Applications in continuous process instrumentation appear likely for mass spectrometry by B. W. Thomas
With the ever-increasing market demand for higher quality automotive fuels and lubricants, greater purity day laboratory analytical techniques, chemicals, and more consistent feedthe science of mas$ spectrometry is stocks for synthesis operations, there about ready to extend its sphere of is currently a growing need for rapid applications beyond the laboratory and more complete analysis data on and into the highly activated field of flowing process streams. The process continuous process instrument,at'ion. mass spectrometer, although not yet So successful have been the complex capable of fully automatic measureand expensive laboratory models of ment and control of several variables this 20th century analytical giant that within a stream, does afford a means both manufacturers and potential for rapid qualitative monitoring and users are extremely enthusiastic somewhat less rapid quantitative toward the development, manufac- measurement of multiple components ture, and marketing of the simpler in flowing mixtures. Mass spectrometers expected to be and less expensive process mass spectrometers. These new version mass made available in this country during spectrometers, although developed pri- 1954 will employ three different ion marily for rapid analysis of flowing separation principles. These are the streams, may also satisfy the labora- familiar magnetic deflection, the ion tory analytical needs of many uni- resonance, and the radio-frequency versities and industrial organizations. linear accelerator. Production of Reasons for interest in simple model positively charged ions or molecular instruments are straightforward. Mar- fragments in each instrument is ket demands for complex and costly accomplished by bombardment of analytical instruments have declined neutral molecules with low energy rather sharply during the past 2 electrons from a hot wire filament. Separation of masses in the magnetic years. Most industrial and research organizations with extensive analytical deflection process instrument results requirements are already operating one from passage of the ions at right angles or more of the laboratory model instru- to the field of a permanent magnet. ments. Management is anxious to For a given voltage across the ion reduce the expense of transmitting accelerator slits all masses are prosamples from process to laboratory. jected toward the magnetic field with Process control instruments gener- the same kinetic energy. Upon pasally monitor only one component, sage through the magnetic field, the quality, or characteristic of a product. positively charged particles experience Examples of such instruments are non- path curvatures inversely propordispersion infrared analyzers, ultra- tional to their masses, as in Figure 1, in violet spectrophotometers, specific which SIand Xzare ion accelerator slits, gravity recorders, refractive index H is the 60' sector magnetic field, monitors, and dielectric constant and ml, m2, and m3 are separated ion meters. Measurement of a single groups with increasing molecular variable or component is of value in weights. By means of slit St in front control of a process only if the exact of collector plate P it is possible to relationship is known between that H variable or compound and the desired quality characteristic of the product. Such a relationship is usually not known and in many cases does not + F exist, because of variable interference from minor constituents. Figure 1. Magnetic Deflection
developing during the past 10 A years into one of the most nearly indispensable and widely used presentFTER
November 1953
measure only one mass beam at a time. Scanning of the entire mass spectrum or selection of particular mass groups is achieved by voltage variations on the ion accelerator slits. Shunts are placed across the permanent magnet to permit measurement of low mass particles. This crossed magnetic field instrument is being manufactured and marketed by the Consolidated Engineering Corp., Pasadena, Calif., and further details may be found in CEC Recordings, 7, 8 (April 1953).
Pi Figure 2.
Ion Resonance
The ion resonance instrument makes use of the cyclotron principle in that it employs the field of a permanent magnet and a radio-frequency alternating electric field for separation of masses. Ions resulting from an electron beam parallel to the magnetic field and a t right angles to the alternating electric field experience a toand-fro motion in the electric field and eventually acquire a spiraling motion around the electron beam. For given frequency of the alternating electric field, it is possible for only one mass group of ions to continue in the spiraling motion with an increasing radius until they reach a target on the periphery of the spiral. All other masses possess an out-of-phase relationship with the alternating electric field and cannot gain sufficient radial displacement to reach the target of the instrument. Essential features of the ion resonance mass spectrometer are
INDUSTRIAL AND ENGINEERING CHEMISTRY
85 A
When you're talking
IS
9970 PURE
1
ETHYLENE I
PURE ENOUGH? ...
Problem To secure the highest possible purity in ethylene production, with minimum contamination by ethane and methane. under continuous production conditions.
Instrumentation shown schematically in Figure 2, in which F is the filament, e the electron beam, H the magnetic field, P , the mass target, P, the electron collector plate, and SIand Xp the alternating electric field slits. Scanning of the mass spectrum or selection of a particular mass group for measurement is accomplished by variation of frequency of the alternating electric field. Early experimental work on this instrument, conducted by J. 8. Hipple and coworkers at the Bureau of Standards, is described in Phys. Rat., 82, 697 (June 1951). Further developmental tests and operational techniques were carried out jointly by General Electric Go., Schenectady, X, T..and the Baton Rouge Esso Laboratories of the Standard Oil Development Co. The instrument is manufactured hy General Electric.
..
Approach. Continuous analysis of the product stream, by means of differential infrared absorption. to replace slower batch methods of analysis involving orsat techniques or mass spectrometry.
..
Instrumentation , Baird ASsociates infrared-type Plant Stream Analyzer. for simplicity, speed, sensitivity. proved reliability under plant conditions, and continuous automatic indication.
.Results
...
The Plant Stream Analyzer in this application is calibrated to indicate 95% ethylene purity at scale zero, and 100% a t full scale. Concentration can b e read to an accuracy of 0.1%. Small variations in concentration are revealed almost instantly, allowing process readjustment in ample time to prevent any significant loss in product quality.
PROCESS CONTROLS 86 A
v2
Figure 3.
linear Accelerator
Mass separation in the linear accelerator mass spectrometer is accomplished by means of a radio-frequency alternating electric field. This instrument does not require a magnetic field. After formation by electron impact, all positively charged ions receive the same energy of motion from a direct current voltage and move into a series of evenly spaced sctem grids. As shown in Figure 3, F iq a spiral ribbon filament, dland *A2 a I e n4tle-aperture ion accelerating dits, Vi and are alternating low voltage electrodes with three screen grids each, D is an ion decelleiator grid, and P is an ion collector plate. Since kinetic energy is a function of mass times velocity squared, pat ticles having different masses will also have different velocities. If, upon passage through the grids, the velocity (foi one mass group) and radio-frequency field relationship is such that the direction of the electric field reverses just as a particular mass group passes each grid, that group of ions will receive additional energy from the radio frequency field. All other masses having different velocities will be out-of-phase with the changing electrical field and
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 11
AN INTERMEDIATE WITH MANY USES
ODIUM CHLOROACETATE, Tech.
Wide variety of reactions and ease of handling in processing enable this intermediate by DOW to work efficiently and capably in many industries Sodium chloroacetate, Tech., by Dow is used as rn intermediate in several different type reactions :.nd chemical process applications. Investigate this product for your needs with assurance of top product quality and a dependable supply. Sodium chloroacetate is a fine, white powder in
a stable form for easier handling in 'processing. Prompt delivery of this and your other chemical needs is assured by the widespread Dow distribution system. For an evaluation sample and further information, write to THE DOW CHEMICAL COMPANY, Midland, Michigan, Dept. FC 3-24.
you can depend on DOW CHEMICALS November 1953
INDUSTRIAL AND ENGINEERING CHEMISTRY
87h
Instrumentation mill lose velocity. Thus, it is possible by varying the frequency of the elecatric field to permit only one mass group of ions t o pass through the entire series of gvids for measurement. Other ions will lose enei stopped prior. to reaching a collector plate at the far end of the linear accelerator. Details of the linear radiofrequency mass spectrometer have been published by W. H. Bennett [ J . A p p l . Phys., 21, 143 (196O)J and P. A . Redhead jCanmdiun J . A p p l . Phys., 30, 1-13 (1952)l. Beckman Instruments, Ino., Pasadena, Calif., will market this analyzer.
The Fluidometer System provides an accurate, dependable, and completely automatic method for batching liquids, either light or heavy. It is available in either jacketed or unjacketed construction, and is adaptable to practically any liquid measuring problem, whether it involves gallons, barrels or tank car lots. Equally accurate o n liquids of high or low viscosity. Anything that can be handled through a meter can be accurately batched by the Fluidometer. The automatic reset, an exclusive feature of Fluidometer, is invaluable in large scale production work requiring steady repetition of operations. Bulletin F1-49, giving complete information o n the Fluidometer System, will be sent o n request.
Although handicapped somewhat by a relatively low resolving power of approximately 20, the magnetic deflection instrument has the firm backing of Consolidated Engineering Corp.'s many years of successful experience in the construction, operation, and servicing of analytical mass spectrometers. For the analyses of flowing streams to which this instrument is applicable there is little doubt, that reliable and continuous performance may be achieved with minimum maintenance arid operational dificulties. The ion resonance mass spectrometer is reported to have a resolution near 90 and it should afford a slightly greater sensitivity than is normally available from mass separation tubes in which ion slits are employed. This instrument has an exceptionally high resolution for low masses, as it is capable of complete separation between parent ions from helium and deuterium a t the mass four level. General Electric, manufacturer of the ion resonance instrument, also has had experience in the development and construction of an analyticaltype magnetic deflection mass spectrometer. The linear radio-frequency mass spectrometer is capable of an unusually high ion sensitivity which depends upon the aperture cross sectional area and percentage free space of its screen grids. Resolving power in this instrument increases with the total number of high frequency grids employed, and is reported to approximate 100 for 20 grids. Production of this instrument represents the first experience in the field of mass spectrometry for Reckman Instruments. I n order t o achieve the ultimate in procdss mass spectrometry, it will be necessary for the manufacturer to provide an instrument which will continuously feed spectral data into other computing mechanisms for automatic: control of complex processes.
H E T H E R I N G T O N & B E R N E R INC.
Correspondence ooncerning this column will be forwarded promptly if addressed t o the author,
733 K E N T U C K Y AVE.
yo Editor. INDUSTRIAL AND ENGINEERING CHEMISTRY, l1.i5---16th St., N.W., Washington
and domestic production program Durametallic is geared to engineer or produce the very best in metallic packings and mechanical seals for refineries, chemical plants, pipe lines, ships, power, synthetic rubber and general industry.
..
F I L E NO. F I E M l G H I O l N
THE
j
ySYSTEM
Adaptable to a wide variety of measuring problems
I N D I A N A P O L I S 7, I N D .
6, D. C.
88 A
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 11
dcmp 0
a
1 *
WATER GONDITIONING’S GREATEST STRIDE AHEAD! Two leuders join forces to give you A New and Brouder Water Conditioning Service Yes, two of the great names in water conditioning are united: Refinite Sales Co. has joined Elgin Softener Corporation. Now it is “Elgin-Refinite, Inc.” , . and this linking of products, experience, men and methods truly marks the beginning of a new era for those who seek the answer to a water conditioning problem. You know these firms. Both have played major roles in water conditioning for a long time: Elgin since 1708; Refinite, since 1716. But now through the
.
-
-
-
pooling of the best of all they have learned each has made its greatest gain. The Elgin-Refinite man has something new for you -something he did not have as an Elgin man or as a Refinite man. He has something new in products and viewpoint that enable him to give you the most direct, effective, economical solution to A N Y water conditioning problem. The coupon provides a convenient way to ask for the Elgin-Refinite solution to your problems,
ELGIN REFINITE, INC, A DIVISION OF ELGIN SOFTENER CORPORATION, ELGIN, ILL. REPRESENTATIVES IN PRINCIPAL CITIES
SEND FACTS ABOUT: 0 Water
0
Deionirers;
0
Softeners;
Deaerating Heaters;
0 Clarifiers;
Filters;
Chemical Treatment.
Swimming Pool Equipment. Water Conditioning for:
0 Boilers; 0 Processing; 0 Waterworks;
(If you have other needs attach note)
0
Hurry
Toke Your Time
0 Send
Representative
Cornpony Street
IN C A N A D A : November 1953
0. F. STERNE A N D S O N S , BRANTFORD
1
h
--
Moil to Elgin-Refinite, Inc., 166 North Grove Ave., Elgin, 111.
INDUSTRIAL AND ENGINEERING CHEMISTRY
89 A
Another leading manufacturer using
These Durco Type B Valves have been in sulfuric acid service at the Bristol, Pa., plant for more than 3 years.
T h e D u r c o T y p e B Valves pictured here have been in service since 1950, handling corrosives ranging from dilute sulfuric acid a t 150’ F. to a mixture of concentrated sulfuric acid a n d organic materials a t 200’ F.
Rohm 8 Haas Company manufactures plastics, synthetic resins and chemicals for o w i d e v a r i e t y o f industries. Among the products manufactured at their Bristol plant i s Plexiglas, their acrylic plastic. Plexiglas i s widely used for outdoor signs, transparent aircraft enclosures, automobile stop ond tail light lenses, nameplates for home appliances, and a host of other products.
D U R C O T y p e B Valves are h e a v y - d u t y chemical service plug valves, either t o p or bottom lubricated. T h e y are available with flanged ends in sizes from 1” t o 8”, a n d with screwed ends from Y2’’t o 2” in a wide range of DURCO corrosion resisting alloys including D u r i m e t 20, Chlorimet 2, Chlorimet 3, 18-8-S-Mo, a n d others.
W r i t e for Bulletin V / 2 , and d e termine how D U R C O can help solve your corrosion problems.
90A
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 45, No. 11
