ACID DIGESTION BOMBS Parr '®
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Teflon Lined
With the abilil, tn hold strong acids or alkalis at temperatures well above normal boiling points, Parr Acid Digestion Bombs offer rapid and safe procedures for dis solving inorganic materials in HF, HCI, HNO3 or other strong acids, and for digesting organic samples in strong alkalis or oxidizing acids, all with complete sample recovery without losing any trace elements. These bombs are available in 23 and 125 ml sizes for tempera tures to 150°C and pressures to 1200 psig, and in a 23 ml, high strength design for temperatures to 285°C and pressures to 5000 psig. All have removable, thick-walled Teflon cups in stainless steel bodies with convenient closures, positive seals and other exclusive Parr features. For details, write or phone Parr Instrument Company, Moline, Il. 61265. 309/762-7716 CIRCLE 159 ON READER SERVICE CARD
ANALYTICAL AIDS Chemistry for Toxicity Testing C.W. Jameson and Douglas B. Walters A practical approach to the chemistry requirements for the toxicological evaluation of environmental chemicals. 1984 248 pp ill. 250-40547-4 $29.95
Analytical Pyrolysis Kent J. Voorhees An up-to-date review of the theory, technique and applications of analytical pyrolysis. 1984 496 pp ill. 408-01417-2 $69.95
High Resolution Spectroscopy J. Michael Hollas A comprehensive guide to the principles and tech niques of modern high resolution spectroscopy. 1982 638 pp ill. 408-10605-0 $115.00
Handbook of Anion Determination W. John Williams Offers single-volume coverage of the most important methods for the determination of over 70 anions. 1979 630 pp ill. 408-71306-2 $139.95 To order, or for more information, write:
Butterworth Publishers 80 Montvale Avenue Stoneham, MA 02180
CIRCLE 31 ON READER SERVICE CARD 876 A · ANALYTICAL CHEMISTRY, VOL. 56, NO. 7, JUNE 1984
practicing analytical chemists. Of course, the production of these tables is not a trivial matter, and would re quire rather involved experimental procedures at the state of the art in particle generation and characteriza tion. Nevertheless, when these data do become available, which undoubtedly they will in due time, this should allow researchers to steer around the major ity of interference problems other than those of spectral overlaps, for which tabular data are already avail able (i, 2). ICP Systems. The data available on solvent-loading limitations for or ganic solvents with the ICP have been characterized recently (3). Some typi cal limiting aspiration rates are shown in Table I, together with evaporation factors, E, of the solvents. These data are useful as a guide for organic sol vent introduction to the ICP. The evaporation factor is a measure of the rate of mass loss from an evaporating drop, and is given by: Ε = 48 DvaPsM2(5RT)-2
(1)
where Dv is the diffusion coefficient of the solvent vapor, σ is the surface ten sion, Ps is the saturated vapor pres sure, M is the molecular weight of the solvent, δ is the density, R is the gas constant, and Τ is the absolute tem perature. In general, the ICP has de creasing tolerance to solvents as their evaporation factors increase, and there is an inverse correlation between evaporation factor and limiting aspi ration rate. However, the alcohols have a much greater quenching effect on the plasma than their evaporation factors would indicate, and they may readily extinguish the plasma under normal operating conditions. It is always possible to remove at least part of the solvent vapor by con densation. Two groups of workers have attempted this and shown that the tolerance of the ICP to organic sol vents is greatly improved when a large fraction of the solvent vapor is re moved from the gas stream passing to the plasma (3, 4). This is an indication of how the sample introduction pro cess can be modified to produce analyte closer to the optimum for the at omizer. No published data are avail able on limitations of aqueous sample introduction to the ICP, although clearly water loading in the plasma has a direct influence on plasma prop erties. In fact, it has been shown for certain ionic lines that doubling the water loading entering the plasma can cause a 100-fold reduction in analyti cal signal (5). From a practical standpoint, three important conclusions can be reached. First, it is necessary to introduce sam ple to the atomizer with drops no larg er than a certain maximum size
