published p a p e r s t o t h a t effect, such as t h e two q u o t e d below: Investigators using such common analytical techniques as flame and graphite furnace atomic absorption .. . have made enormous errors in measuring lead concentrations in biological and environmental materials. [Everson J.; Patterson, C. Clin. Chem. 1981, 27, 765.] [Furnace AAS] should at this time still be considered an art rather than a reliable analytical science... . the large number of interferences and the inability of the standard additions technique to compensate for interferences make graphite furnace AAS highly unreliable in many cases. [Boyer, K. W. J. Assoc. Off. Anal. Chem. 1981, 64, 396.] T h e r e is a t e n d e n c y t o believe t h a t Zeeman b a c k g r o u n d correction should be r e c o m m e n d e d only w h e n it is proven t h a t an o r d i n a r y furnace s y s t e m does n o t work. I believe t h i s recomm e n d a t i o n is totally incorrect. I n our experience a quicker, m o r e reliable, a n d less t r o u b l e s o m e p r o c e d u r e can be developed using t h e c o m b i n a t i o n of the stabilized-temperature platform furnace with t h e Z e e m a n b a c k g r o u n d corrector.
Conclusion As I have included negative q u o t a tions from t h e l i t e r a t u r e a b o u t t h e p a s t furnace t e c h n i q u e , I w a n t t o finish with several e x a m p l e s of t h e m a n y more flattering p a p e r s . A r e c e n t p a p e r
THE MARK OF THE EXPERT
c o m p a r e s I C P , t h e D C P , flame AA, furnace AA, a n d electrochemical m e t h o d s for 10 t r a c e m e t a l s in electrol y t e s — t h a t is, in m e t a l chlorides: For the large laboratory the best combination of techniques would be an ICP and electrothermal AAS, whereas for the smaller lab,. . . flame and electrothermal AA would suffice. [Skidmore P. R.; Greetham, S. S. Analyst 1983,108, 171].
nology. Given t h e various characteristics t h a t m a k e u p t h e m o d e r n furnace, including Z e e m a n b a c k g r o u n d correction for difficult samples, t h e g r a p h i t e furnace t e c h n i q u e is now n o more difficult t h a n flame AA a n d p r o b a b l y less difficult t h a n I C P .
A n d finally, George M o r r i s o n , t h e E d i t o r of A N A L Y T I C A L C H E M I S T R Y ,
did a critical review of t h e analytical p r o c e d u r e s available for t r a c e m e t a l d e t e r m i n a t i o n s in biological m a t e r i a l s . His final s u m m a r y is: We see that while many trace element techniques are available for biological analyses, on the basis of the criteria of sample size, pretreatment, sensitivity, accuracy and precision, and cost, the technique of ETA-ÂAS [electrothermal atomization AA spectrometry] offers the greatest opportunity. [Morrison, G. H. Crit. Rev. Anal. Chem. 1979, 8, 287.] T h e r e f o r e , I would conclude t h a t flame AA a n d I C P a r e t h e preferred analytical t e c h n i q u e s a t levels where t h e s e two t e c h n i q u e s a r e useful. T h e choice b e t w e e n t h e two h a s t o d o with t h e p a r t i c u l a r m e t a l a n d t o some ext e n t with t h e m a t r i x . B u t a n y laboratory t h a t m u s t occasionally d o d e t e r m i n a t i o n s a t levels below t h o s e available on flame AA or t h e I C P should be e q u i p p e d to use g r a p h i t e furnace tech-
Walter Slavin is a senior scientist at Perkin-Elmer, working in atomic spectroscopy. He is a 1949 graduate of the University of Maryland in physics and math. He has led Perkin-Elmer's efforts in the field of AAS and has contributed extensively to the development of AA techniques and applications. Slavin has also published widely on instrumentation and applications of fluorescence spectroscopy, far-UVspectroscopy, chromatography, and clinical chemistry.
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