Preparation of iron and nitrogen co-doped carbon material Fe/N-CCM-T for oxygen reduction reaction

In this paper, iron and nitrogen co-doped carbon material with nanotube structure (Fe/N-C_CM-T) was synthesized by pyrolyzing a mixture of Fe salt, chitosan and melamine and displayed high electrocatalytic performance for oxygen reduction reaction (ORR). The structure of the Fe/N-C_CM-T was characterized and their ORR performance in alkaline media was investigated by linear sweep voltammetry, cyclic voltammetry and chronoamperometry. Fe/N-C_CM-T displayed better ORR performance than other carbon materials like Fe/N-C_C-800. The Fe/N-C_CM-800 with a large surface area (302.5 m²/g) especially exhibited the best ORR electrocatalytic performance among the prepared carbon materials, which was also proved by its similar Tafel slope (76 mV decade^?1) to Pt/C catalyst (74 mV decade^?1). Fe/N-C_CM-800 showed similar ORR activity as commercial Pt/C catalyst, but superior tolerance to methanol and stability. Such high ORR performance of the Fe/N-C_CM-T can be attributed to its nanotube structure, high specific surface area (SSA), high graphitic-N and pyridinic-N contents.     

高效液相色谱法测定乳与乳制品中的三聚氰胺

目的建立乳与乳制品中三聚氰胺的测定方法。方法样品用0.1 mol/L的盐酸提取,再用60 g/L的磺基水杨酸沉淀蛋白。缓冲液为10 mmol/L柠檬酸与10 mmol/L辛烷磺酸钠混合溶液,以缓冲液 乙腈(85 15,体积比)为流动相,使用Kromasil KR100-5C8柱,配备有二极管阵列检测器的高效液相色谱仪在200~400 nm范围内对待测组分进行分离和测定。结果样品中三聚氰胺的添加回收率在80%~105%之间,相对标准偏差(RSD,n=6)小于5.24%,方法的定量限为1.0 mg/kg。结论该方法快速、准确,操作简便,能够满足乳与乳制品中三聚氰胺的分析要求。     

三聚氰胺检测技术研究进展

三聚氰胺是一种用途广泛的化工原料,若被人或动物长期摄人会造成生殖、泌尿系统的损害,尤其会对婴幼儿的身体造成严重伤害。本文介绍了三聚氰胺的性质,重点论述了高效液相色谱法、气相色谱-质谱联用法、液相色谱-质谱法等三聚氰胺检测技术的研究进展。     

阳离子交换色谱-紫外检测法检测奶粉中的三聚氰胺

本文建立一种采用去离子水进行溶解和提取,乙酸作为蛋白沉淀剂对奶粉样品进行前处理,采用淋洗液自动发生装置在线产生甲烷磺酸进行梯度淋洗,紫外法进行检测,检测奶粉样品中三聚氰胺的方法。本文亦比较该方法与液相色谱-串联四极杆质谱联用技术的结果,对比结果令人满意。该方法具备结果准确,选择性好,操作简单,耗材使用寿命长,对环境友好等特点。实际样品检测结果和加标回收结果令人满意。     

Milkoscan FT 120对原料乳中硫氰酸钠快速分析

为了建立一种快速测定原料乳中掺假物质的方法,利用红外光谱,采用主成分分析(PCA)回归方法,以本地区具有代表性原料乳样品集为基础建立标准数据模型。在原料乳中加入硫氰酸钠模拟牛奶掺假。通过总结原料乳成分数据的变化规律及调整控制因素以达到预判原料乳掺假和确定掺假物质检出限的目的。该方法具有快速、准确的特点。     

Determination of melamine in dairy products by HILIC-UV with NH2 column

A HPLC method using a NH₂ column for determination of melamine was reported, with acetonitrile-H₃PO₄ (15 mmol L⁻¹, pH = 6.5) (V/V = 88:12) as mobile phase and UV detection at 215 nm. The tested parameters included mobile phase composition, percentage of organic solvent, and buffer concentration, and pH value and UV detection wavelength. Good linearity was observed within the concentration range of 0.005-32 mg L⁻¹ (n = 7, r = 0.9997), the detection limit was 0.003 mg L⁻¹ (S/N = 3). The chromatography mode was considered to be hydrophilic interaction chromatography (HILIC). The method was successfully applied to determine melamine in several dairy products, with acetonitrile as extract solvent of melamine and also as protein precipitant. The spike recovery of melamine was within 73-96%.     

三聚氰胺装置干燥分离系统的操作分析

对干燥系统操作条件的确定、设备选择及工艺设计原理进行了分析,论述了经常出现的问题及其原因所在,并提出解决方案,使干燥系统的操作尽可能稳定.     

浅析国内外对于"仿瓷餐具"技术要求的差异

介绍了我国标准和欧盟、美国和日本食品接触材料法规对于密胺、脲醛模塑制品的技术要求,对其主要差异进行了对比分析.     

湿法磷酸复盐复分解生产精细磷酸钾盐反应动力学研究

研究了三聚氰胺结晶法净化湿法磷酸生产精细磷酸钾盐过程中磷酸三聚氰胺与氯化钾反应的动力学特征,分析了影响反应速度的主要因素,确定了过程的控制步骤,并得到了反应过程的动力学方程。     

GC-MS法测定饲料中的三聚氰胺及类似有机物

建立了一种用于饲料中三聚氰胺类有机物含量的气相色谱——质谱联用检测方法。通过甲醇/水/三乙胺混合液提取饲料中的三聚氰胺类有机物,氮气吹干、硅烷化衍生,再由气相色谱——质谱联用仪检测,苯代三聚氰胺内标法定量。该方法在饲料中三聚氰胺类有机物的加标回收率在82.0%-107.0%之间,相对标准偏差(RSD)不大于10.5%,在0.05mg/L-50.0mg/L范围内呈现良好的线性关系,灵敏度高,最低检测限达到10μg/kg;选择性好,能有效消除复杂基体干扰。可作为常见样品中三聚氰胺类有机物含量检测的确证方法。