Why is this such a good pH Electrode? S H O W N A C T U A L SIZE
Refill aperture for r e f e r e n c e e l e c t r o d e has a r u b b e r c a p t o p r o v i d e a t i g h t seal a g a i n s t l e a k a g e o r creepage.
Special connecting . cable e l e c trically shields the inner conductor and has a t o u g h w a t e r - p r o o f c o v e r . It is n o n - m i c r o p h o n i c , d o e s n o t g e n e r a t e v o l t a g e or c a p a c i t y c h a n g e s to affect meter reading when moved.
Internal E l e m e n t s in glass a n d r e f e r e n c e e l e c t r o d e s are i d e n t i c a l for t h e r m a l a n d e l e c t r i c a l s y m metry to speed t e m p e r a t u r e e q u i l i b r i u m and r e d u c e a s y m m e t r y p o t e n t i a l . C a r t r i d g e f o r m Thalamid , 5 y (thallium amalgam) e l e m e n t s are c h a r a c t e r i z e d by s u p e r i o r s t a b i l i t y and l o w h y s t e r e s i s o v e r t h e e n t i r e t e m p e r a t u r e range, rapid temper a t u r e e q u i l i b r a t i o n and f r e e d o m from polarization.
Stainless steel cap of 1 8 / 8 / 2 c o m position resists the chemical a t t a c k of l a b o r a t o r y a t m o s p h e r e s and provides the mechanical strength for positive and secure clamping.
• p H m e m b r a n e glass is t y p e U ( u n i v e r s a l ) or t y p e Η Τ Α (high t e m p e r a t u r e - h i g h alkali): Type U a g e n e r a l p u r p o s e glass s u i t a b l e f o r all a p p l i c a t i o n s e x c e p t t h o s e involving high temperature and h i g h s o d i u m ion c o n c e n t r a t i o n s (high alkalinity) simultaneously. R e s p o n s e is v e r y c l o s e t o t h e N e r n s t i a n t h e o r e t i c a l and l i n e a r e v e n in h i g h l y a c i d s o l u t i o n s . S o d i u m i o n r e s p o n s e is v e r y l o w ( i n s i g n i f i c a n t b e l o w p H 12.5 at room temperature) and, even m o r e i m p o r t a n t , it is s t a b l e w h e r e s i g n i f i c a n t . T y p e U glass e l e c t r o d e s m a y be u s e d c o n t i n u o u s l y f r o m 0 ° t o 8 0 ° C, i n t e r m i t t e n t l y t o 1 0 0 ° C. L o w s p e c i f i c r e s i s t a n c e a l l o w s a 0.5 m m wall w i t h a total r e s i s t a n c e of 1 0 0 - 1 5 0 m e g o h m s (10 m m b u l b ) at r o o m t e m p e r ature. The heavy wall, high in h e r e n t glass s t r e n g t h and c a r e f u l f a b r i c a t i o n r e s u l t in a s t r o n g , shock resistant construction.
Liquid junction c o m p r i s e s a plat inum thread seated into the glass w a l l of t h e r e f e r e n c e e l e c t r o d e . This j u n c t i o n p r o v i d e s l o w r e s i s tance with a low electrolyte leak rate a n d is r e s i s t a n t t o c l o g g i n g by s l u r r i e s a n d v i s c o u s s o l u t i o n s . J u n c t i o n s are l o c a t e d i m m e d i a t e l y above the pH-sensitive surface for m i n i m u m sample r e q u i r e m e n t .
There are a lot of reasons. Reasons like the scientific re finement of old-world glassworking skills. Like continual innovation wed to more than a quarter-century of experi ence. And a specially focused understanding of e l e c t r o chemistry, glass-materials re search, and quality control. All of these skills have con tributed—and continue to con tribute—to the technological sophistication of this decep tively simple looking combina tion electrode, which we use so casually and take so much for granted. The thought and care we've put into our combination elec trode are detailed on this page. And we'll be happy to send you further information on this electrode and on our separate glass and reference electrodes of comparable quality.
EHS-Z-UI
S-30072-15 COMBINATION ELECTRODEGeneral Purpose, Type U, Sargent-Welch 45.00 S-30072-20 COMBINATION ELECTRODEHigh Temperature, High Alkali, Type ΗΤΑ, Sargent-Welch 46.50
SARGENT-WELCH Scientific instruments, apparatus, chemicals. Sargent-Welch Scientific Company 7300 N. Linder Ave.; Skokie, Illinois 60076 Chicago/Anaheim/Birmingham/Cincinnati Cleveland/Dal las/Denver/Detroit Springfield, N.J./Toronto/Montreal/Vancouver
T y p e ΗΤΑ - f o r a p p l i c a t i o n s in w h i c h t h e e l e c t r o d e is e x p o s e d simultaneously to high alkalinity a n d t e m p e r a t u r e s t o 1 3 0 ° C. S o d i u m i o n e r r o r is v e r y s m a l l and r e m a i n s s t a b l e e v e n after t h e e l e c t r o d e has b e e n u s e d at h i g h temperatures.
Internal buffer is s p e c i a l l y c o m p o u n d e d for s t a b i l i t y w i t h t e m p e r ature change and with time, and for c o m p a t i b i l i t y with the glass s u r f a c e . N o m i n a l p H is 7, s u i t e d t o all c o m m o n p H m e t e r s .
CIRCLE 1 8 8 O N
READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL. 44, NO. 11, SEPTEMBER 1972
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