- Email: [email protected]
Mercury chloride film anode. I. Study of the characteristics of a mercury chloride film anode by chronopotentiometric methods.
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
1960
Absll"(~cls Section
A 33
of a film of m e r c u r y c h l o r i d e that e f f e c t i v e l y 1,imits the continuous Hg oxidation. Such a M e r c u r y Chloride Film Anode (M. C. ]b. A.) may be used for the oxidation of s u b s t a n c e s in the bulk of the solution. The authors study the analytical applications of such an e l e c t r o d e in the p a r t i c u l a r case of oxidation of o r g a n i c compounds and c o m p a r e it favourably with Pt o r oth er i n e r t m e t a l e l e c t r o d e s . C h r o n o p o t e n t i o g r a r n s obtained f o r the oxidation of N, N - d i m e t h y l - p - p h e n y l e n e d i a m i n e (DPP) in d i c at es that the r e a c t i o n p r o c e e d s independently of the film r e a c t i o n but that c a l i b r a t i o n c u r v e s m u s t be made. The use of the M. C. F. A. e l e c t r o d e is r e s t r i c t e d to p i t ' s of l e s s than 5. This, coupled with the i n t e r f e r e n c e of lligh c o n c e n t r a t i o n s of c e r t a i n anions like iodide, phosphate and sulfate, r e p r e s e n t s the most s e r i o u s r e s t r i c t i o n s to M. C. F. A. ' s a n a l y t i c a l u s a g e . A f u r t h e r i n t e r e s t i n g p o s s i b i l i t y of this e l e c t r o d e is its use as a working cathode o r anode in solutions containing both r e d u c i b l e and oxidizable s p e c i e s . P. Mac. [104] DROP-SCALE CHRONOP(JTENTIOMETRY. R.T.Iwamoto, R.N.Adams and H. Lott. (Dept. of Chemistry, University of Kansas, U. S. A. ) Anal. Chim. Acta, 20 (1959) 84. Chronopotentiometry has been successfully carried out on one drop of solution. Two assembles were used, the working electrode being Pt or Hg. Ttds arrangement enabled determinations to be performed in one or two minutes. The oxidation of fcrrocyanide and iodide ions and the reduction of ferricyanide ions were made at the Pt electrode. The reduction of Zn ions was studied at the Hg electrode. A potential hold-up was clearly indicated during the oxidation of iodide ions obtained by electrolyzing 0.07 ml of a 5.10-6 M potassium iodide solution, 1 M in sulfuric acid, givinga total of 3.5.10 -I° equivalents of iodide ions. P. Mae. [105] MERCURY CHLORIDE FILM ANODE. If. INVESTIGATION OF THE CHARACTERISTICS OF THE MERCURY CHLORIDE FILM ANODE BY VOLTAGE - SCAN METHOD. Th. Kuwana and 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 Kansas, U . S . A . ) Anal. Chim. Acta, 20 (1959) 60. In c h r o n o p o t e n t i o m e t r y , the M e r c u r y Chloride F i l m Anode ( M . C . F . A . ) was f o r m e d in the p r e s e n c e of the s u b s t a n c e s to be oxidized in the background potassium chloride solution. This l e d to d i f f i c u l t i e s of n o n - r e p r o d u c i b i l i t y or no p a s s i vation in c a s e s w h e r e the substance to be oxidized f o r m e d v e r y stable sal t s with m e r c u r o u s ion, or was s t r o n g l y a b s o r b e d on the Hg s u r f a c e . This difficulty m ay be e l i m i n a t e d by f o r m i n g the film by v o l t a g e - s c a n p r i o r to the introduction of the oxidizable substance. The IVi.C. F . A . shows, for many o r g a n i c m o l e c u l e s , c h a r a c t e r i s t i c s c o m p a r a b l e to the Pt e l e c t r o d e . Oxidation c u r v e s w e r e t r a c e d f o r N,Nd i m e t h y l - p - p h e n y l e n e d i a m i n e (DPP), 8-arnino- 1,3, 6 - n a p h t h a l e n e t r i s u l f o n i c acid, aniline, hydroquinone and p - h y d r o x y d i p h e n y l a m i n e . The M. C. F . A . has a h i g h e r background o v e r v o l t a g e than the Pt e l e c t r o d e . The p o l a r o g r a p h i c wave of p - n i t r o a n i l i n e is not obtained at a Pt e l e c t r o d e . A w e l l defined wave is o b s e r v e d at the M . C . F . A . at ca. I . i V vs. s a t u r a t e d c a l o m e l e l e c t r o d e . The s e n s i t i v i t y of the M. C. F.A. by v o l t a g e - s c a n is s o m e 10-fold g r e a t e r than that of c h r o n o p o t e n t i o m e t r y . P r e l i m i n a r y e x p e r i m e n t s indicate that the s e n s i t i v i t y m ay be enhanced by s t i r ring the solution. The r e p r o d u c i b i l i t y is of the o r d e r of 5 %. P. Mae. [1~06] DIE DIELEKTRIZITATSKONSTANTE ALSANALYTISCHE KENNZAHL. F. Oehme. (Inst. phys. chem. Anal. , Weilheim, Deutschland. ) Angew.Chem., 71 (1959) 401. Uber die Messung, Definition der Dielektrizit~itskonstante (DK) und den zur Messunggebrauchten Messkondensator wird zusammenfassend berichtet. Durch die Messungen der quaslstazion[iren DK hinaus geben Untersuehungen der Frequenzabhiin~gkeit der DK und des'dielektrischen Verlustes Einblicke in die molekulare Feinstruktur. ,~s wird in weiterem darauf hingewiesen, dass die gemesse-
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
1960
Absll"(~cls Section
A 33
of a film of m e r c u r y c h l o r i d e that e f f e c t i v e l y 1,imits the continuous Hg oxidation. Such a M e r c u r y Chloride Film Anode (M. C. ]b. A.) may be used for the oxidation of s u b s t a n c e s in the bulk of the solution. The authors study the analytical applications of such an e l e c t r o d e in the p a r t i c u l a r case of oxidation of o r g a n i c compounds and c o m p a r e it favourably with Pt o r oth er i n e r t m e t a l e l e c t r o d e s . C h r o n o p o t e n t i o g r a r n s obtained f o r the oxidation of N, N - d i m e t h y l - p - p h e n y l e n e d i a m i n e (DPP) in d i c at es that the r e a c t i o n p r o c e e d s independently of the film r e a c t i o n but that c a l i b r a t i o n c u r v e s m u s t be made. The use of the M. C. F. A. e l e c t r o d e is r e s t r i c t e d to p i t ' s of l e s s than 5. This, coupled with the i n t e r f e r e n c e of lligh c o n c e n t r a t i o n s of c e r t a i n anions like iodide, phosphate and sulfate, r e p r e s e n t s the most s e r i o u s r e s t r i c t i o n s to M. C. F. A. ' s a n a l y t i c a l u s a g e . A f u r t h e r i n t e r e s t i n g p o s s i b i l i t y of this e l e c t r o d e is its use as a working cathode o r anode in solutions containing both r e d u c i b l e and oxidizable s p e c i e s . P. Mac. [104] DROP-SCALE CHRONOP(JTENTIOMETRY. R.T.Iwamoto, R.N.Adams and H. Lott. (Dept. of Chemistry, University of Kansas, U. S. A. ) Anal. Chim. Acta, 20 (1959) 84. Chronopotentiometry has been successfully carried out on one drop of solution. Two assembles were used, the working electrode being Pt or Hg. Ttds arrangement enabled determinations to be performed in one or two minutes. The oxidation of fcrrocyanide and iodide ions and the reduction of ferricyanide ions were made at the Pt electrode. The reduction of Zn ions was studied at the Hg electrode. A potential hold-up was clearly indicated during the oxidation of iodide ions obtained by electrolyzing 0.07 ml of a 5.10-6 M potassium iodide solution, 1 M in sulfuric acid, givinga total of 3.5.10 -I° equivalents of iodide ions. P. Mae. [105] MERCURY CHLORIDE FILM ANODE. If. INVESTIGATION OF THE CHARACTERISTICS OF THE MERCURY CHLORIDE FILM ANODE BY VOLTAGE - SCAN METHOD. Th. Kuwana and 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 Kansas, U . S . A . ) Anal. Chim. Acta, 20 (1959) 60. In c h r o n o p o t e n t i o m e t r y , the M e r c u r y Chloride F i l m Anode ( M . C . F . A . ) was f o r m e d in the p r e s e n c e of the s u b s t a n c e s to be oxidized in the background potassium chloride solution. This l e d to d i f f i c u l t i e s of n o n - r e p r o d u c i b i l i t y or no p a s s i vation in c a s e s w h e r e the substance to be oxidized f o r m e d v e r y stable sal t s with m e r c u r o u s ion, or was s t r o n g l y a b s o r b e d on the Hg s u r f a c e . This difficulty m ay be e l i m i n a t e d by f o r m i n g the film by v o l t a g e - s c a n p r i o r to the introduction of the oxidizable substance. The IVi.C. F . A . shows, for many o r g a n i c m o l e c u l e s , c h a r a c t e r i s t i c s c o m p a r a b l e to the Pt e l e c t r o d e . Oxidation c u r v e s w e r e t r a c e d f o r N,Nd i m e t h y l - p - p h e n y l e n e d i a m i n e (DPP), 8-arnino- 1,3, 6 - n a p h t h a l e n e t r i s u l f o n i c acid, aniline, hydroquinone and p - h y d r o x y d i p h e n y l a m i n e . The M. C. F . A . has a h i g h e r background o v e r v o l t a g e than the Pt e l e c t r o d e . The p o l a r o g r a p h i c wave of p - n i t r o a n i l i n e is not obtained at a Pt e l e c t r o d e . A w e l l defined wave is o b s e r v e d at the M . C . F . A . at ca. I . i V vs. s a t u r a t e d c a l o m e l e l e c t r o d e . The s e n s i t i v i t y of the M. C. F.A. by v o l t a g e - s c a n is s o m e 10-fold g r e a t e r than that of c h r o n o p o t e n t i o m e t r y . P r e l i m i n a r y e x p e r i m e n t s indicate that the s e n s i t i v i t y m ay be enhanced by s t i r ring the solution. The r e p r o d u c i b i l i t y is of the o r d e r of 5 %. P. Mae. [1~06] DIE DIELEKTRIZITATSKONSTANTE ALSANALYTISCHE KENNZAHL. F. Oehme. (Inst. phys. chem. Anal. , Weilheim, Deutschland. ) Angew.Chem., 71 (1959) 401. Uber die Messung, Definition der Dielektrizit~itskonstante (DK) und den zur Messunggebrauchten Messkondensator wird zusammenfassend berichtet. Durch die Messungen der quaslstazion[iren DK hinaus geben Untersuehungen der Frequenzabhiin~gkeit der DK und des'dielektrischen Verlustes Einblicke in die molekulare Feinstruktur. ,~s wird in weiterem darauf hingewiesen, dass die gemesse-