Determination of Acetyl in Methyl Acetate
Table II.
Vol. of Hz0 added, ml. 0 0.5 1.0 1.5 2.0 3.0 5.0
(Direct hydrolysis with KOH, 40 ml. 0.1N KOH) % Recovery of acetyl with: HzO in KOH reagent, % 39 mg. acetyl 78 mg. acetyl (0.05) 1.1 2.4 3.6 4.8 7.0 11.1
as indicator (1 ml. 0.1N KOH mg. CH&OO-).
60.8, 47.5 75.7, 7 7 . 2 93.1, 9 3 . 1 96.0, 9 6 . 0 101.0,100.0 101.0, 100.0 101.0, 100.0
= 5.9
LITERATURE CITED
(1) ASTM “1965 Book of ASTM Standards,” Part 20, pp. 891-2, American
for Testing and Materials, E i z l p h i a , 1965. (2) Cheronis, N. D., Ma, T. S., “Organic
25.5, 2 3 . 1 73.2, 6 8 . 4 90.4, 8 4 . 6 93.8, 9 3 . 8 95.4, 9 6 . 0 97.2, 9 8 . 4 99.1; 9 8 . 5
Functional Group Analysis,” pp. 175-6 Interscience, New York, 1964. (3) Critchfield, F. E., “Orpanic Functional Group Analysis,” -pp. 141-3, Macmillan, New York, 1963. (4) Hi?? J., “Physical Organic Chem2nd ed., pp. 275-7, McGrawil , New York, 1962. ;ty, (5) Jolly, S. C., “Official, Standardised and Recommended Methods of Anal-
ysis,” pp. 79-80, W. Heffer & Sons Ltd., Cambridge, 1963. (6)Mazor, L., Meisel, T., Anal. Chim. Acta 20, 130 (1959). (7) “Official Methods of Analysis of the Association of Official Agricultural Chemists,’’ W. Horwith, Ed., 10th ed., pp. 185, 420, AOAC, Washington, 1965. (8) Parr, N. L., “Laboratory Handbook,” p. 7/96, George Newnes Ltd., London, 1963. (9) Siggia, S., “Quantitative Organic
Analysis Via Functional Groups,” 3rd ed., p. 139, Wiley, New York and London, 1963. (10) Snell, F. D., Biffen, F. M., “Cornmercial Methods of Analysis,” Revised ed., pp. 343, 435-6, 725, Chemical Publishing Co., Inc., New York, 1964. W-. H. GREIVE K. F. SPOREK M. K. STINSON Owens-Illinois, Inc. Corporate Research Technical Center 1700 N. Westwood Ave. Toledo, Ohio 43607
Application of Radiometric Techniques to Quantitative Paper Chromatography of Iron, Copper, Manganese, and Cobalt SIR: Van Erkelens (2) mentions the possibility of performing quantitative analysis of traces of metals separated by paper chromatography. He precipitated the elements in the chromatograph with radioactive hydrogen sulfide, but gave no data whereby sensitivity or precision of the method could be estimated. I n another paper ( I ) , Van Erkelens described a n analysis for lead using phosphate labeled with P32after separation from a number of interfering elements. This method was extended by Welford (3) and showed high sensitivity, but again no data were presented on the precision of the method. This method describes the quantitative determination of iron, cobalt, copper, and manganese on paper chromatograms. After the chromatographic separation, radiometric methods were used t o determine these four ions. The usefulness of the radiometric method of analysis for these ions was demonstrated by an analysis of NBS Standard Reference Material No. 671, nickel oxide, which contained traces of Fe, Co, Cu, Mn, Cr, Ti, Mg, and Al. EXPERIMENTAL
I n developing a method of separation, synthetic solutions of the ions of interest were used as well as solutions of the nickel oxide sample. The first step in the procedure for the separation of the trace elements in the nickel oxide consisted of spotting several 0.01-ml. aliquots of the sample dissolved in 9 N hydrochloric acid on Whatman No. 1
4
I n order to estsblish the R, factors for the ions of interest, sufficient concentration of test solutions of the nickel oxide was used t o render the spots of copper, cobalt, and iron visible when treated with alkaline sodium sulfide. The manganese was detected using sodium peroxide. The other ions, which remained near the origin, were detected with appropriate spray reagents. The R, factors distance ion moved from origin distance solvent moved from origin
Figure 1 . Separation of trace constituents in nickel oxide standard ref. material No. 671 using the solvent system. methyl ethyl ketone-conc.
HCI (92 : 8)
chromatographic paper which had been purified by washing with 3N hydrochloric acid. The separations were then accomplished by descending chromatography utilizing a solvent consisting of 8 parts concentrated hydrochloric acid and 92 parts methyl ethyl ketone. The papers were removed from the chromatographic tank, air dried, and placed in a tank saturated with ammonia vapor in order to neutralize the hydrochloric acid. They were then removed from the tank and air dried again.
were 0.99 Fe, 0.77 Cu, 0.60 Co, 0.26 Mn, 0.08 Ti, 0.06 Cr, 0.06 hl, and 0.06 Mg, as determined by three replicate separations (see Figure 1). After establishing the R, factors, corresponding areas on additional chromatograms were cut out and analyzed quantitatively. The phosphates of iron, copper, and manganese were precipitated with radioactive trisodium phosphate (0.12M with lo5 c.p.m. of P32 per ml.) in 50-ml. beakers. The papers were removed, washed with water, and air dried. The labeled precipitates were assayed with a beta proportional counter. llanganous ion was oxidized with alkaline hydrogen peroxide (15 ml. of 30% hydrogen peroxide diluted to a liter with IN sodium hydroxide), washed with water, and air dried. The paper containing the resultant manganese dioxide was equilibrated with a solution containing Co60 in an ammonium hydroxide-ammonium chloride buffer, pH 10.00. After washing with distilled water, the adsorbed Coao was assayed using a scintillation NaI(T1) well counter. VOL. 38, NO. 9, AUGUST 1966
1265
Table I. Analysis of a Sample of Nickel Oxide (NBS, SRM No. 671) Av. Amount amount Rel.
[email protected] Cation present, % found, % dev.,\% No. det. Rel. error, % Method of analysis Fe f a 0.39 0.37 7.1 8 -5.7 Ppt'd with phosphate labeled with Pa* c u +a 0.20 0.19 6.8 8 -5.0 Ppt'd with phosphate labeled with Paz Mn+P 0.13 0.134 39.5 6 $3.0 Ppt'd with phosphate labeled with Pa2 0.13 0.138 3.8 8 +5.8 Adsorption of Cow on man aneae dioxide Mn+: co z 0.31 0.316 4.1 8 -1.9 Exchange of Fe69 with Co*($Fe(CN),,] 4 For a single determination.
The cobalt was precipitated on the paper by reacting it with a saturated solution of potassium ferrocyanide. The papers were then washed with water, with 0.1N hydrochloric acid, and then with water again. The papers were equilibrated with Fe59 solution to allow exchange with the ferrocyanide, washed with water, dried, and counted with a NaI(T1) scintillation well counter. Standard curves were prepared for each element by plotting counts per minute us. micrograms. The experimental points were fitted to a straight line by least squares analysis. Blanks were subtracted fpom all data for each element. Washing of the papers wm a very important factor in minimizing the blank. The method of vvashing was standardized to give the highest precision. The paper was washed by gentle shaking with 5 ml. of water for 10 minutes. After the first wwh the paper was removed from the beaker with forceps coated with Teflon allowing the water to drain off the paper, then the paper was placed in a second beaker containing 5 ml. of water. The procedure was repeated for a third time.
RESULTS AND DISCUSSION
Table I lists the results obtained along with data on the precision and accuracy of the method. The amounts analyzed were 3.9 pg. of iron, 2.0 pg. of copper, 3.1 pg. of cobalt, and 1.3 pg. of manganese. The limit of detection is 0.1 pg. for iron, 0.02 pg. for cobalt, and 0.01 pg. for manganese. The data show quite satisfactory precision except the labeled manganese phosphate precipitate. Efforts are under way to improve this precision. NBS Standard Reference Material No. 671 was certified by the use of gravimetric and spectrochemical techniques. No precision or accuracy is given on the certificate, but assuming that the recommended value is close to the true amount present, an estimate of the accuracy is given in Table I. The main advantage of the paper chromatographic method is that it permits the analysis of a number of elements in the same sample. The radiometric methods which are used to de-
termine the separated elements have a greater sensitivity than most other methods of quantitative analysis which have been applied to chromatographic separation on paper or thin layer plates. Additional studies are in progress to extend the use of these radiometric procedures on chromatographs to other elements. LITERATURE CITED
(1) Van Erkelens, P. C., Anal. Chim. Acta 25, 570-578 (1961) (2) Van Erkelens, P. C., Nature 172, 357-8 (1953'1. (3) Welford, G. A., Chiotes, E. L., Morse, R. E., ANAL.CHEM.36, 2350 (1964).
A. R. LANDGREBE T. E. GILLS J. R. DEVOE
Radiochemical Analysis Section Analytical Chemistry Division Institute for Materials Research National Bureau of Standards Gaithersburg, Md. 20760
Semiquantitative Estimation of Nitrogen in Ammonium Faujasite by Differential Thermal Analysis SIR: The use of differential thermal analysis as a tool in the analysis of minerals and inorganic compounds (8) and solid catalysts (5) is well known, and a review of significant developments in the thermal analysis field has recently been published by Murphy (6). Thermal analysis techniques have also been employed in the characterization of synthetic zeolites (8,Q). I n the course of studies on the properties of zeolites, we have observed an association between the presence of exotherms near 4O0-55O0C. in the DTA pattern (run in oxygen atmosphere) of ammonium Y faujasite and the loss of zeolitic ammonium groups. Further examination revealed that the intensity of this DT.4 exotherm was proportional to the amount of zeolitic nitrogen (in the range of 0.2-5'%). Thus, a semiquantitative method of estimating zeolitic ammonia is afforded. 1266
ANALYTICAL CHEMISTRY
(5 ml./min. a t one atmosphere) of dry O2 established. The reactor was An R. L. Stone Difthen heated to the appropriate temferential Thermal Analyzer, Model perature and the catalyst calcined DS-19 was used for DTA analyses for 3 hours. The reactor was then (10' C./min., 0 . 2 mv. full scale, sealed off and transferred to a dry 150 mesh Vycor reference). A Conbox, where zeolite samples were placed solidated Electrodynamics Corp. in dry vials for Kjeldahl nitrogen deModel 21-103 mass spectrometer optermination and DTA analysis; cataerated a t 70 e.v. was used for gas lyst samples for infrared analysis were analyses. ,A Perkin-Elmer 421 specprepared in the dry box by mulling with trophotometer was used for infrared Fluorolube S (Hooker Electrochemical analyses. Co.). This procedure was repeated Reagents. The crystalline ammofor NH4Y samples calcined at temperanium Y faujasite (NH4Y) was pretures of 200-500' C. pared from a synthetic sodium Y Similarly, effluent gas studies were aluminosilicate by repeated ion exeffected by calcining zeolite samples change with warm 10% aqueous (7.44 grams, 17.0 ml.) in dry O2 or NH,C1 solution. Its unit cell composition was (NH4)as.9.(Na)6.1.(A102)51,He (1.2 ml./min.) for 3 hours at 550" C., and collecting the total effluent (SiOz)141. (HzO)Z. gas over 10% aqueous HzSOain a conProcedure. Zeolite (4 grams, 5 ml. ventional gas collection apparatus. mesh) was placed Tn a n elecAfter vigorous shaking to complete trically-heated, tubular Vycor-glass the adsorption of XHa, the volume of reactor fitted with axial glass thermogas was recorded, and samples were couple well, and a continuous flow EXPERIMENTAL
Apparatus.
