Evaluation of the results from an inter-laboratory comparison study of the determination of acrylamide in crispbread and butter cookies

Analytical methods currently employed for determination of acrylamide (AA) in two carbohydrate-rich food samples, crispbread and butter cookies, obtained commercially, and native and spiked bread extract samples have been evaluated in a collaborative study. The objective of the study was to obtain information about the performance of the participating laboratories when analysing samples with an AA content close to the limit of quantification (LOQ) and at a higher AA level, and to investigate the influence of sample-preparation procedures on the results of the analysis. For this purpose an aqueous native extract of white bread crumb, a fortified extract, and AA standard solutions, the analyte content of which were not disclosed to the participants, were included in the study. A total of 62 laboratories, applying seven different measurement techniques and a broad spectrum of analyte extraction and sample-preparation procedures reported their analytical results. Because the measurement data were not normally distributed, they were evaluated by application of robust statistics. The relative performance of the laboratories was highlighted by calculation of z-scores. For the crispbread sample, especially, a large percentage of the calculated z-scores were outside the satisfactory range. From their distribution it became obvious that one of the analytical techniques might be biased, if not applied correctly. Consequently, the impact of the applied methods was examined in more detail. Information about the analytical technique, extraction solvent, quantity weighed, calibration method, clean-up, and the experience of the participating laboratories were extracted from the analytical protocols and transcribed into a data matrix which was evaluated by multifactor analysis of variance. The applied measurement technique seems to have a statistically significant influence on the analytical results.     

亚甲蓝-三乙酰基丙酮合锰(Ⅲ)配合物体系光敏化引发丙酰胺聚合反应研究

<正> 染料和三乙酰基丙酮合锰(Ⅲ)配合物(Mn(AA)_3)体系,作为聚合过程的引发物质而用于非银盐成像工艺中.Chaberek等在水溶液中研究了硫堇-二乙酰基丙酮合铜(Ⅱ)和铝(Ⅲ)体系,认为首先是金属配合物水解生成的配体发生酮-醇互交,而配体的烯醇式阴离子是引发聚合的活性物质.我们曾报道了硫堇-Mn(AA)_3体系在醇溶液中光敏化引发丙烯酰胺聚合的研究,发现在醇溶液中,敏化引发聚合的活性物质,显然不同于水溶液中的情况.本文研究了亚甲蓝-Mn(AA)_3体系在醇溶液中敏化引发丙烯酰胺聚合,表明它是比硫堇-Mn(AA)_3更为有效的光敏化引发体系.     

丙烯酰胺与玉米淀粉接枝共聚物的合成及其吸水性能研究

本文以硝酸铵为引发剂N，N-亚甲基双丙烯酰胺为交联剂，将丙烯酸胺与玉米淀粉接枝共聚合成了吸水剂。实验表明，当脱水葡萄糖单元与丙烯酰胺摩尔比为1：4，交联度为0．2％时，其吸水率最高可达18g／g，其对1％食盐水的吸收率为其吸水率的90％左右。然后，将以上吸水树脂以10％NaOH于60℃水解3h，制备了另一种吸水剂，吸水率约提高了16倍，但其吸1%食盐水的能力只有其吸水能力的10％左右。     

丙烯酰胺在聚乙二醇水溶液中的聚合动力学

用改进溴法对丙烯酰胺 (AM)在聚乙二醇 (PEG)水溶液中聚合动力学进行研究 .在单一和氧化还原引发体系中分别考察了引发剂、单体和PEG用量、不同HLB值乳化剂以及聚合温度等因素对动力学的影响 .得到AM聚合速率与过硫酸铵 (APS)浓度的 0 91次方成正比 ;单一APS和APS 三乙醇胺 (TEA)氧化还原引发体系中的AM聚合表观活化能分别为 96 1和 4 2 3kJ mol.     

A study on the production of PMMA/P(MMA-AAm) composite polymer particles and the effect of acrylamide content on the adsorption behaviors of biomolecules

 A series of poly(methyl methacrylate)/poly(methyl methacrylate-acrylamide) composite polymer particles was prepared with varying proportions of acrylamide in the copolymer shell layer. Adsorption behaviors of some biomolecules and specific activity of adsorbed trypsin were studied. The hydrophobic interaction between the composite polymer particle surfaces and biomolecules decreased with increasing acrylamide content. Received: 7 February 2001 Accepted: 16 May 2001     

Environmentally friendly method for the determination of acrylamide and trimethylolpropane in paper packaging materials by liquid chromatography with tandem mass spectrometry

A simple, rapid, and environmentally friendly method was developed for the determination of acrylamide and trimethylolpropane in paper packaging materials. No organic solvent was used and the matrix effect was investigated. The extract was directly analyzed by liquid chromatography with tandem mass chromatography for quantification and confirmation. The chromatographic separations were performed on a ZORBAX HILIC Plus (2.1 mm × 150 mm, 3μm; Agilent, USA) column with only one mobile phase (100% water). Calibration curves for acrylamide and trimethylopropane were achieved with concentrations ranging from 0.4 to 20 mg/kg and the corresponding r² values were 0.998 and 0.999, respectively. The recoveries were >85% with relative standard deviations <10%. The validated method was applied to the analysis of 50 real samples, and positive results were obtained for 30 samples. The result indicated that trimethylolpropane is associated with inks and printing activity and acrylamide is widely used as a papermaking additive in many paper packages. The concentrations of acrylamide and trimethylolpropane ranged from 0.41 to 7.5 and 0.50 to 8.8 mg/kg, respectively. The results of this study revealed that this method could be used accurately and precisely.     

Morphological investigation of styrene and acrylamide polymer microspheres prepared by dispersion copolymerization

 The morphology of the styrene and acrylamide copolymer microspheres prepared by dispersion copolymerization in an ethanol/water medium was investigated. The effects of the styrene/acrylamide ratio, ethanol/water ratio and stabilizer concentration on the particle size and size distribution were studied. It was found that the initial solubility parameter of the system was the key factor in the process. The comonomer acrylamide also played an important role in the particle size and size distribution in the presence of cross-linking agent (divinylbenzene). Received: 29 October 1999 Accepted in revised form: 29 November 1999     

Direct determination of acrylamide in food by gas chromatography-high-resolution time-of-flight mass spectrometry

Simple and rapid gas chromatographic (GC) method employing a high-resolution time-of-flight mass analyzer that enables direct analysis (no derivatization) of acrylamide in various heat-processed foodstuffs has been developed and validated. Co-isolation of acrylamide precursors such as sugars and asparagine, constituting the risk of results overestimation due to additional formation of analyte in hot GC injector, is avoided by the extraction with n-propanol followed by solvent exchange to acetonitrile (MeCN). Introduction of a novel purification strategy, dispersive solid phase extraction, based on addition of primary-secondary amine (PSA) sorbent into deffated extract in MeCN, provides a significant reduction of some abundant matrix co-extracts (mainly free fatty acids). Isotope dilution technique (d₃-acrylamide as an internal standard) is employed for compensation of potential target analyte losses and/or matrix-inducted chromatographic response enhancement. Limits of quantifications (LOQs) ranged between 15 and 40 μg kg⁻¹ and recoveries were between 97 and 108% depending on the examined food matrix. The repeatability of measurements (expressed as relative standard deviation, R.S.D.) was as low as 1.9% for potato crisps containing acrylamide at a level of 1 mg kg⁻¹. Slightly higher values (R.S.D. < 4.0%) were achieved for breakfast cereals and crisp bread with approximately 10 times lower content of this processing contaminant. Trueness of results generated by this new method was demonstrated via FAPAS^® (Food Analysis Performance Assessment Scheme) interlaboratory proficiency tests.     

PVA改性PAMPS-PAM超高力学性能双网络水凝胶的制备

采用紫外光引发聚合制备了聚乙烯醇(PVA)改性的聚(2-丙烯酰胺基-2-甲基丙磺酸)-聚丙烯酰胺(PAMPS-PAM)双网络(DN)水凝胶.测定并比较了PVA改性前后PAMPS-PAM双网络水凝胶的溶胀动力学;通过扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PVA改性前后PAMPS-PAM双网络水凝胶的压缩及拉伸性能.结果表明,经PVA改性后的PAMPS-PAM双网络水凝胶有较高的溶胀比;0.82%PVA用量的PAMPS-PAM双网络水凝胶在90%压缩形变率下仍保持完整、最大拉伸应力达到0.5 MPa,大幅提高PAMPS-PAM双网络水凝胶的力学性能.     

聚乙二醇对PAMPS/PAM双网络水凝胶性能的影响

采用紫外光引发聚合制备了聚乙二醇(PEG)改性的聚(2-丙烯酰胺-2-甲基丙磺酸)/聚丙烯酰胺(PAMPS/PAM)双网络水凝胶.测定并比较了PEG改性前后双网络水凝胶的溶胀动力学以及单网络水凝胶中丙烯酰胺(AM)的吸收量;用扫描电子显微镜(SEM)观察了单网络水凝胶的结构;测定PEG改性前后双网络水凝胶的压缩及拉伸性能.结果表明,经PEG改性后的双网络水凝胶有较高的溶胀比;改性后单网络水凝胶更易吸收AM;改性后双网络水凝胶压缩形变率达到90%以上、拉伸形变率是未改性双网络水凝胶的2倍.