1860
ANALYTICAL CHEMISTRY SUMMARY AND CONCLUSION
Table C 1 2 4
6 8 10
11.
Corresponding Optical Density x = 108 X D“
-Values of 1 2
2
for Expt. No.
3 4 38 . . . 42 , . . 93 108 100 111 225 226 224 215 356 348 358 . . . 493 501 482 494 646 615 635 613
5 40 97 222 372 488 624
.tb
f/CC
G/Cd
40.0 101.8 222.4 358.6 491.6 626.6
40.00 50.09 55.60 59.75 61.45 62.66
1.155 1.684 0.491 0.832 0.396 0.622
Observed, 95% Confidence Interval0 35.34 44.66 45.41 54.77 54.24 56.96 57.10 62.40 60.35 62.55 60.93 64.39
D = -log(T/To). b li: = mean z.
C = bilirubin content. d s d C is estimated standard deviation of li:/C for value of C given for tabular row. e Based on R. A. Fisher’s t - distributioD in the usual way (I).
In estimating the bilirubin content of a submitted serum sample three tubes should be employed: the serum reagent blank, the serum sample, and a tube containing 0.04 mg. of bilirubin as a control on the reactivity of reagents. If the serum sample is hemolyzed, the serum reagent blank should cancel the effect of the hemolysis. If the sample contains a large amount of bilirubin. the blank and sample can be diluted with sodium benzoate-uiea solution.
The method described for the total bilirubin content of serum is simple, rapid, and precise. In a series of 20 routine serum samples examined for total bilirubin, only one developed the typical rose-mauve color of azobilirubin. It was thus possible to eliminate 19 of the samples from further consideration with the consequent saving of time. According to Peters and Van Slyke ( 6 ) , the serum of normal individuals contains between 0.1 and 0.25 mg. of bilirubin per 100 ml. of serum. This paper is concerned only with the total bilirubin content of serum. LITERATURE CITED
(1) ddler, A , , and Strauss, L., Klin. Wochschr., 1, 2285 (1922). (2) Fisher, R. A., “Statistical Methods for Research Workers,” p. 120, New York, Hafner, 1950. (3) Goodson, W.H., and Sheard, C. S., J . Lab. Clin. Med., 26, 423 (1940-41). (4) LIaclay, E., Am. J . M e d . Technol., 17, 267 (1951). ( 5 ) Malloy, H. T., and Evelyn, K. A., J . Bid. Chem., 119, 4S1 (1937). (6) Peters, J. P., and Van Slyke, D. D., “Quantitative Clinical Chemistry,” Vol. 2, p. 917, Baltimore, Williams and Wilkins. 1932. (7) Powell, IT. N., Am. J . Clin. Path., 14, 55 (1944). RECEIVED for review July 18, 1952. Accepted hugust 28. 1932.
Table for Calculation of
“5
Concentration
By Mass Spectrometric Isotope Analysis LYNN D. ABBOT”, JR., AND MARY J. DODSON Department of Biochemistry, Medical College of Virginia, Richmond, Va.
TABLE has been found to be very useful in saving the time of L4 calculation involved in the analysis of nitrogen samples
for “5 concentration by the isotope-ratio mass spectrometer. Concentration of N15 was calculated a t intervals of current
~ ~
~-
ratios
(129) by the formula:
(128)
Atom yoS
Conversion Table z29
Ratio - to Atom yo 128
N16
For interpolation, a d d 0.0005 t o a t o m % E15 for each 0.00001 increase in ratio, a n d round off t o 3 figures. Atom Atom Atom Atom % N1S Ratio % N15 Ratio % “5 Ratio % Si3 Ratio 0.00720 0.3587 0.00930 0.4627 0.01280 0.6357 0.01700 0.8432 0.00725 0.3611 0.0093B 0.4653 0.01290 0.6410 0.01710 0.8475 0.00730 0.3636 0.00940 0.4677 0.01300 0.6460 0.01720 0.8525 0.00735 0.3662 0.00945 0.4704 0.01310 0.6506 0.01730 0.8576 0.00740 0.3686 0.00950 0.4728 0.01320 0.6557 0.01740 0.8628 0.00745 0.3710 0.00955 0.4753 0.01330 0.6605 0.01750 0.8673 0.00750 0.3735 0.00960 0.4779 0.01340 0.6653 0.01760 0.8726 0.00755 0,3761 0.00965 0.4801 0.01350 0.6707 0.01770 0.8772 0.00760 0.3785 0.00970 0.4826 0.01360 0.6752 0.01780 0.8819 0.00765 0.3811 0.00975 0.4852 0.01370 0.6803 0.01790 0.8873 0.00770 0.3836 0.00980 0.4876 0.01380 0,6854 0.01800 0.8921 0.00775 0.3859 0,00985 0.4902 0.01390 0.6901 0.01810 0.8969 0.00780 0.3885 0.00990 0.4926 0.01400 0.6949 0.01820 0.9017 0.00785 0.3909 0.00995 0.4951 0.01410 0.7003 0.01830 0.9066 0.00790 0.3934 0.01000 0.4975 0.01420 0.7052 0.01840 0.9116 0.00795 0.3959 0.01010 0.5025 0.01430 0.7097 0.01850 0.9166 0.00800 0.3984 0,01020 0.5074 0.01440 0.7148 0.01860 0.9217 0.00805 0.4010 0.01030 0.5123 0.01450 0.7199 0.01870 0.9259 0.00810 0.4034 0.01040 0.5173 0.01460 0.7246 0.01880 0.9311 0.00815 0.4088 0.01050 0.5225 0.01470 0.7294 0.01890 0.9363 0.00820 0.4083 0.01060 0.5272 0.01480 0.7348 0.01900 0.9408 0.00825 0.4108 0.01070 0.5322 0.01490 0.7397 0.01910 0.9461 0.00830 0.4132 0.01080 0.5371 0,01500 0.7446 0.01920 0.9506 0.00835 0.4158 0.01090 0.5420 0.01510 0.7491 0,01930 0.9560 0.00840 0.4182 0.01100 0.5470 0.01620 0.7542 0.01940 0.9606 0.00845 0.4207 0.01110 0.5519 0.01530 0.7593 0,01950 0 9653 0.00850 0.4232 0,01120 0 5568 0.01540 0.7639 0.01960 0.9709 0.00855 0.4257 0.01130 0.5618 0.01550 0.7692 0.01970 0.9756 0.00860 0.4281 0.01140 0.5669 0.01560 0.7740 0.01980 0.9804 0.00865 0.4307 0 01150 0.5718 0.01570 0.7788 0,01990 0.9852 0.00870 0.4331 0.01160 0 5767 0.01580 0.7837 0.02000 0,9901 0.00875 0.4355 0 01170 0.5817 0.01590 0.7887 0.02010 0.9950 0.00880 0.4380 0.01180 0.5865 0.01600 0.7937 0.02020 1.0000 0.00885 0.4405 0.01190 0.5914 0.01610 0.7987 0.00890 0.4431 0.01200 0,5963 0.01620 0.8032 0.00895 0.4454 0,01210 0.6013 0.01630 0.8084 0.00900 0.4480 0.01220 0 6064 0.01640 0.8130 0.00906 0.4505 0.01230 0.6113 0.01650 0.8183 0.00910 0,4529 0.01240 0.6161 0.01660 0.8231 0.00915 0.4551 0.01250 0.6211 0.01670 0.8278 O.M)920 0.4579 0.01260 0.6262 0.01680 0.8333 0.00925 0.4604 0.01270 0 6309 0.01690 0.8382
Note:
I 5 =
100 -
2R
+1
(1”)( 8 ) n-here R = ~
(129
Zz8 = ion current of mass 28 ZZ9 = ion current of mass 29
Tables of reciprocals ( 1 ) n’ere used, and it was found that interpolation as indicated was satisfactory for the authors’ purposes. Ratios less than 0.00720 occasionally may be obtained. In these cases extrapolation may be made readily and accurately by subtracting 0.0005 from the atom % “5 for each 0.00001 decrease in ratio. I t is evident that the table can be expanded or modified further to suit individual needs. For convenience two sheets of data may be combined back to back with transparent plastic covers to provide a protected table for ready reference. Such covers are obtainable from American Kleer Vu Plastic, Inc., 57 Thames St., Brooklyn, N. Y. LITERATURE CITED
(1) Fisher, R. A., and Yates, F., “Statistical Tables for Biological, Agricultural and Medical Research,” 2nd ed., London, Oliver and Boyd, 1943. ( 2 ) Rittenberg, D., “Preparation of Gas Samples for Mass Spectrographic Isotope Analysis,” in Wilson, D. W., el al., “Preparation and Measurement of Isotopic Tracers,” Ann Arbor, Mich., J. W. Edwards, 1948. RECEIVED for review J u n e 30, 1952. Accepted Beptember 8, 1952.
