N E W CHEMICALS
Controlled Pore Glasses T h r e e smaller sizes of controlled-pore diameter glass packing for permeation c h r o m a t o g r a p h y have been introduced. T h e y a r e 75, 125, a n d 175 angstroms, with pore diameters to within ± 1 0 % . Other s t a n d a r d pore sizes available a r e 240, 370, 700, 1250, a n d 2000 angstroms. All pore diameter varieties a r e available in t h r e e particle sizes: 3 6 75, 75-125, a n d 125-177 microns. Other pore sizes can be m a d e t o order. All of these column packings a r e sold in quantities of 100 cc. Prices a r e $22.50 per 100 cc. Corning Glass Works, Corning, N . Y . 14830. 607-962-4444 501
Pure Nucleotides A new line of nucleotides consists of 75 basic high-purity nucleotides which complement t h e company's established line of 230 enzymes for research, diagnosis, a n d commercial use. T h e new p r o d u c t g r o u p includes nucleotides, coenzymes, a n d related biochemicals. C u s t o m e r s a r e assured guarantees of p u r i t y a n d uniformity in these p r o d ucts. P r o d u c t descriptive literature is available. W o r t h i n g t o n Biochemical Corp., Freehold, N . J . 07728. 201-462-3838 502
Polyethylene Standard Reference Materials T h e Office of S t a n d a r d Reference Materials of t h e National B u r e a u of S t a n d a r d s announces the availability of two polyethylene s t a n d a r d reference materials: one linear a n d t h e other branched. T h e molecular-weight distribution of the new linear polyethylene ( S R M 1475) h a s been determined so t h a t t h e new material can b e used to calibrate gel permeation chromatograp h y i n s t r u m e n t s over a \vide molecularweight range. This S R M is also certified for t h e limiting viscosity n u m b e r (intrinsic viscosity) a t 130°C in three solvents : 1 -chloronaphthalene ; 1.2,4trichlorobenzene; a n d d e c a h y d r o n a p h thalene. T h e melt-flow rate and density a r e also certified. T h e branched polvethylene ( S R M 1476) is certified for limiting viscosity n u m b e r a t 130°C with t h e same three solvents, a n d for melt-flow rate a n d density. I t should be useful in several areas of research. Prices a r e : S R M 1475, $100 p e r 50 g ; S R M 1476, $75 p e r 50 g. Office of S t a n d a r d Reference Materials, N a t i o n al B u r e a u of S t a n d a r d s , Washington, D . C . 20234
New toploading balance is fast, accurate... y et RUGGED! N e w T o r b a l ET-1 toploader (160g capacity, 1 mg accuracy) makes accurate weighing easier and more foolproof than ever before. N E W EASE thanks to complete digital display without the use of optical projections or verniers to read, no estimating. N E W EASE because the one piece construction of the exclusive Torsion weighing mechanism has no knife edges to chip, wear or collect dust —hence there's no loss in accuracy. N E W EASE — thanks to the electronic null readout feature, the ET-1 is not affected by sensitivity changes —from temperature or humidity variations or effects of foreign matter or wear. As long as you can see the null needle move for a 1.0 mg weight change, then a difference of 1.0 mg in weight-reading means 1.0 mg —today, tomorrow, next month, next year. N E W EASE because the ET-l's Torsion mechanism is far less affected by vibration than optical balances. You can use an ET-1 in conditions other balances can't take. N E W EASE thanks to out-of-level accuracy. For minor changes in level of the ET-1, zero point does not change.
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PUT THE TRI-SIL FAMILY TO W/ORK SfSi VOUR LAB This accomplished family of reagents has eased the problems o f thousands engaged in research, quality c o n t r o l , process monitoring and other fields of investigation and analysis. By quickly forming volatile and thermally stable derivatives of polar compounds these reagents make light work and tight determinations of formerly difficult gas phase analyses. In fact, quite a few analytical problems that were practically impossible before have been resolved by silylation of samples preparatory t o GLC or Mass Spec. Many of these procedures are now routine, practical and economical. We have just published a 60 page " H a n d book of S i l y l a t i o n " that is a gold mine of information on silylation and other special techniques of gas phase analysis. It contains a wealth of practical suggestions, methods, references, data on reagents and accessories w i t h current prices. "Handbook of S i l y l a t i o n " is free, but you w o u l d n ' t take anything f o r your copy after you've looked i t over. If you haven't received yours yet d r o p us a note —today. PIERCE CHEMICAL COMPANY P.O. Box 117 Roekford, Illinois 61105 U.S.A. PHONE 815/966-0747
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ANALYTICAL CHEMISTRY, VOL. 4 2 , NO. 6 , MAY 1 9 7 0
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