GAS FACTS published periodically for analytical chemists

Detecting and correcting analytical error Youden' and others have recog­nized that round robin testing can improve analytical accuracy. The historical improvements described here should be of interest to those seeking improvement themselves.

sion line derived from a third order polynomial equation by least squares.

Quarter-to-quarter con­sistency has improved markedly, while CV decreased steadily over the 12 years. These accomplishments were catalyzed by legislative mandate, improved pub­lished analytical procedures, increasing availability of NBS Standard Reference Materials and improved instrumentation.

To assist analytical labora­tories, Scott started a cross reference gas analysis program in 1964, handling all sample preparation, dissemination, statistical analysis and issuing of reports. The plot of coefficient of variation (CV) vs time excerpts 12 years from this study during which more than 100 industrial, govern­ment and independent testing laboratories participated. Separate curves for CO, C02, NO and total hydrocarbons were averaged and a regres-

lYouden, W. J., Graphical diagnosis of interlaboratory test results. Industrial Quality Control. 15.(5)24-28 ( 1959)

Scott services now include natural gas, 02, S02 and other compounds of environmental significance. If you want to learn how it may help you detect and correct unsus­pected sources of analytical bias—and how subscribers can use it in litigation and for proving compliance—get in touch with Ron Geib at Scott.

INFORMATION HOTLINE: 800-331-4953 8:00AM-5:00PM Eastern Time In PA: 215-766-8861

Scott Specialty Gases Fremont, CA · Houston, TX · Plumsteadville, PA · Troy, Ml · Longmont, CO · Wakefield, MA · San Bernardino, CA · South Plainfield, NJ

CIRCLE 149 ON READER SERVICE CARD

Stable Isotope Dilution Analysis of Hydrologie Samples by Inductively Coupled Plasma Mass Spectrometry 1568 Hydrologie reference materials are used to establish the ac­curacy of ICP/MS for determination of Ni, Cu, Sr, Cd, Ba, Tl, and Pb. Ion interferences are identified, and suitable correction methods are evaluated. John R. Garbarino* and Howard E. Taylor, U.S. Geological Survey, Box 25046, MS 407, Denver Federal Center, Denver, Colo. 80225 Anal. Chem., 59 (1987)

Tandem Mass Spectrometry for Collisional Activation of Alkali-Metal-Cationized Fatty Acids: A Method for Determining Double Bond Location 1576 Saturated and unsaturated fatty acids cationized with cer­tain alkali metal ions are desorbed by fast atom bombard­ment. The ions are then collisionally activated to give re­mote charge site decomposition indicative of hydrocarbon chain length and double bond location. Jeanette Adams and Michael L. Gross*, Midwest Center for Mass Spectrometry, Department of Chemistry, University of Ne­braska—Lincoln, Lincoln, Neb. 68588-0362

Anal. Chem., 59 (1987)

Aids for Analytical Chemists Wet Ashing in Biological Samples in a Microwave Oven under Pressure Using Poly(tetrafluoroethylene) Vessels 1582 Prasad Aysola, Perry Anderson, and Cooper H. Langford*, Department of Biological Sciences and Chemistry, Concordia Uni­versity, 1455 de Maisonneuve Boulevard West, Montreal, Quebec, Canada H3G1M8 Anal. Chem., 59 (1987)

Packing-Induced Brittleness in Polyimide- and Aluminum-Clad Fused-Silica Capillaries 1583 Soon M. Han and Daniel W. Armstrong*, Department of Chemis­try, Texas Tech University, Lubbock, Tex. 79409

Anal. Chem., 59 (1987)

736 A · ANALYTICAL CHEMISTRY, VOL. 59, NO. 11, JUNE 1, 1987

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