Hach DR2400 - Page 595

Phenols
Phenols
Phenols_None_Other_4AM_Eng_Ody.fm Page 5 of 6
Distillation
This procedure is in the Hach Distillation Apparatus Manual in step-by-step
illustrated format.
1. Set up the Hach Distillation Apparatus by assembling the general purpose
apparatus as shown in the Distillation Apparatus Manual. Use the 500-mL
Erlenmeyer flask to collect the distillate. It may be necessary to use a
laboratory jack to elevate the flask.
2. Place a stirring bar into the flask.
3. Measure 300 mL of water sample in a clean 500-mL graduated cylinder. Pour
it into the distillation flask.
4. For proof of accuracy, use a 0.200-mg/L phenol standard (see Accuracy Check
on page 4) in addition to the sample.
5. Using a serological pipet, add 1 mL of Methyl Orange Indicator to the
distillation flask.
6. Turn on the stirrer power switch. Set the stir control to 5.
7. Add 10% Phosphoric Acid Solution drop-wise until the indicator changes
from yellow to orange.
8. Add the contents of one Copper Sulfate Powder Pillow and allow to dissolve
(omit this step if copper sulfate was used to preserve the sample). Cap the
distillation flask.
9. Turn the water on and adjust it so a constant flow is maintained through the
condenser. Set the heat control to 10.
10. Collect 275 mL of distillate in the Erlenmeyer flask, then turn the heat off.
11. Fill a 25-mL graduated cylinder to the 25-mL mark with deionized water.
Add the water to the distillation flask.
12. Turn the still back on. Heat until another 25 mL of distillate is collected.
13. Using a clean graduated cylinder, re-measure the distillate to make sure
300 mL has been collected. The distillate is ready for analysis.
Summary of Method
The 4-aminoantipyrine method measures all ortho- and meta-substituted
phenols. These phenols react with 4-aminoantipyrine in the presence of
potassium ferricyanide to form a colored antipyrine dye. The dye is then
extracted from the aqueous phase with chloroform and the color is measured at
460 nm. The sensitivity of the method varies with the type of phenolic
compound. Because water samples may contain various types of phenolic
compounds, the test results are expressed as the equivalent concentration
of phenol.