UPLC-MS/MS法同时测定食品接触用油墨中20种光引发剂的迁移量

为评估食品接触用油墨中光引发剂的迁移风险,采用超高效液相色谱－串联质谱（UPLC－MS/MS）建立了同时测定食品接触用油墨中20种光引发剂迁移量的方法。以0.1%（体积分数）甲酸和甲醇为流动相进行梯度洗脱,采用多反应监测模式对目标物的定量离子和定性离子进行监测,检测迁移实验后食品模拟物中的20种光引发剂。结果表明,该方法对20种光引发剂的色谱分离效果良好,各物质在0.02～0.5 mg/L质量浓度范围内线性关系良好,检出限为0.01 mg/kg,定量下限为0.02 mg/kg。加标回收率为87.1%～104%,相对标准偏差（RSD）为2.1%～8.6%,在10款样品中共检出4类光引发剂。该方法简单、灵敏、准确,适用于食品接触用油墨中20种光引发剂迁移量的检测。     

超高效液相色谱-四极杆飞行时间质谱法同时测定食品接触用塑料中50种添加剂的迁移量

为评估食品接触用塑料中添加剂的迁移风险,采用超高效液相色谱－四极杆飞行时间质谱（UPLC－QTOF MS）建立了同时测定食品接触用塑料中50种添加剂迁移量的方法。以甲醇和0.01%（体积分数）甲酸－5 mmol/L乙酸铵溶液为流动相进行洗脱,采用目标离子采集（Target MS/MS）模式对目标物的一级离子与二级离子进行监测。结果表明,各物质在0.02～5 mg/L质量浓度范围内线性关系良好,方法检出限为0.01～0.1 mg/kg,加标回收率为92.6%～104%,相对标准偏差（RSD）为0.60%～8.4%。在20款实际样品中有12个样品检出塑料添加剂,其中2个样品检出壬基酚,迁移量为0.033～0.071 mg/kg;6个样品检出抗氧化剂1076和抗氧化剂168,迁移量为0.12～3.3 mg/kg;4个样品检出光引发剂369、光引发剂ITX和光引发剂TPO,迁移量为0.054～4.0 mg/kg。该方法简单、灵敏、准确,适用于食品接触用塑料中50种添加剂迁移量的检测。     

液相色谱串联质谱法测定食品塑料包装材料中22种光引发剂及其迁移量

建立了液相色谱–质谱联用法测定食品塑料包装材料中22种光引发剂的含量及迁移量的方法。包装材料样品与油基食品采用乙腈提取,水基食品加入乙腈与氯化钠提取。22种光引发剂在质量浓度为0.01-1.0μg/mL的线性范围内,与各自的色谱峰面积线性关系良好,相关系数均大于0.99。光引发剂在塑料包装材料中的定量限为0.1 mg/kg。选取4种食品塑料包装材料及4种食品模拟物为基质,加标回收率为70.4%-117.2%,测定结果的相对标准偏差小于20%(n=6)。该方法前处理简单,选择性好,回收率和精密度符合方法确认要求。     

超高效液相色谱-串联质谱法测定食品塑料包装材料中5种光引发剂及其迁移规律

采用超高效液相色谱-串联质谱法测定食品塑料包装材料中5种光引发剂(PIs)及其迁移规律。以Agilent Eclipse Plus C_(18)色谱柱为分离柱,以不同体积比的1g·L~(-1)乙酸铵溶液和乙腈的混合液为流动相进行梯度洗脱,采用电喷雾正离子源选择离子监测模式检测。方法的测定下限(10S/N)为1.38~5.56μg·dm~(-2)。回收率为77.5%~95.0%,测定值的相对标准偏差(n=6)为0.81%~8.9%。5种PIs在不同食品模拟液中的迁移能力不同,其中向30g·L~(-1)乙酸溶液中的迁移能力最强;5种PIs在不同食品塑料包装材料中的迁移能力与材料的阻隔性能密切相关。     

超高效液相色谱/静电场轨道阱高分辨质谱法同时测定塑料食品接触材料中光稳定剂和抗氧化剂的特定迁移量

建立了超高效液相色谱/静电场轨道阱高分辨质谱同时测定塑料食品接触材料中多种光稳定剂和抗氧化剂特定迁移量的方法。采用30 g/L乙酸、体积分数分别为10%、20%、50%的乙醇和油类模拟物(异辛烷)这5种食品模拟物对塑料食品接触材料进行处理,对处理液进行超高效液相色谱/静电场轨道阱高分辨质谱分析,外标法定量。该方法测定的40种目标化合物在相应的范围内均具有良好的线性关系,相关系数均大于0.998,定量限为0.01~1.00μg/L。考察了上述5种食品模拟物中光稳定剂和抗氧化剂的特定迁移量,平均加标回收率为81.46%~94.53%,相对标准偏差为3.25%~9.99%。应用该方法对市售塑料食品接触材料进行了测定,结果在部分样品中检出了不同含量的光稳定剂和抗氧化剂。该方法灵敏度高,定量限低,满足塑料食品接触材料中光稳定剂和抗氧化剂特定迁移量的检测要求。     

GC-MS法快速测定铅笔涂层中18种光引发剂

建立了快速测定铅笔涂层中18种光引发剂的气相色谱-质谱联用法(GC/MS)。样品以二氯甲烷为提取溶剂,在30℃温度下,超声提取30 min后,萃取液用100 mg N-丙基乙二胺(PSA)分散固相萃取净化,以气相色谱-质谱法(GC-MS)测定,外标法定量。18种光引发剂在0.2~4.0 mg/L(或0.1~4.0 mg/L)范围内线性良好,相关系数R²均大于0.997,方法检出限(LODs)为0.4~1.0 mg/kg,定量限(LQDs)为1.0~2.0 mg/kg。3个加标水平(2.0或4.0、10.0和40.0 mg/kg)的回收率在75.2%~115.2%之间,相对标准偏差(RSDs)为1.0%~9.3%(n=6)。该方法可用于铅笔涂层中18种光引发剂含量的高通量检测。     

食品包装材料中7种光引发剂向水性模拟液中的迁移测定

为了考察食品包装材料中光引发剂向食品中迁移的情况,以水性模拟液作为迁移溶剂,用65 μm聚二甲基硅氧烷/二乙烯基苯(PDMS-DVB)纤维头进行固相微萃取结合气相色谱-质谱(SPME/GC-MS)分析方法同时测定食品包装材料中7种光引发剂(PIs)的迁移量。方法的检出限为0.0012～0.0069 μg/L,线性范围为0.03～1.0 μg/L (r2＞0.9909),在3种浓度的添加水平下,加标回收率为70.8%～112.0%,相对标准偏差不大于14.0%。利用建立的方法对20个实际样品进行测定,发现所有样品中均检出二苯甲酮,其中10个样品中检出4-甲基二苯甲酮,3个样品中检出1-羟基环己基苯基甲酮,1个样品中检出安息香双甲醚。该方法的灵敏度高,样品前处理过程简单,无需使用有机溶剂,为食品接触材料表面印刷油墨中PIs向水性样品中的迁移测定提供了参考。     

超高效液相色谱-串联质谱法同时测定食品接触材料及制品中9种抗氧化剂迁移量

为了评估食品接触材料及制品中抗氧化剂的迁移风险,采用超高效液相色谱-串联质谱法(UPLC-MS/MS)建立了同时测定食品接触材料及制品中9种抗氧化剂迁移量的方法。采用C18色谱柱对迁移实验后的食品模拟物中9种抗氧化剂进行分离,1 mmol/L氟化铵和甲醇为流动相洗脱,采用电喷雾离子源(ESI),多反应监测(MRM)正负离子模式进行扫描。结果表明,9种抗氧化剂的色谱分离效果良好,并在0.3~6 mg/L质量浓度范围内与其峰面积均呈良好的线性关系,检出限为0.1 mg/L。加标回收率为93.9%~106%,相对标准偏差(RSD)为0.80%~9.3%。该方法快速高效、线性范围好,适用于塑料食品接触材料及制品中9种抗氧化剂迁移量的检测。     

液相色谱-串联质谱法测定纸质食品接触材料印刷紫外固化油墨中18种光引发剂的迁移量

选取4%(体积分数,下同)乙酸溶液、50%(体积分数,下同)乙醇溶液、95%乙醇溶液和橄榄油作为食品模拟物,模拟了食品接触材料在与不同类型食物接触下的迁移行为。采用液相色谱-串联质谱法测定纸质食品接触材料印刷紫外固化油墨中18种光引发剂的迁移量。迁移试验得到的水基食品模拟液,经过滤后直接进样测定;油基食品模拟液需要经乙腈提取后进行测定。以C18色谱柱为分离柱,以不同体积比的0.1%(体积分数)甲酸溶液和0.1%(体积分数)甲酸乙腈溶液的混合液作为流动相进行梯度洗脱,质谱分析采用多反应监测模式对18种光引发剂的定量离子和定性离子进行监测。18种光引发剂的质量浓度均在3.0～37.5μg·L~(-1)内或质量分数均在0.010～0.125mg·kg~(-1)内与其对应的峰面积呈线性关系,在4%乙酸溶液、50%乙醇溶液、95%乙醇溶液及橄榄油食品模拟物中的测定下限(10S/N)分别为0.03～2.97μg·L~(-1),0.02～2.91μg·L~(-1),0.03～2.88μg·L~(-1)和0.06～9.00ng·g~(-1)。以空白样品为基体进行加标回收试验,所得回收率为86.0%～114%,测定值的相对标准偏差(n=6)不大于9.4%。     

气相色谱-质谱同时测定食品包装材料中9种光引发剂

建立了同时测定食品包装材料中二苯甲酮、4-甲基二苯甲酮、4-氯二苯甲酮、1-羟基环己基苯基甲酮、对二甲氨基苯甲酸乙酯、对二甲氨基苯甲酸异辛脂、2-氯硫杂蒽酮、2-异丙基硫杂蒽酮和2,4-二乙基硫杂蒽酮9种光引发剂的气相色谱-质谱法。通过单因素实验和正交试验确定了以15mL二氯甲烷,于40℃下超声提取20min的样品前处理条件。在优化的柱温程序下9种光引发剂目标物获得较好分离,质谱选择离子扫描定量。方法的检出限(S/N=3)为0.7840~7.699μg/L,3种不同标准添加水平下的平均回收率为92.44%~110.6%,相对标准偏差为1.60%~9.46%(n=6)。方法简便、快速、灵敏、准确,可用于食品包装材料中光引发剂的分析监测。     

Application of ionic liquid in liquid phase microextraction technology

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single‐drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid–liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction.     

Potential-modulation spectroscopy at solid/liquid and liquid/liquid interfaces.

Potential-modulation spectroelectrochemical methods at solid/liquid and liquid/liquid interfaces are reviewed. After a brief summary of the basic features and advantages of the methods, practical applications of potential-modulation spectroscopy are demonstrated using our recent studies of solid/liquid and liquid/liquid interfaces, including reflection measurements for a redox protein on a modified gold electrode and fluorescence measurements for various dyes at a polarized water/1,2-dichloroethane interface. For both interfaces, the use of linearly polarized incident light enabled an estimation of the molecular orientation. The use of a potential-modulated transmission-absorption measurement for an optically transparent electrode with immobilized metal nanoparticles is also described. The ability of potential-modulated fluorescence spectroscopy to clearly elucidate the charge transfer and adsorption mechanisms at liquid/liquid interfaces is highlighted.     

Extensible automated dispersive liquid–liquid microextraction

In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid–liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C₈MIM]NTf₂) is formed through the reaction between [C₈MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf₂) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16–0.45 ng mL⁻¹. The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r > 0.9986) was obtained over the calibration range from 2 to 500 ng mL⁻¹. The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples.     

Electroviscoelasticity of liquid/liquid interfaces: fractional-order model

A number of theories that describe the behavior of liquid-liquid interfaces have been developed and applied to various dispersed systems, e.g., Stokes, Reiner-Rivelin, Ericksen, Einstein, Smoluchowski, and Kinch. A new theory of electroviscoelasticity describes the behavior of electrified liquid-liquid interfaces in fine dispersed systems and is based on a new constitutive model of liquids. According to this model liquid-liquid droplet or droplet-film structure (collective of particles) is considered as a macroscopic system with internal structure determined by the way the molecules (ions) are tuned (structured) into the primary components of a cluster configuration. How the tuning/structuring occurs depends on the physical fields involved, both potential (elastic forces) and nonpotential (resistance forces). All these microelements of the primary structure can be considered as electromechanical oscillators assembled into groups, so that excitation by an external physical field may cause oscillations at the resonant/characteristic frequency of the system itself (coupling at the characteristic frequency). Up to now, three possible mathematical formalisms have been discussed related to the theory of electroviscoelasticity. The first is the tension tensor model, where the normal and tangential forces are considered, only in mathematical formalism, regardless of their origin (mechanical and/or electrical). The second is the Van der Pol derivative model, presented by linear and nonlinear differential equations. Finally, the third model presents an effort to generalize the previous Van der Pol equation: the ordinary time derivative and integral are now replaced with the corresponding fractional-order time derivative and integral of order p<1.     

Measurement of circular dichroism spectra of liquid/liquid interface by centrifugal liquid membrane method.

The direct measurement of the circular dichroism (CD) spectra of liquid/liquid interface has been achieved for the first time by the centrifugal liquid membrane (CLM) method combined with a conventional CD spectropolarimetry. In the sample chamber of the CD spectropolarimeter, a cylindrical glass cell containing small amounts of organic and aqueous phases was rotated at ca. 7000 rpm to generate a two-phase liquid membrane with a high specific interfacial area. The CD spectra of the J-aggregate of protonated 5,10,15,20-tetraphenylporphyrin formed at the toluene/sulfuric acid interface in the rotating cell have been measured. The results demonstrated the novelty and advantages of this method.     

Broad liquid crystalline temperature range of ferroelectric liquid crystals

Novel ferroelectric liquid crystalline compounds, containing the (S)-2-methyl-l -butyl (4-hydroxybiphenyl-4'-carbonyloxy)biphenyl-4-carboxylate mesogenic group and an oligooxyethylene spacer, were synthesized. The mesomorphic properties of these materials were investigated by differential scanning calorimetry (DSC), optical polarizing microscopy (POM) and powder X-ray diffraction measurement. The results indicate that all members of this series exhibit a very broad temperature mesophase range (reaching a maximum around 210°C) including a blue phase (BP), cholesteric (Ch), twist grain boundary A (TGB_A), chiral smectic C (S*_c), and smectic X (S_x) phases. The mesomorphic properties are discussed and a comparison is made with three phenyl rings of ester core analogues.     

Flow of liquid around the encapsulated drop of another liquid

The problem of the infinite uniform flow of liquid around the spherical drop coated with the porous layer is solved. External liquid permeates into the porous layer but is not mixed with the liquid located in the internal cavity of a capsule. The flow inside the porous layer is described by the Brinkman equation; moreover, the viscosity of the Brinkman medium is assumed to be different than the viscosity of pure liquid. The boundary condition of the jump of tangential stresses at the liquid-porous medium interface is used. Velocity and pressure distributions are found and the hydrodynamic force acting on the capsule is calculated. Different limiting cases are considered.