Baseline levels of melamine in food items sold in Canada. I. Dairy products and soy-based dairy replacement products

A variety of dairy and soy-based dairy replacement products (n = 246) purchased from Canadian retail outlets were analysed for baseline levels of melamine (MEL) using a sensitive LC–MS/MS method (method quantification limit = 4 µg/kg). MEL was infrequently detected; only 14% of the items analysed contained quantifiable levels of MEL. The concentrations observed, aside from one recalled sample of candy, ranged from 0.00435 to 0.276 mg/kg, and were at least 10 times lower than the 2.5 mg/kg interim standard for melamine in products containing milk and milk-derived ingredients established by Health Canada. The consumption of foods containing these low levels of MEL does not constitute a health risk for consumers.     

A Rapid and Sensitive Method for Determination of Melamine in Fish,Shrimp, Clam,and Winkle by Gas Chromatography–Mass Spectrometry with Microwave-Assisted Derivatization

A method for rapid and sensitive determination of melamine in aquatic products by gas chromatography–mass spectrometry with microwave-assisted derivatization was proposed in this paper. Melamine was extracted from aquatic product samples using methanol, and the extract was cleaned with a mixed-mode cationic exchange solid phase extraction column. After elution with 5 % ammonia–methanol solution and drying with nitrogen, the residue was derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide containing 1 % trimethylchlorosilane under microwave irradiation for 1 min with a power of 420 W, then detected with gas chromatography–mass spectrometry, and quantified by the external standard method. Some important parameters such as extraction solvent, microwave irradiation power and time, and derivatization reagent volume were investigated and optimized. The results showed that methanol could effectively extracted melamine from aquatic products as well as precipitated the protein in samples. Under the optimum conditions, the detection limit for melamine was as low as 0.006 mg/kg, and the linear range was from 0.02 to 50 mg/kg with a correlation coefficient of 0.9997. The proposed method was applied to the analysis of melamine in aquatic products (fish, shrimp, clam, and winkle), and the recovery for melamine was 89.65–105.16 % with relative standard deviation of 3.0–6.0 %.     

Determination of melamine, ammeline, ammelide and cyanuric acid in infant formula purchased in Canada by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry-based isotope dilution method was developed for the analysis of the triazine compounds melamine (MEL), ammeline (AMN), ammelide (AMD) and cyanuric acid (CYA) in infant formula samples purchased in Canada in 2008 for the purpose of a combined exposure and risk assessment. Infant formula samples were extracted with 1:1 acetonitrile-water, cleaned up on disposable ion-exchange solid-phase extraction cartridges, and analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. MEL and CYA were detected in almost all infant formula products: the highest concentrations observed were 0.32 mg kg(-1) MEL and 0.45 mg kg(-1) CYA. Samples that were relatively high in MEL in this survey tended to be low in CYA, and vice versa. Concentrations of AMN and AMD were very low in all samples. The total of MEL-related compounds (sum of all four analytes) in all samples was below the interim standard of 0.5 mg kg(-1) for infant formula products established by Health Canada.     

Rapid and High-Throughput Determination of Melamine in Milk Products and Eggs by Full Automatic On-line Polymer Monolith Microextraction Coupled to High-Performance Liquid Chromatography

A rapid and high-throughput method for monitoring melamine (MEL) in milk products and eggs was presented. This method was based on a full automatic platform that was composed of on-line polymer monolith microextraction and high-performance liquid chromatography with ultraviolet detection. A poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene dimethacrylate) monolith was selected as the sorbent for purification and enrichment of MEL in milk products and eggs. A novel mixed-mode chromatographic column packed with octyl and sulfonic acid co-bonded silica was employed for quantitative determination of MEL in real samples. Several factors affecting extraction performance were investigated. Under the optimal conditions, the recoveries of MEL in milk products and eggs spiked at three levels of 0.5, 5.0, and 20.0 mg/Kg, ranged from 87.0% to 95.5%, with RSDs less than 6.4%. The limits of detection were 0.024 and 0.018 mg/Kg for MEL in the milk products and eggs, respectively.     

Methods for the analysis of melamine and related compounds in foods: a review

In recent years, two adulteration incidents concerning the addition of melamine (MEL) and related compounds to dairy products and vegetable proteins have occurred in China. These episodes prompted numerous governmental and private laboratories to develop or implement methods for the analysis of a wide variety of food products for MEL and related compounds, including cyanuric acid, ammeline, and ammelide. Methods have been developed for both screening and quantitation purposes; procedures used in the methods range from sensitive hyphenated chromatographic-mass spectrometric techniques to immunoselective assays. Various issues are encountered during the analysis of MEL and related compounds in food products. These issues include contamination, matrix effects, and analyte instability, and their severity varies according to the method used, and matrices and analytes examined.     

酶联免疫吸附法快速测定不同样品 基质中三聚氰胺

目的 探求不同样品基质中三聚氰胺残留量的快速检测方法.为快速筛查不同种类食品中非法添加三聚氰胺提供技术保障.方法 采用酶联免疫吸附法在奶制品(奶粉、液态奶)、成品饲料(鸡饲料、猪饲料)、饲料原料(鱼粉、肉骨粉、豆粕、麸皮)、肉类(鸡肉、猪肉、内脏)等样品基质中添加一定浓度的三聚氰胺进行测定,并对检测结果进行分析.结果 酶联免疫试剂盒对奶制品和肉类检出限均能达到1.0 mg/kg;对成品饲料基质中的三聚氰胺的检测,检出限可达到2 mg/kg,而对饲料原料中的三聚氰胺的检测,检出限都不能达到2 mg/kg.结论 对奶制品中的三聚氰胺检测完全符合我国的临时限量标准;对成品饲料中的三聚氰胺残留的检测同样符合其限量标准(2.5 mg/kg),而对饲料原料中的三聚氰胺的检测,由于不同基质中检出限不同,不能直接采用酶联免疫法进行快速筛查;酶联免疫法也适用于肉类中的三聚氰胺的检测.     

云南省淡水湖泊鱼虾中多氯联苯食用安全性评估

目的对云南省5个淡水湖泊中鱼虾体内的多氯联苯(polychorinated biphenyl,PCBs)污染水平进行调查研究。方法采用气相色谱-质谱联用仪进行检测分析,根据检测结果对云南省淡水湖泊中的鱼虾体内多氯联苯的含量进行食用安全性评估。结果云南省淡水湖泊中鱼虾体内的多氯联苯检出率为90%,多氯联苯的含量范围为ND～1.16μg/kg,平均含量为0.27μg/kg,低于国家标准限量。云南省淡水湖泊中鱼虾体内的多氯联苯按照世界卫生组织(World Health Organization,WHO)规定的多氯联苯毒性当量(toxic equivalent quantity,TEQ)分布于ND～6.51×10~(-5)μg/kg,平均值为1.21×10~(-5)μg/kg,低于欧盟的行动标准限量。结论云南省居民从云南省淡水湖泊鱼虾体内摄入持久性有机污染物多氯联苯的剂量较低,引起的健康风险较低。     

苏州地产水生蔬菜和太湖水产品总汞含量分析

通过微波消解-冷原子荧光光谱法检测苏州地产水生蔬菜与太湖水产品的总汞含量,并研究其分布规律。测定结果显示：螃蟹总汞含量最高,其中雄蟹蟹膏部位高达0.470mg/kg,其他水产品包括白鱼、白虾及螺蛳等总汞含量均较低;水生蔬菜除茭白外,均受到不同程度的汞污染,汞含量已超过我国限量标准,其变化呈现浮叶植物高于挺水植物、裸露植物高于有包裹植物的趋势。     

液相色谱-串联质谱法快速测定鸡肉及组织中的三聚氰胺和三聚氰酸

通过对提取溶剂、净化方法及色谱质谱条件的优化建立鸡组织样品中的三聚氰胺和三聚氰酸同时测定的HPLC-MS/MS 法。样品经乙腈水溶液(70:30,V/V)超声提取,正己烷脱脂,7000r/min 离心后取上清液与乙腈(1:1,V/V)混匀,10000r/min 离心沉淀蛋白,过滤后无需净化即可上机测定,大大缩短了样品处理时间。使用MRM模式检测和同位素内标稀释法定量,进一步提高了方法的准确性和定量线性。在1～500ng/mL 范围内,目标物的峰面积与其质量浓度的线性关系良好(R2 ＞ 0.999);在0.1、1、5mg/kg 的添加水平,鸡组织样品三聚氰胺回收率为87.76%～107.89%,三聚氰酸回收率为87.31%～106.05%,相对标准偏差(RSD)分别为0.58%～2.78% 和1.26%～4.33%;三聚氰胺和三聚氰酸的检测限(LOD)分别为4ng/g 和2ng/g。结果表明,该方法简便、快速、准确,适合鸡组织中三聚氰胺和三聚氰酸的确证和定量测定。     

水产品及水产制品中三聚氰胺检测方法的研究

采用气相色谱-质谱/质谱法（GC-MS/MS）对鲜、冷或冻水产品（养殖鱼、虾、蟹、贝等）及水产制品（干、熏、盐制水产）中三聚氰胺进行了检测。样品采用乙睛和甲醇提取,提取液离心净化,氮气吹干,利用衍生化试剂BSTFA-TMCS（体积比为99∶1）进行衍生化反应、优化仪器条件、考察基体干扰,利用三重四级杆气相色谱联用的多反应监测（MRM）技术,对三聚氰胺衍生物进行定性定量分析。以三聚氰胺衍生物离子对m/z 342〉171、m/z 342〉327离子对进行定性,以m/z 342〉327进行定量。方法的线性范围为0.005μg/L~0.1μg/L;回归方程为y=1 434 164.378 8x-704.012 5,相关系数R2=0.999 4;方法定量限0.03 mg/kg。回收率达90%以上,相对标准偏差RSD〈5.0%。该方法简便、快速、灵敏、准确,适合于水产品和水产制品中三聚氰胺含量的确证和定量测定。     

Biogenic amine contents in selected Egyptian fermented foods as determined by ion-exchange chromatography

Biogenic amines in foods may pose a public health problem. Therefore, histamine, tyramine, putrescine, cadaverine, spermine, and spermidine concentrations were measured in selected food items commonly consumed in Egypt. Foods examined were dairy products (blue cheese and Mesh cheese), meats (fermented and smoked cooked sausage), and fish (smoked and salted fermented fish [Feseekh], salted sardines, and anchovies). Egyptian fermented sausage had the highest concentration of total biogenic amines (2,482 mg/kg), followed by Mesh cheese (2,118 mg/kg) and blue cheese (2,084 mg/kg). The lowest concentration was found in smoked cooked sausage (111 mg/kg). Histamine was found at a high level (521 mg/kg) in Feseekh, and tyramine was highest (2,010 mg/kg) in blue cheese. These results indicate that some traditional Egyptian foods may pose a health risk due to the concentration of biogenic amines, especially histamine.     

Total lipid,fatty acid composition and lipid oxidation of Indian white shrimp (Fenneropenaeus indicus) fed diets containing different lipid sources

BACKGROUND: Seafood is an important constituent of the human diet. In Iran, Indian white shrimp (Fenneropenaeus indicus) is the major cultured shrimp species as a result of market demand, local availability and growth rate. It is mainly reared using commercial feed. The purpose of this study was to evaluate the effects of replacing 50% of the fish oil by vegetable oils in shrimp feed on total lipid, fatty acid composition and lipid oxidation of shrimp muscle. RESULTS: No significant differences in total lipid content (6.1–7.3 g kg^?1) were found between edible tissues of shrimp fed different diets. The major fatty acids in shrimp muscle were palmitic, oleic, lionoleic, stearic, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Higher levels of EPA and DHA were observed in muscle of shrimp fed a diet containing fish oil. Oxidative rancidity, measured as thiobarbituric acid reactive substances, for all shrimps did not exceed 0.2 mg malonaldehyde kg^?1 muscle tissue, which was low and acceptable. CONCLUSION: This study had shown that the fatty acid composition of feed directly affects the fatty acid composition of Indian white shrimp muscle. Farmed Indian white shrimp can be considered as a species of low fat and shrimp muscle was quite stable to oxidation during storage. Copyright © 2009 Society of Chemical Industry     

Analysis of melamine migration from melamine food contact articles

Migration of melamine has been determined for 41 types of retail melamine-ware products in Malaysia. This study was initiated by the Ministry of Health, Malaysia, in the midst of public anxiety on the possibility of melamine leaching into foods that come into contact with the melamine-ware. Thus, the objective of this study was to investigate the level of melamine migration in melamine utensils available on the market. Samples of melamine tableware, including cups and plates, forks and spoons, tumblers, bowls, etc., were collected from various retail outlets. Following the test guidelines for melamine migration set by the European Committee for Standardisation (CEN 2004) with some modifications, the samples were exposed to two types of food simulants (3% acetic acid and distilled water) at three test conditions (25°C (room temperature), 70 and 100°C) for 30 min. Melamine analysis was carried out using LC–MS/MS with a HILIC column and mobile phase consisting of ammonium acetate/formic acid (0.05%) in water and ammonium acetate/formic acid (0.05%) in acetonitrile (95?:?5, v/v). The limit of quantification (LOQ) was 5?ng/ml. Melamine migration was detected from all samples. For the articles tested with distilled water, melamine migration were [median (interquartile range)] 22.2 (32.6), 49.3 (50.9), 84.9 (89.9) ng/ml at room temperature (25°C), 70 and 100°C, respectively. In 3% acetic acid, melamine migration was 31.5 (35.7), 81.5 (76.2), 122.0 (126.7) ng/ml at room temperature (25°C), 70 and 100°C, respectively. This study suggests that excessive heat and acidity may directly affect melamine migration from melamine-ware products. However the results showed that melamine migration in the tested items were well below the specific migration limit (SML) of 30?mg/kg (30,000?ng/ml) set out in European Commission Directive 2002/72/EC.     

A hierarchical Bayesian approach for risk assessment of melamine in infant formula based on cases of related nephrolithiasis in children

Although the 2008 outbreak of nephrolithiasis in children due to melamine-contaminated infant formula has subsided, it remains uncertain whether the present tolerable daily intake (TDI) of melamine provides sufficient protection for young children. To conduct a safety assessment for melamine in infant formula, we established a dose–response relationship based on 13 nephrolithiasis cases selected from 932 children, all of whom were under 5 years of age and had potentially been exposed to contaminated milk in China or Taiwan. According to the children's exposure history, distributions of individual daily melamine intake (mg/kg?BW/day) were reconstructed using Monte Carlo simulations to account for uncertainties in exposure duration and melamine concentrations in the contaminated milk. Based on the simulated individual average daily intake (AVDI) of melamine, subjects were further classified into four separate AVDI groups: high, medium, low and a reference group. A statistical logistic model was then fitted for the dose–response relationship between nephrolithiasis incidence and daily melamine intakes using Markov chain Monte Carlo (MCMC) simulations. Based on the background exposure, spontaneous rate, and mode of action (MOA) of nephrolithiasis in children, the simulated lower bounds of the 95% CIs daily melamine intake ranged from 0.008 to 0.03?mg/kg?BW/day corresponding to an additional risks of 0.1% is proposed as a plausible TDI, which is approximately an order lower than the current WHO-suggested TDI level of 0.2?mg/kg?BW/day. More stringent regulations on melamine levels in infant formula should be considered to protect young children fully.     

三聚氰胺在罗非鱼体内的残留和消除规律研究

以罗非鱼(Tilapia)为研究对象,通过在罗非鱼饲料中添加不同剂量三聚氰胺进行罗非鱼摄食生长试验,研究三聚氰胺在罗非鱼肝脏和肌肉中的残留和消除规律。实验结果表明:(1)罗非鱼连续饲喂含三聚氰胺的饲料50d,添加不同剂量的三聚氰胺对各组罗非鱼的平均体重增长无显著影响(P>0.05);(2)肝脏和肌肉中三聚氰胺的残留量随着各实验组饲料中添加量的增加呈显著递增趋势(P<0.05),低剂量组(1000、5000mg/kg)的肝脏和肌肉中的残留量在2～20mg/kg间,高剂量组(10000、50000mg/kg)的残留量均超过40mg/kg,各组中肝脏的残留量均显著高于肌肉(P<0.05)。停药5d后,罗非鱼的肝脏和肌肉中三聚氰胺的残留量均内显著下降,各实验组的三聚氰胺残留量均降至2.0mg/kg以下,此后则缓慢下降。各实验组中,肌肉的消除时间比肝脏的消除时间长。     

三聚氰胺单克隆抗体的制备及鉴定

为建立三聚氰胺免疫分析方法,采用戊二醛法合成免疫抗原MEL-BSA和包被抗原MEL-OVA,全抗原经紫外吸收法检测证实偶联成功且偶联比约为16∶1。用MEL-BSA免疫BALB/c小鼠,用常规单克隆制备技术筛选获得1株稳定分泌抗三聚氰胺单克隆抗体的细胞株6E3。腹水经纯化后,研究了抗体效价、竞争抑制能力及与结构类似物的交叉反应率,其中抗体效价为1∶64 000,检测线性范围为0.1~3.2 mg/L,IC50为1.01 mg/L,与三聚氰酸、三聚氰酸一酰胺及三聚氰酸二酰胺的交叉反应率均小于0.1%,该方法有望用于三聚氰胺免疫检测试剂的研制开发。     

Melamine contamination in milk powder in Uruguay

Forty samples of milk powder purchased in Uruguay were analysed to assess melamine (MEL) levels. Trichloroacetic acid and acetonitrile were used to extract and precipitate milk proteins previously to clean up of the samples by solid-phase extraction and then were determined by liquid chromatography coupled to ultraviolet detection. The limit of detection (LOD) and limit of quantification (LOQ)of MEL were 0.006 and 0.019 mg kg^?1, respectively. Milk was fortified with MEL at three levels, producing average recoveries higher than 83.8%. The values for positive samples ranged from 0.017 to 0.082 mg kg^?1. Nine samples were positive. Three of them had concentrations between LOD and LOQ. The mean MEL contamination was 0.028 mg kg^?1. Consumption of milk powder containing these levels of MEL does not constitute a health risk for consumers.     

我国8省份市售海产品及其制品中甲醛含量的调查分析

目的了解我国市售海产品及其制品中甲醛的含量。方法采集全国8个省(市、自治区)的农贸市场和大中小超市销售的6种常见海产品及其制品(冰鲜鱿鱼、水发鱿鱼、鱿鱼丝、海虾、虾仁和烤鱼片),共计530份,采用高效液相色谱(HPLC)法检测甲醛含量。结果 6种海产品及其制品均检出甲醛,总检出率为40.57%,含量范围为0.00~950.00 mg/kg。其甲醛平均含量由高到低分别为鱿鱼丝、水发鱿鱼、烤鱼片、冰鲜鱿鱼、虾仁和海虾,检出率分别为52.78%、57.45%、42.50%、49.61%、23.08%和12.24%。结论不同种类海产品及制品中甲醛含量不同且差别较大,可能与其本底水平、甲醛自身变化规律或者后期违法添加有关。总体来看,甲醛含量100 mg/kg,尤其是超过200 mg/kg的产品,应引起关注。     

电聚合制备三聚氰胺分子印迹QCM传感器薄膜及其表征研究

通过研究得出,在聚合电压U为0~1.6V、聚合段数为22、模板三聚氰胺(MEL)浓度为4mmol/L、单体甲基丙烯酸(MAA)浓度为10mmol/L、成膜剂邻苯二胺(o-PD)浓度为18mmol/L条件下,以pH 8.0的BR缓冲液作为溶剂和电解液,用电聚合方法,直接在石英晶体微天平(QCM)传感器电极上修饰的分子印迹薄膜,其对目标分子MEL具有良好的频率表征效果,频移值为59Hz.通过相同3个修饰电极的频率表征变化来看,电极对目标分子的识别表征极不稳定.这与手动进样方式、环境较大噪声和电极本身差异密切相关,难以建立对目标分子的标准曲线(r=0.966)实现准确定量分析.     

Determination of melamine in milk and dairy products by high performance liquid chromatography

A simple, precise, accurate, and validated reverse-phase HPLC method was developed for the determination of melamine in milk (pasteurized and UHT milk) and dairy products (powdered infant formula, fruit yogurt, soft cheese, and milk powder). Following extraction with acetonitrile:water (50:50, vol/vol), samples were purified by filter (0.45 μm), separated on a Nucleosil C8 column (4.6 mm × 250 mm, 3 μm) with acetonitrile:10 mmol/L sodium L-octane sulfonate (pH 3.1; 15:85, vol/vol) as mobile phase at a flow rate of 1 mL/min, and determined by a photodiode array detector. A linear calibration curve was obtained in the concentration range from 0.05 to 5 mg/kg. Milk and dairy products were fortified with melamine at 4 levels producing average recovery yields of 95 to 109%. The limits of detection and quantification of melamine were 35 to 110 and 105 to 340 μg/kg, respectively. The method was then used to analyze 300 samples of milk and dairy products purchased from major retailers in Turkey. Melamine was not found in infant formulas and pasteurized UHT milk, whereas 2% of cheese, 8% of milk powder, and 44% of yogurt samples contained melamine at the 121, 694±146, and 294±98 μg/kg levels, respectively. These findings were below the limits set by the Codex Alimentarius Commission and European Union legislation. This is the first study to confirm the existence of melamine in milk and dairy products in Turkey. Consumption of foods containing these low levels of melamine does not constitute a health risk for consumers.