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Polyunsaturated fatty acids (PUFA) are associated with health benefits. However, high PUFA intake increases the risk of lipid oxidation and formation of potentially toxic lipid oxidation species. The objective of this study was to determine the antioxidant activity of milk fractions (whole milk, skim milk, acid whey, ultrafiltration (UF) permeate) and polyphenol-rich beverages (green tea, grape juice) during simulated gastrointestinal digestion. We also determined the effect of milk and polyphenol-rich beverages on the formation of advanced oxidation species during in vitro digestion of PUFA-rich emulsion. Antioxidant activity during digestion of milk fractions emphasized the important role of proteins (more specifically caseins) and the contribution of fat to the antioxidant capacity of milk. In comparison to milk, the antioxidant activity of polyphenol-rich beverages was at least four times higher. During digestion of a PUFA-rich emulsion, the formation of 4-hydroxyhexanal (4-HHE) and 4-hydroxynonenal (4-HNE) in the intestinal phase were respectively reduced by 60% and 75%, in the presence of milk or polyphenol-rich beverages. Further reduction was observed when the emulsion was co-digested with both, milk and polyphenol-rich beverages (89% for 4-HHE and 93% for 4-HNE). These results suggest that the combination of milk and polyphenol-rich beverages increases the antioxidant activity and synergistically reduces the formation of toxic lipid oxidation species during simulated digestion of PUFA-rich foods.

β-Lactoglobulin hydrolysate was encapsulated in water-in-oil-in-water (W1/O/W2) emulsions. The effects of digestible (linseed) and non-digestible (jojoba and mineral) oil phases on emulsion characteristics and peptide release in gastrointestinal conditions were compared. Peptide release was studied at gastric pH (3) and intestinal pH (7) in the absence of lipase and at intestinal pH (7) in the presence of lipase. Released peptides were analyzed by RP-HPLC and identified by LC-MS. The encapsulation efficiency of the three emulsions was over 90%. The W1/O/W2 emulsion produced from mineral oil had the highest droplet diameter. In the absence of lipase, the proportions of peptides released after 4 h of agitation (37 °C) were significantly lower at gastric pH (4.1%–18.8%) than at intestinal pH (10.6%–35.3%) and varied in the order mineral oil

Muscle carnosine represents an important health advantage of meat. Ground pork samples with intrinsic or added carnosine; fat content; and cooked under low or high intensity as a 2 × 2 × 2 factorial were digested in-vitro. Changes in free carnosine and in markers of lipid (hexanal, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) and protein (protein-carbonyls, thiols) oxidation, and of advanced glycation end-products (AGEs) Ne -(carboxymethyl)lysine (CML) were determined in the saliva, gastric, and duodenal digests. During digestion, the different markers overall indicated increased oxidation and decreased free carnosine. Increasing pork carnosine level significantly reduced protein carbonyls, loss of thiols, and 4-HNE during in-vitro gastric digestion, irrespective of fat and cooking level of the meat. Increased carnosine also significantly reduced hexanal, MDA and CML up to the duodenum phase in moderately cooked lean pork. Besides substantiating the formation of AGEs during digestion, these results show a potentially important role of dietary carnosine occurring in the gastrointestinal tract. PRACTICAL APPLICATIONS: The ailments epidemiologically associated with red meat consumption could be counteracted by ingesting carnosine into meat. The health advantages of dietary carnosine, however, have never been demonstrated during digestion, a unique and complex oxidative environment compounded by the composition and cooking of the meat. The results obtained substantiated that AGEs formation occurred in-vitro in the GIT. They also showed that increased carnosine had an immediate health beneficial role during pork digestion in reducing the formation of different harmful molecules, including AGEs, modulated by the composition and cooking of the meat. However, in exerting this protective role in the GIT, the remaining free level of carnosine, gradually decreased during digestion. Carnosine, as an important meat compositional factor may, depending on the fat content and cooking conditions, change the image of meat from representing a health risk to a health benefit. Carnosine level may also explain discrepancies observed in the literature.

The goal of this study was to examine how yoghurt manufacturing processes influence the synthesis of aromas and to examine links with sensory properties. A traditional product with 4% protein (control) and two Greek-style yoghurts with 10% protein were made using curd centrifugation or milk ultrafiltration. Of 32 potentially aromatic compounds, six were detected only in yoghurt, six showed no changes between milk and yoghurt, 12 increased following fermentation or storage, and eight showed lower concentrations in yoghurt than in the initial milk. For the six compounds that appeared only after fermentation and the 12 others with higher levels in yoghurt than in milk, volatiles were found to increase by 27% on average during storage. The Greek-style yoghurts had higher “perception of acidity” and lower “smoothness” than did the control. Positive or negative correlations between “typical yoghurt flavour” and 12 volatiles were found.

Dairy beverages were produced from milk protein and fortified with linseed oil, which is rich in omega-3 fatty acids. Polyphenol extract was obtained from passion fruit seeds (PFSE) and added to beverages to prevent lipid oxidation. Three passion fruit polyphenol concentrations (0, 0.1 and 1.0 g/kg) were tested and two thermal treatments (pasteurization and sterilization) were applied to dairy beverages. Emulsion stability was measured and lipid oxidation was determined during storage and during simulated digestion. Production of conjugated dienes and aldehydes (propanal and 4-hydroxyhexanal) during storage was significantly reduced in the presence of PFSE and sterilization treatment further increased the resistance to oxidation. During simulated digestion, pasteurized beverages were prone to oxidation, and the addition of PFSE (1.0 g/kg) reduced the formation of propanal and 4-hydroxyhexanal by 85% and 88% respectively. In the absence of PFSE, sterilization treatment reduced aldehyde production during digestion of dairy beverages by more than 70%, which was attributed to the formation of Maillard reaction products. For sterilized beverages, adding PFSE to the formulation only had limited impact on aldehyde formation. These results showed the potential of PFSE and heat treatments to enhance the oxidation stability of beverages containing omega-3 fatty acids.

The addition of propolis to food formulations containing conjugated linoleic acid (CLA) can improve nutritional properties and stability during storage. The purpose of this study was to enrich dairy beverages with both CLA and Canadian propolis extracts and to determine the chemical characteristics of the enriched beverages, with a focus on antioxidant properties and protection against lipid oxidation. Analysis of DPPH, ORAC, color and aldehyde production along with CLA quantification was performed. Adding different propolis extracts increased the antioxidant capacity of dairy beverages enriched with CLA, while pasteurization treatment reduced the antioxidant capacity. The production of aldehydes during storage under light exposure was reduced significantly in the presence of propolis extracts. Since no nutritional loss was observed during processing and storage of dairy beverages, the main advantage of using propolis extract relates to its higher antioxidant capacity and ability to reduce off-flavors associated with aldehyde production.

A method of stir bar sorptive extraction (SBSE) and thermal desorption (TD) with gas chromatography–mass spectrometry (GC-MS) has been developed for qualitative and quantitative analysis of volatile and flavor compounds in grilled beef. To achieve optimum extraction and analysis performance for volatile and flavor compounds, desorption temperature and solid extraction conditions of the method were studied. Grilled beef and grilled beef dripping were analyzed by the developed method with short analysis program, and a total of 57 volatile (31 flavor) compounds, including 12 aldehydes, 13 hydrocarbons, 12 alcohols and ketones, 9 nitrogen- and sulfur-containing compounds, and 10 pyrazine compounds, were identified with little variation in triplicates. Four typical flavor compounds: hexanal, methional, 2-ethyl-pyrazine, and nonanal, were selected from main flavor group for quantitative analysis, and the method showed good linearity within the tested concentration range from 2 ng/g to 0.2 μg/g (n = 3, RSDs 0.998) and good recovery at 38∼45 % by spiked standards of 100 ng/g (n = 3, RSDs ≤ 11 %) in ground grilled beef. The limits of detection (LOD) range was 0.17–0.26 ng/g (S/N = 3, n = 3), and the limits of quantification (LOQ) range was 0.56–0.88 ng/g (S/N = 9, n = 3) for flavor analysts. The simple, fast, and solvent-less method allows us to obtain reliable qualitative and quantitative data of volatile and flavor constituents which are necessary for the beef quality evaluation.

A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC/MS) method was developed to quantify lemon oil components and their degradation products in oil-in-water (O/W) emulsions prepared with sodium caseinate-heated-lactose (NaC-T + Lact) glycoconjugates as wall materials at two pH values (3.0 and 6.8). NaC-T + Lact conjugates had a significantly lower solubility at both pHs. Hydrolysis prior to glycation enhanced the solubility of glycoconjugates. Glycation with lactose did not improve the emulsion activity of NaC, while caseinate glycoconjugates showed much stronger antioxidant activity than the NaC-control sample. This might be due to the presence of melanoidins formed between the sugar and amino acid compounds as supported by the increase in browning intensity. Among the SPME-fibres tested, carboxen/polydimethylsiloxane (CAR/PDMS) provided better results in terms of sensitivity and selectivity for oil lemon components and their degradation products. Storage studies of these emulsions demonstrated that glycated NaC-T + Lact showed protection against peroxidation compared to the control. However, acidic pH conditions altered their stability over storage time. The major off-flavor components (α-terpineol and carvone) were inhibited in emulsions stabilized with glycated NaC, particularly at pH 6.8. The use of NaC-T + Lact conjugates showed improved encapsulation efficiency and stability and could be used as potential food ingredient-emulsifiers for stabilising citrus oils against oxidative degradation in food and beverage applications.

Ovalbumin is one of the principal proteins responsible for IgE-mediated egg allergy. In this study, the effect of thermal processing on the antigenicity of ovalbumin in control ovalbumin, egg white and whole egg powders and incurred pasta preparations were evaluated. Solutions (4% w/v) of control ovalbumin, egg white and whole egg were separately boiled for 0, 5, 10, 15 min and then freeze-dried. Accurately weighed portions of semolina used in the pasta were separately incurred with the egg white and whole egg powders, to give concentrations of 10, 100 and 1000 ppm. Dried pastas were boiled for 15 min. After tryptic digestion, samples were analyzed for the presence of ovalbumin using liquid chromatography–electrospray ionization-mass spectrometry (LC–ESI-MS). Enzyme linked immunosorbent assay (ELISA) kits were also used to detect the presence of egg in the raw and cooked pastas. MS coverage of ovalbumin peptides was higher in non-heated samples compared to heated samples (P

Headspace solid-phase microextraction combined with gas chromatography–mass spectrometry was applied to identify pyrazines in a typical maple syrup characterised by plant ligneous or sawdust flavour. Carboxen/polydimethylsiloxane (85 μm) fibre and Supelcowax 10 column were selected instead of Carbowax/divinylbenzene (65 μm) fibre and VF-5ms column, respectively, because of their high capacity to extract and separate pyrazines. A total of 27 pyrazines were identified. To our knowledge, about half of these compounds had not previously been detected in maple syrup and 15 pyrazines were flavour components.

To increase health benefits, dairy beverages can be enriched with omega-3 fatty acids, although these fatty acids are susceptible to oxidation. The use of oregano extract (OE) and oregano essential oil (OEO) as antioxidants in dairy beverages enriched with 2 g/100 g linseed oil was studied. The OE contained 269 mg gallic acid equivalents per gram and was shown by the DPPH radical assay to have powerful antioxidant activity. During 10 days of storage under light or heat conditions, color, conjugated diene hydroperoxides, hexanal, propanal, and dissolved oxygen concentrations were evaluated in dairy beverages containing various concentrations of OE or OEO. It was found that OE was more efficient than OEO in preventing the formation of conjugated dienes, hexanal, and propanal as well as the depletion of oxygen induced by heat or light oxidation. The addition of OE or OEO did not affect dairy beverage physical stability during storage.

The effect of pH on the capability of whey protein isolate (WPI) and fish gelatin (FG), alone and in conjugation, to form and stabilize fish oil-in-water emulsions was examined. Using layer-by-layer interfacial deposition technique for WPI–FG conjugate, a total of 1% protein was used to prepare 10% fish oil emulsions. The droplets size distributions and electrical charge, surface protein concentration, flow and dynamic rheological properties and physiochemical stability of emulsions were characterize at two different pH of 3.4 and 6.8 which were selected based on the ranges of citrus and milk beverages pHs, respectively. Emulsions prepared with WPI–FG conjugate had superior physiochemical stability compare to the emulsions prepared with individual proteins. Higher rate of coalescence was associated with reduction in net charge and consequent decrease of the repulsion between coated oil droplets due to the proximity of pH to the isoelectric point of proteins. The noteworthy shear thinning viscosity, as an indication of flocculation onset, was associated with whey protein stabilized fish oil emulsion prepared at pH of 3.4 and gelatin stabilized fish oil emulsion made at pH of 6.8. At pH 3.4, it appeared that lower surface charge and higher surface area of WPI stabilized emulsions promoted lipid oxidation and production of hexanal.

The objectives of this study were to evaluate the effect of cultivar, crop year and processing (dry milling, cooking and dehulling) on volatile flavour compounds of field peas using an optimised headspace-solid phase microextraction gas chromatography–mass spectrometry method. Significant differences in area counts of volatile compounds were observed between the different cultivars as well as in area counts of volatile compounds of each cultivar grown in different crop years. Results showed significant reduction in total area counts (TAC) of volatile compounds after cooking and dehulling the seeds. Major differences between whole seeds, cooked and dehulled seeds were found in aldehydes, alcohols, and ketones. Cooked–dehulled peas had the least TAC (7.83E±05) of the volatile compounds compared to the milled-whole peas (6.36E±06), cooked-whole peas (2.00E±06) and milled–dehulled peas (4.33E±06). The results suggest that volatile flavour compounds of different field peas were affected by the cultivar, crop year as well as processing conditions.

The impact of whey protein isolate (WPI) and fish gelatin (FG) deposited sequentially at concentrations of 0.1, 0.5, and 0.75% on the surface of primary oil-in-water emulsions containing 5% flaxseed oil stabilized with either 0.5% fish gelatin or whey protein, respectively, was investigated. The results revealed that the adsorption of WPI/FG or FG/WPI complexes to the emulsion interface led to the formation of oil-in-water (o/w) emulsions with different stabilities and different protection degrees of the flaxseed oil. Deposition of FG on the WPI primary emulsion increased the particle size (from 0.53 to 1.58 μm) and viscosity and decreased electronegativity (from -23.91 to -11.15 mV) of the complexes. Different trends were noted with the deposition of WPI on the FG primary emulsion, resulting in decreasing particle size and increasing electronegativity and viscosity to a lower extent. Due to the superior tension-active property of WPI, the amount of protein load in the WPI primary emulsion as well as in WPI/FG complex was significantly higher than the FG counterparts. A multilayer emulsion made with 0.5% WPI/0.75% FG exhibited the lowest oxidation among all of the multilayered emulsions tested (0.32 ppm of hexanal) after 21 days, likely due to the charge effect of FG that may prevent pro-oxidant metals to interact with the flaxseed oil.

A simple, accessible and reproducible method was developed and validated as an alternative for the determination of nine volatile N-nitrosamines (NAs) in meat products, using a low volume of organic solvent and without requiring specific apparatus, offering the possibility of practical implementation in routine laboratories. The NAs were extracted with dichloromethane followed by a clean-up with phosphate buffer solution (pH 7.0). The extracts were analysed by gas chromatography-chemical ionisation/mass spectrometry (GC-CI/MS) in positive-ion mode using methanol as reagent. Limits of detection and quantification, recovery and reproducibility were determined for all NAs (N-nitrosodimethylamine, N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosodipropylamine, N-nitrosomorpholine, N-nitrosopiperidine, N-nitrosodibutylamine and N-nitrosodiphenylamine). Satisfactory sensitivity and selectivity were obtained even without concentrating the extract by solvent evaporation, avoiding the loss of the nine NAs studied. Limits of detection ranged from 0.15 to 0.37 µg kg(-1), whereas limits of quantification ranged from 0.50 to 1.24 µg kg(-1). Recoveries calculated in cooked ham that had been spiked at 10 and 100 µg kg(-1) were found to be between 70% and 114% with an average relative standard deviation of 13.2%. The method was successfully used to analyse five samples of processed meat products on the day of purchase and 7 days later (after storage at 4°C). The most abundant NAs found in the analysed products were N-nitrosodipropylamine and N-nitrosopiperidine, which ranged from 1.75 to 34.75 µg kg(-1) and from 1.50 to 4.26 µg kg(-1), respectively. In general, an increase in the level of NAs was observed after the storage period. The proposed method may therefore be a useful tool for food safety control once it allows assessing the profile and the dietary intake of NAs in food over time.

The aim of this study was to estimate the distribution, fate, and behavior of p-nonylphenols (p-NPs: p-n-nonylphenol and its isomers), nonylphenol ethoxylates (NP1–17EOs), and nonylphenol carboxylic acids (NP1–2ECs) in the municipal wastewater effluent (MWWE) of the City of Montreal, Canada, and in the receiving waters of the St. Lawrence River. The MWWE was sampled at the Montreal wastewater treatment plant, while surface water was sampled at sites located upstream and downstream of the effluent outfall. Twenty-four hour composite samples were obtained at the treatment plant on three nonconsecutive days during the summer of 2002. Water samples were filtered, then particulate and dissolved phases were extracted using Soxhlet and solid-phase extraction techniques, respectively, prior to LC/MS/MS analysis for the compounds of concern. The effluent contained essentially dissolved (75.4%, 375 kg/day) and particulate (23.7%, 118 kg/day) NP1–17EOs. By contrast, the surface water downstream of the outfall contai...

A method combining simultaneous filtration and solid-phase extraction (SPE) with large-volume injection (LVI) in gas chromatography/mass spectrometry (GC/MS) was developed to determine 13 polar pesticides in surface water. The selected pesticides - 4 organophosphorus, 7 organonitrogens and 2 triazine degradation products - were extracted from 0.5-L samples of filtered and raw water using cartridges filled with a silica-bonded material (1 g of ISOLUTE triazine, C-18) and a depth filter. No obstruction was observed during the extraction of raw water drawn from the St. Lawrence River (concentration of suspended particulate matter (SPM) ranging from 2 to 58 mg L−1). Overall percent recoveries were satisfactory for all the target pesticides (>60%) except desisopropyl-atrazine (more polar), which varied from 29 to 46% according to sample pH. The coefficient of variation was below 10% for the majority of the target pesticides and detection limits ranged from 0.1 to 0.8 ng L−1. Applied to real samples drawn from ...

A method has been developed for determination of twenty-four polar pesticides—nine organophosphorus pesticides, thirteen organonitrogen compounds, and two triazine degradation products—in surface water. It entails extraction of the target pesticides from 1-L water samples by solid-phase extraction (SPE), then gas chromatography (GC) with large-volume (40 μL) injection. Filtered surface water, from the St Lawrence River in Canada and the River Loire and its tributaries in France, was extracted on cartridges filled with 500 mg Carbopack B (120–400 mesh). Analysis was performed by gas chromatography with a thermionic specific detector (GC-TSD) and a mass spectrometric (MS) detector. Overall percentage recoveries were satisfactory (>70%) for all target pesticides, with precision below 10%. Detection limits were between 0.5 and 4 ng L−1.

A method was developed for the determination of coprostanol and steroids, including estradiol-17β, estrone and testosterone in surface water, effluent and mussels. The method is based on the derivatization of steroids containing hydroxyl groups with pentafluorobenzyl bromide (PFB-Br), followed by gas chromatography-mass spectrometric (GC-MS) determination. Estradiol-17β and estrone were successfully derivatized by this method, whereas coprostanol (a sterol compound) and testosterone showed no spectra of the derivatized form, and were therefore determined as free compounds. Surface water and effluent were extracted by liquid-liquid extraction using dichloromethane, while mussels were extracted using a microwave extraction system. The method detection limits of estradiol-17β, estrone, testosterone and coprostanol were 2 ngL−1 for surface water and effluent, and 3 ng g−1 for mussel. Recoveries in spiked reagent water and mussel for the same chemicals ranged from 56 to 87% and 21 to 48%, respectively. Using this method, Estradiol-17β, estrone and coprostanol were detected in surface water, taken from the St. Lawrence River, at concentrations ranging from 2 to 67 ngL−1. Only coprostanol was found in effluent and mussel samples at concentrations of 14667 ngL−1 and 32252 ng g−1, respectively.

Alkylphenol polyethoxylate surfactants (APnEO) are used in many industrial, commercial and household applications. Their widespread use has raised public concern about these chemicals and their degradation products in rivers and waterways. A gas chromatography-mass spectrometry (GC-MS) method was developed to determine 4-nonylphenol, 4-tert-octylphenol, alkylphenolpolyethoxylates (n=1–16), nonylphenolmonoethoxycarboxylic acid and octylphenolmonoethoxycarboxylic acid in surface water, effluent, and mussels. The method is based on the derivatization of analytes with pentafluorobenzyl bromide (PFB-Br), followed by chromatography cleanup and GC-MS determinations. Method detection limits were in the range of 1 ng L−1 for surface water and effluent, and 3ng g−1 for mussel samples. Recovery of farget compounds ranged from 40–102% and 24–111% in water and mussel samples, respectively. Several non-ionic surfactants were detected at concentrations ranging from 0.009 to 10.324 μgL−1 in the St. Lawrence River (surface water and sewage effluent) and at 177 to 12440 ng g−1 in mussels, introduced in this river for 62 days.

The stability of 18 herbicides (ten organonitrogens and eight phenylureas, including four degradation products), selected for the frequency of their detection in the environment, was evaluated under a variety of storage conditions. Large volumes of s ur- face water (4 L) were extracted using large-particle-size graphitized carbon black cartridges (Carbopack B 60-80 mesh). The effe cts of temperature, matrix type, drying and solvent-washing of cartridges on the recovery of these contaminants, after different stora ge periods, were studied and compared to the conservation of surface water in bottles. After two months, there was no significant di ffer- ence between the conserved surface water and the stored cartridges for the selected compounds. Cartridges kept at -20 °C were be t- ter than those stored at 4 °C and 20 °C. The type of matrix water selected, in this case St. Lawrence surface water, appears to hav e a minor effect on the recovery of the target pesticides after cartridge storage. No improvement was observed in the recovery of a ny of the chemicals when the cartridges were dried or washed and stored in a solvent. After immediate surface-water extraction, the mo st practical storage condition for the target herbicides was found to be storage on cartridges in the dark at - 20 °C, with no solven t dry- ing or washing of the Carbopack B material.

The review describes the use of solid-phase extraction (SPE) techniques for monitoring priority pesticides in ground and surface waters. The focus is on triazine herbicides and their degradation products. Data concerning the fate, occurrence, properties and extraction of triazines and their degradation products using different SPE techniques are tabulated and discussed.

The stability of nine organophosphorus insecticides (azinphos-ethyl, azinphos-methyl, diazinon, EPN, ethion, fonofos, malathion, phosmet and parathion-methyl) was evaluated under a variety of storage conditions. Large volumes of surface water (4 l) were extracted using large-particle-size graphitized carbon black cartridges (Carbopack B 60-80 mesh). The effects of temperature, matrix type and drying of cartridges on the recovery of these contaminants, after different storage periods, were studied and compared to the conservation of surface water in bottles. After a 2-month period, all the chemicals stored on cartridges and kept at -20 degrees C remained stable, with recoveries ranging from 70 to 134%. By contrast, phosmet and EPN could no longer be recovered from the bottled surface water. Cartridges kept at -20 degrees C fared better than did those stored at 4 degrees C and 20 degrees C. The type of matrix water selected appears to have kept the target pesticides stored on cartridges from degrading, compared to the Milli-Q water, in which malathion and phosmet were unstable. The effect of the cartridges being either wet or dry made no difference in terms of improving the recovery of chemicals. After immediate surface water extraction, the most practical storage condition for the target insecticides was found to be storage on cartridges in the dark at -20 degrees C, with no drying or solvent washing of the Carbopack B material.

Liquid chromatography with photodiode array detection (LC-DAD) and liquid chromatography with mass spectrometry (LC-MS) are two techniques that have been widely used in monitoring pesticides and their degradation products in the environment. However, the application of liquid chromatography with tandem mass spectrometry (LC-MS-MS) for such purposes, once considered too costly, is now gaining considerable ground. In this study, we compare these methods for the multi-residue analysis of pesticides in surface waters collected from the central and southeastern regions of France, and from the St. Lawrence River in Canada. Forty-eight pesticides belonging to eight different classes (triazine, amide, phenylurea, triazole, triazinone, benzimidazole, morpholine, phenoxyalkanoic), along with some of their degradation products, were monitored on a regular basis in the surface waters. For LC-MS, we used the electrospray ionization (ESI) interface in the negative ionization mode on acidic pesticides (phenoxyalkanoic, sulfonylurea), and the atmospheric pressure chemical ionization (APCI) interface in the positive ionization mode on the remaining chemicals. Different extraction techniques were employed, including liquid-liquid extraction with dichloromethane, and solid-phase extraction using C18-bonded silica and graphitized carbon black cartridges. Eleven of the target chemicals (desethylatrazine, desisopropylatrazine, atrazine, simazine, terbuthylazine, metolachlor, carbendazime, bentazone, penconazole, diuron and isoproturon) were detected by LC-MS at concentrations ranging from 20 to 900 ng/l in the surface waters from France, and six pesticides (atrazine, desethylatrazine, desisopropylatrazine, cyanazine, simazine and metolachlor) were detected by LC-MS and LC-MS-MS at concentrations ranging from 3 to 52 ng/l in the samples drawn from the St. Lawrence River. There was good correlation between the LC-DAD and LC-MS techniques for 60 samples. The slope of the curves expressing the relationship between the results obtained with LC-DAD versus those obtained by LC-MS was near 1, with a correlation coefficient (r) of over 0.93. The identification potential of the LC-MS technique, however, was greater than that of the LC-DAD; its mass spectra, mainly reflecting the pseudomolecular ion resulting from a protonation or a deprotonation of the molecule, was rich in information. The LC-MS-MS technique with ion trap detectors, tested against the LC-MS on 10 surface water samples, gave results that correlated well with the LC-MS results, albeit generating mass spectra that yielded far more information about the structure of unknown substances. The sensitivity of the LC-MS-MS was equivalent to the selected ion monitoring (SIM) acquisition mode in LC-MS. The detection limits of the target pesticides ranged from 20 to 100 ng/l for the LC-MS technique (under full scan acquisition), and from 2 to 6 ng/l for LC-MS-MS. These limits were improved by a factor of almost 10 by increasing the sample volume to 10 l.

To estimate triazine herbicide concentrations and sources in the St. Lawrence River, water samples were collected at its two major inlets (from the Great Lakes, Cornwall station, and from the Ottawa River, Carillon station) and at the outlet (Quebec City station) of the fluvial section. Sampling was carried out over an 18-month period between 1995 and 1996. Triazines were detected only in the dissolved phase at concentrations ranging from 2 to 91, from -1 for atrazine, cyanazine, and simazine, respectively. Dilution models show that, despite the presence of sporadically high concentrations of herbicides in St. Lawrence tributaries during periods of their application, loading from the tributaries is minor. Mass balance calculations show that Lake Ontario is clearly the main source of triazines (~90%) to the St. Lawrence River. During the 1995-1996 hydrological year, Lake Ontario contributed 15.1 × 103 of the 16.6 × 103 kg of atrazine outflowing the St. Lawrence River to the estuary. The difference (1.5 × 103 kg·year-1) can be attributed to tributaries in Quebec, which represent 0.75% of the amount of atrazine spread on farmlands. There is no evidence of the degradation of triazine compounds during their transit time in the river.

A method was developed to analyse 20 polar pesticides-9 organophosphorus, 9 organonitrogens and 2 degradation products of atrazine-simazine and propazine-in large volumes of surface water (1-20 L). During a recent study in our laboratory, the majority of these chemicals (2 < Log Koc < 4) were found in the dissolved phase. This paper presents a new extraction method for pesticides in the dissolved phase, using a fibre glass filter with 0.7 μm porosity. Samples of filtered surface water (1-20 L) were extracted by means of a solid-phase technique, using cartridges filled with 500 mg of Carbopack B (60/80 mesh) graphitized carbon black as adsorbent. The pesticides were monitored by gas chromatography on two DB-5 and DB-210 capillary columns with a nitrogen-phosphorus detector (GC-NPD). With the exception of metribuzin, phosmet and anilazine, percent recoveries were high (70-100%) for all pesticides in a volume of 17.85 L of Milli-Q water compared to percent recoveries in the same volume of filtered s...

During a recent study to determine the fluxes and fates of contaminants in the St. Lawrence River, the majority of organonitrogen pesticides analysed in samples of surface water were found in the dissolved phase. This paper compares two extraction techniques and two analytical techniques for 10 chemicals (metolachlor, seven triazines and two degradation products of atrazine–cyanazine–propazine and simazine) in the dissolved phase in large volumes of surface water, using a fibre glass filter with 0.7 μm porosity. Samples of filtered surface water (1–20 l) were extracted by means of a liquid–liquid technique using the Goulden large-sample extractor, and by means of a solid-phase extraction technique, using cartridges filled with 500 mg of a large particle-size graphitized carbon black as adsorbent: Carbopack B (500–666 μm). The pesticides were analysed by gas chromatography on two DB-5 and DB-210 capillary columns with nitrogen–phosphorus detection (GC–NPD) and by liquid chromatography coupled with mass spectrometry equipped with an atmospheric pressure chemical ionization interface (LC–APCI-MS). The recoveries were high (67–100%) for the majority of the target pesticides in a volume of 17.85 l of Milli-Q water, compared to recoveries in the same volume of filtered surface water (51–102%). The detection limits ranged from 0.4 to 4 ng/l and from 0.6 to 3 ng/l for GC–NPD and LC–ACPI-MS techniques, respectively.

In order to determine the fate of the herbicides atrazine (as well as some of its degradation products) and metolachlor in water and sediments, a method was developed to extract and analyse these compounds. The two matrices were separated completely by centrifugation followed by filtration using nylon filters (0.45 mum). Sediments were extracted with a mixture of methanol-0.1N hydrochloric acid (50:50, v/v) using a wrist-action shaker. Filtered water and extracts of sediments were adjusted to pH 4, then concentrated and purified onto two solid-phase extraction cartridges using in tandem C(18) bonded phase column atop sulfonic acid bonded column (SCX). Atrazine, deethylatrazine, deisopropylatrazine and metolachlor retained by the C(18) column were eluted with ethyl acetate. Chlorodiaminotriazine and hydroxyatrazine retained by the SCX column were eluted with a 50:50 (v/v) acetonitrile-0.1M Na(2) HPO(4) aqueous solution (pH 8.5). The extracts were quantified by high performance liquid chromatography with diode array detector (HPLC-DAD) and by gas chromatography with nitrogen-phosphorus detector (GC-NPD). Overall percent recoveries were about 75% and detection limits were between 0.05 and 0.15 microg/l., and 0.5 and 1.5 microg/kg for water and sediments, respectively.

The combined effect of dissolved gas composition and heat treatment on the oxidative degradation of a dairy beverage enriched with 2% linseed oil was studied. The dairy beverage was saturated with air, nitrogen, or a nitrogen/hydrogen mixture (4% hydrogen) before pasteurization or sterilization. Saturation with either nitrogen or a nitrogen/hydrogen mixture decreased the dissolved oxygen concentration in dairy beverages (Delta = 7.7 ppm), and the presence of hydrogen significantly reduced the redox potential (Delta = 287 mV). Heat treatments also reduced the oxygen content and redox potential, sterilization being more effective than pasteurization. Both pasteurization and sterilization induced the oxidative degradation of the beverages. On average, the propanal concentration increased by a factor of 2.3 after pasteurization and by a factor of 6.2 after sterilization. However, during storage, sterilized beverages resisted light-induced oxidation better than unheated or pasteurized beverages. Furthermore, saturation with nitrogen or a nitrogen/hydrogen mixture significantly reduced oxidative degradation and provided some protection against color changes during storage.

A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC/MS) method was developed using experimental designs to quantify the flavor of commercial Cheddar cheese and enzyme-modified Cheddar cheese (EMCC). Seven target compounds (dimethyl disulfide, hexanal, hexanol, 2-heptanone, ethyl hexanoate, heptanoic acid, delta-decalactone) representative of different chemical families frequently present in Cheddar cheese were selected for this study. Three types of SPME fibres were tested: Carboxen/polydimethylsiloxane (CAR/PDMS), polyacrylate (PA) and Carbowax/divinylbenzene (CW/DVB). NaCl concentration and temperature, as well as extraction time were tested for their effect on the HS-SPME process. Two series of two-level full factorial designs were carried out for each fibre to determine the factors which best support the extraction of target flavors. Therefore, central composite designs (CCDs) were performed and response surface models were derived. Optimal extraction conditions for all selected compounds, including internal standards, were: 50 min at 55 degrees C in 3M NaCl for CAR/PDMS, 64 min at 62 degrees C in 6M NaCl for PA, and 37 min at 67 degrees C in 6M NaCl for CW/DVB. Given its superior sensitivity, CAR/PDMS fibre was selected to evaluate the target analytes in commercial Cheddar cheese and EMCC. With this fibre, calibration curves were linear for all targeted compounds (from 0.5 to 6 microg g(-1)), except for heptanoic acid which only showed a linear response with PA fibres. Detection limits ranged from 0.3 to 1.6 microg g(-1) and quantification limits from 0.8 to 3.6 microg g(-1). The mean repeatability value for all flavor compounds was 8.8%. The method accuracy is satisfactory with recoveries ranging from 97 to 109%. Six of the targeted flavors were detected in commercial Cheddar cheese and EMCC.

This paper describes certain applications for endocrine-disrupting compounds determination. LC-MS was applied using an electrospray ionization (ESI) technique in positive mode for alcohol polyethoxylates and nonylphenol and octylphenol polyethoxylates (NPEOn and OPEOn), and in negative mode for 4-nonylphenol (4-NP) and 4-octylphenol (4-OP) to determine targeted compounds in wastewater and sludge. GC-MS and GC-MS-MS were used to determine 4-NP, 4-tert.-octylphenol (4-t-OP), bisphenol A, estradiol-17beta, estriol estrone, testosterone, 17alpha-ethynylestradioL cholesterol, coprostan-3-ol, coprostan and coprostan-3-one in both surface water and wastewater after derivatization with N,O-bis(trimethyl-silyl)trifluoroacetamide (BSTFA). Extraction from the water samples was by an SPE technique, using either a copolymeric (Oasis HLB) or C18 silica sorbents, depending on the target contaminants. Extraction from the sludge samples was by a Soxtec system using methanol. Percentage recoveries for most of the selected compounds, using either a copolymeric (Oasis HLB) or C18 silica sorbents, were satisfactory (60%). Quantification limits for the target compounds were at ppb levels in both water and sludge samples when using LC-ESI-MS in both positive and negative modes. They reached ppt levels in water when using GC-MS (in large volume injection mode) and GC-MS-MS. The results revealed 4-NP, NPEOn and AEOs in sludge samples at a concentration range of 1.3-8.5 microg/g, and NPEOn, OPEOn and other compounds, such as coprostan and bisphenol A, in surface water and/or wastewater samples at concentrations ranging from the ppt to ppb levels.

Hexachlorobenzene (HCB) is porphyrinogenic in adult female but not in male rats. This study aimed to assess the role of 17β-estradiol in the induction of porphyria by HCB in both sexes by adding or removing the hormone. Groups of intact females, ovariectomized females (Ova), castrated males (Cas), and Cas receiving 17β-estradiol (4 mg/kg, i.m., once a week beginning 2 weeks prior to HCB) were given five consecutive daily doses of HCB (100 mg/kg in corn oil, p.o.). Porphyria was assessed by urinary uroporphyrin excretion measured at days 16, 31, 38, 45, 52, 59, and 87. The percentage of porphyric rats in intact females increased from day 31 (58%) to day 87 (75%), whereas none of the Ova or Cas rats responded. However, administration of estradiol (days 120–169) and another sequence of HCB doses (days 134–138) to the same Ova rats caused porphyria (50% at day 186). Cas rats given estradiol also developed porphyria (43 and 86% on days 31 and 87, respectively). HCB-treated Ova rats given two doses of estradiol at either days 1 and 8 or days 22 and 29 developed a porphyria of similar magnitude (day 52). The role of estradiol cannot be explained by a reduction of pentachlorothiophenol formation, a putative detoxication pathway. Overall, results show that both sexes have the ability to respond to HCB when 17β-estradiol is present and suggest that the sexual dimorphism in HCB-induced porphyria in the rat is related to the hormonal status.

The antioxidant capacity, as well as the concentration threshold for sensorial detection of Canadian propolis fractions in milk were determined. Propolis fractions were obtained using two-step sequential extraction with ethanol and water. Two processing pathways were carried out by interchanging ethanol and water extraction steps. Total polyphenol and flavonoid contents were quantified and ESI-MS fingerprints in negative mode were collected to determine the chemical composition of the propolis and propolis extracts. The ferric-reducing power assay and DPPH· methods were performed to determine antioxidant capacity. For both extraction pathways, the ethanolic extract showed higher polyphenol and flavonoid concentrations and higher antioxidant capacity as compared to commercial propolis and water extracts. The polyphenol composition of the extracts varied according to both, the extraction solvent and the extraction pathway as revealed by ESI-MS fingerprints. The sensory detection threshold concentration in milk was significantly higher in water extracts than in ethanol extracts. It was further increased when ethanol extraction was carried out as the first step and water extraction as the second step. The results of this study suggest that sequential extraction process can be used to produce propolis fractions with different polyphenol composition, antioxidant and sensory properties.