HPLC法测定肉制品中苯甲酸、山梨酸、脱氢乙酸

建立用高效液相色谱二极管阵列检测器测定肉制品中苯甲酸、山梨酸、脱氢乙酸的方法。肉制品中苯甲酸、山梨酸、脱氢乙酸经水蒸气蒸馏,用高效液相色谱二极管阵列检测器测定,外标峰面积法定量。苯甲酸、山梨酸、脱氢乙酸在2~100 mg/kg范围内呈良好的线性关系,3个水平(2.0、20.0、80.0 mg/kg)添加苯甲酸、山梨酸、脱氢乙酸的回收率为84.3%~91.1%,相对标准偏差(RSD)为1.04%~2.06%,检出限为2.0mg/kg。此方法具有简单、快速、准确等优点,适用于脂肪含量较高的肉制品中苯甲酸、山梨酸、脱氢乙酸的测定。     

HPLC法测定肉制品中苯甲酸、山梨酸、脱氢乙酸

建立用高效液相色谱二极管阵列检测器测定肉制品中苯甲酸、山梨酸、脱氢乙酸的方法。肉制品中苯甲酸、山梨酸、脱氢乙酸经水蒸气蒸馏,用高效液相色谱二极管阵列检测器测定,外标峰面积法定量。苯甲酸、山梨酸、脱氢乙酸在2~100 mg/kg范围内呈良好的线性关系,3个水平(2.0、20.0、80.0 mg/kg)添加苯甲酸、山梨酸、脱氢乙酸的回收率为84.3%~91.1%,相对标准偏差(RSD)为1.04%~2.06%,检出限为2.0mg/kg。此方法具有简单、快速、准确等优点,适用于脂肪含量较高的肉制品中苯甲酸、山梨酸、脱氢乙酸的测定。     

高效液相色谱法同时测定面包糕点中苯甲酸(钠)、山梨酸(钾)、安赛蜜、糖精钠和脱氢乙酸(钠)的含量

面包糕点中的苯甲酸(钠)、山梨酸(钾)和脱氢乙酸(钠)、安赛蜜和糖精钠经溶解、离心、过滤后,采用高效液相色谱法同时测定,样品标准加入回收率分别为94.2%～101.6%、93.6%～102.7%、90.8%～99.1%、92.5%～102,3%、91.1%～99.5%,RSD分别为1.8%～10.3%、1.5%～11.2%、1.2～9.5%、1.2～6.8%、1.7%～10.9%.     

高效液相色谱法同时检测酱腌菜中的苯甲酸、山梨酸、脱氢乙酸、安赛蜜和糖精钠含量

酱腌菜经超声提取、离心沉淀、过滤后,采用高效液相色谱法同时检测苯甲酸、山梨酸、脱氢乙酸、安赛蜜和糖精钠的含量;谱图分离效果良好,检出限浓度低,精密度高,标准曲线范围广、线性好,加标回收率高,符合色谱检测的要求,提高了工作效率。     

液相色谱-串联质谱法测定食品中的4种添加剂

建立了食品中安赛蜜、糖精钠、苯甲酸和山梨酸同时检测的液相色谱-串联质谱(LC-MS/MS)检测分析方法。样品经20%甲醇溶液提取,加亚铁氰化钾溶液和乙酸锌溶液沉淀蛋白,加正己烷萃取分离脂肪,以电喷雾电离负离子(ESI-)、多反应检测模式(MRM)进行检测,外标法定量。山梨酸定量下限为0.20 mg/kg,安赛蜜、糖精钠和苯甲酸定量下限均为0.05 mg/kg。方法回收率为84.5%~101.0%,相对标准偏差(RSD)3.0%~9.6%。     

高效液相色谱法测定食品中安赛蜜、山梨酸、苯甲酸、糖精钠、脱氢乙酸的过程优化研究

通过在流动相中引入甲酸并调控梯度程序里流动相中有机相的比例,优化了应用于食品中安赛蜜、苯甲酸、山梨酸、糖精钠及脱氢乙酸等甜味剂和防腐剂检测的高效液相色谱测定法。结果表明,测定方法的优化有效地避免了组分间的相互干扰,实现了五种添加剂的高效、快捷和同时测量。     

食品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸同时检测方法

建立了高效液相色谱法同时测定食品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸的检测方法。食品中的5种添加剂经溶解、提取、定容、过滤后上机测定。方法:采用C_(18)柱;流动相:乙酸铵(0.02 mol/L)︰甲醇=95︰5;柱温:30℃;波长:230 nm;检测器:二极管阵列。样品标准加入回收率为98.2%~100.1%,相对标准偏差(RSD)为0.9%~3.0%。方法简便准确,可用于一般食品样品的常规检测。     

比值导数光谱法同时测定食品中山梨酸、苯甲酸和糖精钠的含量

利用比值导数光谱法,不经分离同时测定食品中山梨酸、苯甲酸和糖精钠的含量.确定山梨酸、苯甲酸和糖精钠的测定波长分别为237.5、208.5和204.5 nm,测定线性范围分别为0.50～4.50、1.60～14.40和10.00～90.00 μg/mL,线性相关系数分别为0.999 7、0.999 6和0.998 6,测定的相对标准偏差＜3.3％(n=11),加标回收率为96.4％～104.1％.     

高效液相色谱法测定食品中苯甲酸、山梨酸和糖精钠

建立了同时测定苯甲酸、山梨酸和糖精钠3种食品添加剂的高效液相色谱法。在流动相为甲醇+0.02 mol/L乙酸铵溶液流动相体系中，通过引入冰醋酸来改变缓冲溶液的酸碱度、改变梯度洗脱比例，进而改善色谱峰分离的选择性。以ANPU-WP C18(250×4.6 mm,5μm)为分离柱，在230 nm测定波长下进行检测，设置流速1.0 m L/min，进样量20μL，甲醇：0.02 mmol/L乙酸铵溶液(pH=6.5)(10∶90,v∶v)为流动相，同时对缓冲溶液的pH以及流动相梯度洗脱程序进行优化。在优化后的最佳色谱条件下，苯甲酸、山梨酸和糖精钠在0.2～20.0μg/mL范围内的质量浓度与对应的峰面积呈良好的线性关系，R2在0.99991～0.99998的范围内，检出限为0.005 g/kg水平，定量限为0.02 g/kg，样品的平均加标回收率为96.9%～98.1%，相对标准偏差为2.2%～2.8%。建立的高效液相色谱同时测定苯甲酸、山梨酸和糖精钠的方法灵敏度较高，操作简便，能够在较短时间内完成检测。适用于食品样品中苯甲酸、山梨酸和糖精钠的定量检测。     

蜂蜜酒中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸含量测定

建立高效液相色谱法同时测定蜂蜜酒中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸5种食品添加剂的检测方法。采用高效液相色谱法,Tech mate ST PAK C18 ES(4.6 mm×150 mm;5μm)色谱柱进行分离,流动相为甲醇:乙酸铵溶液(0.02 mol/L)(体积比5∶95),流速1.0 m L/min,检测波长230 nm。各物质在0.20~20μg/m L范围内呈良好的线性关系。相关系数为0.99951~0.99998,精密度良好,加标回收率92.0%~102.0%,相对标准偏差(RSD)在1.05%~2.58%。该方法准确度较高,重现性好,操作简便,能在20 min内将5种添加剂完全分离,适合蜂蜜酒中添加剂的日常检测。     

碳阳极的氧化性能研究

采用效失重法系统地测定了铝用碳阳极添加硼酸、三氟化铝后在空气中的氧化反应速度常数,结果表明硼酸、三氯化铝的含量在0．5％～2．0％范围内,碳阳极的抗氧化能力有所增强．     

Studies in the process optimization and characterization of low formaldehyde emission urea‐formaldehyde resin by response surface methodology

Stringent control of formaldehyde emission standards the world over has intensified research and development effort to explore several paths for reducing formaldehyde release. A new generation of low odour resins is currently being developed and some resin manufacturers are now programming formaldehyde and urea additions at two or more stages in the overall reaction. This article reports on the studies conducted on a four‐stage condensation process consisting of the first stage involving a high acid environment followed by an alkaline condensation, a condensation under a pH 6, and finally neutralization to pH 7. A programmed variation consisting of changing “the number of additions” and “the duration between additions” of urea to formaldehyde was considered as an effective method to control the molecular weight, molecular weight distribution, and the oligomeric structures. Response surface methodology was employed to optimize the above conditions to produce particle boards with minimum formaldehyde emission and maximum internal bond strength. The studies showed that sequential addition of urea [“the duration between additions” and the “number of additions”] improved the internal bond strength and reduced formaldehyde emission of the particleboards. Detailed resin characterization in terms of the number and weight average molecular weights, molecular weight distribution, polydispersity, percentages of reactive moieties, and interlinking units present in the oligomer could be stipulated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2709–2719, 2007     

Use of functionalized boehmite nanoparticles to improve the hardness and tribological properties of polyurethane films

Plate-like boehmite nanoparticles (BH) produced from aluminum hydroxide by hydrothermal process were functionalized in one step with two different diisocyanates. The amount of free isocyanates that were available for polymerization reaction was determined to be higher in functionalization with the aromatic diisocyanate (diphenylmethane-4,4′-di-isocyanate – MDI). In composite film production MDI functionalized BH (MDI-BH) was used. Polyurethane based nanocomposite films were produced through polymerization of non-functionalized and MDI-BH with two different polyester-polyols that were synthesized by the esterification of 1,4 butanediol with either adipic acid or phthalic anhydride. It was impossible to form films suitable for hardness and tribological tests with non-functionalized BH. Up to 1 wt% MDI-BH additions were effective in increasing the hardness and scratch resistance of films. The increases in abrasion resistance were more significant and followed the increasing trend for MDI-BH additions even up to 5 wt%. The highest increase, which was 400% with respect to the unmodified resin was observed with adipic acid based polyols and this result was obtained at MDI-BH content of 3 wt%.     

硫酸催化葡萄糖制备乙酰丙酸的过程强化

采用高温下稀硫酸催化葡萄糖的方法制备乙酰丙酸。考察了反应温度、硫酸浓度和搅拌转速对葡萄糖转化率和乙酰丙酸收率的影响,并优化确定了最优反应条件。进一步,分析了最优反应条件下不同葡萄糖初始浓度对乙酰丙酸收率的影响。为了提高高浓度葡萄糖底物反应时乙酰丙酸的收率,采用两种不同的补料方法进行实验：分3次,依次加入7%、6%与5%的葡萄糖;每次均添加3%的葡萄糖,共6次。结果表明：①提高硫酸浓度、反应温度和搅拌速度有利于加快葡萄糖转化和乙酰丙酸生成;②高浓度葡萄糖底物不利于乙酰丙酸的生成,且浓度越高,乙酰丙酸收率越低;③通过补料操作,可使乙酰丙酸收率由 44.3%提高至65.9%。     

Production and Thermophysical Properties of BeO Ceramics with the Addition of Nanocrystalline Titanium Dioxide

Refractories and Industrial Ceramics - A slip casting method was used to produce samples of BeO-based composite ceramics with additions of 5 – 30 wt.% of nanocrystalline TiO2 powder. It was...     

Electrophoretic deposition of yttria-stabilised zirconia powder from aqueous suspensions for fabricating ceramics with channel-like pores

Electrophoretic deposition with simultaneous gas bubble formation by electrolysis can be used for producing ceramic green bodies, typically few millimetres in thickness, with unidirectionally aligned channel-like pores. The method is successfully applied to yttria-stabilised zirconia. Two types of aqueous suspension compositions are investigated. Suspensions with acetic acid additions are particularly suitable for forming green bodies with fine pore channels. Only small amounts of acetic acid, promoting the gas evolution, are needed for this purpose. Dissolution of yttria in the acidic range has to be considered, but the required low acid concentrations do not measurably affect the yttrium content of the deposits. Yttria dissolution can be minimised by a suspension composition containing an anionic polyelectrolyte and ammonia instead of acetic acid. The ammonia concentration influences the size of the tubular pores of the deposits formed under constant-voltage conditions. Using structured deposition electrodes, the regularity of the pore arrangement can be enhanced.     

THE EFFECT OF ADDITIONS OF CaO AND MgO ON ENAMEL GLASSES1

An attempt to determine quantitatively the effects of various additions of CaO and MgO to a simple soda-lead-silica glass upon the physical properties of the glass and the working properties of the Same when used as an enamel was made in this investigation. The tests on glass consisted of thermal expansion, softening range, compressive strength, modulus of elasticity, solubility in acid and alkali, and index of refraction.     

可纺性锆溶胶的制备

以氧氯化锆为原料,双氧水为水解促进剂,醋酸为络合剂和稳定剂,采用sol-gel法制备了具有可纺性的氧化锆溶胶。通过测定溶胶黏度和折光指数,对比分析了双氧水和醋酸加入量对溶胶稳定性和可纺性的影响。结果表明:当n(H2O2)∶n(ZOC)=3,n(HA)∶n(ZOC)=0.5~1时,溶胶的稳定性和可纺性最好;制备的溶胶中氧化锆质量分数达到35%以上;醋酸和水解产物发生络合,提高了溶胶的稳定性和可纺性。     

2-Fatty Acrylic Acids: New Highly Derivatizable Lipophilic Platform Molecules

This paper reports the incorporation of an alpha-methylene unit into fatty acid skeletons. Since the new olefin is conjugated with the carboxylate, it is susceptible to 1,4-(Michael) additions. We have used multifunctional thiols and amines for additions at the methylene. The resulting products possess clusters of functionality grouped at one end of a hydrophobic tail. These structural patterns will be of use in the design of new types of bio-based surfactants and polymers. One particularly promising pattern of functionality that can be obtained through oxidation and reduction chemistry is a 2-fatty 1,2,3-propanetriol, or a lipophilized glycerol moiety.     

Methanesulfonic acid-catalyzed additions IV. Additions to methyl linoleate

Varied aromatic compounds including phenol,o-chlorophenol, 2-naphthol, resorcinol, methyl salicylate, anisole, phenetole,p-toluenethiol,p-chlorobenzenethiol and 2-napthalenethiol were added to methyl linoleate. Using methanesulfonic acid as a solvent-catalyst the additions took place as readily as to oleic acid in previous experiments. The recovery of mono-adducts, however, was complicated by the presence of di-adducts and presumably polymeric material. As observed in the earlier oleic acid studies, evidence for the formation of ether intermediates was obtained. The only identified products from arylthiol additions were thioethers. Presented at the AOCS Meeting in Minneapolis, 1963. A laboratory of the E. Utiliz. Res. & Dev. Div., ARS, USDA.