Figure 3. Correspondence of results obtained with the column RIA procedure and the dextran-coated charcoal method patients on digitoxin therapy is immunologically indistinguishable from the digitoxin in the standards. In other words, the antibody recognizes the digitoxin in clinical specimens and standards as identical. As shown in Table II, acceptable results were obtained in a parallelism study over a sixfold range of dilution. These data indicate that various components in the serum, including potentially cross reacting materials, do not interfere in the test.

No abstract

terminated prepolymer when this material was found to react with ethanol during the capping operation. This reaction caused a shift in elution volume of the material, confirming the presence of reactive end groups as opposed to unreacted polyol.The chromatogram of the prepolymer, shown as composite Peak C in Figure 4, was obtained by fractionation on the high permeability limit columns. The long tail in the high molecular weight region indicates that the prepolymer had an extremely broad molecular weight distribution. Although no suitable calibration of elution volume in terms of absolute molecular weight was obtained for this polyurethane, ratios of i V w / J T n and iVz/iRw could be estimated from a polystyrene calibration. By this means it was estimated nw/nn to be 15 and Rz/Rw to be 4.6 where ivn is the number average molecular weight, ,Vw is the weight average molecular weight and Rz is the "z" average molecular weight. ACKNOWLEDGEMENTThe authors acknowledge Hans W. Osterhoudt for his valuable guidance and the work of the Analytical Department of Armstrong Cork Company for its supplementary analyses of materials.

Aqueous solutions of nickel(II), copper(II), and zinc(I1) are quantitatively determined to the low part per billion level by energy dispersive x-ray fluorescence (XRF) spectrometry using selective potentiostatic electrodeposition as a preconcentration technique. Novel, cylindrical monochromators between the sample and detector of the XRF system reduce background levels due to scattering from the reflective electrode surface, and yield greatly improved signal-to-noise ratios. Linear callbration curves were obtained. Minimum detection limits are less than 20 ng for the metals studied.

Many analytical service laboratories are faced not only with increasing sample loads and testing demands, but also with growing record-keeping requirements. Reports to customers, legal archives, quality assurance records, good laboratory practice standards, regulatory oversight, workload justifications to management, and a host of other demands contribute to the paperwork explosion. When this paperwork is coupled with the logistical problems inherent in running a laboratory that must process thousands of samples, the stage is set for the acquisition of a laboratory information management system (LIMS).A LIMS is intended to help manage the daily workflow of the laboratory and act as a paperwork processor. Since 1983, when the functions and configuration of a typical LIMS were described by Dessy (1, 2), a number of