多壁碳纳米管作为吸附剂的QuEChERS-气相色谱-四极杆飞行时间质谱快速筛查淡水产品中145种农药残留

建立了基于多壁碳纳米管(MWCNTs)的新型Qu ECh ERS前处理方法,结合气相色谱-高分辨飞行时间质谱对淡水产品中145种农药残留进行快速筛查。样品采用水和乙腈提取,以MWCNTs为净化吸附剂,用Qu ECh ERS方法处理后,采用气相色谱-四极杆飞行时间质谱(GC-QTOF/MS)检测,外标法定量。研究并优化了提取条件、吸附剂种类及用量、GC-QTOF/MS采集速率及质量提取窗口。在最佳实验条件下,145种农药在5~200μg/kg范围内线性关系良好(r20.98),10,20,100μg/kg 3个添加水平下的回收率为69.4%~114.2%,相对标准偏差(RSD,n=6)为2.2%~13.8%,定量下限为1.1~40.0μg/kg。与传统Qu ECh ERS方法相比,所建立的方法快速、准确,净化效果明显,可显著降低基质干扰。     

玉米粉中吡虫啉、三唑酮、乙草胺与异丙甲草胺的QuEChERS/高效液相色谱-串联质谱快速检测

建立了玉米粉中吡虫啉、三唑酮、乙草胺和异丙甲草胺4种常用农药的Qu ECh ERS/高效液相色谱-串联质谱残留分析方法。前处理采用Qu ECh ERS方法,以乙腈为提取剂,N-丙基乙二胺(PSA)和石墨化碳黑(GCB)为分散净化剂,并利用高效液相色谱-串联质谱在多反应离子监测模式(MRM)下进行检测,基底匹配工作曲线法定量。结果表明:4种农药在0.005~1.000 mg/L浓度范围内均具有良好的线性关系(r2≥0.998);在0.05~1.00 mg/kg加标水平下的平均回收率为74.9%~98.4%,相对标准偏差(n=5)为1.6%~5.3%;方法检出限(LOD)为0.001~0.26μg/kg;定量下限(LOQ)为0.004~0.867μg/kg。该方法分析速度快、灵敏度高、重现性好,适用于玉米粉中吡虫啉、三唑酮、乙草胺和异丙甲草胺4种农药残留的快速检测和确证。     

改进的QuEChERS方法结合气相色谱串联质谱检测韭菜中的多种农药残留

采用改进的Qu ECh ERS方法结合气相色谱串联质谱(GC-MS/MS)检测韭菜中的多种农药残留。样品经含1%乙酸的乙腈匀质提取,采用分散固相萃取剂净化,在GC-MS/MS多反应监测(MRM)模式下进行测定。对Qu ECh ERS方法的提取和净化条件进行了优化。在优化条件下,44种农药残留在10~500μg/kg范围内呈良好线性关系,相关系数的平方(R~2)在0.9971~0.9999之间。在10μg/kg和100μg/kg添加水平下,44种农药的平均回收率为91.5%~119.6%,日内日间相对标准偏差小于14.1%。将所建立的方法用于实际样品的分析中,取得了较好的效果。     

分散固相萃取/气相色谱-三重四极杆串联质谱测定蔬菜和水果中67种农药残留

建立了分散固相萃取/气相色谱-三重四极杆串联质谱法(Qu ECh ERS/GC-MS/MS)同时测定蔬菜和水果中67种常规检测农药的分析方法。番茄样品用1%乙酸乙腈匀浆提取,经分散固相萃取剂净化后,采用气相色谱-三重串联四极杆串联质谱在多反应离子监测(MRM)模式下进行检测,外标法定量。结果表明,67种农药在0.005~0.24μg/m L范围内呈良好的线性关系,相关系数(r2)均大于0.99;番茄、葱、通菜和橙子基质在0.02,0.06,0.12 mg/kg 3个加标水平下,67种农药的平均回收率为60.3%~119.8%,相对标准偏差(RSD)为0.5%~14.7%;方法的检出限(LOD)为0.000 1~0.003 mg/kg,定量下限(LOQ)为0.000 2~0.009 mg/kg。将该法应用于蔬菜、水果中农药残留检测,并与GC,GCP/GC-MS,LC-MS/MS方法进行对比,结果较为满意。该方法简便快捷、灵敏度高、选择性好,具有良好的重现性和稳定性,适用于日常蔬菜水果中农药多残留的快速筛查和确证检测。     

SPE和QuEChERS前处理方法结合LC-Q-TOF/MS检测苹果和番茄中282种农药残留对比研究

利用液相色谱-四极杆/飞行时间质谱(LC-Q-TOF/MS)对比研究了固相萃取(SPE)和Qu ECh ERS两种前处理方法在282种农药残留检测上的效果。以苹果和番茄为基质,分别从基质效应、回收率、重复性、线性关系、检出限和定量限等方面进行了考察与比较。SPE法和Qu ECh ERS法在苹果中呈现出弱基质效应的农药占比分别为87.2%和57.1%,在番茄中为65.6%和42.2%。与SPE相比,Qu ECh ERS法干扰物较多,基质效应较强;在5.0μg/kg添加水平下(n=5),SPE和Qu ECh ERS在苹果中平均回收率在70%~120%的农药占比分别为99.3%和86.9%,在番茄中为92.9%和87.9%;在5.0μg/kg添加水平下(n=5),SPE和Qu ECh ERS在苹果中重复性相对标准偏差(RSD)20%(n=5)农药占比分别为98.9%和86.5%,在番茄中为92.9%和87.6%;SPE和Qu ECh ERS两种方法在苹果中定量限≤10μg/kg的农药占比为100.0%和96.1%,在番茄中为100.0%和98.9%。两种前处理方法均能与高分辨质谱技术相结合并应用于果蔬农药残留的日常检测中,其中SPE净化效果较优,定量更为准确,但步骤稍显繁琐费时,而Qu ECh ERS方法简单快速,故在检测时可根据不同需要进行选择。     

气相色谱串联质谱法测定蔬菜中甲拌磷和克百威及其代谢物的残留量

建立气相色谱–三重四级杆串联质谱法(GC–MS/MS)测定蔬菜中甲拌磷及其代谢产物甲拌磷砜、甲拌磷亚砜,克百威及其代谢产物3-羟基克百威。蔬菜样品经乙腈提取、Qu ECh ERS法净化,GC–MS/MS采用选择反应监测模式(SRM)采集数据后进行分析。5种化合物的含量在检测范围内与色谱峰面积均呈良好的线性,相关系数r2为0.998 0~0.999 6。在0.02,0.05 mg/kg的添加水平下,平均回收率在73.6%~118.2%范围内,测定结果的相对标准偏差小于8.5%(n=6),方法定量限为5~10μg/kg。该方法可用于蔬菜中甲拌磷和克百威及其代谢物的常规检测。     

QuEChERS/高效液相色谱法测定棉花田中吡草醚及其代谢物的残留量

建立了棉花植株、棉籽和土壤样品中吡草醚及其主要代谢物E-1的Qu ECh ERS/高效液相色谱-可变波长紫外检测器(HPLC/VWD)检测方法。样品用乙腈-水混合溶液提取,Qu ECh ERS方法净化,以Ultimate XB-C18色谱柱(250 mm×4.6 mm,5μm)进行HPLC分离,检测波长为246 nm,基质匹配标准品外标法定量。结果表明:吡草醚和E-1在0.01~1.0 mg/L质量浓度范围内呈良好线性关系(r20.999)。在棉花植株、棉籽和土壤中分别进行3个浓度的加标回收实验,吡草醚和E-1在样品中的平均回收率分别为83.5%~106.3%和74.9%~102.3%,相对标准偏差(RSD,n=5)分别为0.5%~5.2%和1.6%~19.2%。吡草醚和E-1的检出限(LOD,S/N3)均为0.1 ng,在棉花植株和棉籽中的定量下限(LOQ)均为0.04 mg/kg,在土壤中的LOQ均为0.02 mg/kg。该方法前处理快速、简单、经济,可用于常规实验室棉花植株、棉籽和土壤样品中吡草醚及其代谢物E-1的残留检测。     

GC-MS/MS法对焙烤食品及其塑料包装材料中25种磷酸三酯类与邻苯二甲酸酯类化合物的同时测定

建立了气相色谱-质谱/质谱(GC-MS/MS)测定焙烤食品及其塑料包装材料中25种磷酸三酯类及邻苯二甲酸酯类化合物的高通量检测方法。焙烤食品以乙腈-丙酮(8∶2,体积比)超声提取,采用50 mg C18和50 mg PSA混合填料进行Qu ECh ERS净化;塑料包装材料经二氯甲烷-甲醇超声提取后直接检测。样液经DB-5 ms色谱柱分离,选择反应监测(SRM)模式测定。25种化合物在各自线性范围内的相关系数不小于0.997 5,方法检出限为10~500μg/kg,平均回收率为80.2%~119.6%,相对标准偏差(n=6)为1.5%~9.4%。该方法操作简单,净化效果好,可有效消除基质效应,适用于不同焙烤食品及其塑料包装材料中磷酸三酯类及邻苯二甲酸酯类化合物的同时测定。     

QuEChERS-UHPLC-MS/MS法测定烟草中硝苯菌酯EI北大核心CSCD

建立了Qu ECh ERS-UPLC-MS/MS测定烟草中硝苯菌酯(2,4-DNOPC)残留的方法。烟草样品采用改进的Qu ECh ERS技术提取,在碱性条件下超声水解后进样分析,采用负离子多反应监测(MRM)模式检测,通过测定2,4-DNOPC相应的水解产物2,4-二硝基-6-(1-甲基庚基)苯酚(2,4-DNOP)来计算烟草中硝苯菌酯残留量。结果表明,2,4-DNOPC质量浓度在0.001~0.5 mg/L范围线性关系良好,相关系数(r2)大于0.999,检出限为3μg/kg,2,4-DNOPC在烟草中的回收率为92.4%~100.5%,RSD为2.5%~3.3%。方法适用于烟草中硝苯菌酯残留量的检测。     

气相色谱-串联质谱法检测大米中20种农药残留

建立了两种可简便、灵敏、快速、批量测定大米中20种农药残留的分析方法。样品经乙腈提取后,使用C18固相萃取柱(SPE)和Qu ECh ERS两种不同净化方法,采用气相色谱-串联质谱选择反应监测(SRM)模式对20种农药进行检测,通过保留时间、选择离子及其相对丰度定性,外标法定量。结果表明,20种农药的线性范围为0.01~0.2μg/m L,相关系数均大于0.99。在0.01,0.05,0.20 mg/kg加标水平下,采用C18柱对大米样品进行提取净化,20种农药的平均回收率为63.3%~96.0%,相对标准偏差(RSD)为1.9%~13.9%;采用Qu ECh ERS方法对大米样品进行提取净化,20种农药的平均回收率为67.7%~121.0%,RSD为1.9%~16.4%。此两种方法无明显差异,为农药多残留检测提供了不同的思路,能够对大批量大米样品进行同时检测,数据准确可靠,回收率与精密度均符合农药残留的分析要求。     

溶剂化的热力学集团展开理论

把二元溶液的过剩内能（excess energy）分成溶剂-溶剂、溶剂-溶质及溶质-溶质相互作用部分。利用集团展开方法给出了二元溶液在正则系综的配分函数的表达式,利用该表达式得到了溶质的偏摩尔内能(partial molar energy)和偏摩尔熵(partial molar entropy)的表达式。在无限稀溶液情形,过剩偏摩尔内能的溶剂-溶剂部分又称重组织内能（reorganization energy）,它反映了溶质存在时对其周围溶剂分子之间的相互作用能的影响。研究表明,在溶质的粒子数密度相对较大时,溶质分子之间的相互作用将影响过剩偏摩尔内能的溶剂-溶剂部分,对于稀溶液,过剩偏摩尔内能的溶剂-溶剂部分与溶质的摩尔分数成线性关系。对低密度二元溶液,溶质的过剩偏摩尔内能和过剩偏摩尔熵也与溶质的摩尔分数成线性关系。     

Polymeric Lids for Microcontainers for Oral Protein Delivery

Oral delivery of proteins and peptides is one of the main challenges in pharmaceutical drug development. Microdevices have the possibility to protect the therapeutics until release is desired, avoiding losses by degradation. One type of microdevice is polymeric microcontainers. In this study, lysozyme is chosen as model protein and loaded into microcontainers with the permeation enhancer sodium decanoate (C10). The loaded microcontainers are sealed and functionalized by applying polymeric lids onto the cavity of the devices. The first lid is poly(lactic‐co‐glycolic) acid (PLGA) and on top of this either polyethylene glycol (PEG) or chitosan is applied (PLGA+PEG or PLGA+chitosan, respectively). The functionalization is evaluated in vitro for morphology, drug release, and mucoadhesive properties. These are coupled with in vitro and ex vivo studies using Caco‐2 cells, Caco‐2/HT29‐MTX‐E12 co‐cultures, and porcine intestinal tissue. PLGA+chitosan shows slower release compared to PLGA+PEG or only PLGA in buffer and the transport of lysozyme across cell cultures is not enhanced compared to the bulk powder. Microcontainers coated with chitosan or PEG demonstrate a three times stronger adhesion during ex vivo mucoadhesion studies compared to samples without coatings. Altogether, functionalized microcontainers with mucoadhesive properties and tunable release for oral protein delivery are developed and characterized.     

Bump-hunting for the proficiency tester--searching for multimodality

Kernel density estimation is a method for producing a smooth density approximation to a dataset and avoiding some of the problems associated with histograms. If it is used with a degree of smoothing determined by a fitness for purpose criterion, it can be applied to proficiency test data in order to test for multimodality in the z-scores. The bootstrap is an essential additional technique to determine how rugged the initially estimated kernel density is: the random resampling of the data in the bootstrap simulates a complete blind repeat of the proficiency test. In addition, useful estimates of the standard error of a mode can be thus obtained. It is suggested that a mode and its standard error can be used as an assigned value and its standard uncertainty.     

Wetting for self-healing and electrowetting for additive manufacturing

Advanced additive manufacturing actively widens its tool box of wettability-related phenomena to be used in production of new items. Novel self-healing engineering materials incorporate vascular networks with two types of nanochannels: the one containing a resin monomer, whereas another one — a curing agent. If such nanocomposites are damaged locally, both types of channels are locally broken, and they release resin monomer and curing agent droplets. These droplets spread by wettability over the nanotextured matrix, touch each other, and coalesce, which triggers polymerization reaction and crack stitching. Wettability-facilitated droplet spreading is accompanied by liquid imbibition in the pores in the nanofiber network. Such process peculiarities are in focus in the present review. An additional process relevant in direct writing and 3D printing is electrowetting (EW). It stems from the change in the contact angle in response to the electric polarization of dielectric substrates. EW allows movement of droplets on horizontal, vertical, and inverse surfaces, which can significantly facilitate the existing direct writing and 3D printing technologies. Accordingly, EW is also in focus in the present review.     

Call for nominations for the Heinrich-Emanuel-Merck Award

News and Announcements

Call for nominations for the Heinrich-Emanuel-Merck Award     

Advances for proficiency testing for genetic laboratory science

Nucleic acid based clinical genetic testing has undergone explosive growth in recent years due in large part to the human genome project. Characterization of the human genome has led to a molecular understanding of the pathogenesis of many human diseases, and ultimately to clinical molecular tests becoming routinely used to diagnose a wide diversity of diseases. This rapid growth in clinical molecular genetic testing coupled with the complexity of the analytical procedures underscores the necessity for proficiency testing (i.e. external quality assessment) to allow laboratories offering such services the ability to evaluate their analytical procedures via inter-laboratory comparisons. The American College of Medical Genetics (ACMG) in partnership with the College of American Pathologists (CAP) have been offering proficiency testing for clinical molecular genetics laboratories since 1995, and presently have more than 230 laboratories from 11 countries enrolled in this program. This paper describes the evolution of this program and several challenges encountered in the delivery of a proficiency testing program for laboratories offering clinical molecular genetic services. Received: 13 April 2002 Accepted: 18 July 2002     

A methodology for choosing parameters for ESR readout of alanine dosimeters for radiotherapy

Spectrometer settings for ESR readout of alanine dosimeters for radiotherapy have been investigated. Several ESR parameters were studied and determined. The main reason for this work is to choose the suitable parameters to increase signal-to-noise ratio and to reduce the uncertainty on ESR readout, which is one of the main components of uncertainty of alanine/ESR dosimetry system for radiotherapy. The new spectrometer settings have been applied for ESR readout of alanine dosimeters irradiated from 1 to 10 Gy. A higher signal-to-noise ratio has been achieved compared to our old spectrometer settings. The extended uncertainty (k=2) has been evaluated in the dose range 2–10 Gy (maximum uncertainty of 4.9% for 2 Gy, while minimum uncertainty of 1.4% for 10 Gy), which implies that the alanine/ESR dosimetry system can be applied to radiotherapy dose level that needs a global accuracy of 5%.