An atomic fluorescence spectrometer (AFS) comprising hollow cathode lamps (HCLs) for excitation and an Inductively coupled plasma (ICP) as sample atomization cell was evaluated. Detection limits for 32 diverse elements studied were comparable to flame atomic absorption (FAA) In general and to ICP-AES, except for the refractory elements where they were as much as 2 orders of magnitude inferior. Linear ranges were 4 to 5 orders of magnitude. Experiments showed that spectral line interferences should be as uncommon as with FAA and matrix effects should be small In most cases, If experimental conditions are carefully selected. Particulate light scattering and molecular fluorescence should be absent for all practical purposes. Since synchronous detection was used, base line shifts and drifts due to nebulizer problems, recombination continua, molecular emission, stray light, and drifts in alignment, and rf power were circumvented. The HCL-ICP-AFS approach is amenable to the analysis of several elements simultaneously.

A comparison of an “end-on” viewed argon inductively coupled plasma (ICP) operated in the horizontal position with the conventional “side-on” viewed argon ICP was carried out using the same experimental setup. The end-on ICP required an air cutoff stream located toward the tip of the luminous discharge, to protect the optics and to increase linearity ranges, and the orifice diameter of the central tube of the torch was widened to 1.9 mm, to improve line/background ratios. With the end-on viewed plasma the linearity ranges, the susceptibility to solute vaporization and to ionization matrix effects, and the detection limits in an organic solvent were insignificantly different from those observed with the side-on viewed plasma. Detection limits with aqueous samples were always significantly lower with the end-on viewed plasma, usually five- to tenfold lower, in a few instances, 20-fold lower. With the end-on viewed plasma the optimal observation region for both single and simultaneous multielement analysis is one and the same and is extremely easy to locate.

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by the direct emission spectrographic technique, using the synthetic matrix curves, and compared with atomic absorption analysis ( Figure 3). For the elements readily determinable by atomic absorption, the agreement obtained was consistently within the precision limits of the two methods thus indicating the reliability of the spectrographic method.In addition, two different lung samples were analyzed by the direct procedure; one by the method of standard additions and the other by the synthetic matrix approach. These values are compared with values obtained by a mass spectrographic procedure (24) in Table IV. Considering the accuracy and precision (f 10-30z) of these two techniques, the agreement is good for nearly all elements.Precision. To estimate the precision of the method, the relative standard deviations of eight representative line ratios are presented for both samples and standards ( Table V). The ratios used herein were accumulated during the course of a single controlled experiment. Thus, they do not reflect variations due to major differences in time, different lots of spectrographic materials, and so forth. These values were also employed to obtain the pooled relative standard deviations (26). Assuming homogeneity of variances, the pooled estimates can be taken as representative of the expected precision over the useful analytical range. In nearly all cases the pooled relative standard deviation was 15% or less; values which are generally acceptable for most biological analysis requirements. Because the calibration curves had slopes closely approximating 45 degrees, the standard deviations calculated for intensity ratios closely estimate the precision to be expected for concentrations.It should be mentioned that freeze-dried animal tissues displayed more favorable burning characteristics than ovendried material. This also resulted in an improvement in precision with such samples. CONCLUSIONA comprehensive, simple, fast, and direct method has been developed which is capable of providing reliable estimates of trace element concentrations in a wide variety of biological materials with adequate sensitivity (27) and precision for most survey purposes. For example, analyses of individual bone, blood serum, animal tissue, plant leaf, and stool samples utilizing only the lower wavelength region produced line intensities suitable for quantitation of 13, 14, 14, 24, and 26 elements, respectively. The fact that wet digestion or ashing is not required minimizes problems of contamination and loss of sample constituents. The simplicity of the sample preparation scheme and the generally universal calibration curves are features which when coupled with a direct reader can further decrease time required for comprehensive biological survey. Assuming homogeneous samples, precision better than 15 percent can generally be expected. Although the evaluation of accuracy at very low concentration levels is always difficult, this method appears to generally produce valid results. An examination of factors affecting the atomic...