Fundamental aspects of flameless atomic absorption using the mini-Massmann carbon rod atomizer

Optimization of instrumental parameters in flameless atomic absorption spectrometry

“…However, owing to the transient nature of signals occurring in flameless AAS, a number of parameters such as dominant time constants of the amplifier-recorder system, modulation frequency, and heating rate affect the analytical performance characteristics, viz., S/N ratio, sensitivity, and linearity of the calibration curves. The effect of the response of the amplifier-recorder system on the resolution of peaks was demonstrated previously (4), while the influence of this factor on the calibration curve for lead was shown by Matousek (5). Theoretical considerations concerning the optimum signal-to-noise ratio with respect to the time constant of the measurement system have been made by L'vov (6) for his furnace.…”

“…caption of Figure 2 or the strip chart recorder will determine the speed of response, i.e., in the case of small time constants of the amplifier, the strip chart recorder will be the limiting factor and with large time constants, the amplifier. Since, however, recorders must be considered as nonlinear systems, we checked the response of the strip chart recorder, as was done previously (4,12), to continuous sine wave input (Figure 4). From this figure, it will be clear that the attenuation of the sine wave amplitude increases with increasing amplitude, but the attenuation rate is constant about 10 dB/oct.…”

Mechanisms controlling graphite furnace atomization and stabilization of beryllium

“…These arguments are based on comparisons of appearance temperatures with the melting point of the monoxide. But, as Massen and Posma demonstrate, such arguments are highly speculative (2). The same investigators (2) also show that the presence of aluminum in the sample increases the appearance temperature for beryllium from about 1500 to 1700 K. Most recently, hightemperature equilibrium calculations by Freeh et al indicate that beryllium should remain nonvolatile up to 1400 K and that relatively large 'volumes of water can lead to gaseous dihydroxide formation at temperatures as low as 1200 K (3).…”

LXXXVI. Atomic spectroscopy atomization systems (Continued)

“…Interference effects can be decreased by using a tube type carbon filament. In one type a 1.5 mm hole is drilled through the rod (34, 43). As with the West filament, the sample is placed in the cavity with a microsyringe.…”