Flexibility in Horizontal Electrophoresis The wide variety of horizontal electrophoresis techniques performed today demands versatility and efficiency in instrument design. The Pharmacia Horizontal Electrophoresis System can perform all the powerful techniques of high resolution IEF, i m m u n o and horizontal gel electrophoresis w i t h one systematically designed apparatus. Consider the adjustable electrodes when running IEF, they make it unnecessary to purchase different lids for each gel size you w i s h to run. Pharmacia Power Supplies can provide the voltage and power that you require for all horizontal electrophoresis techniques. When you need antibodies or ampholytes, agarose or calibration kits, Pharmacia supplies them all and a broad range of chemicals and support media. Find out more about Pharmacia flexibility. Request the brochure — " T h e Pharmacia Horizontal Electrophoresis S y s t e m " today.
Briefs Determination of Ammonium, Nitrate, and Urea Nitrogen in Fertilizer by Gas-Phase Molecular Absorption Spectrometry
535
A m m o n i a a n d u r e a are d e t e r m i n e d t o 0.005% a n d n i t r a t e to 0.015% by weight in fertilizer, based on a 10-g s a m p l e diluted to 500 m L . D a t a for five commercial fertilizers are included. Vincent C. Anigbogu, M a r k L. Dietz, and Augusta Syty*, Department of Chemistry, Indiana University of Pennsylvania, Indiana, Pa. 1570Ô Anal. Chem.,55 (1983) Isolation of Thiophenic Compounds by Argentation Liquid Chromatography 540 Virtually complete s e p a r a t i o n is achieved for one-ring t h i o p h e n e s , a n d b e n z o t h i o p h e n e s are e n r i c h e d by ~ 9 6 % in comparison to napthalenes. William F. Joyce and P e t e r C. Uden*, Department of Chemistry, GRC Tower A, University of Massachusetts, Amherst, Mass. 01003 Anal. Chem.,55 (1983) Laser Modulated Electron Capture Detection for Gas Chromatography 543 Direct vibrational excitation, b u l k gas h e a t i n g , a n d p h o t o d e t a c h m e n t are t h r e e m e c h a n i s m s for laser m o d u l a t i o n of electron c a p t u r e d e t e c t o r response. N o r m a n J . Dovichi and R i c h a r d A. Keller*, Group CHM-2, Mail Stop G732, Los Alamos National Laboratory, Los Alamos, N.M. 87545 Anal. Chem.,55 (1983) Determination of Drugs in Blood Serum by Mass Spectrometry/Mass Spectrometry
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Detection limits for most drugs, with 1 μΐ^ of blood s e r u m placed on t h e solids p r o b e , are in t h e low parts-per-million (ng/mL) range. E x t r a c t i o n reduces t h e detection limits to t h e low parts-per-billion range ( p g / ^ L ) . H a r r y O. B r o t h e r t o n and Richard A. Yost*, Department of Chemistry, University of Florida, Gainesville, Fla. 32611 Anal. Chem.,55 (1983) Pulsed Signal Collection for Laser-Enhanced Ionization Spectrometry
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P u l s e d laser-enhanced ionization signal collection is investigated as a r e m e d y for electrical interference. S a m p l e s with low ionization p o t e n t i a l c o n c o m i t a n t s are t r e a t e d by time-resolved signal recovery. M a r k A. Nippoldt and Robert B. Green*, Department of Chemistry, University of Arkansas, Fayetteville, Ark. 72701 Anal. Chem.,55 (1983)
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354 A · ANALYTICAL CHEMISTRY, VOL. 55, NO. 3, MARCH 1983
