JANUARY 15,1937
ANALYTICAL EDITION
27
I
with a sufficient quantity of the diluent to reduce the bismuth concentration. The alternative, when dealing with Bismuth added, quantities above 0.20 mg. of bismuth per 100 cc., is to deterBismuth mg. found, O.Ool O.O1 0 . 2 5 0.50 ‘.O0 2.00 mine the average density of the bismuth line corrected for mg. : 5::: : :i: :!; : variations in the density of the internal standard and to evaluate the bismuth concentration from the straight-line portion of Figure 2. These curves were plotted from the mean values TABLE11. &COVERY OF BISMUTH FROM TISSUES AND EXCRETA . of repeated observations on a series of solutions prepared by OF A RABBIT adding known quantities of bismuth and the required quantity (Killed one week after the administration of 3.5 mg. of bismuth of the “internal standard” to suitable volumes of the stock TABLEI. BISMUTH RECOVERIES
:
Tissue
:::
::
8 ii 8
intravenously) Weight
Bismuth Found
Mo.
Gams
Blood Liver Spleen Kidneys Heart Lungs Central nervous system Testes Bile Pancreas Muscle Bone Skin Intestinal tract Contents of tract Ears, tail, and feet Remainder Entire carcass Urine Feces Total bismuth found in excreta Total bismuth found
76.1 54.8 0.7 11.5 4.1 6.2 14.0 1.4
0.001 0.013 0.000 0.08
0.000
0.001 0.000
... 2.1
0.000
578.5 132.0 208.4 132.2 164.0 130.0 348.0
0.014 0.18 0.01 0.05 0.03 0.10 0.05 0.633
o.ooo 0.004
~
’
2.24 0.90
-
3.140 __ 3.673
tion has proved very satisfactory, in that the salts present are good conductors and give a very steady arc when used with the technic described (1). Moreover it is free from the excessive creeping which may give rise to incrustations about the crater of the electrodes. Such incrustations result in spectrograms with very dark backgrounds because of the high concentration of incandescent salt particles in the arc.] Then a 0.2-cc. portion is introduced into each of 4 cratered graphite electrodes which are dried at 1200 e. and arced in accordance with the technic dewhile t,he region A2600 to A3800 is scribed for lead (I), photographed.
Applicability, Sensitivity, and Accuracy of Method The recoveries for known amounts of bismuth added to digested portions of beef are tabulated in Table I. In Table I1 are recorded the results obtained from the tissues and excreta of an experimental animal. The weights of tissue available have been recorded in order to indicate the size of samples which can be utilized. The error of analysis, as shown in Table I, naturally depends on the quantity of bismuth encountered. For amounts above 0.20 mg. the error is = t l O per cent. For quantities from 0.01 to 0.20 mg. the error is about 10.01 mg. The greatest proportional error naturally occurs with quantities below 0.01 mg., but the errors in the estimation of extremely small amounts down to 0.001 mg. rarely exceed *20 per cent. (Although much smaller quantities can be detected, a t least as low as 0.00004 mg., quantitative estimations below 0.001 mg. do not appear sufficiently accurate to be useful because of mechanical losses, as those caused by adsorption, and the passage of colloidal bismuth sulfide through the filter paper.) In the case .of material free from iron and containing very little ash, the separation of bismuth is of unnecessary, and it may well be that quantities as low as 0.0002 mg. of bismuth can be dealt with by further concentrating the solution of the ash, Literature Cited
Follo’ving the suggestion Of Lundegardh (’), two curves have been found useful in evaluating the densitometric values for the plates. The curve in Figure 1, in which the opacity ratios (galvanometer throw for the zinc line/galvanometer throw for the bismuth line) are plotted against the bismuth concentrations, is employed when the average opacity ratio of the four spectraindicates less than 0,0004 mg. (0.20 mg. per loo Of bismuth On the arc‘ This lnay be used in estimating higher amounts of bismuth by diluting
(1) Cholak,
J., IND, E ~ GCHEM,, , Anal, Ed,, 7, 287 (1935).
J., J . A ~Chem. , sot., 57, 104 (1935). (3) Lundegardh, H., “Die quantitat>ive Spektralanalyse der Elemente,” P a r t 11, Jena, G u s t a v Fischer, 1934. (4) Olseh, J. “Chemical Annual,” 7th ed., P. 477, NOW York, D. Van Nostrand Co., 1934.
( 2 ) Cholak,
c.9
RECEIVEDJuly 11, 1936. Presented before the Division of Physical and Inorganic Chemistry, Symposium on Spectroscopic Methods of Analysis, at the 92nd Meeting of the American Chemical Society, Pittsburgh, Pa., September 7 to 11, 1936.
Determining Calcium in Blood Serum H. K. MURER,’ Washington Agricultural Experiment Station, Pullman, Wash.
IN
THE determination of blood serum calcium by the Rymer and ~~~i~ (1) modification of the Tisdall (2) method, the separation and washing of the calcium oxalate by Successive centrifuging are very time-consuming. There is also possible loss while decanting and from creeping of the precipitate. By the use Of 30-cc*sintered-glass Buchner nation 3 G. 4),this centrifuging and decanting can be avoided. Place 2 ml. of serum in the test tube, dilute with 2 ml. of water and 0.5 ml. of saturated ammonium oxalate, shake, and allow to stand overnight. Filter on the glass filters, and wash with ammonia water (4 cc. of concentrated ammonia t o 250 ml.). After removing the funnel, rinse out the portion below the filter, 1
Present addresa, 44 Irving St., Cambridge, Mass.
place the funnel on top of test tube in the suction flask, dissolve the precipitate through the filter with three 2-ml. portions of hot N sulfuric acid, applying suction after each addition of acid, and fiTashthe filters with water. &move and rinse the test tube and lower portion of filter into a 50-ml. beaker, heat to boiling, and titrate with dilute permanganate from a Koch automatic microburet. Very satisfactory results were obtained with this method which lends itself well to fast routine work,
Literature Cited (1) Rymer, M.R., and Lewis, R. C., J . Bid. Chem., 95, 441 (1932). (2) Tisdall, F. F., Ibid.2 56, 439 (1923). RECEIVED September 1, 1936.
