Sanitary Analyses
Description
This section is from the book "Beverages And Their Adulteration Origin, Composition, Manufacture, Natural, Artificial, Fermented, Distilled, Alkaloidal And Fruit Juices", by Harvey W. Wiley. Also available from Amazon: Beverages And Their Adulteration.
Sanitary Analyses
When a water is examined solely to determine whether it is contaminated attenton is paid, aside from a bacteriological analysis, especially to the determination of free and albuminoid ammonia and nitrites and nitrates. There are certain points that should be borne in mind when considering a sanitary analysis of a water, viz., when all the figures are high, or certain ones are extremely high, the chemist can usually say with a reasonable degree of certainty that the water is contaminated; but in some cases all of the figures may be low, thus indicating to the chemist that the water is perfectly healthful and yet bacteria may be present which would have a very injurious effect upon the health of the consumer. In such cases a sanitary analysis serves only as an indication and not as a proof, and should be accompanied by a bacteriological examination to give results of a positive nature.
The following is an analysis made in the Bureau of Chemistry of a sample of water, which one can say with a reasonable degree of certainty is contaminated.
Parts per million | |
Free ammonia.............................. | 2.04 (high) |
Albuminoid ammonia....................... | 0.17 (high) |
Nitrogen as nitrates......................... | Trace |
Nitrogen as nitrites.......................... | Faint trace |
Oxygen consuming capacity................. | 4.75 (high) |
Chlorin........................................................................ | 12.00 |
Total solids.................................. | 55.00 |
Following is an analysis of a water which one can say with a reasonable degree of certainty is pure.
Parts per million | |
Free ammonia................................... | Trace |
Albuminoid ammonia........................................................ | 0.02 |
Nitrogen as nitrates.............................. | Trace |
Nitrogen as nitrites............................................................. | Trace |
Oxygen consuming capacity...................... | 0.10 |
Chlorin............................................................................... | 4.00 |
Total solids.................................... | 128.00 |
Following is an analysis of another water which one can say with a reasonable degree of certainty is pure.
Parts per million | |
Free ammonia................................. | 0.03 |
Albuminoid ammonia........................... | 0.06 |
Nitrogen as nitrate.............................................................. | 0.106 |
Nitrogen as nitrite............................... | Trace |
Oxygen consuming capacity............................................. | 0.175 |
Chlorin......................................... | 4.800 |
Total solids..................................... | 355.00 |
A bacteriological examination of this water, also indicated it was pure. It showed only 38 organisms per mil1 (c.c.) and no gas producers in either 0.1 or 1.0 mil.
1 Cubic centimeter.
Following is an analysis made in the Bureau of Chemistry of a water, which is extremely doubtful. One cannot judge of its purity without a careful bacteriological examination and also a further chemical investigation.
Parts per million | |
Free ammonia................................. | 0.80 |
Albuminoid ammonia........................... | 0.108 |
Nitrogen as nitrates............................. | 5.00 |
Nitrogen as nitrites............................ | 0.0005 |
Oxygen consuming capacity...................... | 0.80 |
Chlorin........................................ | 14.50 |
Total solids.................................... | 399.00 |
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