Analytical Tools for Disease Diagnosis in Animals via Fecal Volatilome.

Volatilome analysis is growing in attention for the diagnosis of diseases in animals and humans. In particular, volatilome analysis in fecal samples is starting to be proposed as a fast, easy and noninvasive method for disease diagnosis. Volatilome comprises volatile organic compounds (VOCs), which are produced during both physiological and patho-physiological processes. Thus, VOCs from a pathological condition often differ from those of a healthy state and therefore the VOCs profile can be used in the detection of some diseases. Due to their strengths and advantages, feces are currently being used to obtain information related to health status in animals. However, they are complex samples, that can present problems for some analytical techniques and require special consideration in their use and preparation before analysis. This situation demands an effort to clarify which analytic options are currently being used in the research context to analyze the possibilities these offer, with the final objectives of contributing to develop a standardized methodology and to exploit feces potential as a diagnostic matrix. The current work reviews the studies focused on the diagnosis of animal diseases through fecal volatilome in order to evaluate the analytical methods used and their advantages and limitations. The alternatives found in the literature for sampling, storage, sample pretreatment, measurement and data treatment have been summarized, considering all the steps involved in the analytical process.

A non-destructive sampling method for food authentication using gas chromatography coupled to mass spectrometry or ion mobility spectrometry.

The study of volatile compounds obtained by gas chromatography (GC) coupled to mass spectrometry (MS) or ion mobility spectrometry (IMS) may be very useful to protect food quality, especially when using a non-destructive sampling method. In this work, the authentication of the highly appreciated dry-cured Iberian ham by those techniques was studied and compared. The results obtained show the suitability of a non-destructive sampling method coupled to headspace sampling (HS)-GC-IMS or HS-GC-MS to determine volatile markers in the feeding Iberian pig regime. Although both methods were suitable to differentiate the ham categories, HS-GC-IMS was more sensitive detecting a higher number of compounds than HS-GC-MS, which provided accurate qualitative results. The results of principal component analysis showed that ethanol, 2-propanol and 3-methylbutanol, identified by HS-GC-IMS, and 3-methylbutanal and heptane, identified by HS-GC-MS, could be considered potential markers to identify ham from different feeding regimes.

Seasonal evaluation of the presence of 46 disinfection by-products throughout a drinking water treatment plant.

In this work, we studied a total of 46 regulated and non-regulated disinfection by-products (DBPs) including 10 trihalomethanes (THMs), 13 haloacetic acids (HAAs), 6 halonitromethanes (HNMs), 6 haloacetonitriles (HANs) and 11 aldehydes at different points in a drinking water treatment plant (DWTP) and its distribution network. Determining an increased number of compounds and using accurate, sensitive analytical methodologies for new DBPs can be useful to overcome some challenges encountered in the comprehensive assessment of the quality and safety of drinking water. This paper provides a detailed picture of the spatial and seasonal variability of DBP concentrations from raw water to distribution network. Samples were collected on a monthly basis at seven different points in the four seasons of a year to acquire robust data for DBPs and supplementary quality-related water parameters. Only 5 aldehydes and 2 HAAs were found in raw water. Chlorine dioxide caused the formation of 3 new aldehydes (benzaldehyde included), 5 HAAs and chloroform. The concentrations of DBPs present in raw water were up to 6 times higher in the warmer seasons (spring and summer). The sedimentation process further increased their concentrations and caused the formation of three new ones. Sand filtration substantially removed aldehydes and HAAs (15-50%), but increased the levels of THMs, HNMs and HANs by up to 70%. Chloramination raised the levels of 8 aldehydes and 7 HAAs; also, it caused the formation of monoiodoacetic acid, dibromochloromethane, dichloroiodomethane and bromochloroacetonitrile. Therefore, this treatment increases the levels of existing DBPs and leads to the formation of new ones to a greater extent than does chlorine dioxide. Except for 5 aldehydes, the 23 DBPs encountered at the DWTP exit were found at increased concentrations in the warmer seasons (HAAs by about 50% and THMs by 350%).

Haloacetic acids in swimming pools: swimmer and worker exposure.

For the first time, the exposure of swimmers and workers to haloacetic acids (HAAs) in indoor and outdoor pools was evaluated through the analysis of urine samples. The subjects of this study, 49 volunteers, were male and female workers as well as swimmers (adults and children) who regularly attended an indoor pool (January-June) and an outdoor one (July and August). The results showed that HAAs appeared 20-30 min after exposure and were eliminated within 3 h. After 2 h exposure, urine samples taken from workers contained dichloroacetic (DCAA) and trichloroacetic (TCAA) acids at ~300 and ~120 ng/L levels since HAAs were aerosolized in the indoor ambient, whereas only DCAA was found in some workers' urine samples from the outdoor pool but at ~50 ng/L levels, despite the fact that the outdoor pools generally had somewhat higher levels of HAAs than the indoor pools. After 1 h swimming TCAA, DCAA and MCAA were present at concentrations of ~4400, ~2300, and ~560 ng/L, respectively, in the swimmers' urine in the indoor pool; similar results were obtained from the swimmers in the outdoor pool due to accidental ingestion. Finally, exposure estimates indicate that ingestion is the major route of exposure (~94%), followed by inhalation (~5%) and dermal contribution (~1%).

Determination of halonitromethanes in treated water.

As halonitromethanes (HNMs) have begun to play an increasingly important role as disinfection by-products, the development of a highly sensitive method for their analysis has become a priority. The mass spectrometric behavior of the 9 HNMs revealed that trihalonitromethanes are more unstable than di- or monohalonitromethanes under common chromatographic conditions. The absence of a comprehensive method for HNMs has given rise to the development of the first method for the whole array of these species, involving the selection of a solventless technique. Single drop microextraction in the headspace mode (HS-SDME) was selected as it is inexpensive and easy to operate. Comparative measurements through EPA liquid-liquid extraction (LLE) method for halogenated volatile compounds, show this approach to be superior to the manual LLE procedure (the average limits of detection (LODs) for the 9 HNMs were 0.5 and 1 µg/L for the HS-SDME and EPA methods, respectively), adequate precision (8.2 and 7.0% for HS-SDME and EPA methods, respectively) and does not consume excessive solvent since the total extract (∼2 µL) was injected completely into the GC-MS instrument. The method was used to measure HNMs in treated water and the results were compared to the EPA method in parallel.

Determination of haloacetic acids in human urine by headspace gas chromatography-mass spectrometry.

Haloacetic acids (HAAs) are water disinfection byproducts (DBPs) formed by the reaction of chlorine oxidizing compounds with natural organic matter in water containing bromine. HAAs are second to trihalomethanes as the most commonly detected DBPs in surface drinking water and swimming pools. After oral exposure (drinking, showering, bathing and swimming), HAAs are rapidly absorbed from the gastrointestinal tract and excreted in urine. Typical methods used to determine these compounds in urine (mainly from rodents) only deal with one or two HAAs and their sensitivity is inadequate to determine HAA levels in human urine, even those manual sample preparation protocols which are complex, costly, and neither handy nor amenable to automation. In the present communication, we report on a sensitive and straightforward method to determine the nine HAAs in human urine using static headspace (HS) coupled with GC-MS. Important parameters controlling derivatisation and HS extraction were optimised to obtain the highest sensitivity: 120 microl of dimethylsulphate and 100 microl of tetrabutylammonium hydrogen sulphate (derivatisation regents) were selected, along with an excess of Na(2)SO(4) (6 g per 12 ml of urine), an oven temperature of 70 degrees C and an equilibration time of 20 min. The method developed renders an efficient tool for the precise and sensitive determination of the nine HAAs in human urine (RSDs ranging from 6 to 11%, whereas LODs ranged from 0.01 to 0.1 microg/l). The method was applied in the determination of HAAs in urine from swimmers in an indoor swimming pool, as well as in that of non-swimmers. HAAs were not detected in the urine samples from non-swimmers and those of volunteers before their swims; therefore, the concentrations found after exposure were directly related to the swimming activity. The amounts of MCAA, DCAA and TCAA excreted from all swimmers are related to the highest levels in the swimming pool water.

Optimisation and comparison of several microextraction/methylation methods for determining haloacetic acids in water using gas chromatography.

This article presents the different modes and configurations of liquid-phase microextraction (LPME) through comparison with headspace solid-phase microextraction (HS-SPME) for the simultaneous extraction/methylation of the nine haloacetic acids (HAAs) found in water. This is the first analytical case reported of solvent bar extraction-preconcentration-derivatisation assisted by an ion-pairing transfer for HAAs. In this method, 5 muL of the organic extractant, decane, was confined within a hollow-fibre membrane that was placed in a stirred aqueous sample containing the derivatising reagents (dimethylsulphate with a tetrabutylammonium salt). With heating at 45 degrees C in the HS-SPME method, some organic solvents (extractant, excess of derivatising reagent) are also volatilised and compete with the esters on the fibre (the fibre is damaged and it can be reused only 50-60 times). In addition, the HS-SPME method provides inadequate sensitivity (limits of detections between 0.3 and 5 microg/L) to quantify HAAs at the level usually found in drinking waters. Alternative headspace LPME methods for HAAs require heating (45 degrees C, 25 min) to derivatise and volatilise the esters but, by using solvent bar microextraction (SBME), the extraction/methylation takes place at room temperature without degradation of HAAs to trihalomethanes. Adequate precision (relative standard deviation of approximately 8%), linearity (0.1-500 microg/L) and sensitivity (10 times higher than the HS-SPME alternative) indicate that the SBME method can be a candidate for routine determination of HAAs in tap water. Finally, the SBME method was applied for the analysis of HAAs in tap and swimming pool water and the results were compared with those of a previous validated headspace gas chromatography-mass spectrometry method.

Simultaneous liquid-liquid microextraction/methylation for the determination of haloacetic acids in drinking waters by headspace gas chromatography.

A novel analytical method that combines simultaneous liquid-liquid microextraction/methylation and headspace gas chromatography-mass spectrometry for the determination of nine haloacetic acids (HAAs) in water was reported. A mechanistic model on the basis of mass transfer with chemical reaction in which methylation of HAAs was accomplished in n-pentane-water (150 microl-10 ml) two-phase system with a tetrabutylammonium salt as phase transfer catalyst was proposed. Derivatisation with dimethylsulphate was completed in 3 min by shaking at room temperature. The methyl ester derivatives and the organic phase were completely volatilised by static headspace technique, being the gaseous phase analysed. Parameters related to the extraction/methylation and headspace generation of HAAs were studied and the results were compared with methyl haloacetate standards to establish the yield of each step. The thermal instability of HAAs, by degradation to their respective halogenated hydrocarbon by decarboxylation, and the possible hydrolysation of the methyl esters were rigorously controlled in the whole process to obtain a reliable and robust method. The proposed method yielded detection limits very low which ranges from 0.02 to 0.4 microg l(-1) and a relative standard deviation of ca. 7.5%. Finally, the method was validated with the US Environmental Protection Agency (EPA) method 552.2 for the analysis of HAAs in drinking and swimming pool water samples containing concentrations of HAAs that must be higher than 10 microg l(-1) due to the fact that this method is less sensitive than the proposed one.