- Email: [email protected]
Anodic chronopotentiometry at solid electrodes.
A 32
Journal of Electroanalytical Chemistry
VOL. 1
A d s o r b e n s d u r c h die a d s o r b i e r t e n S c h i c h t e n h i n d u r c h w i r k s a m i s t und c i n c h E i n f l u s s a u f d i e e l e k t r o p h o r e t i s c h e B e w e g i i c h k e i t d e s P r o t e i n s a u s i i b t . So w u r d e g e f u n d e n , class d i e B e w e g l i c b k e i t e n yon a n n c g a t i v e n O b c r f l f i c h c n a d s o r b i c r t e n P r o teinen kleiner sind als erwartet, was vcrmutlich dadurch bedingt ist, dass ein T e i l d e r L a d u n g yon d e r O b e r f l t t c h e d e s A d s o r b c n s k o m p e n s i e r t w i r d . A u c h die G e s t a l t d e r O b e r f l i i c h e b e e i n f l u s s t die B e w e g l i c h k e i t c n . Ha. Re.
[101] E L E C T R O P H O R E S I S O F R I B O N U C L E A S E : I S O E L E C T R I C P O I N T S ON VARIOUS A D S O R B E N T S . L . B . B a r n e t t a n d H. B. B u l l . ( B i o c h e m i s t r y D e p t . , State U n i v e r s i t y of Iowa, U . S . A . ) J . A m . C h e m . S o c . , 81 (1959) 5133. A n v e r s c h i e d e n e n A d s o r b e n t i e n w c r d e n die i s o c l e k t r i s c h c n P u n k t e yon R i b o n u c l e a s e g e m e s s e n und m i t d e m i s o e l c k t r i s c h c n P u n k t d c r gcli~sten R i b o n u c l e a s c v e r g l i c h e n . In e i n e m I ~ f f e r s y s t e m e i n c r I o n e n s t ~ r k c yon 0.05 N w c r d c n b e i 25 ° d i e i s o e l e k t r i s c h e n P u n k t e a n d e n A d s o r b c n t i e n P y r c x g i a s , D o w e x 50 K a t i o n c n austauscherharz, Dowex 2 Anionenaustauscherharz, P a r a f f i n und Nujol b c s t i m m t . G e g e n [ i b e r W e r t e n , die n a e h d e r M c t h o d c yon T i s c l i u s in v c r s c h i c d c n c n P u f f c r systemen gemessen wurden, lasscn sich zum Tell crhebliche Abwcichungcn erk e n n e n , d i e s o w o h l yore v e r w e n d c t e n P u f f c r s y s t c m , a l s a u c h yore A d s o r b e n t a b h~lngig s i n d . Z u r D e u t u n g d i e s e r A b w c i c h u n g e n w c r d c n die W e c h s c l w i r k u n g e n d c r a d s o r b i e r t e n R i b o n u c l e a s e m i t d e m j e w e i l i g e n A d s o r b e n s n~iher u n t e r s u c h t und d i s k u t i e r t . N i c h t in a l l e n F,~illen k a n n e i n e b e f r i e d i g e n d e E r k l t i r u n g g c g e b e n w e r den. Ha. R c . S E E ALSO: [27].
9. O T H E R M E T H O D S
[1021 ANODIC C H R O N O P O T E N T I O M E T R Y A T SOLID E L E C T R O D E S . J . D . V o o r h i e s a n d N. H. F u r m a n . ( F r i c k C h e m . L a b . , U n i v e r s i t y of P r i n c e t o n , N . J . , U. S. A. ) A n a l . C h e m . , 31 (1959) 381. S o m e t i m e d e p e n d e n t e r r o r s in q u a n t i t a t i v e a n o d i c c h r o n o p o t e n t i o m e t r y a t s o l i d e l e c t r o d e s c a n b e e l i m i n a t e d by m e a s u r i n g s h o r t t r a n s i t i o n t i m e s . T h e r e f o r e t r a n s i t i o n t i m e s b e t w e e n 0.3 a n d 1.0 s e c h a v e b e e n s t u d i e d w i t h r e g a r d to p r e c i s i o n . T h e p o t e n t i a l - t i m e c u r v e s w e r e p r e s e n t e d a t a c a t h o d e r a y tube a n d r e c o r d e d b y a c a m e r a . T h e a n o d i c o x i d a t i o n s of a n t h r a c e n e in a c e t o n i t r i l e a n d s u l f a n i l a m i d e in • 1 M p e r e h l o r i c a c i d a r e i n v e s t i g a t e d . In s e v e r a l r e p r o d u c i b i l i t y s t u d i e s the a v e r a g e p r e c i s i o n of the s q u a r e r o o t of the t r a n t 3 i t i o n t i m e w a s 4- 0.6 % (o). T h e a n t h r a c e n e m o l e c u l e is o x i d i z e d by the l o s s of two l o c a l i z e d pi e l e c t r o n s f r o m t h e 9 a n d 10 p o s i t i o n s f o r m i n g a d i c a r b o n i u m ion. T h e o b s e r v e d c h r o n o p o t e n t i o g r a m of t h i s reaction is very well-defined. K1. G r . [103] M E R C U R Y C H L O R I D E F I L M ANODE. I. STUDY O F TH'E C H A R A C T E R I S T I C S OF A M E R C U R Y C H L O R I D E F I L M A N O D E BY C H R O N O P O T E N T I O M E T R I C M E T H O D S . T h . K u w a n a a n d R. N. A d a m s . (Dept. of C h e m i s t r y , U n i v e r s i t y of K a n s a s , U . S . A . ) A n a l . C h i m . A c t a , 20 (1959) 51. T h e a u t h o r s s t u d y the a n o d i c p a s s i v a t i o n of Hg in c h l o r i d e m e d i a by c h r o n o p o t e n t i o m e t r i c m e t h o d s . T h e y o b s e r v e t h a t t h i s p a s s i v a t i o n i s d u e to t h e f o r m a t i o n
Journal of Electroanalytical Chemistry
VOL. 1
A d s o r b e n s d u r c h die a d s o r b i e r t e n S c h i c h t e n h i n d u r c h w i r k s a m i s t und c i n c h E i n f l u s s a u f d i e e l e k t r o p h o r e t i s c h e B e w e g i i c h k e i t d e s P r o t e i n s a u s i i b t . So w u r d e g e f u n d e n , class d i e B e w e g l i c b k e i t e n yon a n n c g a t i v e n O b c r f l f i c h c n a d s o r b i c r t e n P r o teinen kleiner sind als erwartet, was vcrmutlich dadurch bedingt ist, dass ein T e i l d e r L a d u n g yon d e r O b e r f l t t c h e d e s A d s o r b c n s k o m p e n s i e r t w i r d . A u c h die G e s t a l t d e r O b e r f l i i c h e b e e i n f l u s s t die B e w e g l i c h k e i t c n . Ha. Re.
[101] E L E C T R O P H O R E S I S O F R I B O N U C L E A S E : I S O E L E C T R I C P O I N T S ON VARIOUS A D S O R B E N T S . L . B . B a r n e t t a n d H. B. B u l l . ( B i o c h e m i s t r y D e p t . , State U n i v e r s i t y of Iowa, U . S . A . ) J . A m . C h e m . S o c . , 81 (1959) 5133. A n v e r s c h i e d e n e n A d s o r b e n t i e n w c r d e n die i s o c l e k t r i s c h c n P u n k t e yon R i b o n u c l e a s e g e m e s s e n und m i t d e m i s o e l c k t r i s c h c n P u n k t d c r gcli~sten R i b o n u c l e a s c v e r g l i c h e n . In e i n e m I ~ f f e r s y s t e m e i n c r I o n e n s t ~ r k c yon 0.05 N w c r d c n b e i 25 ° d i e i s o e l e k t r i s c h e n P u n k t e a n d e n A d s o r b c n t i e n P y r c x g i a s , D o w e x 50 K a t i o n c n austauscherharz, Dowex 2 Anionenaustauscherharz, P a r a f f i n und Nujol b c s t i m m t . G e g e n [ i b e r W e r t e n , die n a e h d e r M c t h o d c yon T i s c l i u s in v c r s c h i c d c n c n P u f f c r systemen gemessen wurden, lasscn sich zum Tell crhebliche Abwcichungcn erk e n n e n , d i e s o w o h l yore v e r w e n d c t e n P u f f c r s y s t c m , a l s a u c h yore A d s o r b e n t a b h~lngig s i n d . Z u r D e u t u n g d i e s e r A b w c i c h u n g e n w c r d c n die W e c h s c l w i r k u n g e n d c r a d s o r b i e r t e n R i b o n u c l e a s e m i t d e m j e w e i l i g e n A d s o r b e n s n~iher u n t e r s u c h t und d i s k u t i e r t . N i c h t in a l l e n F,~illen k a n n e i n e b e f r i e d i g e n d e E r k l t i r u n g g c g e b e n w e r den. Ha. R c . S E E ALSO: [27].
9. O T H E R M E T H O D S
[1021 ANODIC C H R O N O P O T E N T I O M E T R Y A T SOLID E L E C T R O D E S . J . D . V o o r h i e s a n d N. H. F u r m a n . ( F r i c k C h e m . L a b . , U n i v e r s i t y of P r i n c e t o n , N . J . , U. S. A. ) A n a l . C h e m . , 31 (1959) 381. S o m e t i m e d e p e n d e n t e r r o r s in q u a n t i t a t i v e a n o d i c c h r o n o p o t e n t i o m e t r y a t s o l i d e l e c t r o d e s c a n b e e l i m i n a t e d by m e a s u r i n g s h o r t t r a n s i t i o n t i m e s . T h e r e f o r e t r a n s i t i o n t i m e s b e t w e e n 0.3 a n d 1.0 s e c h a v e b e e n s t u d i e d w i t h r e g a r d to p r e c i s i o n . T h e p o t e n t i a l - t i m e c u r v e s w e r e p r e s e n t e d a t a c a t h o d e r a y tube a n d r e c o r d e d b y a c a m e r a . T h e a n o d i c o x i d a t i o n s of a n t h r a c e n e in a c e t o n i t r i l e a n d s u l f a n i l a m i d e in • 1 M p e r e h l o r i c a c i d a r e i n v e s t i g a t e d . In s e v e r a l r e p r o d u c i b i l i t y s t u d i e s the a v e r a g e p r e c i s i o n of the s q u a r e r o o t of the t r a n t 3 i t i o n t i m e w a s 4- 0.6 % (o). T h e a n t h r a c e n e m o l e c u l e is o x i d i z e d by the l o s s of two l o c a l i z e d pi e l e c t r o n s f r o m t h e 9 a n d 10 p o s i t i o n s f o r m i n g a d i c a r b o n i u m ion. T h e o b s e r v e d c h r o n o p o t e n t i o g r a m of t h i s reaction is very well-defined. K1. G r . [103] M E R C U R Y C H L O R I D E F I L M ANODE. I. STUDY O F TH'E C H A R A C T E R I S T I C S OF A M E R C U R Y C H L O R I D E F I L M A N O D E BY C H R O N O P O T E N T I O M E T R I C M E T H O D S . T h . K u w a n a a n d R. N. A d a m s . (Dept. of C h e m i s t r y , U n i v e r s i t y of K a n s a s , U . S . A . ) A n a l . C h i m . A c t a , 20 (1959) 51. T h e a u t h o r s s t u d y the a n o d i c p a s s i v a t i o n of Hg in c h l o r i d e m e d i a by c h r o n o p o t e n t i o m e t r i c m e t h o d s . T h e y o b s e r v e t h a t t h i s p a s s i v a t i o n i s d u e to t h e f o r m a t i o n