lOOr
Table II.
Run
EG
1 2
72 0
3 4 5
71.3
73.9 72.1 72.4 72.9
Av . Std. dev. f l . 1
Precision of Method
Peak height DEG TEG 55.1 49.0 55 4 48 ~- 2 54.3 48.1 53 9 46.6 48 5 56.8 55.1 48.1 ~
G
63.7
62 9 .~ .
60 5 61.3 63 6 62.4
40-
G
Lz
0
B Lz
20-
-
n.
A1.l
A0 9
i~l.4
5
IO TIME
Figure 3.
strate that separated glycerol and TEG. A 10% P P E on Fluoropak was also capable of resolving the composite mixture. EG-DEG-TEG-G, but there was some overlapping between the glycerol and DEG. This was eliminated by using a column containing 10% PPE and 2% Carbowax 20111. This mixture gave a well-defined separation of D E G and glycerol. with no effect on the glycerol and T E G separation (Figure 1). An estimation of the preci4on of the method is shonn in the data listed in Table 11, obtained by analyzing a compo4te mixture of glycol in methanol. The composition of the mixture on a weight to volume basis \vas: 2.067, EG, 2.23% DEG, 5.13% TEG. 5.47% G. The sample size used in the injection n a s 20 11. ‘Ihe glycerol peak is not
15
20
25
- MINUTES
Chromatogram of mixture of Cellosolves A. 6. C. D.
E.
F. G.
H. 1.
Monoglyme Diglyme Butyl Cellosolve Methyl Carbitol Glycerol a-monomethyl ether Butyl Carbitol Phenyl Cellosolve Benzyl Cellosolve m-Ethoxyphenol
as reproducible as the other three, but is still satisfactory for most applications. The column life appears to be indefinite, as, after approximately 500 analyses over 3 mont.hs, there was no apparent change in resolution.
technical assistance in carrying out this program. LITERATURE CITED
(1) Cordone, M. J., Compton, J. W.,
ANAL. CHEX. 2 5 . 1869-74 (1953).
( 2 ) Ginsburg, L., Z&d.,31, 1822-4 (1959). ACKNOWLEDGMENT
The authors express their gratitude to F. Gardiner Pearson and Lyle H. Phifer for many valuable suggestions a,nd to Virginia S. Schukraft for her
(3) Nadeau, H. G., Oaks, D. M., Zbid., 32,
1760-2 (1960).
IBRAHIM GHANAYEXI m I L L I A M B. S W A S N American Viscose Corp. Marcus Hook, Pa.
Absorption Flame Photometry SIR: Dr. J. TI7. Robinson of Esso Research and Engineering Co., Linden, I% J., . has been kind enough to call m y attention to several erroneous statements in my review “Absorption Flame Photometry,” rrhich appeared in XKAL. CHEX. 34, s o . 5, 210R-20R (1962). These statements were largely based on my interpretation of his lecture (ref. 93 of the review). I should like to sup1)ly the corrected information herewith. Robinson prepared hollow-cathode lamps from many other metals besides tantaluni and tungsten (page 211 R, column 2. paragraph 3). The burner :idapter (page 212R, column 1, paragraph 2) was tried on only three metals, an insufficient number to permit judging its success. Rohinson’s new burner
1848
ANALYTICAL CHEMISTRY
(following paragraph) had not been used a t the time for emission flame photometry under the conditions described, but it was used for emission and absorption as described in his later paper [Robinson, J. TV., Harris, R. J., Anal. Chim. Acta 26, 439-45 (1962) 1. Neither was this burner (page 212 R, column 2, center) tried with oxyacetylene. Robinson did in fact detect vanadium by absorption in oxycyanogen (page 216 R , column 2, paragraph 4) a t a concentration of 300 p.p.m., but, as he points out, this is hardly useful for the determination of vanadium in petroleum. He was able to confirm David’s results for molybdenum (same column, paragraph 7 ) although, using an oxyacetylene flame, he was not able to
attain David’s sensitivity. The high sensitivity reported for platinum (page 216 R, column 3, bottom) was obtained by means of the adapter mentioned above; without the adapter the sensitivity was one tenth as great. Lastly (page 219 R , column 1. end of paragraph l ) , Robinson disclaims having worked with the sputtering technique. I apologize for these misinterpretations which could have been avoided by correspondence with Dr. Robinson before publication. It should be added that the data in Table I (11. 214 R) are in px. not 7’ as stated in the caption. PAUL T. GILBERT,JR. Beckman Instruments, Inc. Fullerton, Calif.
