Use of InfraredSpectroscopy in DrugAnalysis

molecular weight. In contrast, hemoglobin and albumin are compounds of uniform molecularweights. This may well be one of the reasons for the differences in the efficacy of these coating materials. Our results clearly show that hemoglobin and albumin are not ineffective as coating material, but are less effective than PVP, dextran, T40 and T70 when separating free from bound folate under the conditions used in our test system. We agree entirely with the comments of Kamen and Caston. It is also our own experience that varying the concentration of the coating material in the medium inwhichthecharcoal is suspended influences the differential adsorptivity of the charcoal. However, this aspect was not the major aim of our study. The particular concentrations of coating materials that we chose are representative of widespread practice. We were also concerned about the increasingly severe quenching effect and the problems of solubilization that the higher concentrations of coating material cause in the scintillants. It is, of course, desirable to keep these interferences at a tolerable minimum and consequently choose concentrations of coating material that are a compromise between optimal separation property and optimal conditions for liquid scintillation counting.