godl
8-
0.7r
l.5
Z
1.4
pj 1.3
n 4oppn
Z
2 1.2 [x
0 I./ cn m Q
1.0 0.9
500
0.8
600
700
WAVELENGTH 0.7
800
IN n/p
Figure 3. Variation in absorbance of iron dinitrosoresorcinate solution with iron concentration (p.p.m.) in presence of moderate amount of dinitrosoresorcinate in neutral solution
0.6
acetate, bromide, chloride, citrate, tartrate, perchlorate, iodide, nitrate, sulfite, thiosulfate, and thiocyanate.
0,5 0.4
LITERATURE CITED
0.3
(1) Morgan, G. T., Moss, J. E., J . Chem. SOC.121, 2857 (1922). (2) Nichols, M. L., Cooper, S. R., J . Ani. Chem. SOC.47, 1268 (1925). (3) Saywell, L. G., Cunningham, B. B.,
0.2 0.1
600
500
700
WAVELENGTH
800
IN
my
Figure 2. Variation in absorbance of iron dinitrosoresorcinate with increasing iron concentration DNR. 10-W Fe(ll), M X 1 0 - 5 I , 5; 2, 7.5; 10. pH 4.4 1 . 5 ; 2, 7.5; 3, io. p~ i o
3,
Fe(lll), M
X lo-’
Correction
4, 5. pH 4.4 5. pH 10
4,
case. I n both cases the colored complex was stable under atmospheric conditions for 12 hours. EFFECTOF TEMPERATURE. On heating solutions of iron(I1)-dinitrosoresorcinate complex, the color faded gradually, turning yellow at about 65’ C., and was slowly restored on cooling. EFFECT OF ORGANIC SOLVENTS. Ethyl alcohol and ethylene glycol when present in high concentration caused a negligibly small increase in the color intensity of the complex, whereas isopropyl alcohol and acetone caused fading of the color, and in the latter solvent the solution became dirty green after a few hours. EFFECTSOF IONS. The possible interference of ions was studied on solutions ‘containing 2.0 p.p.m. of 1384
IND.ENG. CHEM.,ANAL. ED. 9, 57 (1937). (4) Vogel, A. I., “Textbook of Practical Organic Chemistry,” pp. 166, 169, 170, 171, Longmans, Green, London, 1959. (5),Vogel, A. I., “Textbook of Quantitative Inorganic Analysis,” pp. 628-9, Longmans, Green, London, 1959. (6) Zbid., p. 869. (7) Ibid., p. 870. RECEIVEDfor review January 15, 1962. Accepted July 5, 1962.
ANALYTICAL CHEMISTRY
iron(I1). The absorbance curves were determined and then compared with the standard for the same amount of iron(I1) without the added ions. No interference was caused by 1000 p.p.m. of lithium, sodium, and potassium; 500 p.p.m. of ammonium, calcium, strontium, barium, aluminum, magnesium, and manganese(I1) ; 100 p.p.m. of U02+2 and molybdenum; and 50 p.p.m. of zinc. On the other hand, 20 p.p.m. of chromium(III), 10 p.p.m. of tungsten, 2 p.p.m. of. copper(I1) and nickel, and 1 p.p.m. of palladium and cobalt caused appreciable interference. Bismuth and silver must be completely absent from the solution because of the formation of precipitates. No interference was shown in concentration as high as 500 p.p.m. for
Use of an Ionization Chamber for Measuring Radioactivity in Gas Chromatography Effluents I n this article by James Winkelman and Arthur Karmen [ANAL. CHEM.34, 1067 (1962) 1, two references were omitted inadvertently. On page 1067, column 2, second full paragraph, follow ing “Proportional counters have been constructed suitable for operation a t high temperatures” there should be a reference to Wolfgang, R., Rowland, F. s., ANAL.CHEM.30,903 (1958), and following “ionization chambers have been used at room temperature following combustion of the sample,” there should be a reference to a paper by Cacace, F., Guarino, A,, Inam-ul-Haq, Ann. Chim. (Rome) 50, 919 (1960).
