Permanently modified platform

The typical features of chemical modifiers used in graphite furnace AAS are exemplified by the use of hydrofluoric acid as a modifier in the determination of Cu and Mn in seawater [328], and by the use of CaCl2 and ZrOQ2 as modifiers in the determination of B [329]. Tsalev et al. [330] determined Cd and Pb with stabilized phosphate deposited on permanently modified platforms, while Pereira-Filho et al. [331] used Zr and Pd + Mg as modifiers in the determination of Al, Cd, and Pb in biological slurry samples dispensed on Lvov platforms. They studied the elemental distributions of P, S, Ca, Ti, Fe, Zr, Hf, and Pd on these platforms by micro synchrotron radiation X-ray fluorescence and the morphology of the platforms by scanning electron microscopy. 

Georgieva R., Chakarova K. K. and Petrov Jr. 1.1. (2002) Electrothermal atomic absorption spectrometric determination of cadmiiun and lead with stabilized phosphate deposited on permanently modified platforms,... 

Maia et al. [332] eliminated interferences in the direct determination of Hg in powdered coal samples by means of analyte transfer during the pyrolysis step from the platform to a graphite tube wall. This graphite tube was permanently modified with Pd, and detection limits in the range of 0.025-0.05 pg/g were obtained. In simultaneous multi-element determinations of Cu, Cr, Al, and Mn in urine, Pd was also very successfully used as a matrix modifier [333]. The use of Pd as a modifier, and also in combination with dynamic background correction techniques such as the Smith-Hieftje technique (see Section 4.6.3), enables a considerable enhancement of the analytical accuracy of AAS, as shown in the case of As determinations [334]. 

Barbosa et al. (2001) described a method for the determination of Bi in whole blood and urine using ET AAS. The method used a pyrolytically coated integrated platform tube coated with a tungsten-rhodium mixture, which acted as a permanent chemical modifier, and this improved the furnace tube lifetime by 80%. Urine samples were diluted 1 + 1 (v/v) and blood samples 1+4 (v/v) with 1% HNO3 Triton X-100. Samples (20 p,L) were injected into the modified tube with a 10 xL volume of Rh. Reported LODs were 3 JgL and 8 igL for urine and blood, respectively. 

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