固相萃取-气相色谱质谱联用法测定酱油中3种氯丙醇类污染物

目的 建立一种固相萃取-气相色谱质谱联用测定酱油中多组分氯丙醇类污染物的检测方法.方法 酱油样品上样于硅藻土萃取柱,用乙酸乙酯洗脱目标物,再经七氛丁酰基咪唑衍生化,色谱柱为HP-5MS毛细管柱(30 m ×0.25 mm ×0.25μm),采用气相色谱-质谱法测定,内标法定量.结果 本法中的1,3-二氯-2-丙醇(1,3-DCP)、2,3-二氯-1-丙醇(2,3-DCP)及3-氯-1,2-丙二醇(3-MCPD)的检出限分别为0.4,0.6和0.9μg/kg,线性范围5～100μg/kg(r2 ＞0.999);加标回收实验在5、20及50μg/kg浓度下进行,重复测定5次,3种添加浓度下1,3-DCP、2,3-DCP及3-MCPD的平均回收率分别为92.3％ ～ 99.2％、99.3％ ～ 103.4％、74.5％ ～ 93.5％,精密度分别为0.5％～5.5％、1.4％～4.6％、3.2％～14.3％.结论本法安全、高效、简单、灵敏,适用于大批量酱油样品中氯丙醇类污染物的检测.     

稳定性同位素稀释技术结合GC-MS测定酱油中多组分氯丙醇的研究

目的　以两种同位素内标建立同时测定酱油中 4种氯丙醇的GC -MS方法。方法　试样中加入稳定性氘代同位素内标 ,采用硅藻土Extrelut NT进行基质固相分散萃取结合固相萃取净化酱油试样 ,经七氟丁酰衍生化后 ,在DB - 5毛细管柱中经程序升温得到良好的分离 ,用选择离子储存 (SIS)定量。结果　各个氯丙醇在进样量为 2 0～ 5 0 0pg范围内线性良好 (r >0 999) ,3-氯 - 1,2-丙二醇 (3-MCPD)、1,3-二氯丙醇 (1,3-DCP)和 2 ,3-二氯丙醇 (2 ,3-DCP)的定量限分别为0 0 0 3、0 0 0 5和 0 0 0 5mg kg ;3种浓度水平下加标重复测定 6次 ,回收率分别为 98 8%～ 115 %、75 0 %～ 119%和 93 6 %～ 132 % ,精密度分别为 6 99%～ 16 2 %、3 80 %～ 9 2 5 %和 7 0 7%～10 4 %。结论　该方法具有较高的灵敏度、准确度、精密度和特异性 ,满足了酱油样品中痕量氯丙醇的分析要求。     

The effects of domestic cooking on the levels of 3-monochloropropanediol in foods

The results are reported of a study to determine the effect of domestic cooking procedures on the level of 3-monochloropropane-1,2-diol (3-MCPD) in selected foods. Samples of 23 foods comprising stock cubes, gravies, a cake mix, batters, breads, cheese and meats were subjected to a range of cooking procedures including grilling, toasting and microwaving. The resulting levels of 3-MCPD were compared with those present in the foods before cooking. Grilling and toasting produced substantial increases in the 3-MCPD content of bread, forming up to 0.3mg/kg, and of most cheeses, resulting in levels of up to about 0.1mg/kg. Microwave cooking produced elevated 3-MCPD levels in some cheeses. Frying laboratoryproduced batters increased 3-MCPD levels to about 0.1mg/kg whereas a retail batter contained no detectable 3-MCPD when fried. The remaining foods showed little or no discernible increase on cooking.     

Simultaneous determination of ethyl carbamate,chloropropanols and acrylamide in fermented products,flavoring and related foods by gas chromatography–triple quadrupole mass spectrometry

A simultaneous determination method was established by gas chromatography–triple quadrupole mass spectrometry (GC–MS/MS) for ethyl carbamate, acrylamide and chloropropanols (1,3-dichloropropane-2-ol (1,3-DCP), 2,3-dichloropropane-1-ol (2,3-DCP), 3-monochloropropane-1,2-diol (3-MCPD) and 2-monochloropropane-1,3-diol (2-MCPD)) in fermented products, flavoring and related foods. Ethyl carbamate-d₅, 1,3-DCP-d₅, 3-MCPD-d₅ and acrylamide-d₃ were used as isotope internal standards for ethyl carbamate, DCPs, MCPDs and acrylamide, respectively. The sample was extracted and cleaned in one single step by a combined clean-up column packed with Extrelut™ NT and primary secondary amine (PSA). The concentrated extract was directly injected without derivatization, separated by an Innowax (cross-bonded polyethylene glycol) capillary column and measured by GC–MS/MS. The calculated limits of detection (LODs) in the sample matrix were 1.8, 1.0, 2.1, 5.3, 5.1 and 5.0 μg kg⁻¹ for ethyl carbamate, 1,3-DCP, 2,3-DCP, acrylamide, 3-MCPD and 2-MCPD, respectively. The average recoveries in different matrices at three spiked concentration levels (20, 100 and 400 μg kg⁻¹) were 88.6–112, 92.6–103, 92.1–106, 86.2–107, 90.4–109 and 91.0–105% with relative standard deviations (RSDs) (Average RSDs in bracket) of 4.4–10.2 (6.4%), 3.7–7.3 (5.4%), 3.9–7.7 (5.2%), 4.4–9.3 (6.4%), 4.1–10.7 (6.3%) and 3.7–7.9% (5.6%), respectively. Two to six contaminants were simultaneously found in some of the soy sauce samples. Ethyl carbamate, acrylamide, 3-MCPD and 2-MCPD were found in the instant noodle flavoring. Trace levels (<12 μg kg⁻¹) of ethyl carbamate, acrylamide or 3-MCPD were detected in tomato sauce and salad dressing. Both ethyl carbamate and acrylamide were found in some of the curry products and Chinese yellow rice wine. Only ethyl carbamate was found in beer and grape wine.     

Toxic contaminants of thermo‐oxidatively processed edible oils/fats

Processing of edible oils during refining of the crude oil, or when used in frying, often exposes the oils to thermal and oxidative stresses. However, because of weaknesses inherent in their chemical structure, oils subsequently undergo structural decomposition and transformation in response to thermooxidative stresses. Whereas some of the decomposition products from the processed oils confer some value additions to the oils and the foods prepared in them (e.g. flavor, color, texture, and even stability), a number of edible oils' degradation products are known to be potentially toxic, and at reasonably high quantity, can compromise the health and wellbeing of consumers. This article describes the sources and updated knowledge on major toxic compounds that are generated during high temperature processing and usage of vegetable oils.     

Esters of 3-chloro-1,2-propanediol (3-MCPD) in vegetable oils: Significance in the formation of 3-MCPD

3-Mono-chloropropane-1,2-diol (3-MCPD) is a contaminant that occurs in food in its free (diol) form as well as in an esterified (with fatty acids) form. Using a simple intestinal model, it was demonstrated that 3-MCPD monoesters and 3-MCPD diesters are accepted by intestinal lipase as substrates in vitro. Under the chosen conditions, the yield of 3-MCPD from a 3-MCPD monoester was greater than 95% in approximately 1 min. Release from the diesters was slower, reaching about 45, 65 and 95% of 3-MCPD after 1, 5 and 90 min of incubation, respectively. However, in human, the hydrolysis of 3-MCPD esters is unlikely to release 100% as 3-MCPD, as triglycerides and phospholipids are hydrolysed in the intestine liberating 2-monoglycerides. Assuming a similar metabolism for 3-MCPD esters as that known for acylglycerols in humans in vivo, the de-esterification in positions 1 and 3 would thus be favoured by pancreatic lipases. Therefore, 3-MCPD, and 3-MCPD-2 monoesters would be released, respectively, from the 1-/3-monoesters, and the diesters potentially present in food. Hence, information on the exact amounts of the partial fatty acid chloroesters, i.e. 3-MCPD mono- and diesters, is important to assess the contribution of foods to the bioavailability of 3-MCPD. Therefore, a rapid method for the determination of the ratio of 3-MCPD monoesters to diesters in fats and oils was developed using gas chromatography-mass spectrometry (GC-MS) and isotopically labelled 3-MCPD esters as internal standards. The analysis of 11 different samples of fat mixes typically employed in food manufacturing demonstrated that a maximum of about 15% of the total amount of 3-MCPD bound in esters is present in the monoesterified form. The potentially slower release of 3-MCPD from 3-MCPD diesters, and the mono- to diesters ratio suggest that 3-MCPD esters may in fact contribute only marginally to the overall dietary exposure to 3-MCPD. Further work on the bioavailability, metabolism and possible toxicity of chloroesters per se is warranted.     

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. D₅-3-MCPD (for 3-MCPD and 2-MCPD) and d₅-1,3-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-Et₃N) 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.     

氯丙醇检测方法研究进展

氯丙醇类化合物是国际公认的食品污染物,包括3-氯-1,2-丙二醇(3-MCPD)、2-氯-1,3-丙二醇(2-MCPD)以及双氯取代的1,3-二氯-2-丙醇(1,3-DCP)和2,3-二氯-1-丙醇(2,3-DCP)。文章综述了国内外氯丙醇检测方法的研究进展,包括气相色谱(GC)法、气质联用(GC/MS)法、气相色谱双串联质谱(GC/MS/MS)联用法以及其它新的检测方法。     

Esters of 3-chloro-1,2-propanediol (3-MCPD) in vegetable oils: Significance in the formation of 3-MCPD

3-Mono-chloropropane-1,2-diol (3-MCPD) is a contaminant that occurs in food in its free (diol) form as well as in an esterified (with fatty acids) form. Using a simple intestinal model, it was demonstrated that 3-MCPD monoesters and 3-MCPD diesters are accepted by intestinal lipase as substrates in vitro. Under the chosen conditions, the yield of 3-MCPD from a 3-MCPD monoester was greater than 95% in approximately 1 min. Release from the diesters was slower, reaching about 45, 65 and 95% of 3-MCPD after 1, 5 and 90 min of incubation, respectively. However, in human, the hydrolysis of 3-MCPD esters is unlikely to release 100% as 3-MCPD, as triglycerides and phospholipids are hydrolysed in the intestine liberating 2-monoglycerides. Assuming a similar metabolism for 3-MCPD esters as that known for acylglycerols in humans in vivo, the de-esterification in positions 1 and 3 would thus be favoured by pancreatic lipases. Therefore, 3-MCPD, and 3-MCPD-2 monoesters would be released, respectively, from the 1-/3-monoesters, and the diesters potentially present in food. Hence, information on the exact amounts of the partial fatty acid chloroesters, i.e. 3-MCPD mono- and diesters, is important to assess the contribution of foods to the bioavailability of 3-MCPD. Therefore, a rapid method for the determination of the ratio of 3-MCPD monoesters to diesters in fats and oils was developed using gas chromatography-mass spectrometry (GC-MS) and isotopically labelled 3-MCPD esters as internal standards. The analysis of 11 different samples of fat mixes typically employed in food manufacturing demonstrated that a maximum of about 15% of the total amount of 3-MCPD bound in esters is present in the monoesterified form. The potentially slower release of 3-MCPD from 3-MCPD diesters, and the mono- to diesters ratio suggest that 3-MCPD esters may in fact contribute only marginally to the overall dietary exposure to 3-MCPD. Further work on the bioavailability, metabolism and possible toxicity of chloroesters per se is warranted.     

A Novel Method for Simultaneous Monitoring of 2-MCPD, 3-MCPD and Glycidyl Esters in Oils and Fats

The availability of a reliable methodology for the quantification of fatty acid esters of monochloropropropanediol (MCPD) and glycidol is essential for understanding the mechanism of formation of these process contaminants and for developing effective mitigation strategies. While several analytical methods for the determination of MCPD esters have already been developed and evaluated, only very few procedures are currently available for the analysis of glycidyl esters. This work presents a new indirect method for the simultaneous quantification of fatty acid esters of 2-MCPD, 3-MCPD and glycidol. The method is based on the acid-catalyzed conversion of glycidyl esters into 3-monobromopropanediol (3-MBPD) monoesters which, owing to the structural similarity to MCPD esters, are quantified by using the procedure we previously optimized for the analysis of MCPD esters. The critical step of the method, which is the conversion of glycidyl esters, was optimized by testing different reagent concentrations and varying other condition settings. The novel method showed good repeatability (RSD <2.5 %) and between-day reproducibility (RSD ≤5 %). The limit of detection was 0.04 mg/kg for bound 2-MCPD and 3-MCPD and 0.06 mg/kg for bound glycidol. The trueness of the method was evaluated by the analysis of spiked samples and by interlaboratory comparison.