Topics in..
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Chemical Instrumentation
feature
Edited by GALEN W. EWING, Seton Hall University, So. Orange, N. J. 07079
These articles are intended to serve the readers of THIS JOURNAL by calliny allenlion lo new developments i n the theory, design, or availability of chemical laboralory instrumentation, or by presenting useful insights and ezplanations OJ topics that are of practical importance to those who use, m leach /he use of, modern instrumentation and instrumental techniques. The editor invites correspondence from prospective contributors.
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XLIII. Mass Spectrometers
-Part
Three
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Commercial Spectrometers GALEN W. EWING
The following drscriptions arc nrmngrrl alphnl~etically hy compmics. Spceialplu'poseinstnimenta, sr~chnalcnkdebertors, sr:ucely npplicnblc to mass spectrometry, are not includrd. Priccs nrs given in thousands of dollars, and arc only approximate, vnrying with sclcction of optional nceessories.
Aero Voc Corporation ,l his company offcrs as their moat
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ndvnnccd mass spcctrometcr thc Modcl 686, which is optimiacd for high sensitivity in trace gas andysis whcro only moderatc resolution is reqnircd. I t i~ ilhlstrntod in Figlire 24, with an accessory gas chromstograph inlet systom. Tho analyeer itself includes two magnctic sectors in tandem, oriented to doHcet tho he;m in opposite direotions. This is followcd by xn electrost,atic cncrgy filter and an electron multiplicr detector. The mnsa range is 1 to 500 amu, with unit resolution of 250 (1% cross contriln&n). Thc dctcction limit is q ~ ~ o t etod be better than 2 parts in 108 for gases of less than 50 molecular weight, present as impurities in argon ($27).
A similar instrnmcnt, the Model 685, can he had a t lowcr cost and with relaxed specifications (2 to 300 xmu, reaohttion 200; $16). Thc IKodcl 610-611 is n rlesktop, 60' pelmencnt-magmlt sector, spcctromcter with :L mass xmgo to 300 nmlt (500 optional), :md a resolrltion of 200-250 ($6, without vacuum systcm). ,\or0 Vnc also offcrs several mass nnnlyscrfi intendcd for process control, and n series of r e a i d d gas xnalyaers.
Avco The Avco Model 90000 mass ~pcet,rometcr is a 90"-deflcctian mngnctir scetor instrument wirh resolution of bctter than 6000 (10% valley dcfinitian). I o n s e m l x ol)served with m/e as high : ~ s10,000, The xn:~lyaer is nniqnc in Lhst thc ion hcnm cnters the magnctic field a t ;L small angle (12") from normall which permits morc flosil,ility in focus through mcehnnical ndj~~stments in thc poait,ion of t.hc magnet. The field is nccorutcly progrsmmcd with thr aid of 3. I M - ~ f f c rpral,o t and amplifier with the mngnct windings in its fccdb:wk' loop. Avco spccinliaes in custom desigh of spcct,rometer s y r t c m ~l~uiltaronnii the basic nnit, lntt with ehoicc of n variety of sollrePs,.detcctors, nnrl othrr fcaturra. A data analysis system (Modcl 91000) is nvsil:tldc which ties thc mass spretrometcr to an Avco PCIJ 8-1200 digital eompotcr, so that the campntcr rontrols t,hc operstion of the spectrometer ns well xs procevsing the ncquit.ed data.
Fig"m 25. Be"dh Model 3012 The-of-Flight Morr Spectrometer. The heated inlet system of Figure 3 appears a t the l e h with o micramonometer. The vacuum system is controlled from the panel beneoth the expored spectrometer tube. The electronic controls ore located in the main sloping panel. The rmoller sloping unit to the right contoins lhe controls for the Knudren source. The read-out oscillorcope can be reen a t lhe extreme right.
of 500 (1% contribution). The ion flight path is 200 cm long, leading to a magnetic electron multiplier detector. An optionnl gating featurc (peak diminstor) permits attenuating thc signal due to any aelected m/e species by a factor of lo4. This can he usctl to prcvent, ovurlosding thp detector, ns with thc hclium carrier in gas chl.omntography (336). The Modcl 3015 is similar l ~ hnr t provision for obscrving negative as well as positive ions. Another morlificntion incorporntes n lnscr microprohe sourcc (see ~ i g :6 ) . The hlodel MA-1, shown in liigurr 26, is reprcsent,at,ive of sevornl smaller timeof-Hight spectromcters. I t covcrs tho range 0 to 500 amu with nnit resolution of
Bendix Corporation Figure 24. Aero Vac Model 686 Mass Spectrometer Troce Gas Anolyrer. The left-hand portions ore the m a u spectrometer proper; the valves ond electrical controls for o gar chmmotogroph inlet system oppeor a t the right.
A numl,er of models of timc-of-Hight spcctrometcrs arc availnl~le. One of thest?, the Modd 3012, s large research infitroment, is shown in Figorc 25. I t covers z rangr of 0 to 1200 nmu, with a resolution
Figure 26. Bendix Model M A - l Time-of-Flight Moss Spectrometer. The vacuum controlr ore beneath the toble, the electronicr above.
(('onlinirrrl on
pitgr. A2.7.4)
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Chemical instrumentation Consolidated Electrodynamics (Bell 8 Howell) This company, frequently known by its initials CEC, has one of thr more extensivc lines of mass spectrometers manufactured in America. The most elaborate of these is Model 21-110, a doublefocus mass spectrometer and spectrograph with MattauchHerzog geometry (Fig. 27). I t offers sample-handling facilities for gascs, liquids, and solids. A variety of ion sources can be employed, including electron bombardment, K F spark, surface ionization, and Knudsen cell. Detection is by photoplate, electrometer, or electron multiplier. Resolution with the gas source is a t least 30,000 (10% ',valley definition), with the spark source, 2000 or better. The mass range extends to 2500 arnu ($100-120).
Figure 27. CEC Model 21-1 1 0 Double-Focus Mass Spectrometer. The multiple source unit is seen a t the left-hand end of the spectrometer tube; the electric rector oppeors just over the fourth electronk panel; the magnetic 3ector is next, followed by the multiplier detector and [behind it) the photoplate looding mechanism. The racks to the right carry doto-proces3ing ond recording equipment.
The CEC Model 21-104 (Fig. 28) is a. high-precision, general-purpose instrument with a 180" magnetic sector. I t covers the range up to 2000 amu. The resolution is norrndly 600 (10% valley), but can be increased to about 2500 by reducing the width of the collector slit, with a concomitant reduction in sensitivity ($4&60).
Figure 28. CEC Model 2 1 - 1 0 4 Mar, Spectrometer. The botch inlet ryrtem stand. o t the left next t o the magnet. The cylindrical unit projecting to the right d the magnet houses the electrometer preamplifier.
Figure 29 shows the CEC Model 21-490, a. 90" magnetic-sector spectrometer. This instrument features a high degree of compactness. Its elo~troniccircuits are
packaged in easily replaceable function (Continued on page AZ37)
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/ Journal o f Chemical Education
Circle No. 148 on Readerr' Service Card
Chemical instrumentation
Figure 29. CEC M o d e l 2 1 - 4 9 0 M o r r Spectrometer. The source is to the left of the mognet, the detector t o the right; recorder not shown.
modulcs. Thc mass range is 12 to 1000 rtmo, with unit resolution up to 1000 (10% valley; 818). An elcctric sector can be purchased as a kit, to convert to the 21491, a double-focus version ($23). This increases tho resolution to about 25,000. These models are intended for general organic and allied applications including gas chromatography. The CEC Model 21-703 spectrometer shown in Figure 30 is a 60" magnetic-sector instrument designed for use in modcrn
cell types. Masses 2 to 1000 amu can be covrrcd; nominal unit resolution is 600 (10% valley; $90-100).
Figure 30. CEC M o d e l 2 1 - 7 0 3 Mar. Spectrometer. The source housing a n d the magnet con b e reen o b o r e the pump system o f the left, a n d the electron multiplier high u p a b o v e the magnet. The arched structure a t the t o p is a b r i d g e t o carry cobler from one unit t o the other.
CEC Model 21-621 is n. versatile spectrometer built on a modolar basis which pcrmits over 100 different combinations. The ani~lysercan be either eycloidal or quadqtpolo. This is a general-purpose instrument adaptable to such uses ns isotopc ratios in gases, gas impurities, blood and hreath gases, and engine exhaust analysis ($8-20). The CnC Model 21-614 is a dual-mode (Continued on page AS%)
Chemical lnstrurnentntion spectrometer for residual gas snalyris. T o covcr the mass range 12 to 200 amu it operates on the cycloidnl principle, b u t for masses 2 to 11 the electric field is turned off and tho spectrometer operates as a 180" deflection sector instrument. It is designed for use in research on electronic vacuum tnhea, vacuum monitoring, atmospheric analysis, ete. ($8). Tho Madcl 21-615 is a nimpler ver~ionwhich covers m s w s 2 to 100 amu in a singlo scan of the eyeloidel analyzer. (53.5) Unit resolution for the 21-614 is 150, for the 21-615, 50 (1% contribution). Model 21-440 is a comparable residual gas snslyser with quadrupole operation, mass range 1 to 300, unit resolution twice the mass number
($5). Electronic Associates, Inc. (EAI)
EAI offers two models of qusdn~pole spectrometers. Thc Quad-300 (Fia. 31) is a versatile laboratory instrument with mass range extending to 800 nmn, and with resolution twicr thc mnsn numher u p to 500. Thc scan can he cxccutrd nutomatically a t various spcedn np to 0.1 scc, fast e n o ~ g hfor many kinetic applic~tiona. Rcnd-out can be by ascilloscopc, oscillogmph, pcn reeordcr, or dircct eonncction to a digital computer ($20). The Qllnd160 is an nlxidged vcrsion which eovcrs thc mngc 1 to 300 amu (%14).
Figure 31. EAI Quod-300 Mar. Spectrometer. The square box with four volver is o rtoiolersdeel inlet ,yrtem. The circulor plate adjoining it covers the actual inlet orifice. The quodrupole rods, not visible, extend horizontally bock behind the cover plate. Both orcillo.cope and orrillograph can be seen in the larger electronic rock.
R.kI also furnishes two residual gas nnnlysers which are in effect the ahovc spectrometers supplied without a sampling system and weuum pumps, to he installed in a mtstomer's vncmm system. Thew nre, respectively, thc Quad-250.4 and Qnad-15OA. Finnigan Instruments Corporation
(Continued on page A240) A238
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Chemicarl Instrumentation opcrates in three ranges, 1-100, 10-250, and 50-750 amn. Resolutiun ia Lwice the mass number. Scan times as small as 500 microseconds a t r e possible. The electron multiplier features replaceable dynodes. In gas chromatographic applications, full sensitivity is obtained without the need of s. helium separator (1620).
Figure 32. Finnigon 1015 Loboratory Moar Specfrometer. The electronic conrole ia to the left, the vocvvm console to the right.
JEOLCO Figure 33 shows the type of construction adopbed by J a p m Electron Optics. All components are exposed to vicw, which makes for convcnicnce in servicing. Opemtar's controls arc collected in one area. The model shonrn, JMS-OlSG, follows the Mattauch-Hersog design, with a mass range of 1 to 3200 smu for photographic detection, 1 to 2900 for electrical detection. The unit resolution is 20,000 (10% valley). The JMS-O1SC is similar, but with resolution of 35,000; tho mass range is 1 4 4 0 0 (electrical dctcction) and 1-3200 (photogrsphie). It. e m be fitted with an RE' spark sourcc for trace element analysis. Model JMS-OlU(M) is a MatbauchHersog instrumentre~trictedto s, spark
Figure 33. JEOLCO Model JMS-OlSG Double Focus M a s Spectrometer, The rampling r p t e m Is on the console to the immediate left of the instrument proper. The electron-bombardment ion source is in the center foreground. The photoplate loading mechonim a t the for end is operated b y means of a hand wheel from the front.
(Continued on page A24S)
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Journal of Chemical Education
Chemical Instrumentation source and photographio detection; mass range 1 to 2000, resolntion 8000 or more.
J o h n s t o n Laboratories, Inc. Figure 34 shows the external appearance of a unique instrument called a Coincidence Mass Spectrometer. I t consists of a time-of-flight spectrometer in which secondary electrons produced in the ionizing events are pulled out of the ianiring beam in the opposito direction from thc flight path far positive ions. Then if thc rate of production of ions is not too great (less than lo4 ions per second) each individual ion and its associated electron can he detected separately. The time takcn by the cloctron to reach its detector is negligible compared to the time required for the ion to traverse the 100-cm drift tube to its detector. Hence the elapsed time between ~ignnlsfrom the two detectors will h e n measure of the velocity of the ion as aeceleratcd hy an applied potential, hcncc a measure of its m / e rntio. This timo lag is converted to pulse amplitude by a time-to-pnlse hright converter and fed to n conventional pulse-height nndyzer. This allows aimultnneous accumulation of the entire mass spectrum, or any portion of it, with continuous visual display on an oscilloscope of the spectrum as it sccumulates. This spectrometer is well suited to measurements of extremely tenuous ssmples or of low-efficiency ioniring processes. For
Figure 34. Johnston Laboratories CMS Coincidence Mass Spectrometer. The ionization chamber is near lhe l e h end of the 1-meter drift tube. Atthe for l e h i r the detector d secondary electronr, m d a t the for right a similar detector of positive ions. The inset unit in the center panel ir o 400-channel pulse-height analyzer.
section is provided with temperature eontrol for isothermal or programmed operation, 25-350°C. It is connected to the mass analyzer through a patented helium separator which gives a hundredfold enrichment. Provision is made for introducing samples to the mass spectrometer without the use of the chromatograph. Masses can he observed up to 1200 amu with unit resolution of 1000 (10% v d e y ; $45). The LKB-9000 has several accessories of npocial interert. One of these is a mass marker, far which a Hall-effect probe is mounted in the field of the electromagnet. Thc output voltage from tho probe is amplified, squared, and digitized, and the resulting signel used to imprint mess cdibration marks on tho oscillograph paper. A second accessory is s, peak matcher, a cathode-ray oscilloscope with associated d k a d e resistances, which permit two peaks to he brought into apparent superposition in such a way that the ratio of their masses
examplo, measurements on the ionization of molecules by x-rays have been carried out a t signal levels as low as a few molecules ionized per hour. The mass range is specified as 1-500 amu with a resolr~tion of 250 (10% valley; $100). LKB Instruments, Inc. The LKB-9000 is an integrated combination of gas chromatograph and 60%ector mass spectrometer (Fig. 35). The GC
Figure 35. LKB-9000 Gar Chromotogroph Moss Spectrometer. The analyzer unit i, to the left, the peak motching accesrory in the center, the operating conrole next, and at the far right, the magnetic tape recording unit.
(Conlinued on pare AAb44)
Volume 46, Number 4, April 1969
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Chemical lnstrumentatien can he determined precisely. This enables one to establish m/e values to better than 10 ppm. Another accessory is an accelerating-voltage alternator. This unit switches the accelerating voltage rapidly between two or three mass numbers (within 10% of each other). This is particularly useful in the simultmeous observation of two or three species unresolved by the gas chromatograph. A magnetic tape data acquisition system is also available.
Nuclide Corporation In addition to eustom-designing maw spectrometers, Nuclide offers several standard models. The 12-90-G is a general-purpose ~pectrometerwith a 90" mngnetic sector which covers thc rnngr 1-3500 amu with resolution of 3000 (1% contribution; $40-60). Model 6-60-G is similar, hut with a smallcr radius magnet of 60" angle. I t s range cxtends t o 2000 amu, resolution 1500 ($35-45). 130th of these models use many components in common and may be assembled in many configurations. A time-of-flight spectrometer is also available, ns Model TOF-1. I t s range is 150 amu, resolution 60 ($14). Nuclide lists a variety of other sperinlpurpose spectrometers.
Perkin-Elmer Corporation P-IS ha8 one model (270) mado in their Connecticut plant, and sevcrd (designntions starting with RM) imported from Hitachi in Japan. Thc Model 270 (Fig. 36) is n Nier-Johnson instn~mentdesigned specifically for g m ehromatogrsphie use. A modified version of the P-Ji Model '900 Gas Chromatograph is built in as an integral part of the 270, but can be bypassed for conventional introduction of liquid and solid samples into the ionization chamber. The mass range cxtends to 3300 amu with unit resolution 850 (loyo valley; $30).
Figure 36. Perkin-Elmer Model 270 GC-DF Analytical Mas Spectrometer. The left-hand port of the console conrirtr d o Model 900 Gas Chromatograph and its controls.
Figure 37 shows tho Model RMU-6, typical in general appearance of the many Hitachi-Perkin-Elmer models. I t uses x 90", singlp-focus, magnetic sector, and will scan to 2400 amu in seven ranges. lJnit resolution is quoted as 2000 with standard slits and 6000 with a special slit ~ystcm, (Co'onlimrctl on pagr ,4246)
Chemical Instrumentation
M a r l Speclrometer, with heoted gas inlet system.
lioth l,y tllc 50% v:tllc,y crilc~.io~t.A nrlml,rr of varintiuns can ilo ma& on t,his hnsic unit, inelnrling surfnco ianis:rtion and Tinudsm cell murccs, and douhle detection for isotope rntio mcnsurements ($40-60). Thc RMCT-7 is a Sier-Johnnon dorhlcfoew ~~~modcl in thc same serics as the IlMU-6; it covers massrs to 2400 nmu with unit resolution 20,000 (50% valley; b70-100). Model RMH-2 prcscnts the highest pcrfarmnnce mailnhlc from this company. I t is also a Nier-Johnson type, and covers thc range of masses t o 4800 &mu with resolution of 70,000 (10% valley; 8125). Model R M S 4 repreiients u. vcrsatilo economy modcl with ;L 60"mngnctic sector. The rango is 1-1200 amu. With the standnrd slits the resohltion is 750; ~ i t h optional variable slits, this can he inrrcased to 1100 (10% valley; $25). Perkin-Elmrr has rcccntly nnnowwxl thc avail:tt,ility of tho DDA-1 Digital Data Acquisition aystcm for direct, high-speed digitization of mass spectral information with eomputcr-compntiblo magnetic tape. I t can bc u a d with tho RMlT-6 neries of spectrometers or ot,her compnrnhle instruments. ~
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~~
Picker Nuclear-AEl
Figure 38. Picker-AEl Model MS-702 M a s Spectrometer. A viewing port immediately behind the ion source occupier the center of the conrole. An addition01 cobinet, not shown, contoinr power rupplie% and other oncillory electroni~equipment.
(Contintmion page A2.58)
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Chemical Instrumentation P i c k r r ofrers fivr hnsic s p c c t r o m c t w s ,
:dl manuf;lctorea in E n g l a n d I I ~ .\El. h l o d d \IS-702 ( f o t m e r l y 418-7) i s :L X I : ~ t t : ~ ~ ~ r h - I I , ~ i~n~szI or ug m ~ n t (Fig. 38), r a t h a r i m : ~ l l w :LMI m o w mmp:&ct t h a n u s t d f o r t h i s g r o m d r y . I t r:m a b s e ~ v c m : w c s to 3 2 5 0 nmu, w i t h unit r c s o l n t i o n of 3000 f o r t h o spa1.k source o r 20,000 f o r o l r c t r a n l r o m l ~ : t ~ d m m t .D r t r e t i o n i s e i t h e r photograplrir. or by electron multip l i e r ( 8 5 1 1 5 ) Figure 3 9 i s a t y p i c a l p h o t o g r a p h i c rccord, cxposcd t h r o u g h n r o t n t i n g s t e p scetar t o g i v e a series o f graded expaaurcs. .\lode1 .\1S-90" (formerly M S - 9 ) i s a doul,le-focus spcctlmmcter w i t h t h e N i e r .Johnson configuration (Fig. 40). I t covers
Figure 40. Conrole of Picker-AEl MS-902. The rix uniform knobs at the left, together with the olcillolcope, permit precire determinotion of mars rotior.
rnnsscs up t o 7200 t m u , and h a s a gunrnnt,ecd resolution of 70,000 (10% valley), t h o u g h n r c s o l u t i a n a p p r o a c h i n g 90,000 h n a lmn n r h i c v e d (89&125).
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T h c M S - 1 2 (Fig. 41) i s s high-resolution, single-focus design w i t h s 90" m a g n e t i c sector, w h i c h w i l l eovcr masses t o 900 nmu w i t h a r e s o l u t i o n of 5000 (10% valley). I t i s p a r t i c u l a r l y s u i t e d t o use w i t h a gas c h r o m a t o g r a p h a n d f o r organic i d e n t i fication (550-75). T h e M i n i m a s s @ (Fig. 42) is n residual gna a n a l y z e r w h i r h mn cover mnsses t o 2 4 0 smn w i t h r e s o l u t i o n of 2 0 (loyo vnllcy). I t uses a 180' m n g n c t i c sector. T h e analyzer haoning can be c i t h e r glass or m e t a l a n d t h u s c n n h e affixed p c r mnnently t o m y vacuum ~ y ~ t o m (63). h d a t a s c q u i s i t i a n a n d analysis system (IUSDS-1) h a s heen devised t o acecpt d a t a f r o m t h c XIS-902 a n d f e e d it t h r o u g h s u i t a l d c intesfacine, i n t o a P D P - 8 d i g i t a l e o m p o t c r ( D i g i t a l Equipment C o r p .
. ... .... .- /.:
Figure 3 9 . A typical mars spectrum recorded on the Picker-AEl MS-702. The steel sample w a r energized by a high-voltage spark. Some of the lines indicated ore too faint to show up in this reproduction of the spectrum, but were visible on the originol plate.
Figure 41. Picker-AEl Model MS-12 Mars Spectrometer. The oven for the inlet system can be seen on the further module.
(Conliiied on pnge A250)
NUCLIDE MASS SPECTROSCOPE GUIDE This guide has been prepared to outline the instrumentation offered by the world's only manufacturer whose product line conslsts prlmarlly of MASS SPECTROSCOPES and related components and services:
I
TYPICAL APPLICATIONS
Analysis and Structural Detepinations of Gases, Volatile Liqulds and Solids, Organic and
...-,
lnnrmnir 2nd
Effluents
--
cr
INSTRUMENT 6-604 12-90-6 12-go-G/GC 12-90-GDF
Medium Resolution High Resolution integrated MS/GC combo Ultra-High Resolution I‘, ?n nnnr snnrtrnm~tor ,, "",""", Ultra-High Resolution Spectrograph (>30,000)
GRAFdG
Analysis of Solids. Thermodynamics of Solids and Solid-LiquidGas Systems, Ion Bombardment (Sputtering), Ion-Molecule Studies
GRAFX 12-90-DFS 6-60-HT 12-90-HT 6-60.08
Isotope Ratio Difference Determinations of Gases associated wlth Geochemistry, Biochemistry Physical Chemistry Problems, and Stable Isotope Tracer Studies
6-60-RMS 6-60-RMSIWR
Spark Source Spectrograph Spark Source Spectrometer Knudsen Cell Studies Knudsen Cell Studies Ion Bombardment Studies of Surfaces Miniature Mass spec-]on Source combination
1-904
6-60-RMS/ST 12-9-RMS 12-90-CG
I
For Further Informotion Writelor Call
A248
I
C. 0, N, S, Ar, Xe, etc. Wide Range Analyzer Tube for Ratios of Species of High AM/M like H. He, also. Split Tube for H/D Studies also. Higher Resolution and Sensitivity than 6-60-RMS lsotoee Ratio Deteiminations of Corrosive Gases, e.g. UF6
TYPICAL APPLICATIONS
INSTRUMENT
Isotope Ratio Difference
6-60-S or SU
Reactor Monitoring. Accountability, Geochronology, Tracer Studies, I sotope Dilution Analysis
12-90-S or SU
Spectorr (RF)
Small Sample Gas Analyses-Argon Dating, Rare Gas in Meteorites. Returned Lunar Samples, etc.
4.5-@-ASS
All kinds
Components and Kits
Journal o f Chemical Education
TOF (Time of Flight) Mono- & Quadrupole 2-90.~6
6-@-SGA
Medium Resolution Thermionic Source High Resolution Ultra-High Abundance
Sensitivity (10"~ 100 for Uranlum) Non-Magnetic Total/ Partial Pressure Analyzer For Rapidly changing Systems Mass Filters "Nude" Mass Spec for Use lnslde Vacuum Chambers All-Glass Static Analyzer System for Ultra-Small Samples All-Metal Static Analyzer for UltraSmall Samples (10-" cc STP) For Builders of Do-It-Yourself Spectroscopes and Ion Beam Experiments
6 4 2 Eort College Avenue State College, Po. 16801 (814) 238-0541
CIIEIO NO. 134 on Readus' Service Card
/
-
Residual Gas Analysis, Resoiratarv Analvsis. Process Monitoring, Pollution Studies, Contained Environments, Leak Detection, Solar System Exploration, Space Simulators
I
NUCLIDE CORPORATION
12-90 or 15-90 Tandem & Three Stage
SOME COMMENTS
Chemical Instrumentation
Figure 42. Picker-AEl Minima& or residual g a r .no1rer.
spectrometer
Maynard, Mass. 01754). Thc accompnnying progtmns pcrmit dct,crmination of elcmrntnl compositions and intensities, ns well ns precise pmk matching.
Figure 43. Varion Model M - 6 6 Mars Spectrometer. The onolyzer ir located in the righthand console.
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journal of Chemical Education
Varian Associates
The Model If46 Ihs Spcctrometer illustrated in Pig. 43 is n eyeloidsl instnlment intended for routine organic chemistry including gas chrometography. I t s mass rnngc crtcnds to 2000 smu, with a rcsolotion of Ixttcr than 4000 (50% penk width). In thc
