Spring Lake reservoir of Macomb, Illinois, is a typical model of the drinking water supply of some midwestern towns of the United States. Water samples collected periodically in 1980 and 1981 from this lake were tested for mutagenicity using the Tradescantia micronucleus (Trad-MCN) test, a highly sensitive mutagen-detecting bioassay. Water samples from 1981 were also analyzed chemically. The micronucleus (MCN) frequency peaked (12-14 MCN/100 tetrads) in mid-July in both years, as compared with the average frequency (5 MCN/100 tetrads) of the base-line control that was maintained in nutrient solution (prepared with distilled water and pure chemicals). Drinking water from the tap was tested in parallel with lake water, and its mutagenicity tended to fluctuate with the mutagenicity of the lake water.

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Using the Spectronic 20The fluorescence process is characterized by high sensitivity and selectivity which makes it an extremely important analytical tool that has become useful and valuable in practically all areas of chemistry. We believe the student should be introduced to this technique in the laboratory. This paper proposes a simple method by which a fluorometer can be constructed for use in the laboratory to acquaint the student with the fluorescence technique. This method consists of modifying a Bausch and Lomb Spectronic 201 to convert it to a filter fluorometer. The equipment

Precision. On the same day, a single penicillin V fermentation sample of a series was analyzed 71 times. The following results were obtained: Average value of 8764 units per milliliter with a relative standard deviation of 0.9%. Dayto-day (TV = 50) analyses of penicillin V fermentation samples gave an average value of 7710 units per milliliter with a relative standard deviation of 2.4%.The AutoAnalyzer Method vs. the Manual Method. The two methods agreed with a correlation coefficient of 0.97Interference. Only a few substances are able to reduce a molybdoarsenic acid-mercuric chloride reagent at room temperature. Among these are strongly reducing salts such as ferro and stanno salts, as well as ascorbic acid and hydroquinone. These substances were not found in any measurable concentrations in the fermentation substrates which were used. However, degradation products of penicillin, such as penicilloic acid, penilloic acid, penillic acid, and penicillamine may be found. Penicilloic acid, the active agent in the method, reacts with molybdoarsenic acid-mercuric chloride to the greatest extent. Penilloic acid interfered slightly (less than 10%), whereas penillic acid and penicillamine exerted strong interference, e.g., 10 mg of penicillamine per milliliter gave a reading corresponding to 10000 units of penicillin G per milliliter. However, this interference did not affect the final calculated penicillin concentration, since the blank corrected for interference of this nature.Conclusion. The AutoAnalyzer modification of Pan's procedure results in a method with a high order of specificity, accuracy, precision, and speed of analysis, as well as a high sensitivity. In addition, only very small amounts of sample are required for each analysis. ACKNOWLEDGMENTThe author is very grateful to P. W. Hansen for his valuable help during the preparation of this manuscript.