impressive ion analysis Anions in Mineral Water 1. C I 2. N 0 3 " 3. Unknown 4. S O 4 - 2
Cations in Beer 1. Na + 2. NH4 + 3. K+
mated mass assignments in magnetic spectra. The ideal reference material provides intense peaks'at close intervals throughout the mass range of interest, preferably at m/z values where ions from the sample do not occur. Perfluorinated analogs have long been popular because intermolecular hydrogen bonding is eliminated (all hydrogen atoms are replaced by fluorine atoms), because fluorine is monoisotopic, and because the multiplicity of fluorine atoms provides a significant negative mass defect that allows the reference ions to be distinguished from sample ions at higher resolution. A number of perfluorinated compounds have been used as mass markers in the middle mass range. Poly(perfluoropropylene oxide) provides good reference spectra to about 3500 under electron impact (22) and good positive or negative ion spectra with chemical ionization (23). It is also suitable for positive or negative ion fast atom bombardment. Perfluoroalkyl phospholonitrilates, henceforth called phosphazenes, provide in-
Work between 2000 and 4000 still falls into the truly notable category, and success above 4000 with anything besides polystyrene can probably still be classified as heroic.
Organic Acids in Glyoxal 1. Oxalate 2. Glyoxylate 3. Glycolate 4. Formate
These chromatograms dramatically show the potential of Ion Chromatography for rapid, high-sensitivity analysis of ions in complex matrices. Wescan's single-column approach to Ion Chromatography goes beyond conventional IC to provide unprecedented savings in both initial investment and operating cost. That's why more and more laboratories are updating their capability with Wescan Ion Analyzers.
WESCAN
Just contact us. We'll gladly provide you with the facts that helped others decide on Wescan.
Wescan Instruments, Inc. 3018 Scott Blvd. Santa Clara, CA 95050 (408) 727-3519
Ion Chromatography... the single-column way
impressive price! Wescan Ion Analyzer Systems can cost as much as 45% less than comparable units. CIRCLE 237 ON READER SERVICE CARD 108 A · ANALYTICAL CHEMISTRY, VOL. 54, NO. 1, JANUARY 1982
tense molecular ions at masses approaching 4000 in electron impact (4), field desorption (24), chemical ionization (23), and positive and negative ion fast atom bombardment (23). Fragment ions are few and far between, particularly with the soft ionization techniques, and often mixtures of phosphazene homologues are used to minimize gaps in the spectrum. Perfluorinated alkyltriazines can also be used as counting standards above mass 1000 (23,24). A number of nonfluorinated oligomers have also been proposed as mass marking standards, particularly for use with field desorption. These include oligomeric mixtures of polystyrene (8,25), polypropylene glycol (8), poly(2,2,4-trimethyl-l,2-dihydroquinodine) (25) and 2,6-dimethylpolyphenylene oxide (26). Polyethylene glycol is sometimes used in this laboratory as a mass marking standard for fast atom bombardment spectra. Various alkali halide salts, e.g., Csl and KI, are also being used as mass
