Perkin-Elmer burner

Figure 14.8—Burner for an atomic absorption instrument. This type of burner is used in models 3100 3300 from Perkin-Elmer. (Reproduced by permission of Perkin Elmer.)...

Apparatus. A Perkin-Elmer model 303 atomic absorption spectrometer equipped with a DCR-1 readout accessory and a strip chart recorder was used for all determinations. A Boling burner was used for all determinations made in the air-acetylene flame except for copper where a single-slot, high-solids burner was used. The nitrous oxide burner was used for refractory elements. Burner and instrument settings used were those recommended by the manufacturer s handbook. 

The instrument used was a Perkin-Elmer Model 360 atomic-absorption spectrometer with the burner removed. A Varian Techtron mercury hollow-cathode lamp was used as the light source and the wavelength and band width were set at 253.7 and 0.2 nm, respectively. The lamp current was 4.5 mA. 

Procedure Use a Perkin-Elmer 403 atomic absorption spectrophotometer equipped with a deuterium arc background corrector, a digital readout device, and a burner head capable of handling 20% solids content. Blank the instrument with water following the manufacturer s operating instructions. Aspirate a portion of the Standard Preparation, and record the absorbance as As then aspirate a portion of the Sample Preparation, and record the absorbance as Av. Calculate the lead content, in milligrams per kilogram, of the sample taken by the formula... 

Slavin, W., A burner-atomizer for atomic absorption spectrophotometry. Atomic Absorption Newsletter No. 10. Perkin-Elmer Corp., Norwalk, Conn. (February 1963). 

Fig. 2 Comparison of atomic absorption burner (A) and ICP argon plasma torch (B). (Courtesy of Perkin-Elmer Instruments.)...

Figure 28-11 A laminar-flow burner used in flame atomic absorption spectroscopy. (Courtesy of Perkin-Elmer Corporation, Norwalk, CT.)...

Atomic absorption instrumentation. Perkin-Elmer model 403 or equivalent instrument, equipped with deuterium background corrector, arsenic hollow cathode lamp, triple-slot burner head and a strip chart recorder. 

The copper in hemocyanin is directly and quantitatively involved in the oxygenation reaction. All incoming hemocyanin solutions are analyzed for copper with a Perkin-Elmer atomic absorption spectrophotometer. The analyses are carried out by diluting the stock solution with distilled water and feeding the solution to the burner. 

Molecules formed in the flame can have absorption bands at the analytical wavelengths of particular elements. ITiese molecular bands occur most often when low temperature flames or special burner systems of peculiar design are used. With Perkin-Elmer s air-acetylene burner, one such interference has been noted when barium is determined in the presence of a large excess of calcium, calcium molecules absorb radiation at the barium wavelength. Even this interference vanishes in the higher temperatures generated by a nitrous-oxide-acetylene flame. 

The design of the premix burner shown in Figure 10 also presents a number of other advantages and disadvantages as compared with the total consumption type. The flame is not very luminous, and flicker and turbulence are quite low, so that for many elements the flame contributes no apparent noise to the output (Figure 8). Furthermore, there is rather little dependence of absorption upon sample flow rate. This is of benefit in two ways. First, the length of sample capillary, and its depth of immersion in the solution, are not very critical, so that samples can be aspirated from any vessel. For total consumption burners, by contrast, Petri dishes or very small sample containers are often recommended. Second, viscosity interferences caused by variations in sample concentration are minimized, though not eliminated. In the Perkin-Elmer burner, when the sample flow rate is cut by a factor of 2, absorption is reduced by approximately 4%. 

The chamber of the Perkin-Elmer burner is made of remarkably inert Penton plastic, so that, in very extensive analytical work involving hundreds of instruments, cross-contamination of samples has not been a problem. For the sake of certainty, a blank is usually run for a few seconds after every sample. When very high concentrations of an element are run, there will be some persistence. For example, after several percent sodium are aspirated for some time, traces of sodium will persist in the flame up to a few hours, unless the burner is taken apart and cleaned. 

Interferences. One study of relative interferences is shown in Figure 12. Here the effect of fluoride concentration on the absorption of barium is measured, both when a total consumption burner and a Perkin-Elmer premix burner are used. It will be seen that the effects are negligible with the premix burner, and immediate and severe with total consumption (J). In another study, it was found that the presence of phosphate interferes seriously with the absorption of magnesium with a total consumption burner (9). With a well-designed premix unit, there is no such effect (2). 

Several elements (Zn, Pb, Cuy Ni, Ca, Mg, Fe, and Mn) are determined routinely in water samples using atomic absorption spectroscopy. Sodium and potassium are determined by flame emission. The preparation of the samples the analytical methody the detection limits and the analytical precisions are presented. The analytical precision is calculated on the basis of a sizable amount of statistical data and exemplifies the effect on the analytical determination of such factors as the hollow cathode sourcey the ffamey and the detection system. The changes in precision and limit of detection with recent developments in sources and burners are discussed. A precision of 3 to 5% standard deviation is attainable with the Hetco total consumption and the Perkin-Elmer laminar flow burners. 

To investigate this matter of precision further, as well as the limit of detection, two other types of burners and various hollow cathode lamps were tested under similar conditions. The primary objective was to compare a new single flame total consumption burner, operated on a hydrogen-air fuel mixture, with a premix burner using acetylene and air for fuel. The total consumption burner is the Hetco type, and was used with the Jarrell-Ash spectrophotometer. The premix burner is the Perkin-Elmer type and it was tested as a part of the Perkin-Elmer Model 290 Atomic Absorption Spectrophotometer. Synthetic standards for Ca, Mg, Fe, Pb, and Cu were analyzed in varying concentrations. The data was assessed on both a short-term (daily) basis, where new standard curves were prepared daily, and on a long-term basis, where the shift in the calibration curve was included in the data. 

The Jarrell-Ash Corporation has designed a similar burner, as shown in Figure 9-5, but have included a slot-type head to convert the burner to a laminar flow system. This arrangement is shown in Figure 9-6. The laminar flow head was intended primarily for atomic absorption measurements but also is useful for flame emission. The Perkin-Elmer laminar flow burner is shown in Figure 9-7. 

FIGURE 9-7 Perkin-Elmer laminar flow burner. [Courtesy the Perkin-Elmer Corp.]... 

Other burners separate the nebulization process and the flame by producing small liquid droplets in a nebulizing chamber before the sample enters the flame. Figure 10-12 shows this process in the Perkin-Elmer unit. 

HQ. 3. Schematic design of a mixing chamber burner for AAS (Courtesy of Perkin-Elmer). 

Set up the atomic absorption spectrophotometer for the air/acetylene flame analysis of cadmium according to the SOP (5.8.) or the manufacturer s operational instructions. For the source lamp, use the cadmium hollow cathode or electrodeless discharge lamp operated at the manufacturer s recommended rating for continuous operation. Allow the lamp to warm up 10 to 20 min or until the energy output stabilizes. Optimize conditions such as lamp position, burner head alignment, fuel and oxidant flow rates, etc. See the SOP or specific instrument manuals for details. Instrumental parameters for the Perkin-Elmer Model 603 used in the validation of this method are given in Attachment 1. 

A Perkin-Elmer (PE) Model 603 spectrophotometer equipped with a manual gas control system, a stainless steel nebulizer, a burner mixing chamber, a flow spoiler and a 10 cm. (one-slot) burner head was used in the experimental validation of the flame AAS analytical technique. A PE cadmium hollow cathode lamp, operated at the manufacturer s recommended current setting for continuous operation (4 mA), was used as the source lamp. Instrument parameters are listed in Attachment 1. 

Fig. 90. Burner-nebulizer assembly for flame atomic absorption spectrometry, a Burner head with mixing chamber b nebulizer c impactor bead d impact surfaces e nebulizer socket. (Courtesy of Bodenseewerk Perkin Elmer, Uberlingen.)...

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