电化学方法检测生乳中氯离子

通过循环伏安法探讨银电极在氯离子测试液中电化学反应机理,以此为基础建立一种快速检测生乳中氯离子的电化学方法。结果表明,银电极在氯离子测试液中正向扫描时,银失去电子氧化成银离子,然后与溶液中的氯离子结合生成氯化银沉淀;而负向扫描时,氯化银还原为银。在生乳中掺盐后,用10%的三氯乙酸溶解生乳样品,通过离心除去蛋白质和脂肪,加入1 mol/L Na₂SO₄,得到提取液,经检测提取液可知,银电极产生一对氧化还原峰,且峰电流与生乳中氯离子浓度在0.03~0.21 mol/L范围内呈线性关系。此方法检出限为0.001 mol/L,回收率和相对标准偏差分别在93.3%~113.7%和2.33%~4.89%,与GB5009.44-2016银量法比较无明显差异。此法样品预处理简单、测定速度快、成本低,能较好的运用于实际生产线。     

比浊法测定啤酒中的氯离子

采用氯化银比浊法直接测定啤酒中微量的氯离子,研究了测量波长、稳定时间、酸度、稳定剂对结果的影响.最佳实验条件为:检测波长440nm,线性范围0～6μg/mL,方法检测限为0.0321μg/mL.该法测定啤酒中不同浓度微量氯离子的相对标准偏差小于0.5%,加标回收率为97.7%101.3%.结果表明,该法准确、快速、简便,其它的常见离子无干扰,适用于啤酒厂的日常检测.     

浓度直读法快速测定酱菜中的氯离子

建立一种简便快速测定食品中氯离子的新型分析方法,用超声波辅助技术处理酱菜样品,用氯离子选择性电极浓度直读法测定。结果表明：在总离子强度调节缓冲剂pH5.50、柠檬酸三钠添加量0.20g/L、硝酸钾浓度0.80mol/L时,样品测定的相对标准偏差为1.9%～2.9%(n＝5)、加标回收率为94.1%～105.6%、氯离子的最低检出限为1.20×10-5mol/L,与国标法对照测定,F检验和t检验表明两种方法无显著性差异。该法成本低廉、简便快速,利于普及推广,用于样品的现场快速分析,结果满意。     

流动注射——渗析膜分离分光光度法测定牛奶中的氯离子

<正> 牛奶中氯离子含量的测定是牛奶质量化验项目之一。患有乳腺炎的奶牛产的牛奶中氯离子浓度明显地高于正常的奶牛。测定牛奶中氯离子含量的方法多采用硝酸银滴定法。国内有人报道过使用离子选择电极测定牛奶中的氯离子。流动注射分析是近年来发展起来的自动化溶液分析方法,其效率     

不锈钢抛光溶液的分析

针对钢铁类产品的电解抛光溶液滴定终点难以确定,实测与理论计算不符,及加入掩蔽剂试验复杂且结果不准确等问题,配制不锈钢抛光溶液进行分析测定.给出不锈钢抛光溶液的工艺参数:磷酸850～1 000g/L,硫酸250～350g/L,铬酐50～60g/L.配制磷酸质量浓度862g/L,硫酸质量浓度262g/L,铬酐质量浓度60g...     

大豆蛋白的流变特性及其粘度的数学模型研究

本文利用L-90型流变仪对大豆蛋白溶液的流变特性及其粘度的变化规律进行测定和研究。结果表明大豆蛋白溶液在低浓度下( <6% )表现为牛顿流体,在高浓度( >6% )下表现为非牛顿流体。温度对大豆蛋白溶液流变特性的影响比较复杂。通过DPS数据处理软件对实验数据进行非线性回归分析,建立大豆蛋白溶液的浓度和粘度的数学模型以及温度对大豆蛋白溶液粘度影响的数学模型。     

离子色谱法测定糖蜜样品中氯离子、硫酸根和硝酸根含量

目的 建立离子色谱法测定糖蜜样品中氯离子、硫酸根离子和硝酸根离子含量的方法。方法 使用去离子水对样品进行准确定容的稀释,之后对稀释后样品溶液过IC Na柱净化后上机测定样品的氯离子、硫酸根和硝酸根含量。使用Ion Pac _^TMAS19(4 mm × 50 mm)为分析柱,KOH淋洗液的浓度为35.0 mmol/L,流速1.0 mL/min,进样体积50 μL,外标法定量。结果 氯离子、硫酸根、和硝酸根标准溶液在0.05 ~ 2.0 mg/L浓度范围内呈现良好线性关系,R_²大于0.99,检出限0.02 ~0.1mg/L。在1.0 ~ 4.0 mg/L添加浓度上,回收率范围为85.4%~102.6%,相对标准偏差3.63%~10.64%。结论 该方法操作简便且快速准确,能够有效测定糖蜜中的氯离子、硫酸根和硝酸根含量,满足糖蜜中氯离子、硫酸根和硝酸根的检测需求以及样品的分析测定。     

氯离子选择电极法测定肉品中的食盐含量

为找到一种可以快速准确测定食盐含量的方法,本文对溶液酸度、离子强度及干扰离子的影响进行了研究,探索了氯离子选择电极法适宜的测定条件.结果表明:在离子强度为0.1,含0.2mol/L KNO3的HAc-NaAc(pH5.0)溶液中NH+4对测定结果没有影响,S2-干扰严重,加入ZnAc2可以消除.该方法的线性范围为10-4～100mol/L,检出限为0.0108mmol/L,回收率为96.86%～103.10%,RSD为0.51%(n=10).     

Ag-H柱去除氯离子提高包装水中溴酸盐的检测精度

采用Ag-H柱去除饮用水中高浓度的氯离子,离子色谱抑制型电导检测器检测包装饮用水中微量澳酸盐.Ag-H柱除氯效果可达99%,当澳酸盐的浓度在2.0～50.Oμg/ L范围内具有良好的线性关系,相关系数0.9999,定量检出限为2.Oμg/L,样品加标回收率大于94%,该方法适用于含氯离子浓度较高的包装饮用水中微量澳酸盐含量的测定.     

龙须菜多糖的流变性研究

通过测定不同条件下龙须菜多糖的黏度变化,对龙须菜多糖的流变性进行研究.结果表明:龙须菜多糖溶液具有良好的流变性能.龙须菜多糖溶液为"非牛顿流体";溶液的黏度随着浓度的增加而增加,当溶液浓度达到0.6%时成凝胶;在酸、碱溶液中非常稳定;具有良好的耐盐稳定性和抗降解性能;冻融变化使龙须菜多糖的黏度有所增加;苯甲酸钠、微波和超声波处理等对龙须菜多糖溶液的黏度有一定的影响.     

A new route to synthesis silver nanoparticles on polyamide fabric using stannous chloride

Here, a one step in situ synthesis of silver nanoparticles on polyamide fabric was successfully performed using stannous chloride (SnCl₂) as a reducing and cetyltrimethylammonium bromide as a stabilizing agent. The treated fabrics were characterized with X-ray diffraction, field emission scanning electron microscope, and energy dispersion spectrum. The antibacterial activities of the fabrics against two diverse bacteria were examined and the fabrics color measured with reflectance spectrophotometer. The results revealed well loading and distribution of Ag NPs on the fabric surface with a crystal size of 16 nm with good antibacterial properties.     

高效液相色谱法测定氯化钾口服液中羟苯乙酯的含量

目的建立高效液相色谱(high performance liquid chromatography,HPLC)测定氯化钾口服液中防腐剂羟苯乙酯含量的分析方法。方法采用Eclipse XDB-C_(18)柱(250 mm×4.6 mm,5μm),甲醇:水(80:20,V:V)为流动相,流速为1.0 mL/min,检测波长为254 nm,柱温为40℃。结果羟苯乙酯在20.16~403.20μg/mL范围内线性良好,标准曲线方程为Y=8.18×10~4X+88.2(r=0.9992),平均加样回收率为99.22%,相对标准偏差(relative standard deviation,RSD)为1.0%(n=6)。结论该方法简便,准确可靠,灵敏度高,适合用于氯化钾口服液中羟苯乙酯含量测定。     

Sensory study of different sodium chloride substitutes in aqueous solution

The reduction of salt (sodium chloride) in food is one of the major challenges facing the food industry today and is motivated by the positive association between dietary salt intake and some diseases. Thus, the objectives of this study were to determine the equivalent amount of different sodium chloride replacements required to promote the same degree of ideal saltiness in aqueous solution and to study the sensory profile of sodium chloride and its substitutes using temporal dominance of sensations (TDS) analysis. The relative potencies of potassium chloride, monosodium glutamate, potassium phosphate, calcium lactate and potassium lactate compared to an aqueous solution with 0.75% sodium chloride were 74.75%, 59.52%, 60.48%, 11.40% and 4.96%, respectively. An evaluation of the sensory profiles of potassium chloride, potassium phosphate, calcium lactate and monosodium glutamate revealed saltiness as well as other tastes, including bitterness, sourness, umami and an unidentified undesirable taste as being dominant. The potassium chloride was the only one which showed temporal sensory profile similar to sodium chloride.     

牛奶中阿莫西林含量表面增强拉曼光谱检测方法的建立

以香水百合花瓣绿色合成的银溶胶为表面增强拉曼散射（SERS）活性基底，建立了牛奶中阿莫西林含量的SERS检测方法。对SERS检测条件进行了优化，考察了银溶胶浓度、银溶胶与阿莫西林溶液的体积比和氯化钠溶液的添加与否对SERS检测的影响。试验结果表明：当银溶胶浓度为106.04 μg/mL、银溶胶与阿莫西林溶液的体积比为41且不添加氯化钠的条件下，获得的SERS信号最强。在该条件下，阿莫西林标准溶液的浓度与1 055 cm^-1 处拉曼特征峰的SERS信号强度在1～1 000 μg/mL 范围内有良好的线性关系，方法的最低检出浓度可达到1 μg/mL。3份加标牛奶中阿莫西林的加标回收率为84.51%～93.62%，相对标准偏差（RSD）为5.16%。该方法简单方便，可实现牛奶中一定浓度阿莫西林的检测。     

可控粒径纳米银的制备与研究

为了解决以Ag NO3前驱体制备纳米银胶体粒径不稳定的问题,采用一种新的合成材料,以氢氧化二氨合银为前驱体,葡萄糖为还原剂,聚乙烯吡咯烷酮为表面活性剂,通过对反应机理的深入研究,找到最佳反应条件并采用液相还原法制备出粒径可控的纳米银胶体。通过XRD（X射线衍射仪）、TEM（透射电子显微镜）、ZETA电位仪等现代分析测试手段,研究了纳米银胶的形貌、粒径大小以及稳定性。分析发现,以此种方法制备的纳米银胶体具有粒径可控、尺寸均一、分散性良好等特点。     

非织造布增强聚氯乙烯多孔膜的制备及其微结构调控

为了改善聚氯乙烯（PVC）膜通量低、力学性能差等不足,提出一种PVC多孔膜的制备方法。以PVC为成膜聚合物,γ-丁内酯为溶剂,聚乙二醇、纳米二氧化硅和环氧大豆油为添加剂,以非织造布为增强体,采用溶液相转化法制备PVC多孔膜。通过形貌观察、纯水通量、截留率、孔径及其分布、孔隙率以及力学性能测试,考察了PVC固含量对多孔膜结构与性能的影响。结果表明,所得PVC多孔膜横截面为均质海绵状孔结构,上表面均匀分布着大量微孔结构,随PVC固含量的增加,膜横截面及上表面孔径减小,纯水通量降低,膜表面水接触角增大,亲水性降低,膜纯水通量可达1000L/(m2?h);膜对碳素墨水具有良好的截留性能,截留率可达92.8%;膜的断裂强度均大于20 MPa,且随PVC固含量升高而增大。     

Headspace GC/MS analysis of residual vinyl chloride and vinylidene chloride in polyvinyl chloride and polyvinylidene chloride products

A headspace GC/MS analysis method for the simultaneous determination of residual vinyl chloride (VC) and vinylidene chloride (VDC) in polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) products was developed. A test sample was swelled overnight with N,N-dimethylacetamide in a sealed vial. The vial was incubated for 1 hour at 90 degrees C, then the headspace gas was analyzed by GC/MS using a PLOT capillary column. The recoveries from spiked PVC and PVDC samples were 90.0-112.3% for VC and 85.2-108.3% for VDC. The determination limits were 0.01 microg/g for VC and 0.06/microg/g for VDC, respectively. By this method, VC was detected in two PVC water supply pipes at the levels of 0.61 and 0.01 microg/g. On the other hand, VC and VDC were not detected in any of the food container-packages or toys tested.     

Hydrolytic stability of terephthaloyl chloride and isophthaloyl chloride

The phthaloyl chloride isomers, terephthaloyl chloride (TCl) and isophthaloyl chloride (ICl), are high production volume chemicals used in polymers to impartflame resistance, chemical resistance, and temperature stability and as water scavengers. In these studies, we determined the hydrolytic stability of TCl and ICl and their hydrolysis products in aqueous solutions. Hydrolysis rates for TCl and ICl were initially determined by gas chromatography/flame ionization detection in water buffered at pH 4.0, 7.0, and 9.0 and 0 degrees C for up to 30 min. Subsequent studies determined the products from TCl and ICl hydrolysis. The parent phthaloyl chlorides (TCl and ICl), their intermediate hydrolysis products (designated as the "half-acids"), and their stable hydrolysis products (terephthalic acid (TPA) and isophthalic acid (IPA)) were determined by high-performance liquid chromatography. The half-lives (t(1/2)) of TCl and ICl ranged from an average of 1.2 to 2.2 min and from 2.2 to 4.9 min, respectively, at pH 4-9 and 0 degrees C. The observed first-order rate constants (k(obs)) ranged from an average of 530 to 1100 (x 10(5) s(-1)) for TCl and 240 to 520 (x 10(5) s(-1)) for ICl. Both phthaloyl chlorides formed their respective short-lived intermediates, in which one of the two carboxylic acid chloride functionalities reacts with water to form the carboxylic acid ("half-acid"). Subsequently, the half-acids underwent further hydrolysis so that greater than 90% of the initial phthaloyl chloride hydrolyzed in less than 60 min at 0 degrees C. The hydrolysis products TPA and IPA were hydrolytically stable, undergoing no further transformations after 20 min at pH 7 and 25 degrees C. This work demonstrated that TCl, ICl, and their respective half-acids will not be persistent in aqueous systems for a time sufficient to have a sustained toxicological effect on aquatic organisms (less than 1 h). Performing additional aquatic toxicity studies, biodegradation studies, and potentially mammalian studies on TCl and ICl are unnecessary since the existing information on TPA and IPA with the hydrolysis data presented here is sufficient to address questions on the fate and effects of these two substances in aqueous environments.     

鲢鱼骨中油脂提取方法的研究

目的 研究鲢鱼骨中鱼油的提取最佳工艺。方法 对比高温蒸煮、热风干燥、冷冻干燥不同处理方式, 将鲢鱼骨粉碎后, 以提取率为指标, 分别研究索氏提取、稀碱水解、酶法水解三种鱼油的提取方式, 并对稀碱水解法进行正交实验方案设计。结果 综合考虑, 采用稀碱水解法提取具有较高的应用价值。稀碱水解法的最优条件为温度85 ℃、pH10.0、料液比1:2、时间40 min, 鲢鱼骨油提取率为39.83%。结论 采用热风干燥法对鱼骨进行前处理, 稀碱水解法提取鲢鱼骨中脂肪提取率最高。