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1949
PHOTOGRAPHIC DEVELOPERS
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no Elon or hydroquinone. The absorption curves of this mix before and after extraction are shown in curves A and B, Fig. 6. There is some change in curve shape but in view of the close agreement at 270 and 290 millimicrons, it is probable that only a very small error, if any, would be introduced into the analysis of Elon and hydroquinone by this difference. Elon (2.00 grams per liter) was then added. Curve C, Fig. 6, shows the resulting absorption curve. The sample was then extracted. Curve D, Fig. 6, shows that the Elon was extracted quantitatively in the presence of Elon monosulfonate.
From the above results obtained in the extraction studies of hydroquinone monosulfonate, quinone, and Elon monosulfonate, the extraction of a used tank sample with ethyl acetate would remove only Elon and hydroquinone. In the case of quinhy drone (i.e., semiquinone-type compounds) , however, approximately half of the material present is probably extracted as hydroquinone.
Procedure
280 30O 320
Wavelength m/i
Fig. 5 — Extraction study with quinone and hydroquinone.
A, quinone.
B, solution A after extraction.
C, solution A with hydroquinone added.
D, solution C after extraction.
Pipet a 25-milliliter sample of the used developer into a 125-milliliter separatory funnel and add 3 drops of phenolphthalein. Add drop wise 7 normal sulfuric acid until the indicator turns colorless. (The resulting solution should have a pB. of 8.0 to 8.5.) Record the volume of acid added.
Extract three times with 25-milliliter portions of water-saturated ethyl acetate (75 milliliters altogether), discarding the ethyl acetate layer each time. Dilute 1.00 milliliter of the extracted developer with 100 milliliters of pH 5 acetate buffer and determine the absorbancy at 290 and 270 millimicrons. Correct these absorbancies for the volume change by using the following formula :
(absorbancy) (25 + ml 7N H2SO4) (25)
corrected absorbancy.