Spectrophotometric Determination of Bischlorophenol and Other Phenolic Compounds ARNOLD J. SlNGER AND E l f I S U E L R . STERS Research Laboratory. .-lntni-i-dent, Inc., Jersey City 6 , .\. J .
HE bischlorophenol compounds have been widely used for Tmiidenproofing fabrics and are now being increasingly used in the pharmaceutical and medical fields. The methods available for the quantitative determination of these compounds are based upon halogen determination ( 4 )or colorimetric phenol determinations ( 2 ) . Gottlieb and Marsh ( 9 ) devised a method using 4-aminoantipyrine, which haa been widely adapted but has the disadvantage of being extremely sensitive to p H variation, giving the test color in the absence of the test material with p H variations. The reaction reported by Gibbs ( 1 ) and Snell ( S ) , using 2,6dibromoquinone chloroimide to form 2,6-dibromoindophenols with phenolic compounds having an unsubstituted para position, was found to be adaptable for the authors’ test compounds. This reagent is directly quantitative for: ( I ) bis(2-hydrouy-5-chlorophenyl)methane, (11) hexachlorophene [2,2’-methylenebis(3,4,6trichloro)phenol, (111) thymol, (117) phenol, and other phenolic compounds.
conformed with the Beer-Lambert law within the range of the assay, as is shown in Figure 3. METHOD OF EXTRACTION
Because the phenolic conipounds were incorporated in mixtures of soluble and insoluble ingredients, it was necessary to develop a method for their quantitative extraction. The extraction method v a s based upon the ready solubility of these compounds, without ’ sodium hydroxide solution. The compounds hydrolysis, in 1% were rather insoluble in water but soluble in 1% sodium hydroside.
INFLUENCE O F pH
The development of color and its intensity are greatly influenced by the hydrogen ion concentration. Determinations were made a t hydrogen ion concentrations from p H 9.0 to 10 using the potassium chloride-borate-hydroxide buffer. The readings were obtained colorimetrically and are shown in Figure 1. The optimum pH was found to be 9.8. 80 W
z
WAVELENGTH
c
c
Figure 2.
60
IN
MILLIMICRONS
Spectral Transmittance
z
Ln
IOC
(L
c W z
90
40
BC @= a Y
ZO
W
7c
2
s
6C
3,
s 1. Bis(2-hydroxy-5-chlomphenyl)methane 11. 2,2’-Methylenehis(3,4,6-trichloro)phenol, bis(2-hydroxy-3,5,6trichlorophenyl)methane, hexachlorophene 111. 3-p-cymenol IV. Phenol
5c
4c
While the development of color intensity was greatest a t pH 9.8, the color was more stable a t pH 11, standing without detectable change for several hours a t this concentration. Therefore, after development of the color, the pH was raised for greater color stability.
I-
SPECTRAL TRANSMITTANCE
LT
3c
s L zc
The spectral transmittance was determined a t intervals of 25 mp with the Beckman Model B spectrophotometer, using the “blue” tube with slit widths from 0.3 to less than 0.1 mm. a t sensitivity one. Maximum absorption was found to be (Figure 2): I, 580 mp: 11,680 m r ; 111,575 mp; and I\’, 600 mp. CONFORMITY WITH BEER-LAMBERT LAW
Standard solutions containing from 1 to 8 micrograms per ml. of the various compounds were reacted and measured and the resulting concentration curve was plotted on semilog paper. The straight lines obtained demonstrated that the color development
Y/ML.
Figure 3. 51 1
2
4 6 CONCENTRATION
8
Effect of Concentration on Transmittance
ANALYTICAL CHEMISTRY
1512
Table I.
Batch A B
c
Percentage Recovery Obtained in Routine Control Analysis C.ompound
I I
I 111 I11 I.' I11 G (no I or 111 present)
D E
Theoretical Yield, Gram 0.25 0.25 0 25 0.25 0 25 0 '13
Actual Yield, Gram 0.24575 0.24625 0.242 0.241 0,24525 0.24475
Recovery,
70
98.3 98.5
96.8 96.4 98.1 97.9 0.0
The samples were extracted by shaking for 30 minutes and filtering through paper. The filtrate m s used for the determinnt ion, REAGENTS
.\. Standard Solution. Dissolve 20 mg. of I, 11, 111, or I V in 100 ml. of 1%sodium hydroxide solution. B. 2,&Dibromoquinone Chloroimide Reagent Solution. Dissolve 80 mg. of 2,6-dibromoquinone chloroimide in 25 ml. of acetone-free ethyl alcohol. C. Buffer Solution, pH8.3. (Khen 5ml.of lY0 sodium hydrosi t k are added to 10 ml. of buffer solution, a p H of 9.8 is obtained.) Boric acid Potassium chloride Sodium hydroxide Distiiled water t o make
12.369 grams 14.911 grams 1.60 grams 1000 nil.
D. Sodium Hydroxide, 1% solution. SPFXTROPHOTO?vIETRIC CALIBRATION WITH STAKD4RD SOLUTIONS
.Accurately measure 1 ml. of standard solution for each 2 niicrograms per ml. final concentration of the chemical into a 100-ml.
volumetric flask. Add sufficient 1% sodium hydroxide to make 5 ml. and then add 10 ml. of buffer solution C. Add 2,6-dibromoquinone chloroimide, reagent B, a t the rate of 1 ml. for each 500 micrograms of the compound sought. Allow the color to develop for 15 minutes and then add 3 ml. of 1% sodium hydroxide solution. Bring to volume with distilled water. The optical determinations were made using a reference cell of the same solutions but without the addition of reagent B. QUANTITATIVE DETERMINATION IN MIXTURES
Accurately weigh a sample of the material to be assayed t o give a total of 25 mg. of I, 11, 111, or I V into an iodine flask and add 1% sodium hydroxide to 100 nil. Shake occasionally during 30 minutes and filter through paper. Lse an aliquot t o proceed as for spectrophotometric calibration with standard solutions. Concentrations may be determined by plotting a line for the instrument used and reading direct (the least accurate), by the use of an included standard, or by comparison with the pure standard (the most accurate method). Any reasonably accurate photoelectric colorimeter can be used. I n routine analysis of products containing bis(2-hydrosy-5chloropheny1)niethane and hexachlorophene, a recovery of 95% or hrtter is obtainrd (Table I). LITERATURE CITED
(1) Gilibs, H. D., J . B i d . Cheni., 72, 649-64 (1927). (2) Gottlieb, S.,and Marsh, P. B., IXD. ESG.CHEM.,A N ~ LED., . 18, 16-19 (1946).
( 3 ) Snell, F. D.. and Stiell, C . T., "Colorimetric Methods of ,inalysis," Vol. 11, pp. 369-71, S e w Tork, D. Van Nostratid Co., 1936. (4) Willard, H. H., and Thompson, J . J., J . Am. Chem. S O C .52, , 1893 (1930).
RECEIVED October 11, 1950.
Special Atmosphere Excitation in Generalized Semiquantitative Spectrographic Analysis J4NUS Y. ELLENBURG' & V I LOUIS E. OWEN' Chemistry Section, .VEPA Project, Oak Ridge, T e n n . 'HE very useful seniiquarititative spectrographic analj tical procedure developed by Harvey ( 2 ) is based upon constant minimum detectability limits for spectral lines produced under reproducible direct current arc excitation conditions, Practical sensitivity limits are usually set by excessive background density Mechanical sectoring of the light beam is normally employed to give readable photographic densities while permitting the complete consumption of a sample. It has been found in the SEPA laboratories that the use of a special atmosphere chamber (Figuie 1) developed by one of the authors ( 4 ) decreases the background intensity to a point permitting the spectral light of the sample to be photographed without sectoring. A real improvement in the signal-noise ratio occurs in this process. The atmosphere chamber used in this work was designed 2 years ago primarily for use in attenuating cyanogen banding. Many workers (3, 5 ) had found that such attenuation made available useful spectral regions otherwise obscured by the cyanogen bands. The work with special atmosphere excitation employing the chamber made apparent the presence of effects on the distributions of spectral energy. These effects have been e\ploited in the analytical scheme reported here and in a procedure for determining trace metals in biological material. During the same period many other spectrochemical Iaboratorics were a150 investigating the use of special atmospheres (6). Present address, Analytical Laboratory Department, Y-12 Plant, Carbide a n d Carbon Chemicals Co., Oak Ridge, Tenn. 2 Present address, Aircraft Gas Turbine Division, General Electric Co , O a k Ridge, Tenn. 1
EXPERIMERTiL DETAILS
The experimental procedure for this modified Harvey technique has been based upon a 5-mg. sample plus 5 mg. of powdered graphite as a diluent. The total mix is arced in carbon electrodes cut as illustrated in Figure 2. The sample electrode size was selected to give proper sample-electrode consumption rates for the excitation conditions employed. Carbon electrodes were specifically k4"pchosen rather than graphite C A R B O N COUNTER' on the basis of performance. ELECTRODE The lomer sample temperatures created in graphite I If4 CATHODE electrodes necessitate longer arcing times for complete sample vaporization, to the detriment of the procedure. 0.210 A special atmosphere of 20% oxygen plus 80% helium 0.096" ir by volume was introduced into the quartz chamber 0.291 surrounding the electrodes. Input gas flow was mainCARBON S A M P L E tained a t 15 cubic feet per ELECTRODE hour with a pressure of 3 I 'k'' inches of water. Moving ANODE plate studies of cyanogen band attenuation indicated that 15 seconds' flush time was ample to rid the chamber of air. Complete consumption of the sample required a Figure 1. Electrode 60-second ara with a current Shapes for Harvey Method density of 1 ampere per sq. in Special Atmospheres 3
T
1
T
1
