超高效液相色谱-串联质谱法测定牛奶和奶粉中6种聚醚类抗生素残留量

建立了用于检测牛奶和奶粉中拉沙洛菌素、莫能菌素、尼日利亚菌素、盐霉素、甲基盐霉素和马杜霉素铵6种聚醚类抗生素残留量的超高效液相色谱-串联质谱分析方法.用乙腈提取样品中的聚醚类抗生素,提取液经HLB固相萃取柱净化,采用超高效液相色谱分离,以电喷雾离子源正离子多反应监测模式进行质谱分析.6种抗生素在0.5～100.0 μg/L范围内均呈线性,相关系数r>0.99.在空白样品中添加6种聚醚类抗生素的回收率均在74.0%～98.5%之间; 精密度(RSD)4.8%～17.2%.牛奶中6种聚醚类抗生素检出限均为0.2 μg/L;奶粉中6种聚醚类抗生素检出限均为1.6 μg/kg.     

超高效液相色谱-串联四极杆质谱联用分析鸭蛋黄中的苏丹红Ⅰ～Ⅳ

建立了鸭蛋黄中苏丹红Ⅰ～Ⅳ号的超高效液相色谱-串联四极杆质谱联用（UPLC-MS/MS）的分析方法。采用乙腈提取样品中的苏丹红,加水反沉淀除去蛋白质和脂肪等杂质,冷冻后高速离心,取上层清液供UPLC-MS/MS分析。经Waters Acquity BHE C18超高效液相色谱柱分离,串联四极杆质谱多反应监测模式检测,4种物质的检出限均为0.05 μg/L,实际样品中4种物质的检出限为10 μg/kg。采用标准添加法测定苏丹红的回收率,100.0,200.0,300.0 μg/kg 3个不同添加水平的回收率为50.2%～101.3%。实验结果表明该方法灵敏度高,检出限低,确证能力强,分析时间短,可满足高通量食品样品中苏丹红的日常检测。     

凝胶净化/超高效液相色谱串联质谱法测定调味酱中32种工业染料

建立了调味酱中32种工业染料的超高效液相色谱串联质谱分析方法。样品用乙腈均质提取,经凝胶色谱净化,浓缩后,以甲醇定容,超高效液相色谱分离,串联四极杆质谱多反应监测方式监测。结果表明,32种工业染料在各自的线性范围内线性关系良好,相关系数(r)均大于0.994,定量下限为0.2～5.0μg/kg,加标回收率为53%～115%,相对标准偏差为3.9%～22.4%。该方法具有前处理简单、净化效果好、灵敏度高的优点,适用于调味酱中多组分工业染料的快速确认和定量检测。     

超高效液相色谱-串联质谱法对奶制品中苯甲酸雌二醇残留的测定

建立了测定牛奶和婴儿配方奶粉中苯甲酸雌二醇的超高效液相色谱-串联质谱方法.样品前处理采用酶解、甲醇提取,经C18和NH2基固相萃取柱净化后,苯甲酸雌二醇由超高效液相色谱-串联质谱分离,并在正离子电离模式和多反应监测模式下,用基质匹配标准校正方法补偿基质效应,以氘代诺龙-d3为内标进行定量检测.牛奶和婴儿配方奶粉中苯甲酸雌二醇的检出限分别为0.07、0.39 μg/kg,定量下限分别为0.2、0.95 μg/kg.在4、10 μg/kg加标水平下,牛奶和婴儿配方奶粉中苯甲酸雌二醇的回收率为76% ～90%,相对标准偏差为5.0% ～15.2%.     

超高效液相色谱串联质谱分析牛乳中24种磺胺类药物残留

建立同时测定牛乳中24种磺胺类药物多残留的超高效液相色谱-电喷雾串联质谱 (UPLC-ESI-MS/MS)分析方法.样品经改良的QuEChERS技术提取和净化,采用ACQUITY UPLCTM BEH C18色谱柱(100 mm × 2.1 mm, 1.7 μm ),0.25%乙酸水溶液和乙腈作为流动相进行梯度洗脱,超高效液相色谱分离,电喷雾离子源电离,正离子多反应监测模式进行定性和定量分析.24种药物在5～100 μg/kg浓度范围内线性良好,相关系数r均大于0.99,以5,25和50 μg/kg 3个浓度水平进行添加回收率实验,样品的平均回收率在64.2%～110 9%之间,相对标准偏差为3.2%～13.1%,方法的检出限为0.21～1.62 μg/kg.方法重现性好、灵敏度高、分析时间短、确证能力强,适用于牛乳中磺胺类药物多残留的确证检测.     

人参中农药多残留的超高效液相色谱-串联质谱分析方法研究

以传统中药人参为研究对象, 建立一种同时检测人参中46 种农药多残留的基质固相分散-超高效液相色谱-串联质谱(MSPD-UPLC-MS/MS)方法. 前处理方法分别采用N-丙基乙二胺(PSA)和乙腈作为MSPD的分散剂和洗脱剂, 检测方法采用正负离子同时扫描, 利用超高效液相色谱-串联质谱在分时段多反应监测模式下进行定量和定性分析. 大部分农药在5～500 μg/kg 范围内线性关系良好, 在低(10 μg/kg)、中(50 μg/kg)、高(100 μg/kg)三个浓度水平上的添加回收率平均值在70%～110%之间, 相对标准偏差(RSD)小于15% (n＝3), 定量限小于0.01 mg/kg, 能够满足农药多残留分析要求. 该方法通用性强、选择性好、灵敏度高、简单廉价.     

同位素稀释液相色谱-串联质谱法测定动物性食品中的双酚A、壬基酚及辛基酚

建立了动物性食品肉、蛋和奶中双酚A、壬基酚和辛基酚的超高效液相色谱-串联质谱( UPLC-MS/MS)检测方法.比较了固相萃取法(SPE)和凝胶渗透色谱法(GPC)两种前处理技术,探讨了前处理过程中目标化合物背景污染的来源.最终采用乙酸乙酯-环己烷(1∶1,V/V)超声提取,经GPC净化后进行超高效液相色谱串联质谱分析.3种目标化合物的线性范围为0.25～1600 μg/L,相关系数R2＞ 0.999;对肉和鸡蛋样品,方法的定量限( LOQ)为0.2μg/kg;奶粉样品的LOQ为0.4 μg/kg.目标化合物在3个不同水平的加标回收率为85.9％～117.0％,RSD＜ 20％.应用本方法对市售动物性食品肉、蛋和奶进行了分析,壬基酚的检出率最高,含量为0.27～1357 μg/kg,此外还检出了双酚A.     

UPLC-MS/MS对鳗鱼中26种喹诺酮类及磺胺类抗生素药物残留的快速测定

建立了快速测定鳗鱼中喹诺酮类和磺胺类抗生素药物残留量的超高效液相色谱-电喷雾串联质谱方法.采用乙腈-二氯甲烷混合溶剂提取样品中的残留物,经固相萃取小柱净化,以液相色谱-串联质谱仪测定,外标法定量.该法对喹诺酮类和磺胺类药物的线性范围为0 ～50 μg/kg,相关系数均大于0.990;在2.0、5.0、10、20 μg/kg 4个添加水平范围内的回收率为63% ～95%;相对标准偏差为1.0% ～10.0%.适用于鳗鱼中喹诺酮类和磺胺类药物残留的定量测定.     

超高效液相色谱-电喷雾串联质谱法对饲料中匹莫林的测定

建立了超高效液相色谱-串联质谱测定饲料中匹莫林的方法.饲料样品经甲醇-乙腈溶液提取,取部分上清液氮气吹干,用甲醇和水分步溶解后用正己烷除脂,Waters Oasis HLB固相萃取小柱净化,然后用Waters Acquity UPLC BEH C18色谱柱(2.1 mm×50 mm i.d.,1.7 μm)分离,以甲醇和0.1%甲酸-水溶液为流动相进行梯度洗脱,外标法定量.对前处理及液相色谱和质谱条件进行优化.结果表明,匹莫林质量浓度在1 ～500 μg/L范围内线性良好,相关系数大于0.999;在5.0 ～200 μg/kg的添加水平下,匹莫林的平均加标回收率为77% ～86%;相对标准偏差为4.4% ～7.9%;方法的检出限低至2.0 μg/kg,定量下限低至5.0 μg/kg.该方法灵敏度高、稳定性好,可满足饲料中匹莫林残留的检测与确证的要求.     

超高效液相色谱-电喷雾串联质谱法测定饲料中残留的三聚氰胺

饲料样品经1%三氯乙酸-二甲基亚砜提取,Waters Oasis MCX柱净化,超高效液相色谱分离,最终采用电喷雾串联四极杆质谱进行检测。结果表明,三聚氰胺在饲料中的含量范围为10～5000 μg/kg时,线性关系良好(r＞0.99)。在10～100 μg/kg 的添加水平范围内的平均回收率为83%～94%,相对标准偏差为4.2%～6.5%。该方法的检出限为10 μg/kg。     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Reactions in droplets in microfluidic channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

乙基香兰素研究前景

报导了近几十年来国内外关于乙基香兰素的研究进展与动态,并简单介绍了本文作者在该方面所取得的研究成果,参考文献33篇。     

Gemini表面活性剂合成进展

系统总结了近百种Gemini表面活性剂的合成路线和方法,并且按照其结构特点分门别类地进行比较和归纳,对今后Gemini表面活性剂的合成发展方向提出了一些看法,这对促进此类新颖表面活性剂的工业化进程将具有指导意义。     

钙与人体及临床

钙是宏量元素，是人体中含量较高的元素之一，体内99％的钙构成骨骼和牙齿以及维持骨骼结构，1％的钙调节人体重要生理功能。钙的含量过高或过低都与许多疾病有关，只有保持一种平衡状态，才能使机体处于正常环境。     

Trends in education in analytical chemistry

Summary At the session of the WPAC of Fechem on education in analytical chemistry it was concluded that it is now essential to include chemometrics and basic knowledge of computers in all courses on analytical chemistry.

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Tendenzen in der analytisch-chemischen Ausbildung

Zusammenfassung Bei einer Tagung der WPAC über die Lehre auf dem Gebiet der analytischen Chemie wurde bei der Betrachtung neuer Aspekte festgestellt, daß vor allem Chemometrie und Grundkenntnisse in Computertechnik in die Ausbildung aufgenommen werden sollten.

     

AGET ATRP in the Presence of Air in Miniemulsion and in Bulk

Summary: The recently developed initiation system, activators generated by electron transfer (AGET), is used in atom transfer radical polymerization (ATRP) in the presence of a limited amount of air. Ascorbic acid and tin(II ) 2‐ethylhexanoate are used as reducing agents in miniemulsion and bulk, respectively. An excess of reducing agent consumes the oxygen present in the system and, therefore, provides a deoxygenated environment for ATRP. ATRP of butyl acrylate is successfully carried out in miniemulsion and in the presence of air. During polymerization the radical concentration remains constant. The polymerization reaches over 60% monomer conversion after 6 h, which results in polymers with a predetermined molecular weight = 14 000 g · mol⁻¹ and a low polydispersity ( = 1.23). AGET ATRP of styrene is also successful in bulk in the presence of air, as evidenced by linear semi‐logarithmic kinetics, which leads to polystyrene with an of 13 400 g · mol⁻¹ and a low polydispersity index ( = 1.14).

Appearance of miniemulsion before and after the reducing agent ascorbic acid was added (left); and GPC traces representing molecular weights during the AGET ATRP of BA in miniemulsion in the presence of air (right).