CHECKING THE 2 0 8 . Perkin-Elmer's Abraham Savitzky explains the inner work­ings of P-E's new model 208 Vapor Fractometer to American Cyanamid's Anthony Andreatcli in Perkm-Elmer's booth at the Pittsburgh analytical conference

Chromatography: Full Speed A h e a d Pittsburgh Conference points up changes in gas chromatographs as suppliers show off new models

\JT \κ i*hrnnii»toc*raphv. nfter t;iInner ο short breather to pick up some refine­ments, is now moving full speed ahead with new design concepts that push right through previous limitations. Chromatographs, some feel, are enter­ing the "second generation."

Visitors to the Pittsburgh Confer­ence on Analytical Chemistry and Ap­plied Spectroscopy caught evidence of this on all sides as they heard such phrases as "up to 200.000 theoretical plates/* "materials that boil at up to 600° C , " and "sensitivities of 10 ir» mole."

Perkin-EImer, for instance, unveiled its new model 20S Vapor Fractometer. Gone is the conventional packed column and the thermal conductivity detector. The 208 uses a capillary, or Golay, column. And because of the

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high resolution and small amount of sample used by the column, the unit incorporates a highly sensitive flame ionization or beta-ray ionization de­tector. Result of this combination, ac­cording to P-E: a unit that can pick up components at a level of about 10 " gram and that has a resolution of up to 200,000 theoretical plates with a 200 ft. column. Furthermore, says P-E, flow, pressure, and reasonable changes in temperature do not affect the instru­ment.

The flame ionization detector meas­ures ion current in a hydrogen flame when ionizable molecules of column effluent are passed through it. The beta-ray detector measures ion current produced when metastable argon (car­rier gas) molecules collide with, and in turn ionize, the molecules of organic

vapor in the column effluent. The ar­gon molecules are made metastable by radiation from a beta emitter.

^ Temperature Push. A new high in temperature was reached at Pitts­burgh as Consolidated Electrodynamics brought out its new type 26-203 chromatograph. The unit operates with column temperatures as high as 500° C. Thus, says Consolidated, materials that boil at up to 600° C. can be analyzed. Included here: high molecular weight waxes and oils, plas-ticizers, silicone oils, fatty acids, gly­cols, nitriles, and diglycerides.

Columns for the 26-203 are made of stainless steel, come in 8 in. to 50 ft. lengths. Partition type columns can be used at temperatures up to 400° C. and adsorbent type columns using alumina, carbon, or silica gel can be operated at up to 500° C. The heat sink is made of a special bronze alloy; the seals are of Ceramicite.

F&M Scientific added a third vari­able to its new gas chromatograph: programmed temperature. With this instrument, the column can be heated from room temperature to 400° C. with a linear heating rate from 3° to 48° C. per min.; nine heating rates are available. Injection port and detector are kept at constant temperature with individual heaters.

F&M explains that the programmed heating results in slowing down the ini­tial fast traveling components and speeding up the later slow traveling components. This, says the company, gives better separation of peaks than does an isothermal column.

When the column reaches the upper temperature limit, it can either be held at this temperature or automatically cooled to room temperature by a blower. F&M points out that the chromatograph can also be used iso-thermally.

• Enters Field. American Instru­ment, now in the chromatography field, showed off its new chromatograph at the Pittsburgh exhibit. The Aminco unit operates at column temperatures up to 250° C , comes with helically coiled packed columns. However, it is designed to accept capillary columns up to several thousand feet long.

Perhaps the biggest feature of the Aminco chromatograph is its detec­tors. The company has designed a thermistor detector that it says will de­tect as little as 10 s mole at 250° to 300° C. The thermistors can be easily removed and a hot wire unit inserted. In addition, the chromatograph has

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an r-f g low detector that can be placed ι in series with either of the other two. I Thus detector makes use of a erystai- ι co^ntroîîeu r-f oscillator that provides j ionization potential to the electrodes I of a discharge tube located in the oven, j Tlhe detector measures changes in ioni- I zfeiion current produced by the r-f [ discharge. I

Wheelco division of Barber-Colman j exdiibited its new ionization detector, I wliich uses a radioactive source and I argon carrier gas to provide ionization I current with the column effluent. Us- I irtg capillary columns, the detector ap- | proacries sensitivities of 10 ir» mole, the | company says. !

In the area of process chromato- j graphs, Perkin-Elmer has a reverse flow I system for its unit. By reversing the I flow of carrier gas at a given point I ir* the analysis, it is possible to group j remaining components into one peak. I P-E explains that in some processes, a J single peak that combines the heavier I components may be of more interest J than separate peaks for each. I

Meter Checks Moisture C o n s o l i d a t e d d e v e l o p s meter to monitor moisture in liquid plant streams I

C^ONTSOLEDATED Electrodynamics has filled a long missing void in process in­strumentation— an instrument to meas­ure moisture in liquid plant streams. The device, the Liquid Moisture Moni­tor, c^n detect water levels as low as 1

MOISTURE CHECK. Jerome P. Kersten of Columbia-Southern hears about Consolidated's new moisture moni­tor from CEC's Richard Anderson

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