Document 917z4aNMR60G7zaepe8L8V1xe

1 Monsanto Chemical Company W* Oi KHUMMPULH PLAH1 LABORATORY STANDARD ANALYTICAL METHOD PRODUCT General Method No. 2 TEST Color - APHA (Hazen) THIS FORM 1 1 SUPERSEDES METHOD m REVISES INSTRUCTIONS DATE IIIUID PAOE number wmt2te/n2s2t/57----------- 1 or 3 IB S1V0.007 RFS ATTACHMENTS GWM ISSUED ON 3/25/53 SCOPE This method determines the color of liquid or molten materials in which the tints or hues are not very pronounced. The colors are estimated by comparison with APHA color standards contained in 50 ml. tail-form Nessler tubes. EQUIPMENT a. Matched 50-ml. tail-form Nessler tubes (Sargent S-21035). b. Hollow polyethylene stoppers, 25 mm high, to fit Nessler tubes (Fisher Scl. Co., 14-645, size S-2). kEAGENTS a. Potassium Chloroplatinate (KaPtCla), Purified (Fisher P-158). b. Cobaltous Chloride (CoCl2.6HaO), A.R. (Mallinckrodt 4532). c. Hydrochloric Acid (HCl), A.R. (Mallinckrodt 2612). Preparation of the APHA Stock Solution: 1. Weigh accurately on an analytical balance 1.245 g. potassium chloroplatinate (an equivalent of 0.5 g. Platinum) and 1.000 g. cobaltous chloride (CoCl2.6H20) (an equivalent of 0.25 g. Cobalt). 2. Transfer both components to a 1 liter volumetric flask con taining about 300 ml. distilled H20. 3- Add 100-ml. cone. HCl and swirl to dissolve. .t 4. Make up to volume with distilled water, mix thoroughly, and store in a black-painted bottle. This is the APHA Stock Solution. It has a color of APHA 500. NOTE: In the absence of a reliable supply of potassium chloroplaffinate, chloroplatlnic acid may be substituted. Prepare as follows: 1. Dissolve 0.500 grams metallic platinum in aqua regia 0s^021 STLCOPCB4089444 ' Product: General Method No. 2 Test: Color - APHA (Hazen) 1 Method No. 10,007 Page 2 of 5 pages 2. Remove the HNOa by repeated evaporation to dryness after adding an excess of hydrochloric acid. ' jj. Dissolve this product with 1.000 g. C0CI2.6H2O as directed above. ' Preparation of the APHA Standards 1. To prepare standards, add the proper volume of the stock solu tion according to this chart, to a set of matched, tail-form, 50 ml. Nessler tubes. APHA Std. ml. Stock Sol'n. APHA Std. ml. Stock ; 3 0-5 30 3.0 5 0.5 40 4.0 8 0.8 50 5.0 10 1.0 60 6.0 15 1.5 80 8.0 20 2.0 100 10.0 25 2.5 200 20.0 NOTE: For every unit of APHA, 0.1 ml. of the Stock Solution is used. 2. Dilute the contents of each tube to the mark with.distilled water. . j5. Stopper each tube with a polyethylene stopper and mix by in verting several times. 4. The prepared standards are kept in a closed box stoppered with the polyethylene stoppers to prevent contamination and evapora tion. APHA Standards should be prepared every month to insure accuracy. DETERMINATION 1. Fill a standard 50 ml. tail-form Nessler tube to the mark with the material to be tested. , 2. Remove the stopper from the standard tube which you estimate . ' most nearly the color of the sample. The intensity of light passing through the sample is observed and compared with that of the standard. * . 5. Make the observation by looking downward through the tubes upon a white surface placed in such a position that non-glaring dayllght is reflected through the columns of liquid. For night work, the regular daylight lamps can be used. DSW 551028 - ( I STLCOPCB4089445 Product: General Method No.. 2 Teat: Color - APHA (Hazen) Method No. 10,007 Page 3 of 3 pages 4. Continue comparing until you locate the standard which most nearly matches the sample. 5. Interpret the comparison to the nearest APHA Standard. Report the results to the nearest APHA Standard, or by Interpolation between standards. DISCUSSION This method Is good only up to a color Intensity of about 100. The APHA suggests dilution to read the higher values. We have found, however, that not all materials can be treated in this manner. For values above 100, we report approximate colors as determined by com parison to 300, 400, and 500 APHA standards and interpolation between these standards. Even a slight turbidity causes a higher apparent color. For samples which exhibit turbidity. It is suggested that they be centrifuged * and the color of the supernatant determined by the preceding method. REFERENCES a. "Standard Methods for the Examination of Water, Sewage, and Industrial Wastes", 10th Edition (1955), American Public Health Association, page 88 ff. b. "Procedure for Laboratory Service Section" W.G.K. Plant Laboratory, 6/21/56, page 71. The information contained herein is, to our best knowledge, accurate; but all recommendations or suggestions are mads without guarantee, since the conditions of use are beyond our control. Monsanto disclaims any liability foj loss or damage incurred in connection with the use of the above. DSW 551029 STLCOPCB4089446