Indirect polarographic determination of trichlorfon and dichlorvos

Summary A method of indirect polarographic determination of trichlorfou and dichlorvos was elaborated. Glyoxal, the product of alkaline hydrolysis of both these organophosphorus insecticides, condenses with o-phenylendiamine to forming quinoxaline, which is polarographically reduced, giving a well-developed two-electron wave. The relation of the concentration of the insecticides and corresponding diffusion current is recti linear in the broad concentration range of 0–8 mg. The standard deviation of this method is ± 1.2% for 400 jig and ± 5.2% for 3.0 g of trichlorfon respectively.

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Indirekte polarographische Bestimmung von Trichlorfon und Dichlorvos

Zusammenfassung Es wurde eine Methode zur indirekten polarographischen Bestimmung von Trichlorfon und Dichlorvos ausgearbeitet. Das Produkt der alkalischen Hydrolyse der beiden Organophosphor-Insecticiden, Glyoxal, wird mito-Phenylendiamin bei der Entstehung von Chinoxalin kondensiert. Chinoxalin wird bei gegebenen Arbeitsbedingungen auf der Quecksilber-Tropfelektrode bei Entstehung einer gut entwickelten Zwei-Elektronenwelle reduziert. Die Linearität der Abhängigkeit der Intensität des polarographischen Diffusions-Stromes von der Konzentration der Insecticide ist gültig bei den experimentellen Bedingungen im breiten Konzentrationsbereich von 0–8 mg. Die Standardabweichung der polarographischen Methode betragt für 400 g ± 1,2 und für 3 g ± 5,2%.

     

单扫描极谱法测定牛奶中三聚氰胺的质量浓度

建立了单扫描极谱测定牛奶中三聚氰胺的定量分析方法.在浓度为0.12 mol/L的NaOH和浓度为0.16 mol/L的KCl底液中,三聚氰胺于-0.5 V(vs.Ag/AgCl)出现灵敏的极谱还原峰,三聚氰胺质量浓度在6.3x10-3～1.26 mg/L范围内与导数峰高呈线性关系,检出限1.73x10-3 mg/L.该方法简便快捷,已用于牛奶中三聚氰胺质量浓度的测定,回收率为96.7%～106.6%.     

1-(2-吡啶偶氮)-2-萘酚光度法测定蕨菜中痕量锌的研究

研究了用Zn2 -1-(2-吡啶偶氮)-2-萘酚分光光度法测定蕨菜中痕量锌的最佳条件。其表观摩尔吸光系数为1.42×104L/mol·cm,Zn2 含量在0～100μg/50mL范围服从比尔定律,检测限为0.5μg/dm3。相对标准偏差在1.3%～2.1%,回收率在98%～103%。测得结果与用原子吸收法验证的结果非常吻合,法准确度和精密度均较好,操作简便、快速、该法可用于蕨科草本植物中痕量锌的快速测定。     

Square-wave polarographic determination of tin in products of the food processing industry

A square-wave polarographic method suitable for measuring tin in canned products and raw materials for food industry was examined. After wet digestion of the sample tin was directly determined from the acidic stock solution gained. If 10 ml of the stock solution was equivalent to 1 g sample,--varying sensitivity of the instrument--tin could be determined in the range of 5 micrograms/g--400 micrograms/g with +/- 5% relative error. By increasing sensitivity of the instrument this range could be extended to as little as 0,5 micrograms tin/g sample. The optimal quantity of hydrochloric acid to be added to the sulphuric acid solution of the digested sample before the instrumental measurement was determined by means of model solutions. Examinations concerning interference of lead were also performed. It is established, that if the ratio of Sn/Pb is at least 4/1, lead does not interfere with the polarographic tin determination. If the ratio of Sn/Pb is 2/1 or 1/1 tin content can be calculated after measuring the height of the peak of lead in sulphuric acid electrolyte. The method was applied for several canned products and comparative tests were performed with the spectrophotometric method given in the Hungarian standard MSZ 3612/7-77.     

食品中邻苯二甲酸酯测定方法的优化

建立了分散固相萃取测定食品中18种邻苯二甲酸酯类化合物(PAEs)的方法。纯油脂样品采用正己烷饱和乙腈提取净化;油脂含量较低的食品,采用10%叔丁基甲醚-乙腈溶液提取;提取液经相应的分散固相萃取管净化后,气相色谱-质谱联用仪进行测定。确定了纯油脂和低油脂食品中PAEs的测定方法,16种PAEs检出限达到1.5 mg/kg,DIDP/DINP检出限为9.0 mg/kg。纯油脂样品回收率80%~110%,RSD<6.5%,低油脂样品回收率60%~90%,RSD<8.4%。另外对蒸馏酒的测定方法进行了改进,以提高方法的稳定性,回收率为90%~110%,RSD<5.2%。本方法对前处理设备要求低,试剂消耗量小,方法简单易操作,适用于日常检测工作。     

鱼油海藻糖酯的合成与表面性质研究

分别以EPA乙酯、DHA乙酯和海藻糖为原料,在非水相酶反应体系中合成了EPA和DHA的海藻糖酯,采用硅胶柱层析和半制备高效液相色谱对反应液进行分离纯化,得到各自的单酯,并利用电喷雾质谱、核磁共振方法确定了两种单酯的结构.EPA海藻糖单酯和DHA海藻糖单酯的HLB值分别为10.39、9.97,因此可作为O/W型表面活性剂.利用Douy环法分别测定了30、40、50、60%时EPA海藻糖单酯、DHA海藻单酯的表面张力,发现二者的表面张力随温度的升高而降低.对其临界胶束浓度(CMC)进行计算表明,CMC随温度升高略有下降,并且DHA海藻糖单酯的CMC比EPA海藻糖单酯的CMC大约低1个数量级.     

Square-wave polarographic determination of heavy metals in vegetables with special regard to cadmium]

The cadmium contents of 104 foods mostly of vegetable origin (market samples from a highly industrialized area in the GDR) were determined by means of square-wave polarography. The values obtained are in good agreement with literature data about the cadmium contents of foods, and they are not indicative of an increased contamination of the products under investigation compared to other industrialized countries.     

纺织品邻苯二甲酸酯测定的不确定度评估

依据GB/T 20388-2006<纺织品邻苯二甲酸酯的测定>,采用超声波萃取、气相色谱-质谱法测定纺织品中的6种邻苯二甲酸醋类增塑剂.以邻苯二甲酸二(2-乙基)己酯(DEHP)为例,对整个测量过程中不确定度的来源进行了分析,并对不确定度各个分量进行了评定、合成,最后给出了合成不确定度.     

食用油脂中3-MCPD脂肪酸酯和缩水甘油脂肪酸酯分析方法研究进展

随着对油脂中3–MCPD脂肪酸酯(ME)和缩水甘油脂肪酸酯(GE)研究和检测技术的不断更新,在精炼棕榈油中发现了ME存在,且在大多数食用油脂中发现了GE存在。ME和GE作为两类食用油脂加工过程中产生的污染物,对人体可能存在致癌性。目前对ME和GE的检测有直接方法和间接方法 2种,直接方法主要是对油样处理或不处理后直接用LC–MS、LC–MS/MS、LC–TOF–MS、GC–MS等进行检测;间接方法是将ME和GE醇解为3–MCPD和缩水甘油酯,苯硼酸或七氟丁酰咪唑衍生化后用GC–MS或GC–MS/MS检测。该文对现有的ME和GE检测方法的样品处理过程、仪器条件、结果等加以比较和分析探讨。     

染料木素乙酰阿魏酸酯抗氧化及清除自由基活性研究

采用几种化学及生物学模型考察了染料木素乙酰阿魏酸酯的清除自由基能力、螯合金属离子能力及保护DNA免受自由基损伤能力.研究结果表明,染料木素酯化修饰物比染料木素具有更强的清除DPPH·、·OH自由基的能力,且保护DNA免受羟基自由基损伤的能力与染料木素相当,但染料木素酯化修饰物比染料木素螯合金属Fe2+离子的能力有一定程度的减弱.此外,本文还探讨了酯化产物与其抗氧化及清除自由基活性之间的构效关系,为寻求与自由基相关疾病新药的发现、食用功能因子的开发等奠定实验基础.     

食用油中氯丙醇酯污染及检测方法研究进展

食用油在精炼加工过程中会产生氯丙醇酯类物质,对食用油的安全造成影响,因此加强检测方法研究,提高检测水平尤为重要。对食用油中氯丙醇酯的组成、来源及危害进行了综述,对目前食用油中氯丙醇酯的检测方法(间接测定法和直接测定法)进行了介绍,其中详细分析了各种检测方法的原理及前处理过程等对检测结果的影响,并提出了今后的研究方向。以期为保证食用油安全性方面的研究提供参考。     

全自动样品处理平台在食用油脂中氯丙醇酯和缩水甘油酯测定的应用研究

目的 建立一种在线全自动快速测定食用油脂中氯丙醇酯（MCPDE）和缩水甘油酯（GE）含量的分析方法,并考察植物油种类、温度等因素对GE转化为3-氯-1,2-丙二醇（3-MCPD）的影响。方法 参考AOCS Cd 29c-13基本原理,将样品置于全自动样品前处理平台进行水解、氯代、液-液萃取和衍生,采用毛细管柱（DB-5MS柱）分离,多反应监测模式（MRM）采集,内标法定量。结果 5种植物油中GE的转化率差异不明显,但温度的影响略大,当10℃下水解7 min时,MCPDE和GE水解基本完成。3-氯-1,2-丙二醇酯（3-MCPDE）、2-氯-1,3-丙二醇二酯（2-MCPDE）和GE的检出限均为5μg/kg（以醇计）,在0～0.4μg/mL范围内浓度与峰面积比值呈良好的线性关系（决定系数R2≥0.999）;在20～2 500μg/kg范围内加标,MCPDE和GE的回收率范围为90.3%～109.7%,相对标准偏差（n=6）为1.3%～7.7%,精密度上全自动方法优于手工前处理操作。与食品安全国家标准方法（送审稿）进行对比,方法间结果具有可比性,将该方法用于FAPAS考核样的测定,结果满足...     

Occurrence of thyroid hormone activities in drinking water from eastern China: contributions of phthalate esters

Thyroid hormone is essential for the development of humans. However, some synthetic chemicals with thyroid disrupting potentials are detectable in drinking water. This study investigated the presence of thyroid active chemicals and their toxicity potential in drinking water from five cities in eastern China by use of an in vitro CV-1 cell-based reporter gene assay. Waters were examined from several phases of drinking water processing, including source water, finished water from waterworks, tap water, and boiled tap water. To identify the responsible compounds, concentrations and toxic equivalents of a list of phthalate esters were quantitatively determined. None of the extracts exhibited thyroid receptor (TR) agonist activity. Most of the water samples exhibited TR antagonistic activities. None of the boiled water displayed the TR antagonistic activity. Dibutyl phthalate accounted for 84.0-98.1% of the antagonist equivalents in water sources, while diisobutyl phthalate, di-n-octyl phthalate and di-2-ethylhexyl phthalate also contributed. Approximately 90% of phthalate esters and TR antagonistic activities were removable by waterworks treatment processes, including filtration, coagulation, aerobic biodegradation, chlorination, and ozonation. Boiling water effectively removed phthalate esters from tap water. Thus, this process was recommended to local residents to reduce certain potential thyroid related risks through drinking water.     

食品中氯丙醇脂肪酸酯含量测定的方法研究

基于GB 5009.191—2016《食品安全国家标准食品中氯丙醇及其脂肪酸酯含量的测定》,对3-氯-1,2-丙二醇脂肪酸酯和2-氯-1,3-丙二醇脂肪酸酯及其内标绝对响应值较低、多个实验室间数据差异较大等问题进行了研究,重点对正己烷、不同酯键断裂试剂和反应时间进行了验证和优化。结果表明:正己烷对测试结果无影响,最佳的酯键断裂试剂为0.5 mol/L甲醇钠-甲醇溶液,最佳酯键断裂反应时间为2 min。通过国际比对和多品牌标准品比较,确定了多个实验室间数据差异较大原因主要来自于内标物质的纯度差异以及标准曲线内标物质与样品中加入的内标物质不同。建议样品测试时,应尽可能使标准曲线使用的标准物质及内标物质与样品中添加的内标物质相同,并同法处理,从而提高数据准确性。     

Water utilisation,energy utilisation and waste water management in the dairy industry: A review

Energy consumption, water utilisation and waste production are now important environmental issues. However, compilations of data are not readily available, making it difficult for companies to assess how they are performing. This review aims to summarise the data that are available, including some benchmarking values. Also discussed are techniques for reducing water and energy consumption and waste production, tools for monitoring this and assistance that is available to improve efficiency ratios and reduce costs associated with these issues. Using information in this review, an individual company should be able to compare its performance against others producing similar products, nationally or globally in order to set and maintain rational benchmarking values to improve its performance and deal with environmental concerns.     

糖酯酶促合成及抗真菌活性的初步研究

研究了糖酯对食品中腐败真菌的抗菌作用。以脂肪酶作为催化剂,采用丙酮-分子筛体系进行反应,经硅胶柱层析法分离纯化制备得到糖酯。分别测定几种糖酯在不同pH值条件下对草酸青霉、塔宾曲霉、卷枝毛霉和黑根霉的抗菌效果。结果表明,果糖月桂酸酯对草酸青霉和塔宾曲霉的抗菌作用最强,并随浓度的增大,其抗真菌活性也随之增强。果糖月桂酸酯除对供试真菌的菌落直径大小有影响外,还影响到了菌落薄厚和产色素情况,其抗菌活性受pH值影响较大,在中性条件下的抗真菌活性低于酸性和碱性条件。     

A simple method for the determination of carbaryl and 1-naphthol in fruit juices by high-performance liquid chromatography-diode-array detection

Carbaryl (Sevin) is a widely used N-methylcarbamate insecticide. In this study, a simple and sensitive reversed-phase, high-performance liquid chromatography method with diode-array detection has been developed for the determination of low levels of carbaryl and its degradation products 1-naphthol in several kinds of canned pure fruit juice. The compounds were captured on a C18 cartridge. The analytes were separated on a C18 column using a linear gradient of 40 to 60% acetonitrile in water in a period of 20 min. The extraction recoveries of carbaryl and 1-naphthol were in the range 93.5 to 98.0% and 90.7 to 96.0% for fruit juice, respectively. The detection limit was below 0.8 ng/ml and the calibration curves showed good linearity between 0.9998 and 0.9999.     

食用油中常见塑化剂的GC-MS法快速测定

为快速有效地检测食用油中的污染物邻苯二甲酸酯类物质,建立了GC-MS联用法对邻苯二甲酸酯类物质检测方法。PAEs在0.05~5.00 mg/L范围内线性关系良好,相关系数R2﹥0.997,仪器检出限大部分低于10μg/L;在0.5 mg/L和5.0mg/L的基质加标水平下,测得PAEs精密度的RSD在5.30%左右,精密度较好;在0、0.5、5.0mg/L三个基质加标水平下,PAEs的回收率在76.8%~118.0%之间,相对标准偏差(RSD)在3.86%~9.15%之间;与国标和其他方法相比,该实验方法样品前处理简单,分析时间少,实验成本低,检测效果好,准确度高,适用于质检和品控部门对食用植物油中的PAEs进行快速大量地检测。本论文还对PAEs的预防提出了一些措施,这在维护食品安全方面具有重要意义。