An i n t e r f a c e d e v i c e c o n s i s t i n g o f sampling v a lve, dispenser, t i m i n g c i r c u i t , and c o a n a l y t e a d d it i o n i s d e s c r i b e d . The l i q u i d chromatograph e l u e n t i s dispensed ( 3 7~~) t o t h e g r a p h i t e f u r n a c e o f an H i t a c h i 170-70 Zeeman e f f e c t atomic a b s o r p t i o n spect r o m e t e r which serves as an element s p e c i f i c d e t e ct o r . The a d d i t i o n o f c o a n a l y t e reduces t h e v o l a t i l -1075 1076 VICKREY, BLJREN, AND HOWELL i t y f o r nonmetals and increases t h e s e n s i t i v i t y f o r these elements a t low c o n c e n t r a t i o n . The i n t e r f a c e i s c o n t r o l l e d by a t i m i n g c i r c u i t comprised o f 555 t i m e r i n t e r g r a t e d c i r c u i t s and a l l o w s automated s i ng l e element a n a l y s i s o f t h e e l u e n t w i t h a n a l y s i s r e p e t i t i o n r a t e o f approximately one p e r minute. The r e s u l t s u s i n g t h i s i n t e r f a c e f o r t h e m o n i t o r i n g o f t h e s e p a r a t i o n o f several selenium c o n t a i n i n g compounds ( u s i n g N i 2 + as coanalyte) i s discussed.

The e f f e c t o f g r a p h i t e f u r n a c e s u r f a c e t r e a t m e n t , and t h e a d d i t i o n o f " m a t r i x m o d i f i e r s " such as n i c k e l o r lanthanum on t h e observed selenium a t o m i z a t i o n s i q n a l i n e l e c t r o t h e r v a l a t o m i c a b s o r p t i o n a n a l y s i s has been i n v e s t i q a t e d . t h a t t h e 1466 VICKREY AND BUREN the graphite surface which leads to more efficient atom formation.The role of the surface was investigated monitoring the atomic absorption signal generated from graphite furnaces which were untreated, pyrolytic graphite-coated, zirconium-or tantalum-coated, and metal-coated followed by pyrolytic graphite coating.dependence of the analyte signal on the concentration of added metal was investigated for these surfaces. The optimum results obtained were the metal-coated/pyrolytic graphite-coated cuvettes.These cuvettes showed reduced effect of "matrix modifier," suggesting that the surface treatment can replace the ''matrix modifer. '