辣椒制品中大红粉的筛查及检测

采用自制的微型GPC柱对辣椒制品中的非食用色素进行筛查,筛选到一种未知的脂溶性非食用色素,采用紫外可见光谱法、高效液相色谱法、液相色谱-质谱/质谱法及液相色谱-飞行时间质谱法对该未知色素与市售化工染料大红粉进行比较分析,发现该未知色素为大红粉(Pigment Scarlet Powder).为了有效开展食品中大红粉的检测,建立了一种直接溶剂提取法对辣椒制品中大红粉进行检测的方法,该方法操作简便,可实现对辣椒制品中大红粉的快速检测,并在部分辣椒制品中检出大红粉.     

电感耦合等离子体质谱法测定食醋中镉、铬、铜、锰含量

目的:分析食醋中金属元素镉、铬、铜、锰含量。方法:用硝酸-过氧化氢体系微波消解处理样品,应用电感耦合等离子体质谱法(ICP-MS)对样品进行测定,测定时以钇作为内标来校正由于基体效应和信号漂移对测量造成的影响。结果:测定的14种不同食醋中镉、铬、铜、锰含量的均值分别为22.31,241.55,222.69μg/L和9733.12μg/L。该方法的回收率为90.8%～108.6%,相对标准偏差为1.78%～2.49%,检出限为范围0.003～0.108μg/L。结论:方法具有准确、快速、检出限低、灵敏度高等优点。与GB/T 5749-2006生活饮用水卫生标准对金属元素的限值相比,某些食醋中Cd,Cr,Mn含量比较高,应该引起足够的重视。     

Numerical modeling of a microwave plasma CVD reactor

This paper presents the results of numerical simulation of a microwave CVD reactor operating in CW and pulsed regimes. Dependencies of discharge parameters on the hydrogen pressure and microwave power have been studied. The possibility to use the pulse–periodic regime of discharge for deposition of diamond films has been analyzed. It is shown that a pulsed discharge may be used to improve the quality and increase the growth rate of the films.     

GC-MS法测定药用复合包装袋中异氰酸酯

目的利用气相色谱-质谱(GC-MS)技术建立同时测定药用复合包装袋中8种异氰酸酯含量的方法。方法将药用复合包装袋剪成尺寸(长×宽)不大于5 mm×5 mm的小碎片,采用二氯甲烷超声萃取40 min;萃取液经氮吹浓缩后,采用GC-MS法分析。采用TG-5MS色谱柱,将进样口温度设为200℃,柱温箱初温设为40℃,在程序升温条件下可实现8种异氰酸酯的有效分离。结果8种异氰酸酯在质量浓度为0.02~5.0 mg/L时,线性关系良好,相关系数R²均大于0.997,检出限为0.001~0.006 mg/kg。药用复合包装袋中的异氰酸酯在低、中、高等3个浓度水平下的加标回收率为80.3%~111.7%,相对标准偏差为0.6%~5.1%。结论该方法操作简便、灵敏度高、准确度好,可为药用复合包装袋中异氰酸酯的检测分析提供技术支持。     

LA-ICP-MS测定高纯金中铁含量的不确定度评定

对激光剥蚀-电感耦合等离子体质谱法(LA-ICP-MS)测定高纯金中铁含量的不确定度进行了评定,对标准物质、工作曲线和测量重复性的各分量的不确定度进行分析与计算,并计算出扩展不确定度。结果表明,测定高纯金中的铁含量为2.349 mg/kg时,不确定度为0.836 mg/kg,不确定度主要来源于标准物质的不确定度。     

浅析皮革和毛皮中甲醛含量测定新旧标准差异

比较分析了测定皮革和毛皮中甲醛含量的GB/T 19941新和旧标准在标准名称、仪器设备、试验步骤等方面的主要差异;建议新标准实施后注意公式和标准曲线的变更,及时与客户沟通试验方法等;指出了因测定方法的不同而影响产品检验结果和标准适用性的问题,为生产者、检测机构和消费者等提供参考.     

火花放电原子发射光谱法分析钢铁屑状样品的探讨

屑状样品其外观呈无规则状态,并具有一定的流动性。在一般情况下,它不能完全覆盖仪器的激发孔,无法形成一个密闭的氩气气氛,因此不能采用火花放电原子发射光谱法直接检测。为了能采用该法测定屑状样品,试验将钢铁屑状样品进行分类,根据各类金属屑状样品的强度和硬度选择合适的制样方法,将样品制备成规则的块状样品。其中塑性和韧性较好的样品采用冷压法制样,而超高强度、脆性大以及不适合冷压法制样的样品采用熔融法制样。制备好的样品选择合适的校准曲线,采用控样法,对样品进行定量分析。对样品10个不同部位测定的数据进行统计,测定结果的相对标准偏差(RSD,n=10)均小于2%,符合标准JJG 768—2005中的A级要求。用一级或二级标准物质/样品进行验证,测定值与认定值的差值都在标准物质规定的不确定度范围内。     

火花放电原子发射光谱多功能光谱夹具的研究与应用

为了解决了目前光谱夹具的单一性问题,研究并开发了多功能光谱夹具,并将其用于火花放电原子发射光谱分析中。多功能光谱夹具是融合了传统的立式和卧式夹具的原理改进而成,通过合理的拆卸设计,完成棒、线、管、片材和球状样品的分析测试。根据卧式光谱夹具的原理,可用于外径或宽度在1.0~10mm之间棒、线、管、片材样品分析;另外该夹具根据立式光谱夹具的原理,将圆球形样品借助不锈钢钢管、弹簧及螺栓完成了向棒材样品转换,通过定位板和V型板的定位,可用于外径在2.5~10mm之间钢球样品的测定。     

国内外食品分类系统研究

食品分类系统是食品安全监管工作的基础。本文通过整理和分析国内外主要食品分类系统，指出我国现有食品分类系统中存在的主要问题，并提出建议，为完善我国食品分类系统提供参考。     

Biogenic platinum-based bimetallic nanoparticles: Synthesis,characterization, antimicrobial activity and hydrogen evolution

In this study, platinum-based silver nanoparticles (Pt@Ag NPs) were synthesized by the green synthesis method, and their catalytic effects on hydrogen production were investigated. The characterization measurements of the synthesized NPs were performed by TEM, UV–Vis, XRD, and FTIR. According to TEM characterization results, Pt@Ag NPs had an average size of 5.431 nm. In experiments based on catalytic reactions for hydrogen production, test measurements were made at different parameters. It was observed that as the concentrations of the substrate and catalysts increased, the catalytic reaction accelerated, and the hydrogen release increased. Likewise, it was determined that hydrogen production increased with increasing temperature in different temperature experiments. The turnover frequency, entropy, activation energy, and enthalpy values are calculated as 702.38 h⁻¹, -160.5 J/mol.K, 32.48 kJ/mol, and 29.94 kJ/mol, respectively. According to the reusability test results, it was observed that the average reusability was found to be 85% after 5 cycles and it was confirmed that the NPs showed high-catalytic activity. In addition, the biological activities of Pt@Ag NPs, including antimicrobial, antioxidant and anticancer were tested. Pt@Ag NPs synthesized using Hibiscus sabdariffa (Hs) extract are thought to have the potential to be used in both biomedical and catalytic applications. The use of Pt@Ag NPs in the hydrogen production process shows great promise for green energy studies because it is environmentally friendly, non-toxic, and low cost.