Sensitive method for the determination of 1,3-dichloropropan-2-ol and 3-chloropropane-1,2-diol in soy sauce by capillary gas chromatography with mass spectrometric detection

Volatile flavor profiles of douchis from different origins and varieties based on GC-IMS and GC-O-QTOF/MS analysis

The present study comprehensively characterized the flavor differences between different varieties of douchis from different origins using headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) coupled with gas chromatography-olfactometry-quadrupole time-of-flight mass spectrometry (GC-O-QTOF/MS). A total of 91 volatile organic compounds (VOCs) were identified using HS-GC-IMS and 70 VOCs were identified using GC-O-QTOF/MS, mainly including acids, aldehydes, esters and alcohols. Additionally, 23 key aroma-presenting compounds were screened in five douchi species using relative odor activity value (ROAV) and the aroma compounds that contributed the most to the aroma varied among the five douchi species. Comparative analysis of the GC-IMS and GC-O-QTOF/ MS results yielded 13 VOCs that were detected by both techniques. Nonanal, hexanal, eucalyptol, 1-octen-3-ol, isoamyl acetate, and 2-pentylfuran were identified as key VOCs in the douchi species using both methods. These findings will provide deeper insights for exploring flavor differences in douchi from different geographic sources.

Characterization of key aroma-active compounds in different types of Douchi based on molecular sensory science approaches

To attain the differences in the flavor profile of Douchi, the key aroma-active compounds of three types of Douchi were investigated. The "Sauce-like", "Smoky", "Nutty", "Roast", "Caramel", and "Flower" of Douchi were favored by customers. Further, a total of 179 volatile compounds were identified using HS-SPME-GC-MS, and 29 aroma compounds were detected using GC-O-MS. Based on the quantification, 9, 13, and 10 compounds were regarded as aroma-active compounds in Yangjiang Douchi (YJ), Pingjiang Douchi (PJ), and Liuyang Douchi (LY), respectively. Moreover, the mixture of these aroma-active compounds successfully simulated the main aromas of PJ, LY, and YJ. And omission experiments confirmed that guaiacol was the key aroma compound for LY, benzene acetaldehyde, dimethyl trisulfide, and 2-acetyl pyrrole were important for YJ, benzene acetaldehyde and 3,5-diethyl-2-methyl pyrazine notably contributed to key aroma of PJ.

Rapid Sample Enrichment, Novel Derivatization, and High Sensitivity for Determination of 3-Chloropropane-1,2-diol in Soy Sauce via High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel, simplified derivatization method and a rapid sample preparation process using carbon yarn as a sorbent for the determination of 3-chloropropane-1,2-diol (3-MCPD) in soy sauce via high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. 3-MCPD was first enriched and purified with carbon yarn and then eluted with a methanol-water solution. Subsequently, the analyte underwent derivatization with p-(dimethylamino)-phenol for sensitive detection via HPLC-MS/MS. The limit of detection and the limit of quantitation for 3-MCPD were validated to be 0.5 and 1.0 μg/kg, respectively. Spiking experiments showed recoveries between 83 and 94%, with a relative standard deviation of ≤10%. The method was further validated with a certified reference material. Furthermore, 11 real soy sauce samples from local markets were tested by using this method. These results reveal the widespread 3-MCPD contamination. Consequently, this study offers a preferable alternative for the sensitive, accurate, and precise determination of 3-MCPD in soy sauce.

Methods, principles, challenges, and perspectives of determining chloropropanols and their esters

Chloropropanols and their esters are a group of food contaminants that have various toxicities to the human body. Research and control to chloropropanols and their esters is important to food safety. Therefore, the sensitive, accurate, precise, and effective determination of chloropropanols and their esters is highly essential to study their concentration, formation, and mitigation. The indirect method, commonly applied in the determination of chloropropanols and their esters, is based on the cleavage of ester bond, extraction, and derivatization. The conventional indirect method will still be the mostly used method in the near future due to its good sensitivity and feasibility, although its parameters need to be chosen and optimized according to sample stuffs and chloropropanol concentrations. Meanwhile, direct method and other quantitative methods should also be developed for special applications, such as studying the profile of chloropropanol esters and rapid screening protocol. The challenges and future perspectives of these methods are discussed in this review. This review can provide a reference on the selection, designation, and modification of methods for determining chloropropanols and their esters.

Characteristic fingerprints and volatile flavor compound variations in Liuyang Douchi during fermentation via HS-GC-IMS and HS-SPME-GC-MS

The present study investigates volatile organic compound (VOC) compositional changes in Liuyang Douchi during fermentation via a HS-GC-IMS and HS-SPME-GC-MS combination approach. A total of 115 VOCs were identified from Douchi, most of which were accumulated during pile fermentation. Notably, most alcohols and acids decreased with fermentation, while esters, ketones, pyrazines, and phenols accumulated during pile fermentation. Depending on the VOCs identified by GC-IMS/MS, the different fermentation stages of Douchi could be facilely distinguished. Of these, 49 VOCs were regarded as the marker VOCs of Douchi in different fermentation stage: hexanol, hexanal, and propanoic acid was the marker VOCs of the black beans before fermentation and contributing beany and grassy odors; 1-octen-3-ol and 3-octanone supplying a mushroom aroma to the Douchi fermented for 3-9 days; and esters and pyrazine, especially ethyl acetate and 2,6-dimethylpyrazine, contributing the cocoa, fruity, and nutty aromas of matured Douchi.

Air-assisted liquid-liquid microextraction of total 3-monochloropropane-1,2-diol from refined edible oils based on a natural deep eutectic solvent and its determination by gas chromatography-mass spectrometry

In this paper, a fast, sensitive, and selective sample preparation procedure was presented for the determination of 3-monochloropropane-1,2-diol (3-MCPD) in refined edible oils using gas chromatography-mass spectrometry. In this method, firstly, the sample lipids and analyte fatty esters are saponified by sodium hydroxide under sonication. After that the analyte was derivatized using phenylboronic acid (as the derivatization agent) and the obtained derivative was extracted during an air-assisted liquid-liquid microextraction procedure (AALLME). Six different deep eutectic solvents (DESs) were prepared as the extraction solvents and the most effective extraction for 3-MCPD was obtained in the presence of a natural DES (NDES) consisting of choline chloride (ChCl)-acetic acid (AcOH). Important variables such as sodium hydroxide concentration and volume, sonication time, temperature, extraction solvent type and volume, and phenylboronic acid concentration and volume have been optimized. Using the optimum conditions, broad linear range (0.88-1000 ng g^-1), suitable coefficient of determination (0.995), and low limits of detection (0.26 ng g^-1) and quantification (0.88 ng g^-1) were obtained. Relative standard deviations for intra- (n=8) and inter-day (n=6) precisions at a concentration of 5 ng g^-1 were 2.6 and 3.2%, respectively. The developed method has been successfully applied to 3-MCPD determination in refined edible oil samples including sunflower, corn, and canola oils.

Preparation and Uses of Chlorinated Glycerol Derivatives

Crude glycerol (C3H8O3) is a major by-product of biodiesel production from vegetable oils and animal fats. The increased biodiesel production in the last two decades has forced glycerol production up and prices down. However, crude glycerol from biodiesel production is not of adequate purity for industrial uses, including food, cosmetics and pharmaceuticals. The purification process of crude glycerol to reach the quality standards required by industry is expensive and dificult. Novel uses for crude glycerol can reduce the price of biodiesel and make it an economical alternative to diesel. Moreover, novel uses may improve environmental impact, since crude glycerol disposal is expensive and dificult. Glycerol is a versatile molecule with many potential applications in fermentation processes and synthetic chemistry. It serves as a glucose substitute in microbial growth media and as a precursor in the synthesis of a number of commercial intermediates or fine chemicals. Chlorinated derivatives of glycerol are an important class of such chemicals. The main focus of this review is the conversion of glycerol to chlorinated derivatives, such as epichlorohydrin and chlorohydrins, and their further use in the synthesis of additional downstream products. Downstream products include non-cyclic compounds with allyl, nitrile, azide and other functional groups, as well as oxazolidinones and triazoles, which are cyclic compounds derived from ephichlorohydrin and chlorohydrins. The polymers and ionic liquids, which use glycerol as an initial building block, are highlighted, as well.

Determination of Key Volatile Compounds Related to Long-Term Fermentation of Soy Sauce

The changes of volatile compounds in soy sauce during long-term fermentation (12 months) were investigated using solid-phase microextraction (SPME) and stir bar sorptive extraction (SBSE). A total of 144 and 129 compounds were identified in soy sauce with long-term fermentation by SPME and SBSE, respectively. The contents of most compounds, such as acids, aldehydes, benzene and benzene derivatives, esters, lactones, pyrazines, pyrones, and pyrroles, showed a tendency to increase, whereas those of alcohols and ketones decreased according to long-term fermentation. In addition, principal component analysis and partial least squares discriminant analysis were applied to discriminate soy sauce samples according to fermentation periods and determine key volatile compounds related to long-term fermentation. The initial fermentation stages were mainly associated with some alcohols, ketones, and lactones, whereas the later stages were strongly associated with most esters, some phenols, benzene and benzene derivatives, and pyrroles. Moreover, the key volatile compounds associated with long-term fermentation in soy sauce samples were ethyl 3-methylbutanoate (ethyl isovalerate), ethyl pentanoate (ethyl valerate), 1-octen-3-yl acetate, 3-(methylthio)-1-propanol (methionol), ethyl benzoate, ethyl 2-phenylacetate, 1-(1H-pyrrol-2-yl)ethanone (2-acetylpyrrole), and 5-pentyl-2-oxolanone (γ-nonalactone). PRACTICAL APPLICATION: This study investigated changes of volatile compounds in soy sauce during long-term fermentation (12 months) using solid-phase microextraction and stir bar sorptive extraction. In addition, the key volatile compounds associated with long-term fermentation in soy sauce samples were determined. These results may help to predict the effective contributors related to long-term fermentation of soy sauce and improve the quality of soy sauce during long-term fermentation.

Improvement of a GC-MS analytical method for the simultaneous detection of 3-MCPD and 1,3-DCP in food

Chloropropanols such as 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloropropan-2-ol (1,3-DCP) are produced by heat treatment in the presence of fat and hydrochloric acid during the manufacture of food stuffs such as hydrolyzed vegetable protein and soy sauce. 3-MCPD and 1,3-DCP have been detected in several foods. An efficient, highly selective GC-MS method was developed to determine the concentration of 3-MCPD and 1,3-DCP in food. Calibration curves for 3-MCPD and 1,3-DCP were constructed, and a correlation of determination (r²) ≥ 0.9990 was obtained. The limits of detection and quantitation for 3-MCPD in food were 0.6 and 2.0 µg/kg, respectively, and those for 1,3-DCP were 0.2 and 0.6 µg/kg, respectively. To the best of our knowledge, this GC-MS-based method is a newly improved analytical procedure for the simultaneous separation and determination of 3-MCPD and 1,3-DCP, at once and at low levels (µg/kg).

Simultaneous Analysis of 3-MCPD and 1,3-DCP in Asian Style Sauces Using QuEChERS Extraction and Gas Chromatography-Triple Quadrupole Mass Spectrometry

Acid hydrolyzed vegetable protein (aHVP) is used for flavoring a wide variety of foods and also in the production of nonfermented soy sauce. During the production of aHVP, chloropropanols including 3-monochloropropane-1,2-diol (3-MCPD) and 1,3 dichloropropane-2-ol (1,3-DCP) can be formed through the reaction of the hydrochloric acid catalyst and residual fat and the reaction of 3-MCPD with acetic acid, respectively. 3-MCPD is a carcinogen, and 1,3-DCP has been classified as a genotoxic carcinogen. The European Union (EU) has set a maximum concentration of 0.02 mg/kg of 3-MCPD in aHVP, and the Food and Drug Administration (FDA) set a guidance limit of 1 mg/kg of 3-MCPD in aHVP. 1,3-DCP is not an approved food additive, and the Joint FAO/WHO Expert Committee on Food Additives (JEFCA) has set a limit at 0.005 mg/kg, which is close to the estimated method detection limit. Currently there are few analytical methods for the simultaneous determination of 3-MCPD and 1,3-DCP without derivatization due to differences in their physical chemical properties and reactivity. A new method was developed using QuEChERS (quick, easy, cheap, effective, rugged, and safe) with direct analysis of the extract without derivatization using gas chromatography-triple quadrupole mass spectrometry (GC-QQQ). Additionally, a market sampling of 60 soy sauce samples was performed in 2015 to determine if concentrations have changed since the FDA limit was set in 2008. The sampling results were compared between the new QuEChERS method and a method using phenylboronic acid (PBA) as a derivatizing agent for 3-MCPD analysis. The concentrations of 3-MCPD detected in soy sauce samples collected in 2015 ( Collapse

Key Words

• 1,3-DCP
• 3-MCPD
• soy sauce

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MESH Headings

• Carcinogens/analysis
• Carcinogens/isolation & purification
• Chemical Fractionation/methods
• Flavoring Agents/analysis
• Food Contamination/analysis
• Gas Chromatography-Mass Spectrometry/methods
• Limit of Detection
• Propane/analogs & derivatives
• Propane/analysis
• Propane/isolation & purification
• alpha-Chlorohydrin/analysis
• alpha-Chlorohydrin/isolation & purification

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Grants

• FD999999 Intramural FDA HHS

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Affiliation(s)

Susan Genualdi U.S. Food and Drug Administration, 5001 Campus Drive, College Park, Maryland 20740, United States
Patricia Nyman U.S. Food and Drug Administration, 5001 Campus Drive, College Park, Maryland 20740, United States
Lowri DeJager U.S. Food and Drug Administration, 5001 Campus Drive, College Park, Maryland 20740, United States

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Analysis of 3-MCPD and 1,3-DCP in Various Foodstuffs Using GC-MS

3-Monochloro-1,2-propanediol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) are not only produced in the manufacturing process of foodstuffs such as hydrolyzed vegetable proteins and soy sauce but are also formed by heat processing in the presence of fat and low water activity. 3-MCPD exists both in free and ester forms, and the ester form has been also detected in various foods. Free 3-MCPD and 1,3-DCP are classified as Group 2B by the International Agency for Research on Cancer. Although there is no data confirming the toxicity of either compound in humans, their toxicity was evidenced in animal experimentation or in vitro. Although few studies have been conducted, free 3-MCPD has been shown to have neurotoxicity, reproductive toxicity, and carcinogenicity. In contrast, 1,3-DCP only has mutagenic activity. The purpose of this study was to analyze 3-MCPD and 1,3-DCP in various foods using gas chromatography -mass spectrometry. 3-MCPD and 1,3-DCP were analyzed using phenyl boronic acid derivatization and the liquid-liquid extraction method, respectively. The analytical method for 3-MCPD and 1,3-DCP was validated in terms of linearity, limit of detection (LOD), limit of quantitation, accuracy and precision. Consequently, the LODs of 3-MCPD and 1,3-DCP in various matrices were identified to be in the ranges of 4.18~10.56 ng/g and 1.06~3.15 ng/g, respectively.

Development and validation of an improved method for the determination of chloropropanols in paperboard food packaging by GC-MS

The objective of this study was to develop an improved analytical method for the determination of 3-chloro-1,2-propanediol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in paper-type food packaging. The established method includes aqueous extraction, matrix spiking of a deuterated surrogate internal standard (3-MCPD-d₅), clean-up using Extrelut solid-phase extraction, derivatisation using a silylation reagent, and GC-MS analysis of the chloropropanols as their corresponding trimethyl silyl ethers. The new method is applicable to food-grade packaging samples using European Commission standard aqueous extraction and aqueous food stimulant migration tests. In this improved method, the derivatisation procedure was optimised; the cost and time of the analysis were reduced by using 10 times less sample, solvents and reagents than in previously described methods. Overall the validation data demonstrate that the method is precise and reliable. The limit of detection (LOD) of the aqueous extract was 0.010 mg kg(-1) (w/w) for both 3-MCPD and 1,3-DCP. Analytical precision had a relative standard deviation (RSD) of 3.36% for 3-MCPD and an RSD of 7.65% for 1,3-DCP. The new method was satisfactorily applied to the analysis of over 100 commercial paperboard packaging samples. The data are being used to guide the product development of a next generation of wet-strength resins with reduced chloropropanol content, and also for risk assessments to calculate the virtual safe dose (VSD).

A novel approach of periodate oxidation coupled with HPLC-FLD for the quantitative determination of 3-chloro-1,2-propanediol in water and vegetable oil

A novel approach of periodate oxidation coupled with high-performance liquid chromatography (HPLC)-fluorescence detection (FLD) for the quantitative determination of 3-chloro-1,2-propanediol (3-MCPD) has been established. The essence of this approach lies in the production of chloroacetaldehyde by the oxidization cleavage of 3-MCPD with sodium periodate and the HPLC analysis of chloroacetaldehyde monitored by an FLD detector after fluorescence derivatization with adenine. The experimental parameters relating to the efficiency of the derivative reaction such as concentration of adenine, chloroacetaldehyde reaction temperature, and time were studied. Under the optimized conditions, the proposed method can provide high sensitivity, good linearity (r(2) = 0.999), and repeatability (percent relative standard deviations between 2.57% and 3.44%), the limits of detection and quantification were 0.36 and 1.20 ng/mL, respectively, and the recoveries obtained for water samples were in the range 93.39-97.39%. This method has been successfully applied to the analysis of real water samples. Also this method has been successfully used for the analysis of vegetable oil samples after pretreatment with liquid-liquid extraction; the recoveries obtained by a spiking experiment with soybean oil ranged from 96.27% to 102.42%. In comparison with gas chromatography or gas chromatography-mass spectrometry, the proposed method can provide the advantages of simple instrumental requirement, easy operation, low cost, and high efficiency, thus making this approach another good choice for the sensitive determination of 3-MCPD.

Investigation of the kinetics and mechanism of the glycerol chlorination reaction using gas chromatography-mass spectrometry

As a primary by-product in biodiesel production, glycerol can be used to prepare an important fine chemical, epichlorohydrin, by the glycerol chlorination reaction. Although this process has been applied in industrial production, unfortunately, less attention has been paid to the analysis and separation of the compounds in the glycerol chlorination products. In this study, a convenient and accurate method to determine the products in glycerol chlorination reaction was established and based on the results the kinetic mechanism of the reaction was investigated. The structure of main products, including 1,3- -dichloropropan-2-ol, 2,3-dichloropropan-1-ol, 3-chloro-1,2-propanediol, 2-chloro- 1,3-propanediol and glycerol was ascertained by gas chromatography-mass spectrometry and the isomers of the products were distinguished. Apidic acid was considered as the best catalyst because of its excellent catalytic effect and high boiling point. The mechanism of the glycerol chlorination reaction was proposed and a new kinetic model was developed. Kinetic equations of the process in the experimental range were obtained by data fitting and the activation energies of each tandem reaction were 30.7, 41.8, 29.4 and 49.5 kJ mol-1, respectively. This study revealed the process and mechanism of the kinetics and provides the theoretical basis for engineering problems.

Hydrolysis and H2O2-assisted UV photolysis of 3-chloro-1,2-propanediol

3-Chloro-1,2-propanediol (3-MCPD) is a chlorinated alcohol that is often formed as a by-product in the manufacturing of food products. In addition, 3-MCPD may be a disinfection by-product from wastewater treatment by chlorine and may be present in drinking waters from purification plants using epichlorohydrin-linked cationic polymer resins as flocculants. Due to concerns about the toxicity of 3-MCPD and its potential presence in water samples, the removal of 3-MCPD from water should be addressed and examined. For the first time a systematic examination of the removal of 3-MCPD via hydrolysis and photolysis processes is presented. 3-MCPD is shown to undergo hydrolysis at near neutral pH values, but at much slower rates than can be obtained by UV/H2O2 processes. 3-MCPD does not undergo rapid direct photolysis. Re-evaluation of temperature and pH dependent hydrolysis rate data indicates that hydrolysis is first order with respect to [OH(-)].

Analysis of heat-induced contaminants (acrylamide, chloropropanols and furan) in carbohydrate-rich food

Heat-induced food contaminants have attracted attention of both the scientific community and the public in recent years. The presence of substances considered possibly or probably carcinogenic to humans has triggered an extensive debate on the healthiness of even staple foods. In that respect, acrylamide, furan and chloropropanols are the main substances of concern. Their widespread occurrence in processed food, which concomitantly causes considerable exposure to humans, led either to the setting of maximum limits (for some chloropropanols) or at least the initiation of monitoring programmes in order to put risk assessment on a solid data basis. Acrylamide, furan and chloropropanols are small molecules with physicochemical properties that make their analysis challenging. Their amount in food ranges typically from below the limit of detection to hundreds of micrograms per kilo or even milligrams per kilo. However, a number of recently published scientific reports deal with the analysis of these substances in different kinds of food. The aim of this publication is to give an overview of analytical approaches for the determination of acrylamide, furan and chloropropanols in foodstuffs.

Photochemical degradation of 1,3-dichloro-2-propanol aqueous solutions

The photochemical oxidation of 1,3-dichloro-2-propanol (1,3-DCP) was studied by following the target compound degradation, the total carbon removal rate by a total organic carbon (TOC) analyzer and by identifying the oxidation products by gas chromatography-mass spectrometry (GC-MS). The reaction was performed in a batch recycle reactor, at room temperature, using UV radiation provided by a low pressure 12W Hg lamp and H(2)O(2) as oxidant. Chloride ions, formic, acetic and chloroacetic acid were measured by ion chromatography. Apart from the chloride ions and the organic acids, the presence of 1,3-dichloro-2-propanone and chloroacetyl chloride was also detected and a possible pathway is proposed for the degradation of the parent compound. Complete degradation of 1,3-dichloro-2-propanol was achieved and the TOC removal reached as much as 80% at the end of the reaction time. The effect of the initial concentration of hydrogen peroxide was investigated and it was established that higher concentrations of H(2)O(2) slow down the reaction rate. Finally, the effect of the initial concentration of 1,3-DCP was investigated.

Determination of 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in soy sauce by headspace derivatization solid-phase microextraction combined with gas chromatography–mass spectrometry

This study proposes a method for identifying 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in aqueous matrices by using headspace on-fiber derivatization following solid-phase microextraction combined with gas chromatography-mass spectrometry. The optimized SPME experimental procedures for extracting 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in aqueous solutions involved a 85 microm polyacrylate-coated fiber at pH 6, a sodium chloride concentration of 0.36 g mL(-1), extraction at 50 degrees C for 15 min and desorption of analytes at 260 degrees C for 3 min. Headspace derivatization was conducted in a laboratory-made design with N-methyl-N-(trimethylsilyl)-trifluoroacetamide vapor following solid-phase microextraction by using 3 microL N-methyl-N-(trimethylsilyl)-trifluoroacetamide at an oil bath temperature of 230 degrees C for 40 s. This method had good repeatability (R.S.D.s < or = 19%, n = 8) and good linearity (r2 > or = 0.9972) for ultrapure water and soy sauce samples that were spiked with two analytes. Detection limits were obtained at the ng mL(-1). The result demonstrated that headspace on-fiber derivatization following solid-phase microextraction was a simple, fast and accurate technique for identifying trace 1,3-dichloro-2-propanol and 3-chloro-1,2-propandiol in soy sauce.

The selective neurotoxicity produced by 3-chloropropanediol in the rat is not a result of energy deprivation

The biochemical mechanism of toxicity of the experimental astrocyte neurotoxicant and food contaminant S-3-chloro-1,2-propanediol (3-CPD) has been proposed to be via inhibition of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We have confirmed this action in liver, which shows inhibition to 6.0+/-0.7% control at the neuropathic dose of 140 mg/kg. However, GAPDH activity in brain only fell to a minimum of 54+/-24% control, and the concentrations of lactate and pyruvate (the downstream products of GAPDH), showed no pre-neuropathic decreases in 3-CPD susceptible brain tissue. There was no inhibition of GAPDH activity in primary astrocyte cultures at sub-cytotoxic exposures. We therefore sought alternative mechanisms to explain its toxicity to astrocytes. We were able to show that 3-CPD is a substrate for glutathione-S-transferase and also that, after bioactivation by alcohol dehydrogenase, it generates an irreversible inhibitor of glutathione reductase. In addition, incubation of brain slices from the 3-CPD-vulnerable inferior colliculus produces a depletion of glutathione and an inhibition of glutathione-S-transferase that is not seen in equivalent slices taken from the 3-CPD-resistant occipital neocortex. A smaller but significant and similarly regionally selective decrease in glutathione content is also seen in vivo. We conclude that 3-CPD does not produce its astrocytic toxicity via energy deprivation, and suggest that selective bioactivation and consequent disruption of redox state is a more likely mechanism.

The simultaneous separation and determination of chloropropanols in soy sauce and other flavoring with gas chromatography-mass spectrometry in negative chemical and electron impact ionization modes

Both gas chromatography-mass spectrometry in electron ionization (GC-MS-EI) and negative chemical ionization (GC-MS-NCI) modes are reported in this paper for the simultaneous determination of 1,3-dichloropropan-2-ol (1,3-DCP), 2,3-dichloropropan-1-ol (2,3-DCP), 3-chloropropane-1,2-diol (3-MCPD) and 2-chloropropane-1,3-diol (2-MCPD) in soy sauce and other flavoring. D(5)-3-MCPD (for 3-MCPD and 2-MCPD) and d(5)-1,3-DCP (for 1,3-DCP and 2,3-DCP) were used as the deuterium isotopic labelled internal standards. The feasibility of using heptafluorobutyric anhydride modified with triethylamine (HFBA-Et(3)N) as a new derivatization reagent to replace heptafluorobutyrylimidazole (HFBI) is proposed. Liquid/liquid extraction with hexane was introduced for high lipid content samples. A small survey was carried out of soy sauces (103 samples) and instant noodles (45 samples) and the applicability of GC-MS-NCI and GC-MS-EI was assessed in these different matrices.

Determination of 3-chloropropane-1,2-diol as its 1,3-dioxolane derivative at the μg kg−1level: Application to a wide range of foods

This paper reports the application of a GC/MS method for the quantification of 3-chloropropane-1,2-diol (3-MCPD) at low microg kg-1 levels through the determination of its 1,3-dioxolane derivative to a wide range of foodstuffs. The proposed protocol is based on the methods generally performed in control laboratories. The two main stages of the method - the solid-phase extraction and the purification of the derivatives - have been optimized. The within-laboratory reproducibility meets the official performance criteria for verifying 3-MCPD at the 20 microg kg(-1) limit stipulated by the European Community for soy sauce. The limit of quantification was below 5 microg kg(-1) for all the foodstuffs analysed. This method offers a valuable alternative to the draft CEN European Standard: instead of diethyl ether, much safer ethyl acetate is used; derivatization is more selective; and reagents are common stable chemicals. This method was successfully applied to toasted bread, savoury crackers, cheese, soups, including vegetable-based soups, meat products such as salami, vegetable oils, sauces, soy sauce and related products. Upon checking the method performance in the case of vegetable oils, the unexpected presence of monobromopropanediols was detected.

A rapid and sensitive GC–MS method for determination of 1,3-dichloro-2-propanol in water

A rapid analytical method for sensitive determination of 1,3-dichloro-2-propanol (1,3-DCP) in river water has been developed. 1,3-DCP is extracted from water with ethyl acetate. After filtration through sodium sulfate the ethyl acetate phase is analyzed by gas chromatography-mass spectrometry. The method uses 1,3-DCP-d5 as internal standard. Different extraction solvents, concentrations of ammonium sulfate in the water samples, and the effect of humic acid were tested and their influence on the recovery of DCP has been evaluated. The method quantification limit was 0.1 microg L(-1). For spiked water samples (0-5.2 microg L(-1), n=21) a repeatability coefficient of variation of 5.4% was obtained. The average recovery rate of 1,3-DCP was 105+/-3% (n=21). Stability tests, which were carried out with Danube river water, led to an estimated 1,3-DCP degradation rate of 0.008+/-0.0008 day(-1) at 6 degrees C.

Determination of 3-Chloropropane-1,2-diol in Liquid Hydrolyzed Vegetable Proteins and Soy Sauce by Solid-Phase Microextraction and Gas Chromatography/Mass Spectrometry

Headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography/mass spectrometry (GC/MS) method was developed to determine 3-chloropropane-1,2-diol (3-MCPD) in hydrolyzed vegetable protein and Chinese soy sauce. The 3-MCPD was firstly derivativized with phenylboronic acid in aqueous solution at 90 degrees C for 10 min, then extracted by HS-SPME and finally detected with GC/MS, parameters related to both the derivative reaction and the HS-SPME process were optimized. The proposed method has a linear range of 0.0194-394 microg g(-1), a detection limit of 3.87 ng g(-1) (S/N = 3), and a precision of RSD = 7.5% (n = 5). Seventeen real samples, including four HVPs and thirteen soy sauce samples, were analyzed to examine the feasibility of the proposed procedure; with a concentration of 3-MCPD and acceptable recoveries at 0.71 microg g(-1) spiked levels were obtained. Being simpler, faster and more environmentally benign than the existing methods, this method is accurate and suitable for routine analysis.

Survey of chloropropanols in soy sauces and related products purchased in the UK in 2000 and 2002

The results of surveys to investigate the levels of 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in UK retail samples of soy sauces and similar products are reported. The products, sampled in 2000 and 2002, were analysed for 3-MCPD using an established solvent extraction technique with a reporting limit of 0.01 mg kg(-1), which also detected 2-monochloropropane-1,2-diol (2-MCPD), and for 1,3-DCP by an automated headspace method with a reporting limit of 0.005 mg kg(-1), which also detected 2,3-dichloropropanol (2,3-DCP). In the 2000 survey, 3-MCPD was quantified in 32 of 100 samples. After normalization to 40% dry matter, it was quantified at or above 0.02 mg kg(-1) in 25 of the samples and in excess of 1 mg kg(-1) in 16 samples, the highest containing 82.8 mg kg(-1). 2-MCPD was found in 26 samples, at up to 17.6 mg kg(-1) after normalization to 40% dry matter. The presence of 1,3-DCP was detected in 17 of the samples, at levels between 0.006 and 0.345 mg kg(-1). 1,3-DCP was only detected where 3-MCPD was present, but the levels of 1,3-DCP and 3-MCPD were not correlated. 2,3-DCP was detected in 11 samples at levels ranging from 0.006 to 0.043 mg kg(-1). In the 2002 survey, 3-MCPD was quantified (> 0.01 mg kg(-1)) in only eight of 99 samples and 2-MCPD in three samples. After normalization to 40% dry matter, 3-MCPD was present at or above 0.02 mg kg(-1) in seven of these, the maximum level being 35.9 mg kg(-1). 1,3-DCP was detected in this sample alone, at 0.017 mg kg(-1).