INSTRUMENTATION


INSTRUMENTATIONpubs.acs.org/doi/pdf/10.1021/ac60119a773their badges inorder to indicate a lan- guage preference. All rep...

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INSTRUMENTATION

Some 1 4 0 0 p e o p l e from 4 7 countries a t t e n d e d the 15th International Congress of Pure a n d A p p l i e d Chemistry

THE m a n y pleasant and commendOFable things which can and will be said about the X V t h Congresso Internacional de Quimica P u r a e Aplicada here in Lisbon, Sept. 8 to 16, none can describe completely t h e charm and vitality of Lisbon and the superb hospitality of its enterprising citizens. This analytical congress, attended by some 1400 people from 47 countries, has a truly international aspect and all participants have been "color coded" in their badges in order to indicate a language preference. All reports to t h e contrary notwithstanding, and despite its widespread use, English,is not t h e best resource in Europe. French is still indispensable and we were reassured, if faintly, t o note t h a t we were not alone in occasional effort to mutilate t h a t beautiful tongue. Among t h e dozens of distinguished Portuguese who labored well in excess of one year to organize this congress, three were exceptionally helpful in enabling us t o obtain material for this column and t o describe a t least one aspect of its several activities. We are able to present a picture of these three gentlemen. I n the center is D . Antonio Pereira Forjaz, professor and director of the Faculty of Science of the University of Lisbon a n d president of t h e Portuguese Society of Chemistry and Physics, who served as president of the congress. On the left is Pierre Laurent, professor of t h e I n stituto Superior Técnico, secretary of the congress, and well-known authority on organic chemistry, especially essential oils. Professor Laurent is on loan to the Portuguese government by the French government and has done much to establish laboratories of organic chemistry a t the institute. On the right is Antonio Hercuiano de Carvalho, also professor at the Instituto Superior Técnico. Through the courtesy Of the latter, we are able to present a view of the laboratory of electrochemistry and electroanalysis (this page). T h e students in this laboratory receive detailed instruction in every phase of electroanalysis a n d in the equipment are several familiar American instruVOLUME

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ments as well as fine examples of European manufacture. Experiments in polarography, amperometric titration, electrodeposition, and high frequency titrations are performed here. An example of the s p e c t r o g r a p h s equipment in an adjoining room of the laboratory is shown below, right. Several floors of the spacious institute were devoted to meetings, and a general exhibition of textbooks, apparatus, chemicals, and analytical instruments. American, British, and continental manufacturers were well represented by

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a fairly complete offering of instruments and apparatus. Several views of the equipment booths are shown on the next page. Invited lectures were given by Tselius, Martin, Kolthoff, Marti, Chariot, Feigl.

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Pierre Laurent, D. Antonio Pereira Forjaz, and Antonio Hercuiano de Carvalho

m Laboratory of electrochemistry and electroanalysis, Instituto Superior Técnico, Lisbon

Large glass-quartz spectrography laboratory of electrochemistry and electroanalysis

11, N O V E M B E R

1956

63 A

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instrument abstracts Applied Physics

Corporation/Pasadena/California

Double Monochromator Provides Low Stray Light, High Resolving Power Spectrophotometer users can m e a s u r e high absorbance values with the s a m e speed, a c c u r a c y and relia­ bility a s other m e a s u r e m e n t s by using a C a r y Recording Spectrophotometer which incorporates a double mono­ c h r o m a t o r to virtually eliminate s t r a y light and provide unusually high r e ­ solving power. W i t h single m o n o c h r o m a t o r in­ s t r u m e n t s , s t r a y light interferes so g r e a t l y with m e a s u r e m e n t s a t high absorbance values t h a t the d a t a ob­ tained and conclusions d r a w n a r e often meaningless. Frequently, such d a t a are reported in the l i t e r a t u r e a n d it is impossible to confirm this d a t a -with careful w o r k using a relia­ ble i n s t r u m e n t . S t r a y light can be corrected for, b u t a g r e a t deal of e x t r a d a t a and t e ­ dious calculations a r e required which largely n e g a t e s t h e convenience of a recording spectrophotometer. In the C a r y Recording Spectrophotometer, the problem of s t r a y light is handled b y prevention r a t h e r t h a n correction. The double m o n o c h r o m a t o r reduces

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s t r a y light to a negligible a m o u n t over the entire r a n g e of t h e instru­ ment—less t h a n 1 p p m for the most part. H i g h r e s o l v i n g p o w e r in t h e double m o n o c h r o m a t o r results not only from dispersion which is twice a s g r e a t , but a b e r r a t i o n s in one-half of the m o n o c h r o m a t o r m a y be concelled in the other half. Also, by com­ bining two different t y p e s of dispers­ ing elements, the a d v a n t a g e s of each m a y be combined to give b e t t e r per­ formance over a wide r a n g e . I n t h e C a r y Model 14, for e x a m ­ ple, a prism and a g r a t i n g are com­ bined to give high resolving power over the entire ultraviolet, visible and near infrared regions. Resolving power is about 1A in the visible and ultraviolet and 3A in the n e a r infra­ red—nearly ten times the a c c u r a c y offered by single m o n o c h r o m a t o r in­ struments. F o r complete design and per­ formance information on C a r y R e ­ cording Spectrophotometers, w r i t e for bulletin ACS-19.

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n^ 1ρ n II 11 The HC1 spectrum, above, is the rotational fine s t r u c t u r e , a n d the p a t t e r n of a large peak |

Schopfer, Cruse, Duyckaerts, Debiesse, Schwarzenbach, Wernimont, Zacherl, Herculano de Carvalho, and Forbes, and will be published in book form b y Birkhâuser of Basle. Among the m a n y scientific papers presented a t t h e congress, a few of exceptional interest are mentioned: P a cault's rapid and convenient electronic device for the measurement of magnetic susceptibility, Liberti's use of coulometry for titrating the effluent of chromatographic columns, and the ultramicrospectrophotometric analysis of paper chromatograms by M m e . Lacourt of Brussels.

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followed by a smaller one is due to the presence of two chlorine isotopes. These p e a k s a r e s e p a r a t e d by a b o u t 10A (3cm-I) VIBRATING REED AMPLIFIER IMPROVES MASS SPECTROMETER PERFORMANCE

The C a r y Vibrating Reed Ampli­ fier, Model 36, is being used in a n increasing n u m b e r of m a s s spectrom­ e t e r installations w h e r e high molec­ u l a r weight analyses m a k e rapid scanning of m a s s n u m b e r s desirable. The Model 36 combines rapid r e ­ sponse with high sensitivity. Response is critically damped, with an 0.1 sec. n a t u r a l period (98.6 percent response in 0.1 second). T h u s a r a n g e of 100 m a s s n u m b e r s can be a c c u r a t e l y scanned in as little as one minute. Sensitivity and r a n g e are such t h a t as little as 10- l s a m p e r e s and up to 10- ' ' a m p e r e s can be measured to a if»

reproducibility of 0.2 percent with­ out change of r a n g e . Stability of the Model 36 is superior too —zero drift is less t h a n 10- | δ amperes. A n o t h e r C a r y i n s t r u m e n t of in­ t e r e s t to m a s s s p e c t r o m e t e r users is the Model 31 Vibrating Reed Elec­ t r o m e t e r . I t is preferred for m e a s ­ uring ion currents in work where extreme response speed is not re­ quired, such as isotope determina­ tions. Sensitivity of t h e Model 31 is 10- 7 amperes, and like the 36 it h a sl 7 high stability — less t h a n 5 χ 10a m p e r e s zero drift. W r i t e for bulletin ACE-19.

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Ca /*.(/ instru m cuts : SPECTROPHOTOMETERS V I B R A T I N G REED AMPLIFIERS

APPLIED PHYSICS C O R P O R A T I O N

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RAMAN

ELECTROMETERS

SPECTROGRAPH

INFRARED ANALYZERS

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ULTRAVIOLET

3 6 2 WEST COLORADO STREET /

PASADENA

ANALYZERS Τ /

CALIFORNIA

For further information, circle numbers 64 A-1, 64 A-2 on Readers' Service Card, page 79 A

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Equipment booths a t exhibition ANALYTICAL

CHEMISTRY