Abstract
A method for the quantitative measurement of minute amounts of chloroform has been described by Cole. 1 An attempt was made to use this test to determine the amount of chloroform in sea water, in which small marine organisms were being anesthetized. Certain difficulties were encountered, many of which arose from the fact that the accuracy of the test was not known. This led to the study of the accuracy of the test discussed below.
A series of 105 tests were made upon a given concentration of chloroform in sea water. The test consists of mixing 2 cc. of 20% NaOH in distilled water, 1 cc. of pyridine and 1 cc. of the chloroform solution in a test tube and placing the latter in a water bath at 100° C., a red or pink color appearing in the mixture at this time. Precautions are taken to eliminate errors due to evaporation. When the chloroform is in sea water a precipitate forms; this is thrown down with a hand centrifuge. When distilled water is used no precipitate is formed. The tube is then cooled to about 18° C. and placed in a comparator box so arranged that several tubes can be arranged one behind the other, the color within the tubes being summated to give an intensity of color greater than that of any one of the tubes so arranged. The single tube containing the test solution is in this way compared with one or more standards and its chloroform content determined. The standards consist of tubes containing solutions of basic fuchsin in acidified 50% alcohol and are prepared according to Cole 1 ; they are of various color intensities and represent 0.5, 0.1, 0.05, 0.01, 0.005, 0.001, 0.0005 and 0.0001% of chloroform.
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