CHEMICALS
N E W CHEMICALS
REAGENTS MATERIALS
Cation Exchange Resin
Radioactivity Standards
A solid chelating agent, Dowex Che lating Resin A-l, has a styrene-divinylbenzene matrix with iminodiacetic acid groups attached. I t is almost waterwhite and possesses good physical, chemical, and thermal stability. This resin is used for the removal of trace heavy metals from alkali or alkaline earth salts, and may be used for the concentration of trace polyvalent metals, and for the separation of closely related metals. The relative selectivities of this resin for some di valent cations at pH 5 (acetate buffer) are P d > C u > > F e > N i > P b > M n » C a ^ M g . J. T. Baker Chemi cal Co., Phillipsburg, N. J. 501
A new radioactivity standard sample, cobalt-57, and three re-issues of previously available standards, zinc-65 and two concentrations of sodium-22, are now available from the National Bureau of Standards. All are in solu tion form except the zinc standard which is prepared as a point source de posited on mylar film. Cobalt-57 (Standard Sample No. 4941), about 5 ml., is an electron-cap turing nuclide with a half-life of 270 days and a nominal activity of 3 X 104 dps./ml. It is used in Mossbauer-effect experiments and as a tracer in vitamin B 1 2 studies. Re-issued zinc-65 (NBS Standard Sample No. 4992) has a nominal activ ity of 4 Χ 104 y ps. and its half-life is 244 days. Both sodium-22 standards (NBS Standard Sample Nos. 4921-B and 4922-C) have a half-life of 2.59 vears. Nominal activitv of No. 4921-B
Scintillating, Ion Exchange Resin for Radioisotope Analysis The resin, in the form of spherical beads, is a cross-linked polymer which contains ionizing sulfonic (—S0 3 H) groups and fluorescent compounds. Radioactive isotopes adsorbed from aqueous solution can be counted by coupling the resin on which they are adsorbed to a multiplier phototube and pulse counter. Counting efficiencies of 50% for Sr»°, and 30 to 50% for Pu 230 , Po 210 , and Am 241 are possible for a method using a Lucite cup optically coupled to a phototube with an aluminum re flector. Using a standard liquid scin tillation counter with a conventional counting vial, counting efficiencies of 12% for Ni 8 3 and 60% for Tl 2 0 4 are reported. The cation resin is available in the H + form. Tracerlab, 1601 Trapelo Road, Waltham 54, Mass. 502
(3 ml.) is 15 X 10s dps./ml. and No. 4922-C (5 ml. is 15 Χ 104 dps./ml. Standard materials issued by the National Bureau of Standards are de scribed in Standard Materials, Miscel laneous Publications 241 available for 30 cents from the Superintendent of Documents, U. S. Government Print ing Office, Washington 25, D. C. 504
Plutonium Standard A plutonium sample (NBS standard sample No. 949) 99.7% pure contains 0.5 gram of Pu metal in a glass am poule under an argon atmosphere. The Atomic Energy Commission in cooperation with the NBS is making the sample available only to persons li censed by the AEC. Orders must be placed on NBS-285 form. National Bureau of Standards, Washington 25, D. C. 505
13" x 6" χ 10". Wt: 10 lbs. Supplied with protective carrying case and dust cover.
Ion Exchange Resin A microspherical resin, designated Chromobeads is available. Uniformity of the beads preserves a particle size in the 18-25 micron range assuring preparation of a chromatographic column with negligible interspaces. Chromobeads give the maximum sur face/volume relationship. Each batch of Chromobeads is accompanied by a photomicrograph of the resin particles present, a sample chromatogram, and the exact prescription for the buffer gradient used to make the chromato gram. Technicon Chromatography Corp., Chauncey, Ν. Υ. 503
PRECISELY RIGHT! Triple Weigh Precision Balances provide the unique flexibility of three-times scale by counterweighing with no loss in accuracy! Available in a full range of twenty-nine models from 0-3 mg thru 0-50 gm and grain ranges from 0-10 gr thru 0-125 gr, accurate up to 0 . 1 % . Also available: Surface Tension for film elasticity and penetration experiments; Specific Gravity and denier-calibrated Precision Yarn Balances. Custom designs for specific applications. Write today for Bulletin FB-2-9500:
FP E
ROLLER-SMITH
PRECISION
BALANCES
S t a n d a r d in t h e b e s t - e q u i p p e d l a b s for o v e r 5 0 y e a r s
Federal Pacific Electric C o m p a n y N e w a r k 1, N . J . t i r c l e Mo 2 3 5 on Readers' S e r v i c e Card
VOL. 34, NO. 10, SEPTEMBER 1962 · 167 A
