Correlation Analysis of the Carboxyl and Carbonyl Groups of Natural Organic Matter and the Formation Potential of Trihalomethanes and Chloral Hydrate.

Natural organic matter (NOM) has always been considered the main precursor of disinfection by-products (DBPs) during the chlorine disinfection of drinking water. This research focuses on investigating the correlation between the functional group (carboxyl and carbonyl groups) content of NOM and the formation of trichloromethane (TCM) and chloral hydrate (CH). The quantitative determination of carboxyl groups, carbonyl groups, TCM, and CH were conducted during the drinking water treatment processes with different coagulant dosages and with/without pre-oxidation by KMnO4 or NaClO. The most appropriate coagulant for the removal of conventional components was polyaluminum chloride (PAC), and the dosage was 110 mg/L. Up to 43.7% and 14.5% of the carboxyl and carbonyl groups, respectively, were removed through the coagulation and sedimentation processes, which can be enhanced by increasing PAC dosage. The filtration process further increased the removal rates of these two functional groups to 59.8% and 33.5%, respectively. The formation potential of the TCM and CH decreased as the PAC dosage increased. Pre-oxidation by KMnO4 (0.8-1.0 mg/L) effectively controlled the formation of DBPs while increasing the carboxyl and carbonyl group content. Pre-oxidation by NaClO decreased the formation of TCM rather than CH, and a suitable amount (0.5-1.0 mg/L) decreased the carboxyl and carbonyl groups. It was found that there was a good linear correlation between carboxyl groups and TCM and CH. The linear fit R2 values of the carboxyl groups to TCM and CH were 0.6644 and 0.7957, respectively. The linear fit R2 values of the carbonyl groups to TCM and CH were 0.5373 and 0.7595, respectively.

Concentrations and correlations of disinfection by-products in municipal drinking water from an exposure assessment perspective.

Although disinfection by-products (DBPs) occur in complex mixtures, studies evaluating health risks have been focused in few chemicals. In the framework of an epidemiological study on cancer in 11 Spanish provinces, we describe the concentration of four trihalomethanes (THMs), nine haloacetic acids (HAA), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), four haloacetonitries, two haloketones, chloropicrin and chloral hydrate and estimate correlations. A total of 233 tap water samples were collected in 2010. Principal component analyses were conducted to reduce dimensionality of DBPs. Overall median (range) level of THMs and HAAs was 26.4 (0.8-98.1) and 26.4 (0.9-86.9) µg/l, respectively (N=217). MX analysed in a subset (N=36) showed a median (range) concentration of 16.7 (0.8-54.1)ng/l. Haloacetonitries, haloketones, chloropicrin and chloral hydrate were analysed in a subset (N=16), showing levels from unquantifiable (<1 µg/l) to 5.5 µg/l (dibromoacetonitrile). Spearman rank correlation coefficients between DBPs varied between species and across areas, being highest between dibromochloromethane and dibromochloroacetic acid (r(s)=0.87). Principal component analyses of 13 DBPs (4 THMs, 9 HAAs) led 3 components explaining more than 80% of variance. In conclusion, THMs and HAAs have limited value as predictors of other DBPs on a generalised basis. Principal component analysis provides a complementary tool to address the complex nature of the mixture.

Yield of trihalomethane, haloacetic acid and chloral upon chlorinating algae after coagulation-filtration: Is pre-oxidation necessarily negative for disinfection by-product control?

Effect of pre-chlorination and pre-ozonation on Microcystis aeruginosa (MA) and Coccomyxa subellipsoidea (CS) as disinfection by-products (DBPs) precursors was investigated after coagulation-filtration. Pre-chlorination considerably decreased the autofluorescence of algae cells but barely influenced cell granularity. In comparison, after pre-ozonation more algae cells were associated with decreased cell size; yet less reduction in the autofluorescence was observed. In MA case, pre-chlorination increased the residual algae density after coagulation-filtration by 132%-146% while pre-ozonation enhanced the algae removal by 26%-28%. In CS case, algae removal was improved by pre-chlorination (32%-45%) and pre-ozonation (7%-45%). Pre-chlorination enhanced the removal of algogenic organic matters (AOM) by coagulation-filtration, especially for tryptophan-like and soluble microbial products. Effect of pre-ozonation on the fluorescence intensity of AOM after coauglation-filtration depended on AOM species and the ratio of [ozone dose]:[algae density]. In both MA and CS cases, chlorine increased the yields of trihalomethane (THM, 25%-78% and 51%-103%), haloacetic acid (HAA, 140%-360% and 167%-233%) and chloral (50%-161% and 68%-108%), respectively. Pre-ozonation decreased the total DBPs yields. For MA-added suspensions, ozone decreased the production of THM, HAA and chloral by 15%-37%, 28%-39% and 60%, respectively. In CS case, chloral yield was decreased by 12%-31% while THM formation was largely unchanged. HAA production varied by ± 1.5 µg/L.

The effect of boiling water on disinfection by-product exposure.

Chloraminated and chlorinated waters containing bromide were used to determine the impact of boiling on disinfection by-product (DBP) concentrations. No significant changes were detected in the concentrations of the dihalogenated haloacetic acids (DXAAs) (i.e., dichloro-, bromochloro-, dibromoacetic acid) upon boiling of chloraminated water, whereas the levels of the trihalogenated haloacetic acids (TXAAs) (i.e., trichloro- (TCAA), bromodichloro- (BDCAA), dibromochloroacetic acid (DBCAA)) decreased over time (e.g., 9-37% for TCAA). Increased DXAA concentrations (58-68%) were detected in the boiled chlorinated sample, which likely resulted from residual chlorine reacting with DXAA precursors. TCAA concentration was unchanged after boiling chlorinated water for 1 min, but a 30% reduction was observed after 5 min of boiling. BDCAA concentrations decreased 57% upon boiling for 1 min and were completely removed after 2 min of boiling, whereas DBCAA was removed after boiling chlorinated water for 1 min. Trihalomethane concentrations were reduced in both chloraminated (74-98%) and chlorinated (64-98%) water upon boiling. Boiling chloraminated water for 1 min reduced chloroform concentration by 75%. Chloroform was reduced by only 34% in chlorinated water after a 1 min boil, which indicates that simultaneous formation and volatilization of chloroform was occurring. Most of the remaining DBPs (e.g. haloketones, chloral hydrate, haloacetonitriles) were removed by at least 90% after 1 min of boiling in both samples. These data suggest that other mechanisms (e.g., hydrolysis) may have been responsible for removal of the non-volatile DBPs and further highlight the importance of examining individual species when estimating thermal effects on DBP concentrations.

Liquid chromatographic methods for chloral hydrate determination.

Liquid chromatographic methods, based on reversed-phase (RP) and anion-exchange mechanisms, have been developed for chloral hydrate determination. Both methods are preceeded by derivatization of chloral hydrate. For RP separations, different reagents [namely dansylhydrazine and o-(4-nitrobenzyl)hydroxylamine] have been studied, but the best results have been achieved using 1,2-benzenedithiol with UV detection at 220 nm. The anion-exchange method is based on derivatization with NaOH to form sodium formate that is then analyzed by anion-exchange, with suppressed conductivity detection. Derivatization conditions were optimized in order to reach the best yield of reaction. The optimization of the procedure allowed to determine chloral hydrate with detection limits as low as 0.2 microg/l with good linearity and reproducibility. The anion-exchange method was also applied for chloral hydrate determination in a drinking water sample. A preconcentration procedure has also been studied.

Hydrogen-bonded complexes between chloral hydrate and halide ions in aqueous solution.

The hydrogen-bonded interactions of chloral hydrate and halide ions have been investigated conductometrically at 25.00 degrees C in aqueous solutions. In spite of the strong competing effect of water, the 1:1 associates have relatively high stability constants, in the order of chloride greater than bromide greater than fluoride approximately equal to iodide. The rather low stability of the fluoride:chloral hydrate associate can be explained by the strong hydration of the small fluoride ion. Although the 1:1 association dominates, other stoichiometries cannot be excluded; the cations and the ionic strength seem to have no effect.

Isolation, characterization and quantitation of chloral hydrate as a transient metabolite of trichloroethylene in man using electron capture gas chromatography and mass fragmentography.

A method for the quantitative determination of plasma concentrations of chloral hydrate by electron capture gas chromatography is described. Characterization by multiple ion monitoring confirms, for the first time, that chloral hydrate exists as a transient metabolite of trichloroethylene in man.

Detection of the adulteration of traditional alcoholic beverages by the separation and determination of alprazolam, chloralhydrate and diazepam using reversed-phase high-performance liquid chromatography.

A simple, rapid and reliable reversed-phase high-performance liquid chromatographic method for the separation and determination of psycotropic substances viz., alprazolam, chloral hydrate and diazepam in traditional alcoholic beverages, such as toddy, has been developed. Separation was accomplished using a reversed-phase C18 column with water-methanol-acetic acid (35:65:0.1 v/v/v) as a mobile solvent and a photo-diode array detector at 210 nm. The limits of detection of alprazolam, chloral hydrate and diazepam were determined to be 0.8, 4.5 and 0.4 microg, respectively. The validity of the method was checked by analyzing nearly 200 samples collected from different outlets by enforcement authorities, and the extent of adulteration was determined.

[Examination of the stability of chloral hydrate and its preparation by capillary electrophoresis].

Stabilities of chloral hydrate in an aqueous solution and its medicated syrup were examined by high performance capillary electrophoresis. Analysis of the concentration of chloral hydrate indicated that there was no obvious change in the concentration of chloral hydrate both in the aqueous solution and in the syrup preparation after keeping them for 3 months at room temperature or at 60 degrees C. The lowering of pH was more obvious in the syrup solution than in the aqueous solution, and this tendency was estimated to be due to the formation of hydrochloric acid. We propose that the stabilities of the preparation of chloral hydrate should be monitored by observing pH changes.

Rapid and facile detection of four date rape drugs in different beverages utilizing proton transfer reaction mass spectrometry (PTR-MS).

In this work, we illustrate the application of proton transfer reaction mass spectrometry (PTR-MS) in the field of food and drink safety. We present proof-of-principle measurements of four different drinks (water, tea, red wine and white wine) each spiked separately with four different date rape drugs (chloral hydrate, tricholorethanol, γ-butyrolactone and butanediol). At first, the ideal PTR-MS operating conditions (reduced electric field strength and monitoring the most abundant [fragment] ion) for detection of the drugs were determined utilizing a time-of-flight-based PTR-MS instrument. We then dissolved small quantities of the drugs (below the activation threshold for effects on humans) into the various types of drinks and detected them using a quadrupole-based PTR-MS instrument via two different sampling methods: (1) dynamic headspace sampling and (2) direct liquid injection. Both methods have their advantages and drawbacks. Only with dynamic headspace sampling can rape drug contaminations be detected within a timeframe of seconds, and therefore, this method is the most promising use of PTR-MS as a fast, sensitive and selective monitor for the detection of food and drink contamination.

Micro liquid-liquid extraction combined with large-volume injection gas chromatography-mass spectrometry for the determination of haloacetaldehydes in treated water.

Haloacetaldehydes (HAs) are becoming the most widespread disinfection by-products (DBPs) found in drinking water, besides trihalomethanes and haloacetic acids, generated by the interaction of chemical disinfectants with organic matter naturally present in water. Because of their high potential toxicity, HAs have currently received a singular attention, especially trichloroacetaldehyde (chloral hydrate, CH), the most common and abundant compound found in treated water. The aims of this study are focused on the miniaturisation of EPA Method 551.1, including some innovations such as the use of ethyl acetate as the extracting solvent, the enhancement of HAs stability in aqueous solutions by adjusting the pH ~3.2 and the use of a large-volume sample injection (30 µL) coupled to programmed temperature vaporizer-gas chromatography-mass spectrometry to improve both sensitivity and selectivity. In optimised experimental conditions, the limits of detection for the 7 HAs studied ranged from 6 to 20 ng/L. Swimming pools have recently been recognized as an important source of exposure to DBPs and as a result, in this research for the first time, HAs have been determined in this type of water. Two HAs have been found in the analysed water: CH at concentrations between 1.2-38 and 53-340 µg/L and dichloroacetaldehyde between 0.07-4.0 and 1.8-23 µg/L in tap and swimming pool waters, respectively.

A fatality due to an accidental methadone substitution in a dental cocktail.

A 6-year-old male child was scheduled for a dental procedure requiring conscious sedation. Prior to the procedure, the child was administered a dental cocktail containing chloral hydrate, hydroxyzine, and methadone. After returning from the dentist, the child appeared groggy and was allowed to sleep. A few hours later, he was found unresponsive, and following resuscitation attempts at a local medical center, he was pronounced dead. Toxicological analyses of femoral blood indicated the presence of hydroxyzine at less than 0.54 µg/mL, trichloroethanol (TCE) at 8.3 µg/mL, and methadone at 0.51 µg/mL. No meperidine was detected. The cause of death was reported to be due to the toxic effects of methadone. The toxicological analysis was corroborated by the analysis of the contents of the dental cocktail, which revealed the presence of hydroxyzine, chloral hydrate, and methadone. Residue from a control sample obtained from the same pharmacy, but administered to a different subject, was found to contain hydroxyzine, chloral hydrate, and meperidine. This report represents the first known fatality due to accidental substitution of methadone in a dental cocktail.

Spatial and temporal evaluations of disinfection by-products in drinking water distribution systems in Beijing, China.

Disinfection by-products were determined in 15 water treatment plants in Beijing City. The effects of different water sources (surface water source, mixture water source and ground water source), seasonal variation and spatial variation were examined. Trihalomethanes and haloacetic acids were the major disinfection by-products found in all treated water samples, which accounted for 42.6% and 38.1% of all disinfection by-products respectively. Other disinfection by-products including haloacetonitriles, chloral hydrate, haloketones and chloropicrin were usually detected in treated water samples but at lower concentrations. The levels of disinfection by-products in drinking water varied with different water sources and followed the order: surface water source > mixture water source > ground water source. High spatial and seasonal variation of disinfection by-products in the drinking water of Beijing was shown as a result.

Production of various disinfection byproducts in indoor swimming pool waters treated with different disinfection methods.

In this study, the concentrations of disinfection byproducts (DBPs), including trihalomethanes (THMs; chloroform, bromodichloromethane, dibromochloromethane, and bromoform), haloacetic acids (HAAs; dichloroacetic acid and trichloroacetic acid), haloacetonitriles (HANs; dichloroacetonitrile, trichloroacetonitrile, bromochloroacetonitrile, and dibromoacetonitrile), and chloral hydrate (CH) were measured in 86 indoor swimming pools in Seoul, Korea, treated using different disinfection methods, such as chlorine, ozone and chlorine, and a technique that uses electrochemically generated mixed oxidants (EGMOs). The correlations between DBPs and other environmental factors such as with total organic carbon (TOC), KMnO(4) consumption, free residual chlorine, pH, and nitrate (NO(3)(-)) in the pools were examined. The geometric mean concentrations of total DBPs in swimming pool waters were 183.1±2.5µg/L, 32.6±2.1µg/L, and 139.9±2.4µg/L in pools disinfected with chlorine, ozone/chlorine, and EGMO, respectively. The mean concentrations of total THMs (TTHMs), total HAAs (THAAs), total HANs (THANs), and CH differed significantly depending on the disinfection method used (P<0.01). Interestingly, THAAs concentrations were the highest, followed by TTHMs, CH, and THANs in all swimming pools regardless of disinfection method. TOC showed a good correlation with the concentrations of DBPs in all swimming pools (chlorine; r=0.82, P<0.01; ozone/chlorine; r=0.52, P<0.01, EGMO; r=0.39, P<0.05). In addition, nitrate was positively correlated with the concentrations of total DBPs in swimming pools disinfected with chlorine and ozone/chlorine (chlorine; r=0.58; ozone/chlorine; r=0.60, P<0.01), whereas was negative correlated with the concentrations of total DBPs (r=-0.53, P<0.01) in the EGMO-treated pools.