I337
V O L U M E 22, NO. 10, O C T O B E R 1 9 5 0 chloride begins to precipitate, and above 0.7 N the color formation between the antimony and gossypol is suppressed. Gossypol is reported to be unstable when stored a t room temperature (3): I n order to determine the effect of the decomposition of the gossypol on its use as a spot test reagent, the dry powder and an acetone solution of the material were stored in the’ dark a t an average temperature of 80 F. At the end of 4 months the powder and the solution had darkened somewhat but both were satisfactory for use in the spot test. O
CONCLUSION
Considering all the requirements for a good spot test, gossypol appears to be superior to any other reagent for antimony which has been previously reported in the literature. It is sensitive, highly selective, stable, and readily available. The spot test procedure is very simple, requiring no elaborate conditioning treatments or specialized techniques. ACKNOWLEDGMENT
The authora wish to express their appreciation for financial
assistance given them under a contract with the Office of Naval Research. LITERATURE CITED
(1) Adams, R.,Geissmann, T. A., Dial, W. R., and Fitzpatrick, J. T.,J . Am. Chem. Soc., 63,2439 (1941). (2) Boatner, C. H.,Caravella, M., and Kyame, L., INO. ENO. CHEM.,ANAL.ED.,16,566 (1944). (3) Castillion, L. E., Hall, C. M.. and Boatner, C. H., J . A m . Oil Chemists’ Soc., 25,233 (1948). (4) Denigbs, G.,Chem. Zenlr., 1901, 11, 1214. (5) Eegriwe, E., 2. anal. Chem., 70,400 (1927). (6) Feigl, F.,“Chemistry of Specific, Selective, and Sensitive Reactions,” pp. 8-10, New York, Academic Press, 1949. (7) Feigl, F., Mikrochemie, 1, 74 (1923). (8) Feigl, F., and Neuber, F., Z . anal. Chem.. 62,382 (1923). (9) Feigl, F., and Ordelt, H., Ibid., 64,41 (1924). (10) Fresenius, C.R., Ibid., 1, 444 (1862). (11) Gillis, J., Hoste, J., and Claeys, A., Anal. Chim. Acta, 1, 291 (1947). (12) Wenger, P.,and Blancpain, C. R., Helv. Chim. Acta, 20, 1427 (1937). (13) West, P.W., J. Chem. Education, 18,528 (1941). RECEIVED January 16, 19.50.
Introduction of liquid Samples into the Mass Spectrometer K. M. PURDY AND R. J. HARRIS, Esso Laboratories, Esso Standard Oil Company, Baton Rouge, La.
,/I
announced by the Atlantic Refining Company ( 2 ) . A sinteredglass disk mercury valve is employed in a majority of the techniques now being used for the
/ / Figure 2.
TO SAMPLE N TRODU CT IO N MAN I F O L D
BASKET HEATER W I T H N IC H ROME W I RE HEAT1NG ELEMENT ON INNER WALL OF HE ATER
Modified Apparatus for Viscous Samples
pool of mercury used in the sintered-glass valve, thus eliminating the introduction of air with every sample. A short length of capillary glass tubing is used in making this sampling device. It must, necessarily, be small because of pressure limitations in the mass spectrometer inlet system. The pipet shown in Figure 1 will deliver a volume of about 0.001 ml., if made according to the dimensions shown. A constant-volume capillary pipet was developed in the authors’ laboratories to eliminate disadvantages of other methods of liquid sample introduction investigated. As shown in Figure 1, the pipet is so constructed as to be completely immersed in the
Figure 1. ConstantVolume Capillary Pipet
The bottom of the capillary tube is carefully ground to a point, so that ositive contact with a single point of the fritted plate may be ma&. The top of the capillary is ground to a conical or rounded shape to prevent the collection of a small pool of liquid on top when the capillary is filled with sample. A glass rod of small diameter is secured to the middle of the pipet as a handle to facilitate handling the small pipet. Emery paper has been found to be the most satisfactory medium for grinding these pipets. Emery paper No. 1 is used for
1338
ANALYTICAL CHEMISTRY
Table I.
Reproducibility D a t a Using Constant-Volume Capillary Pipet
8P.mg1e
n-HeDtane "-Heptane %Xylene m-Xylene
Date 1949
5/18 5/19 5/20 5/31
No. of Average Standard Probable Datu. Peak Helght Deviation Emor 7 254.8 0.89 0.60 14 7 10
261.7 1764.0 1787.4
1.19 9.04 9.67
0.83 6.46 0.48
original ginding down, and this is followeu uy rreacmenx with No. 0 paper. A final polish is given to the ground surfaces with No. 00 emery paper. In sampling with the capillar pipet, i t is essential that the order to fill the pipet, the tip capillary he thoroughly clean. is merely touched to the surface of the liquid sample. The sample is drawn into the pipet by capillary setion. A Corning Type F sintered-glass disk covered with mercury is used to introduce the sample into the instrument. Enough mercury must cover the fritted plate to ensure complete immersion of the pipet when the tip contacts the surface of the fritted plate. Reduced pressure beyond the fritted plate then ulls the sample from the pipet and mercury enters the top of t i e pipet and rephees the sample in the capillary. Extreme care must be exercised in introducing samples with the pipet to make direct contact with t,he fritted plate, avoiding any scraping or scratching of the
2:
37.
fritted plate surface, a8 sm capillary. These pipets have been us- a a ~ ~ n c ~ 111 n rc nye ~ eiauurarones for analyzing liquids as high aa Ctg hydrocarbons with the inlet system at room temperature. Typical reproducibility data are shown in Table I. .klvantagrs of this procedure are that coustaut ilvpuratc "01!mi+( re introduced for rxlibrations nnd analyses without LL me&+ iirerncui r e q u i d , and no smsitiviry calculations are required, b e w u 3 e comput*rionu are madc directly from peak heights.
sampi; the whole pipet is gaced in tube A: and the tube is connected to the instfument: Dry ice is packed around the tube while it is evacuated. Then the heater is placed around the tube and gradually heated until all the sample is vaporized from the pipet. LITERATURE CITED
( 1 ) Friedel. A. E.. Sharkey, A. G.. and Hurnbert. C. R., ~ A L C E E M . . ~1572-3 ~. (1949). (2) Taylor. R. C . . and Young. W. S., IND. ENQ.Ca~ar..ANAL.Eo.. 17, 811 (1945).
RECEWED January 18. 1950.
Phenylacetic Ac:id (a-Toluic Acid)
Contributed by DONALD G. GARB)iR AND WALTER C. MCCRONE .irmour Research Foundation. Illinois Inrstitute of Technology, Chicago 16, 111.
0 C>-CH&" O 'H Struotural Formula for Phenylacetic Acid Phenylaoetic wid is soluble in most common solvents. Crystals for x-ray diffraction were gown from water solution and those for optical studies by ncrystallization on a microscope slide from Cargille refractive index liquids. CRYSTAL MORPHOLOQY
X-RAYDIFFRACTION DATA gP:cLGrouP; (1). , , . , -L e 1 1 uimensious. a = 14.m A.: b = 4.98A,: c = 1U.17 A, a = 14.2 A .; b = 4.90A.; c = 10.0A. (1). Formula Weight per Cell. 4. Formula. Weight. 136.14. Density. 1.228; 1.262 (x-ray),
c:,
^ ^
d 14.38 7.08 6.32 5.91 5.05 4.74 4.49 4.33 4.19 4.08 3.81 3.06 3.52 3.34
1.00 Very weak Very weak Very weak
3.16 3.02 2.89 2.79 2.69 2.55 2.48
0.11 0.18 0.53 0.77 Ver weak 8.22 0.14 Very weak 0.59 0.10
0.16 0.13
Very weak Very weak 0.15
Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak Very weak
%A
2.20 2.w 1.9Y 1.87 1.78 1.01
npnrrr. P, .~ Refractirr
S = 1.569
UWX~BLI
A,;
LO
-.I.
BL
= i.om
r V.WI;
0.002; 7 = 1.671 f 0.005. Optic Axial Angles (5893 A,; 25' C.). 2V = 39'; 2E = 67". Dmpersion. v > r siignc. '' ' ' Optic Axial Plane. 010. Sign of Double Re fraction. Positive. Acute Biseetrix. Y . Extinction. 9, A c = 5' in obtuse 8. Molecular Refract; ( R ) (5893 A,; 25' C.). q& = 1.599; R (calcd.) 35.7; 6 (Obpd.).= 37.8. , . .. FUSION DATA. Phenyiaceclc acia melt4 mthout aecomposltlon a t 76" C. It crystallizes without seeding forming flattened rods lying on 100 and some crystals elongate6 parallel to c lying on 010. The crystal front in a mixed fusion nsuall has illdefined profile angles due to solubility. However, B Canaia halsrtm mixed f
I
-
9 I
., .
.
.
