Stabilized temperature platform furnace STPF

The stabilized temperature platform furnace (STPF) concept was first devised by Slavin et al. It is a collection of recommendations to be followed to enable determinations to be as free from interferences as possible. These recommendations include (i) isothermal operation (ii) the use of a matrix modifier (iii) an integrated absorbance signal rather than peak height measurements (iv) a rapid heating rate during atomization (v) fast electronic circuits to follow the transient signal and (vi) the use of a powerful background correction system such as the Zeeman effect. Most or all of these recommendations are incorporated into virtually all analytical protocols nowadays and this, in conjunction with the transversely heated tubes, has decreased the interference effects observed considerably. 

In order to determine Bi by GF AAS under stabilized temperature platform furnace (STPF) conditions using the Pd-Mg modifier, a pyrolysis temperature of 1200 °C must be applied (Hiltenkamp and Werth 1988). The optimum atomization temperature under these conditions is 1900 °C the characteristic mass with Zeeman effect background correction (BC) is 28 pg, while in a non-Zeeman instrument it is about 20 pg. 

Weighed tissue samples (kidney, liver, meat, bone and wool) of approximately 1 and 0.5 g CRM 185 bovine liver were placed in PTFE vessels, 5 ml of concentrated HNO3 and 5 ml of distilled H2O were added. A microwave oven program with temperature and pressure settings of 150°C and 130 p.s.i., respectively, was performed for all analyzed matrices. The digestion solutions were diluted to a final volume of 50 ml all dilution, excluding blood samples, were performed with 1% HNO3. Zinc analysis was performed on a Flame AAS 2100 (Perkin-Elmer), with an air-acetylene flame. Lead and cadmium analysis was performed on a GF-AAS 5100 ZL (Perkin-Elmer). Analysis on GF-AAS were carried out under stabilized temperature platform furnace (STPF) conditions. 

Perkin Elmer introduced, in 1984, a Stabilized Temperature Platform Furnace (STPF) (Figure 49). There are two inert gas flows (internal and external). The heating rate of the furnace is high (about 2000 Ks ), which allows the use of lower atomization temperatures. After the thermal pretreatment a small temperature step (<1600 K) is used in order to prevent the atomization of the sample before the equilibrium has been reached. 

Gas phase interferences due to compound formation of the analyte element with a concomitant should not be very significant in ETAAS because a much longer time is available for dissociation compared to FAAS. It was shown by high-temperature equilibrium calculations that gas phase interferences at the temperatures used in ETAAS should actually be rather insignificant [18], The reason why the literature is nevertheless full of reports on such interferences is largely due to an improper use of this technique. Slavin et al. [19], based on the systematic work of L vov [20], introduced a concept which they called stabilized temperature platform furnace (STPF). It is in essence a package of measures which eliminates most nonspectral interferences in ETAAS by atomization under local thermal equilibrium conditions. 

Interferences, such as background absorption, are reduced to a minimum in the AAS-HGA analytical technique by taking full advantage of the Stabilized Temperature Platform Furnace (STPF) concept. STPF includes all of the following parameters (5.2.) ... 

In LS GF AAS, according to the Stabilized Temperature Platform Furnace (STPF) concept [133], signal evaluation should be done exclusively by means of time-integrated absorbance, the so-called peak area value. Applying this principle to HR-CS GF AAS, a spectrum is obtained which is summed over time, whereby the integrated absorbance at individual pixels A is calculated by ... 

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