Comparison of Methods for Determination of Copper in Serum (pg. per 100 ml.) QxaiyldihydrazideAutomatic Analysis Pooled Serum Acetaldehyde Batho~uproine~ Cuprhoneb Nonfasting Sample 1 217 167 157 Mean 168 9.3 3td. dev. 8.I 8.5 1.5 217 Sample 2 183 173 188 Fasting 129 N.U.d 1224 122 Sample 30 1.4 Std. dev. Sample 4O 134 142 125 323e 2 .3 Std. dev. 2,9-Dimethyl-4,7-diphenyl-l,lO-phenanthroline. b Biscyclohexanone oxalyldihydrazone. c Single determinations. d Not determined. 8 Triplicate determinations. t a b l e I.
volved, and therefore increases the number of samples that can be analyzed by a technician daily. ACKNOWLEDGMENT
The author is indebted to Roy B. Mefferd, Jr., of this laboratory for his suggestions and to Gerald Kessler of Technicon Instruments Corp. for suggesting the pressurized dialysis system. LITERATURE CITED
0
RESULTS
The oxalyldihydrazide-acetaldehyde procedure was the most sensitive of the three methods tested (Figure 2). The three manual methods (3, 5) and the automatic procedure gave comparable but serum copper values (Table I), there was a striking increase in precision
with the latter procedure (standard deviation of 1.5 us. values over 8 with nianual procedures). Besides being less precise, the manual procedures are quite tedious and timeconsuming. The pressurized automatic procedure not only increases precision, but also greatly reduces the labor in-
(1958). (5) Peterson, R. E., Bollier, M. E., ANAL. CHEM.27, 1195 (1955). (6) 8keggs. L. T.,Jr., Am. J. Clin. Pathol. 28,31i (1957). (7) Stark, G. R.,Dawson, C. R., ANAL. CHEM. 30,191 (1958).
New Teehniqwe for Rapid Determination of Resonance Positions of NMR Spectra
B, H. Arison
and
N. R. Trenner,
Merck Sharp h Bohme Research Laboratories, Division of Merck & Co., Inc., Rahway, N. J.
NMR spectroscopy will appreciate the need for a technique more convenient than interpolation for determining resonance positions. One can avoid this somewhat tedious procedure by resorting to a variable scale such as developed by the Gerber Scientific Go., 162 State St., Hartford, Conn. An alternative approach is reported which uses a Sirnmon Model D3 Automega enlarger with a 135-mm. lens and a suitably engraved scale on a 4 X 5 inch glass plate (Figure 1). The scale image is simply projected onto the spectrum, adjusted to the proper size by lining up with an appropriate reference and side band(s), and the resonance positions are read directly. With this HOSE with experience in
Table i. Cornparison of Results Obtained by Scale and Interpolation Methods Scale Interpolation 4.81 4.80 6.12 6.12 6.25 6.25 7.48 7.50 7.96 7.91 8.77 8.77 9.08 9.09 9.18 9.19
technique, the reading time for most spectra can be reduced to approximately 1 minute. The particular scale designed by the authors is in shielding numbers [Tiers, 6. 71. D., J . Phys, Chem. 62, 1151 (195S)l (any other scale, of course, can be engraved) with lines spaced a t 0.05-7 intervals and heavier lines every 0.5 r. One can readily interpolate to the nearest 0.01 T (0.6 cycle at 60 &,IC.),a n accuracy more than adequate for general use. Table I illustrates the agreement
between the two methods from a spectrum chosen at random. The illumination of the scale is sufficient for use in an ordinary lighted room. A range of 7.5 units is adequate since it covers the bulk of proton resonances. ACKNOWLEDGMENT
The scale was prepared with the help of Fred Drexel of the Scientific Glass Apparatus Go., Bloomfield, N. J.
