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Microdetermination of water by titration with fischer reagent
A 20
Journal of Electroanalytical Chemisl~
VOL. 1
10 g o f s a m p l e a r e made up with 5 m l o f 6 % w / v urea solution and with 0.5 ml of 1+1 HC1. Dilute exactly to 250 ml. D i s i n t e g r a t e ~he m e a t and f i l t e r . 40 ml of the filtrate a r e placed in a 50 ml c a l i b r a t e d flask and made up with lead acet at e as d e s c r i b e d for b r i n e s ; t h e r e a f t e r the p r o c e d u r e is the s a m e as l o r b r i n e s . Author i n v e s t i g a t e s also the b e s t conditions for a c o m p l e t e and r e p r o d u c i b l e nit r at i o n r e a c t i o n by p o l a r o g r a p h y , c o u l o m e t r y and absorption s p e c t r o p h o t o m e t r y ; under the proposed conditions nitration is quantitative. Chloride ion i n t e r f e r e s with nitration only if w a t e r is p r e s e n t ; n i tr i te ion i n t e r f e r e s with the p o l a r o g r a p h i c wave and m u s t be r e m o v e d by u r e a ; a m i n o a c i d s (tyrusine, phenylalanine and glutam i n i c acid) have no effect. G. de An. [60] P(gLARt)GRAPHIC OXIDATI()N tJF I~HEN~THIAZINETRANQUILIZERS. l-.Kabasakalian and J. IVicGlottcn. (Chemical Research and Development Div., Schering Corp., Bloomfield, N . J . , U.S.A.) Anal. Chem., 31 (1959) 431. Tranquilizers of the phenothiazine type give a well-defined and reproducible polarographic curve at a Au microelcctrode. Under the same conditions imll wave potentials depend on the substitution of the molecule. The voltametric curves of 14 tranquilizcrs Imve been studied to determine their analytical applicability. The effect of the 2- and 10-substituents are discussed. The half wave ix)t~,ntial is influenced by temperature. Sulfur is the most likely point lor an oxidative attack. The half-wave potential is fairly independent of pll, but analytical det~,rminations should be based on pH controlled acid solutions. Standard deviation is about 0.6%. The voltametric oxidation of these compounds in aqueous sulfuric qcid compares with the existing methods of analysis. KI. Gr.
[61]
MICRODETERMINATION OF WATER BY TITRATION WITH FISCHER R E A G E N T . E. L. Bastian, H. Siegel and A . B . Bullock. (Shell D ev el o p m en t C o . , E m e r y v i l l e , C a l i f . , U . S . A . ) Anal. C h e m . , 31 (1959) 467. An ap p arat u s f o r d i r e c t m i c r o t i t r a t i o n of w a t e r with Karl F i s c h e r r e a g e n t is d e s c r i b e d . Water f r o m 0.01 m g to 3 mg can be detected. A m i c r o c e l l is used with n o r m a l a m p e r o m e t r i c indication by m e a n s of a F i s h e r E l e c t r o p o d e . The standard dev i at i o n is below 1%. KI. Gr. SEE ALSO: [ 2 3 , 3 1 , 3 2 , 8 9 , 97,114,115].
4. POTENTIOMETRY
[62] t;REC1SI~N N U L L - P ~ I N T FOTENTIOME~?RY. A SIMI~LE, RAPID AND A C C U R A T E MET}I~JD F(~R LCgV¢ CONCENTRATION CHLORIDE DETERMINATIONS. H.V. Mahnstadt and J . D . \ V i n e f o r d n e r . (Dept.of Chem, and Chem. E n g , , U n i v e r s i t y of Illinois. U . S . A . ) Anai. Chim. Acta, 20 (195"9) 283. In o r d e r to e l i m i n a t e tne difficult,ten'inherent in t h e r e g u l a r c o n c e n t r a t i o n cell method (absolute potential n~easdrernemt~s);a~i/d r e a d i l y p r o v i d e r e s u l t s of b e t t e r a c c u r a c y , a new technique haS~Been~kteW~[~ed Which is h e r e i n r e f e r r e d to as P r e c i s i o n Null-l~oint l~otentiometry. Thfs nev~'~ rapid and acCurate p o t e n t i o m e t r i c technique is d e s c r i b e d for the d6termlnatiori~0f :chloride in the co n cen t r at i o n range llY o to 10-: M. },or many s a m p l e s r e s u l t s 'can be obtained in l e s s than a m i n t i t e
Journal of Electroanalytical Chemisl~
VOL. 1
10 g o f s a m p l e a r e made up with 5 m l o f 6 % w / v urea solution and with 0.5 ml of 1+1 HC1. Dilute exactly to 250 ml. D i s i n t e g r a t e ~he m e a t and f i l t e r . 40 ml of the filtrate a r e placed in a 50 ml c a l i b r a t e d flask and made up with lead acet at e as d e s c r i b e d for b r i n e s ; t h e r e a f t e r the p r o c e d u r e is the s a m e as l o r b r i n e s . Author i n v e s t i g a t e s also the b e s t conditions for a c o m p l e t e and r e p r o d u c i b l e nit r at i o n r e a c t i o n by p o l a r o g r a p h y , c o u l o m e t r y and absorption s p e c t r o p h o t o m e t r y ; under the proposed conditions nitration is quantitative. Chloride ion i n t e r f e r e s with nitration only if w a t e r is p r e s e n t ; n i tr i te ion i n t e r f e r e s with the p o l a r o g r a p h i c wave and m u s t be r e m o v e d by u r e a ; a m i n o a c i d s (tyrusine, phenylalanine and glutam i n i c acid) have no effect. G. de An. [60] P(gLARt)GRAPHIC OXIDATI()N tJF I~HEN~THIAZINETRANQUILIZERS. l-.Kabasakalian and J. IVicGlottcn. (Chemical Research and Development Div., Schering Corp., Bloomfield, N . J . , U.S.A.) Anal. Chem., 31 (1959) 431. Tranquilizers of the phenothiazine type give a well-defined and reproducible polarographic curve at a Au microelcctrode. Under the same conditions imll wave potentials depend on the substitution of the molecule. The voltametric curves of 14 tranquilizcrs Imve been studied to determine their analytical applicability. The effect of the 2- and 10-substituents are discussed. The half wave ix)t~,ntial is influenced by temperature. Sulfur is the most likely point lor an oxidative attack. The half-wave potential is fairly independent of pll, but analytical det~,rminations should be based on pH controlled acid solutions. Standard deviation is about 0.6%. The voltametric oxidation of these compounds in aqueous sulfuric qcid compares with the existing methods of analysis. KI. Gr.
[61]
MICRODETERMINATION OF WATER BY TITRATION WITH FISCHER R E A G E N T . E. L. Bastian, H. Siegel and A . B . Bullock. (Shell D ev el o p m en t C o . , E m e r y v i l l e , C a l i f . , U . S . A . ) Anal. C h e m . , 31 (1959) 467. An ap p arat u s f o r d i r e c t m i c r o t i t r a t i o n of w a t e r with Karl F i s c h e r r e a g e n t is d e s c r i b e d . Water f r o m 0.01 m g to 3 mg can be detected. A m i c r o c e l l is used with n o r m a l a m p e r o m e t r i c indication by m e a n s of a F i s h e r E l e c t r o p o d e . The standard dev i at i o n is below 1%. KI. Gr. SEE ALSO: [ 2 3 , 3 1 , 3 2 , 8 9 , 97,114,115].
4. POTENTIOMETRY
[62] t;REC1SI~N N U L L - P ~ I N T FOTENTIOME~?RY. A SIMI~LE, RAPID AND A C C U R A T E MET}I~JD F(~R LCgV¢ CONCENTRATION CHLORIDE DETERMINATIONS. H.V. Mahnstadt and J . D . \ V i n e f o r d n e r . (Dept.of Chem, and Chem. E n g , , U n i v e r s i t y of Illinois. U . S . A . ) Anai. Chim. Acta, 20 (195"9) 283. In o r d e r to e l i m i n a t e tne difficult,ten'inherent in t h e r e g u l a r c o n c e n t r a t i o n cell method (absolute potential n~easdrernemt~s);a~i/d r e a d i l y p r o v i d e r e s u l t s of b e t t e r a c c u r a c y , a new technique haS~Been~kteW~[~ed Which is h e r e i n r e f e r r e d to as P r e c i s i o n Null-l~oint l~otentiometry. Thfs nev~'~ rapid and acCurate p o t e n t i o m e t r i c technique is d e s c r i b e d for the d6termlnatiori~0f :chloride in the co n cen t r at i o n range llY o to 10-: M. },or many s a m p l e s r e s u l t s 'can be obtained in l e s s than a m i n t i t e