高效液相色谱法同时测定食品接触材料中抗氧化剂和紫外吸收剂的迁移量

采用高效液相色谱技术,建立了食品接触材料中多种抗氧化剂和紫外吸收剂迁移水平的检测方法。该方法测定的23种目标化合物具有较好的线性关系,相关系数（r²）≥ 0.9998,检出限和定量限分别在0.01到0.22 mg/L之间和0.03到0.85 mg/L之间。依据欧盟指令（EU）No. 10/2011,考察了5种食品模拟物30 g/L乙酸、10%（v/v）乙醇、20%（v/v）乙醇、50%（v/v）乙醇和油类模拟物（异辛烷）中抗氧化剂和紫外吸收剂的迁移量。该方法回收率在92.8%~117.7%之间,相对标准偏差在0.95%~9.72%之间。探讨了不同实验条件对抗氧化剂和紫外吸收剂回收率的影响。结果表明,该方法准确、稳定,完全满足欧盟指令（EU）No 10/2011和GB 9685-2008对食品接触材料及制品中抗氧化剂和紫外吸收剂特定迁移量（SML）的限量要求,并利用该方法测定了30批次食品接触材料中抗氧化剂和紫外吸收剂的迁移水平。     

超高效合相色谱法快速检测塑料食品接触材料中13种紫外吸收剂

建立了一种同时检测塑料食品接触材料中13种紫外吸收剂的超高效合相色谱法。以甲醇为溶剂对塑料食品接触材料样品进行超声提取，经C18固相萃取柱净化，过0.22 μm有机滤膜，采用超高效合相色谱仪分析。选择ACQUTY UPC² HSS C18 SB色谱柱（150 mm×3.0 mm，1.8 μm），以超临界二氧化碳为流动相，异丙醇为改性剂进行梯度洗脱，在最优色谱条件下，13种紫外吸收剂能够在4 min内实现有效分离。结果表明，在各自线性范围内，13种紫外吸收剂的线性关系良好，标准曲线相关系数不低于0.9985，检出限（S/N=3）为0.05~0.15 mg/kg，加标回收率为86.8%~115.7%，相对标准偏差为0.73%~5.61%。该方法快速简便，准确可靠，同时大大减少了有机溶剂的消耗，可用于塑料食品接触材料中13种紫外吸收剂的快速检测。     

液相色谱-串联质谱法同时检测防晒化妆品中的11种紫外吸收剂

建立了防晒化妆品中11种紫外吸收剂的液相色谱-串联质谱检测方法。样品经甲醇-乙醇-水(80:10:10, v/v/v)提取,利用Eclipse XDB-C₁₈色谱柱(150 mm×4.6 mm, 5 μm)分离,以乙腈和0.1%甲酸水溶液为流动相,梯度洗脱。采用多反应监测(MRM)模式进行质谱测定,根据保留时间及质谱图上特征离子的相对丰度比进行定性,外标法定量。结果表明:该方法11种紫外吸收剂的定量限范围为200～500 mg/kg,回收率为77.17%～98.32%,相对标准偏差为2.40%～11.11%。该方法对于膏状和乳状防晒化妆品中的11种紫外吸收剂具有较好的适用性。     

Simple expressions for diffusion coefficient determination of adsorption within spherical and cylindrical absorbents using direct simulation method

Various analytical expressions for solute adsorption kinetics within porous absorbents of defined geometry (planar sheet, cylinder, and sphere) are available in the literature. However, these expressions are limited for practical numerical evaluation because they are based on infinite series. An investigation of these expressions has been carried out and then accurate but simple expressions derived that enable rapid determination of effective diffusion coefficients for adsorption within geometrically categorical absorbents. These involve directly fitting calculated kinetic adsorption curves to experimental ones. A simple one point method is also proposed to estimate the effective diffusion coefficient for an adsorption process within these simple geometrical absorbents as an initial value for a best fit.     

Rapid analysis of 14 ultraviolet absorbents in plastic food contact materials by supercritical fluid chromatography on Sub-2-micron particles

Abstract

A rapid and reliable method based on supercritical fluid chromatography (SFC) technology was established for the analysis of 14 ultraviolet (UV) absorbents in plastic food contact materials. The separation was optimized by employing different chromatographic conditions including stationary phases, organic modifiers, column temperatures and back pressures to achieve appropriate selectivity and resolution. The 14 UV absorbents were analyzed within 4.5?min on the sub-2-micron particles column (ACQUTY UPC² HSS C18?SB) via gradient elution with methanol as the organic modifier. The calibrations were carried out in the concentration range of 0.1–50.0?mg/L (except for UV-329 and UV-320 were 0.2–50.0?mg/L, UV-360 was 0.3–50.0?mg/L), and excellent linearity was observed with correlation coefficients (R²) greater than 0.99. The limits of quantification (LOQ) were in the range of 0.10–0.30?µg/g. The recoveries for accuracy were ranged from 90.4 to 114.1%, and the relative standard deviation (RSD) for repeatability was between 0.67 and 7.23%, respectively. The established method was successfully applied for the analysis of UV absorbents in five plastic food contact materials samples. The SFC method developed in this study can provide an alternative route for routine analysis of UV absorbents in the future.     

Determination of absorption efficiencies of carbon dioxide absorbents by gas chromatography

An HP-5880A gas chromatograph equipped with FID has been used to determine the efficiency of various CO(2) absorbents and some molecular sieves. Temperature, the CO(2) concentration in the absorbed gas mixture and space velocity of the gas mixture have effects on the absorption efficiency to different degrees, but temperature is a controlling factor. It has been established that in gas analysis the systematic errors arising from CO(2) impurities in the carrier gas are negligible when CO(2) is absorbed by carbon dioxide absorbents. Three methods for eliminating blank error are presented. The differential volume method through preconcentrating at the same time but at different flow-rates (DVMST) is proposed as the best method in preconcentration analysis. With the preconcentration technique, the minimum detectable level for CO(2) in a 10-litre sample is around 0.3 ppb(v/v).     

Applications of On-Line SFE/SFC in Environmental Analysis

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorinated Pesticides (OCPs) on different absorbents were extracted and analyzed by a directly coupled supercritical fluid extraction and supercritical fluid chromatography system (on-line SFE/SFC). The influence of various absorbents as sample matrixes on extraction efficiencies was evaluated. In general, the extraction efficiencies were decreased if a matrix had a larger surface area and a smaller pore size. The recoveries of PAHs and PCBs were decreased in inverse proportion to their molar mass. Recoveries of OCPs containing epoxy functional groups were greater than for OCPs lacking this functional group. In conclusion, online SFE/SFC is a rapid (1-2 h) and high recovery (70%-100%) analytical technique.     

Determination of atrazine and simazine in environmental water samples using multiwalled carbon nanotubes as the adsorbents for preconcentration prior to high performance liquid chromatography with diode array detector

Multiwalled carbon nanotubes, a new nanoscale material, has been gained many interests for use in various fields, and has exhibited exceptional merit as SPE absorbents for enrichment of environmental pollutants. This paper focused on the enriching power of atrazine and simazine, two important widely used triazine herbicides and described a novel and sensitive method for determination of these two herbicides based on SPE using multiwalled carbon nanotubes as solid phase absorbents followed by high performance liquid chromatography with diode array detector. Factors that maybe affect the enrichment efficiency of multiwalled carbon nanotubes such as the volume of eluent, sample flow rate, sample pH, and volume of the water samples were optimized. Under the optimal procedures, multiwalled carbon nanotubes as the absorbents have obtained excellent enrichment efficiency for atrazine and simazine. The detection limits of the atrazine and simazine were 33 and 9 ng l⁻¹, respectively. The spiked recoveries of the two analytes were over the range of 82.6-103.7% in most cases. Good analytical performance was achieved from real-world water samples such as river water, reservoir water, tap water and wastewater after primary pretreatment with proposed method. All these experimental results indicated that the developed method could be used as an alternative for the routine analysis of atrazine and simazine in many real water samples.     

Enantiomeric analysis of beta-pinene and limonene by direct coupling of reversed phase liquid chromatography and gas chromatography using absorbents as packing materials

A method based on the use of absorbents as packing materials inside the interface of the online coupling between RPLC and GC is proposed for the enantiomeric analysis of beta-pinene and limonene in essential oils. For that purpose, a comparison of the RSD, detection limit and recovery provided by two absorbents and one adsorbent is included in this study. The results found in this work proved the validity of absorbents as packing materials in online RPLC-GC to determine minor compounds in complex matrices. In particular, PDMS seemed to be specially useful to analyse nonpolar compounds, such as beta-pinene and limonene, since it provided higher sensitivity for this kind of compounds. The developed method was applied to the evaluation of the natural and non-natural character of commercial essential oils by means of the determination of the enantiomeric composition of beta-pinene and limonene.     

Possibilities and limitations of the sequential injection chromatography technique for the determination of anticoccidial agents in water, pharmaceutical formulations and feed

This paper explores the potential of applying reversed-phase sequential injection chromatography (SIC) to determine the anticoccidial agents Lasalocid and Toltrazuril in various matrices including ground water, pharmaceutical formulations and feed. SIC was performed by connecting a 25 × 4.6 mm monolithic C18 column to a 2 m long pathlength capillary flow cell, where the usage of a flow cell lowers the detection limit compared to a conventional short-distance flow cell, providing a simple detection system for these two compounds which are initially poorly UV absorbents.The proposed set-up provides a high injection throughput of 12 h^{− 1}, as well as a limit of detection of 0.019 and 0.010 mg/L for Toltrazuril and Lasalocid, respectively. The repeatabilities obtained (n = 10) were lower than 2% and 4% for Toltrazuril and Lasalocid, respectively.     

Preparation of a multi‐hollow magnetic molecularly imprinted polymer for the selective enrichment of indolebutyric acid

A simple strategy was developed for the preparation of multi‐hollow magnetic molecularly imprinted polymers by incorporating 3‐indolebutyric acid and ferroferric oxide nanoparticles simultaneously into a poly(styrene‐co‐methacrylic acid) copolymer matrix. The as prepared absorbents were characterized using scanning electron microscopy, Fourier‐transform infrared spectroscopy and mercury porosimetry. The adsorption isotherms of indolebutyric acid revealed that there are two types of affinity binding sites in the absorbents. The apparent maximum binding capacity and dissociation constant were 17.88 mg/g and 158.7 μg/mL for high‐affinity binding sites and 9.310 mg/g and 35.04 μg/mL for low‐affinity binding sites, respectively. The results testified that multi‐hollow magnetic molecularly imprinted polymers possessed excellent recognition capacity and fast kinetic binding behavior to the objective molecules due to the high specific surface area as large as 511.3 m²/g. Recoveries of 75.5–86.8% were obtained for the indolebutyric acid spiked at three concentration levels in blank and pear samples.     

基于氧弹燃烧-离子色谱法测定生活垃圾可燃组分中氯和硫的含量

采用氧弹燃烧法对垃圾样品干燥基进行前处理,用碳酸钠(24 mmol/L)和碳酸氢钠(30 mmol/L)以及过氧化氢(2.5%)为吸收液,并用离子色谱法对其处理后吸收液中氯离子和硫酸根含量进行测定,最后换算为样品中氯和硫的含量。氯和硫酸根质量浓度分别在1~50 mg/L与色谱峰面积呈良好的线性相关,其线性相关系数都大于0.999。样品中氯的加标回收率为96.5%~99.1%,硫酸根的加标回收率为92.5%~101%,测定结果中样品的相对平均标准偏差均小于3%(n=5),并用质控样品对方法进行了验证,结果表明样品的前处理方法简单、样品损失少、准确度高,适合于垃圾样品可燃组分中氯和硫含量的测定。     

Analysis of chlorophenols in environmental water using polydopamine‐coated magnetic graphene as an extraction material coupled with high‐performance liquid chromatography

In this work, polydopamine‐coated magnetic graphene nanocomposites were synthesized by a simple solvothermal reaction and self‐polymerization of dopamine, and the as‐made nanocomposites were successfully applied as an effective adsorbent for the preconcentration of the four chlorophenols in environmental water samples before high‐performance liquid chromatography. The polydopamine‐coated magnetic graphene nanocomposites have several advantages such as a high surface area, fast separation ability, super‐hydrophilicity, and high peak intensities for aromatic analytes. Various parameters, including eluting solvent and volume, the amounts of absorbents, extraction time and elution time were optimized. Validation experiments showed that the optimized method had good linearity (r² > 0.9990), satisfactory precision (RSD < 6.7%) and high recovery (90–105%). The limits of detection were 0.013–0.020 μg/L and the limits of quantification ranged from 0.043 to 0.070 μg/L. The results indicated that the proposed method had advantages of convenience, good sensitivity, and high efficiency. The method has been applied successfully to analyze chlorophenols in real water samples.     

Barium oxalate as a selective solid reagent for the absorption of sulphur trioxide

Barium and calcium oxalate monohydrates have been shown to be more suitable absorbents for sulphur trioxide than either anhydrous or hydrated oxalic acid. All four compounds are selective absorbents for the trioxide and do not absorb sulphur dioxide. Similarly all are elective absorbents for sulphuric acid aerosol, although the calcium salt may be decarboxylated under these conditions. Lead oxalate and formate may be suitable for the absorption of SO(3) and H(2)S, and SO(3), H(2)S and SO(2) respectively.     

Enhanced dissolution of cellulose in CO2 switchable system by solvent with low Henry's constants as CO2 absorbent

Cellulose - Organic solvents with low Henry's constants, such as propylene carbonate (PC) and sulfolane, were proposed to be used as CO2 absorbents to increase CO2 absorption capacity in the...     

Preparation of perlite-based carbon dioxide absorbent

A new highly efficient carbon dioxide absorbent consisting of sodium hydroxide, expanded perlite and acid-base indicator was prepared. The absorption efficiency, absorption capacity, flow resistance and color indication for the absorbent were tested and compared with some commercial products. The absorbent can reduce the carbon dioxide content in gases to 3.3 ppb (v/v) and absorbs not less than 35% of its weight of carbon dioxide. Besides its large capacity and sharp color indication, the absorbent has an outstanding advantage of small flow resistance in comparison with other commercial carbon dioxide absorbents. Applications in gas analysis and purification were also investigated.     

Effect of gas environment parameters on operation efficiency of chemical absorbents of carbon dioxide

Effect of main characteristics of the gas medium on the absorbing properties of alkaline chemical absorbents is demonstrated. The following gas flow parameters were examined as variables: carbon dioxide content of the gas flow within the range 0.2–5.0 vol %, gas humidity of 25–90 rel %, and pressure in the zone of the chemisorption process in the range from 2 to 6 MPa. As objects of study served mixed chemical absorbents based on calcium, sodium, and lithium hydroxides.     

无机盐活化剂-氨基酸盐基溶液捕集温室气体CO2

将无机盐K₃PO₄、K₂HPO₄和KH₂PO₄作为活化剂,分别添加于氨基乙酸盐溶液中,形成CO₂活化吸收剂,采用膜接触器 再生循环装置,评价和比较了氨基乙酸盐和活化吸收剂捕集CO₂的性能,研究了活化剂的浓度、气液流速等因素对总体积传质系数、传质通量和捕集率的影响。结果表明,磷酸盐活化剂在氨基乙酸盐吸收剂中,对CO₂的捕集均产生影响,活化效应存在PO₄^3－＞HPO₄^2－＞H₂PO₄^－的规律;添加少量活化剂的作用比添加较多量的活化作用大;活化吸收剂的捕集率明显大于非活化吸收剂;膜吸收流体力学状态的改变,能够改善膜接触器传质性能,增大传质通量,但增大的程度有限。     

3类高关注紫外线吸收剂的前处理与检测技术研究进展

紫外线吸收剂是一种具有强烈吸收紫外线作用的光稳定剂,会对生态环境以及人体健康造成危害,国内外许多国家已制定相关法规限制其使用。该文综述了近几年来国内外关于二苯甲酮类、三嗪类和苯并三唑类3类紫外线吸收剂检测的研究现状,分别对样品前处理与检测技术进行了详细介绍,并对其研究发展趋势进行了展望。     

Use of emanation thermal analysis and evolved gas analysis in thermal study of zinc(II) benzoate complex compounds

Volatile organic compounds (VOCs) are the main factors involved in pollution control and global warming in industrialized nations. Various treatment methods involving incineration, adsorption, etc., were employed to reduce VOCs concentration. Various absorbents, such as activated carbon, zeolite, silica gel or alumina, and so on were broadly used to adsorb VOCs in various industrial applications. Differential scanning calorimetry (DSC) was handled to analyze the thermal characteristics of absorbents. Typically, a scanning electron microscope (SEM) has been used to evaluate the structure variation of absorbents under high temperature situations. In view of pollution control and loss prevention, versatility and analysis of recycled adsorbents are necessary and useful for various industrial applications.