Effect of beta-cyclodextrin on mucochloric acid and 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone.

Cyclodextrins form inclusion complexes with a wide range of guest molecules which wholly, or in part, fit into their hydrophobic cavity. Since no covalent bonds are formed in this complexation, the guests can subsequently be eluted. The possibility of such complexation was envisioned as a means of removing chlorinated furanones from drinking water. Using a combination of infrared and ultraviolet techniques, evidence is presented for inclusion complex formation between mucochloric acid and beta-cyclodextrin in acidic aqueous solutions. Ultraviolet evidence supports the conclusion that under these acidic conditions, mucochloric acid exists in its cyclic form. Solid samples of the mucochloric acid-beta-cyclodextrin complex could be isolated by recrystalization of a 1:1 mole ratio of the above compounds from water at pH approximately 2. Solid sample infrared (potassium bromide or Nujol) showed a carbonyl shift of approximately 20 cm-1 when mucochloric acid was compared to the mucochloric acid-beta-cyclodextrin complex. No such shift was found upon simply grinding together the above components. Thus the carbonyl shift is ascribed to inclusion complexation of mucochloric acid into the beta-cyclodextrin cavity. Melting point and thin-layer chromatographic analyses also yielded supporting evidence for the formation of solid mucochloric acid-beta-cyclodextrin complexes. Pilot studies with 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), suggest a similar beta-cyclodextrin-complex formation in acidic solutions.

Studies on the potent bacterial mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone: aqueous stability, XAD recovery and analytical determination in drinking water and in chlorinated humic acid solutions.

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was detected by gas chromatography/mass spectrometry in drinking water samples from 3 locations in the U.S.A., and also in a chlorinated humic acid solution. MX appears to account for a significant proportion of the mutagenicity of these samples, as measured in the Ames test using strain TA100 without metabolic activation. Studies on recovery of MX from spiked water samples by XAD-2/8 resin adsorption/acetone elution indicated that sample acidification prior to resin adsorption was essential to the effective recovery of MX. The stability of MX in aqueous solution was pH and temperature dependent. At 23 degrees C the order of stability, based on persistence of mutagenic activity was found to be: pH 2 greater than pH 4 greater than pH 8 greater than pH 6. The half-life at pH 8 and 23 degrees C was 4.6 days. One of the degradation products has been tentatively identified as 2-chloro-3-(dichloromethyl)-4-oxo-2-butenoic acid, an open form of MX which appears to be in the "E" configuration. Overall, these results suggest that MX is formed during water chlorination as a result of reaction of chlorine with humic substances, and that a substantial fraction of the MX formed is likely to persist throughout the distribution system.

Mutagenic by-products from chlorination of humic acid.

Chlorination of humic and fulvic acid results in the formation of direct-acting mutagenicity, detectable in the Salmonella/microsome assay (Ames test). This mutagenicity is being characterized as part of an overall effort aimed at evaluating potential health risks associated with the presence of mutagenic chemicals in drinking water. A number of chlorinated organic compounds, including several known mutagens, have been identified and quantified in diethyl ether extracts of chlorinated humic acid solutions. However, the total mutagenicity of these compounds accounts for only about 7% of the original mutagenicity. Synergistic or antagonistic interactions among the identified components have been ruled out as possible explanations for the failure to account for a higher percentage of the activity. Recent progress has been made to separate the activity into neutral and strong acid fractions. Further isolation of the strong acids by high-pressure liquid chromatography (HPLC) has resulted in the purification of the mutagenicity into a major peak of activity with a specific mutagenicity of about 20,000 TA100 revertants per milligram. Several trichlorohydroxyfuranone isomers have been tentatively identified in this fraction. The contribution of these types of compounds to the mutagenicity of chlorinated humic acid is under investigation.

Identification of mutagenic compounds formed during chlorination of humic acid.

Humic acid chlorination products are being studied in an effort to identify the chemicals responsible for the mutagenicity formed during water chlorination. In the present report, 19 chlorinated organic compounds have been identified and quantified in ether extracts of chlorinated humic acid solutions. 10 of these compounds, including a number of chlorinated propanones and chlorinated propenals, are direct-acting mutagens in the Salmonella/microsome mutagenicity assay. The position of the chlorine substituent has been found to be an important factor in the mutagenic activity of these two classes of compounds. The total mutagenicity of the compounds identified thus far, when tested either individually or as a composite, accounts for only 7-8% of the total TA100 mutagenicity, and less than 2% of the TA98 mutagenicity formed during humic acid chlorination. The addition of bromide to the humic acid chlorination reaction results in up to a 2-fold increase in the level of mutagenicity formed.

Analytical investigation of the properties and uses of a new hydrophobic molecular sieve.

Distribution coefficients and capacities have been determined for many different organic compounds on a new molecular sieve called silicalite, which does not adsorb water but does adsorb small organic molecules with diameters up to 6 A, from both liquid and gaseous streams. The characteristics of silicalite have been examined closely and new applications for it are briefly described.

Contaminant levels in animal feeds used for toxicity studies.

Samples of commercial feeds for laboratory rats, guinea pigs, cats, monkeys, rabbits, and hamsters were collected and analyzed qualitatively and quantitatively for selected antibiotics, trace metals, pesticides (organophosphates and chlorinated hydrocarbons), natural agents, and polychlorinated biphenyls (PCBs). The results indicated that antibiotics, parathion, diazinon, aldrin, and the aflatoxins were not detected, whereas, metals, chlorinated hydrocarbon pesticides (except aldrin), and PCBs were continually present. Malathion and estrogen were found occasionally.