standard, and analysed using a Dr Lange MD 70 flame photometer. Each dissolution profile is the average of six separate tablets. 

The calcination of BPH to BA was carried out in a batch calcinator (thermolyne 6000 furnace) which is heated to a predetermined calcination temperature (Fig. 1). During constant temperature experiments, particles were fed into the calcinator, which was in thermal equilibrium at the experimental temperature. At a predetermined time interval, samples were withdrawn using a vacuum sampling tube. Titri-metric method was used to determine the Na2B4C>7 content of sample [10]. The Ca2+ content of samples was determined by Jenway PFP 7 model flame photometer. Bulk density of BA was measured by a standard method [11]. 

Set a suitable flame photometer to a wavelength of 589 nm. Adjust the instmment to zero transmittance against water, and then adjust it to 100.0% transmittance with an aqueous solution containing 200 pig/mL of sodium, in the form of the chloride. Prepare and read the percent transmittance of three other solutions containing 50, 100, and 150 xg/mL each of sodium, and plot the standard curve as percent transmittance versus concentration of sodium... 

A simple emission flame photometer is adequate for Na and K while a more selective emission/absorbance system is necessary for Ca, Mg, and trace metals. The range of trace metals which can be analyzed (e.g., Cu, Zn, Fe, As, Pb, Co, Mo, Se, Cd, Hg) with an instrument depends on the efficiency of atomization, excitation, and light collection, as well as the intensity and stability of the background. Owing to the difficulty of obtaining complete stability of baseline and sensitivity, frequent standardization of instruments is usually necessary. This can... 

Linear calibration lines can be handled quite easily by using LINEST. However, when a calibration curve is not linear, the problem is a little more difficult. The calibration curve in Figure 21-1 shows readings on a series of sodium standards, made using a CIBA-Corning Model 410 flame photometer. The calibration line is noticeably curved. 

The first commercially available flame photometer was introduced in the 1940s by the Perkin-Elmer Corporation. In 1948, Beckmann Instruments, Inc., introduced a flame attachment that could be used with their popular model D.U. spectrophotometer. By the late 1950s, instruments had been developed that used lithium as an internal standard to maximize precision. Autodilution features and microprocessor-controlled operations became widely used options in the 1970s. The most recent significant development was the introduction of cesium as the internal standard, by Instrumentation Laboratory, Inc. (Figs. 1-3). This development makes concurrent lithium determinations more practical. 

Fig. 1 Flame photometer using cesium as the internal standard. (Courtesy of Instrumentation Laboratory, Inc.)...

Presentation of the diluted sample to the flame photometer can make use of an automatic device (details available from Evans Electro-Selenium Ltd.), but a preferable alternative is to attach a polyethylene capillary tube (30 cm long) to the atomizer intake this tube may then be inserted into the diluted samples or into the standard without removing the individual containers from the sample rack. Carry-over from one specimen to the next is negligible. 

The sodium in a series of cement samples was determined by flame emission spectroscopy. The flame photometer was calibrated with a series of NaCl standards that contained sodium equivalent to 0,20.0,40,0,60.0, and 80.0 pg Na20 per ml,. The instrument readings R for these solutions were 3.1.2I 5.40,9. 57.1. and 77..3. 

Results of measurements on standard normal specimens should conform exactly with those obtained by flame photometer on the same specimens. 

The widely used clinical flame photometers have been described in the section above on flame spectrometers and filter photometers. Analyte concentrations and their inherent line intensities are such that samples may be diluted greatly and various difficulties avoided. The burners are small and round so that self-absorption is slight and calibration curves nearly linear. Use of lithium added at a high concentration as the internal standard helps to correct for some of the uncontrolled variables. 

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