高效液相色谱法测定水性酚醛树脂中残留的甲醛和苯酚

采用高效液相色谱法同时测定了水性酚醛树脂粘稠液体中残留的甲醛和苯酚,用2,4-二硝基苯肼对甲醛进行衍生化,然后进行色谱分离。色谱柱:Waters Symmetry C18 (5 μm,4.6 mm × 250 mm);柱温:30 ℃;流动相:甲醇-水(体积比为43∶57);检测波长:苯酚270 nm,甲醛360 nm;运行时间:45 min;流速:0.8 mL/min。方法的相对标准偏差小于5%,检测限小于1 μg/L,加标回收率为96%~105%。使用该分析方法可对该类树脂的质量性能进行有效监控。     

A rapid and selective method for simultaneous determination of six toxic phenolic compounds in mainstream cigarette smoke using single-drop microextraction followed by liquid chromatography–tandem mass spectrometry

Cigarette smoke contains several toxic phenolic compounds, measurements of which are essential from a public health standpoint. This article describes a simple and selective analytical method for quantitative determination of six toxic phenolic compounds (phenol, catechol, resorcinol, hydroquinone, o-cresol, and p-cresol) from mainstream cigarette smoke using single-drop microextraction in combination with liquid chromatography–tandem mass spectrometry. Single-drop microextraction was applied prior to analysis by liquid chromatography–tandem mass spectrometry for the extraction and preconcentration of target phenolic compounds from raw cigarette smoke extract. The effects of the extraction solvent, sampling time, solution pH, salt addition, sample agitation rate, and temperature on the extraction efficiency were examined and optimized. The identification of each analyte was established by chromatographic retention times, analyte-specific fragmentation patterns, and relative peak area ratios of two product/precursor ion pairs. Analytical parameters such as the detection limit, relative recovery, reproducibility, linearity, and enrichment factor were evaluated under the optimized experimental conditions. 1-Decanol was selected as the extraction solvent and the limits of detection were found to be in the range of 0.05-0.3 ng mL^-1 using an extraction time of 12 min. Gradient chromatographic conditions were optimized for the separation of the six phenolic compounds in a run time of 10 min including reequilibration of the column. The present method for determination of phenolic compounds from mainstream cigarette smoke is simple and specific and shows good reproducibility, with relative standard deviations less than 10 % for all targeted phenolics.

超高效液相色谱β-环糊精流动相添加剂法分析卷烟主流烟气中7种酚类化合物

以β-环糊精(β-CD)作为流动相添加剂,建立了一种超高效液相色谱(UPLC)快速分析卷烟主流烟气中对苯二酚、间苯二酚、邻苯二酚、苯酚、对甲酚、间甲酚、邻甲酚的方法。卷烟主流烟气中7种酚类化合物采用YC/T 255-2008标准方法收集,萃取液经0.22 μm微孔滤膜过滤后直接进行UPLC分析。采用ACQUIT UPLC BEH Shield RP18色谱柱,以含有4 g/L β-CD的流动相进行梯度洗脱,采用优化后的荧光检测条件进行检测,分析时间为10 min。实验结果表明: 与目前国内外普遍应用的HPLC方法相比,该方法实现了间甲酚和对甲酚异构体的有效分离,7种酚类化合物的荧光响应强度显著增加。7种酚类化合物在该方法的线性范围内线性关系良好(r＞0.9999), 3个加标水平上平均回收率为95.5%～103.5%,相对标准偏差(RSD)均小于4%,方法的检出限为4～14 ng/cig。     

Fractionation and characterization of phenolic resins by high-performance liquid chromatography and gel-permeation chromatography combined with ultraviolet, refractive index, mass spectrometry and light-scattering detection

HPLC and gel permeation chromatographic (GPC) characterization of complex phenol-formaldehyde resins is described. Reversed-phase HPLC fingerprints the phenolic monomers, dimers and some oligomers. The molecular masses of these phenolic compounds were determined using an ion trap mass spectrometer. GPC analyzes tetrahydrofuran-soluble phenolic polymers beyond HPLC capability. The molecular mass distribution and structural information of the phenolics was determined by both conventional and laser light-scattering calibration methods. GPC with both UV and refractive index detection provides weight concentration of phenolic resin and the molar concentration of the phenol unit in the oligomers or polymers.     

Recent developments in the HPLC separation of phenolic compounds

Phenolic compounds represent a class of highly complex naturally occurring molecules that possess a range of beneficial health properties. As a result, considerable attention has been devoted to the analysis of phenolics in a variety of samples. HPLC is the workhorse method for phenolic separation. However, conventional HPLC methods provide insufficient resolving power when faced with the complexity of real-world phenolic fractions. This limitation has been traditionally circumvented by extensive sample fractionation, multiple analysis methods and/or selective detection strategies. On the other hand, there is an increasing demand for improved throughput and resolving power from the chromatographic methods used for phenolic analyses. Fortunately, during the last decade, a number of important technological advances in LC have demonstrated significant gains in terms of both speed and resolution. These include ultra high-pressure liquid chromatography (UHPLC), high-temperature liquid chromatography (HTLC), multi-dimensional separations as well as various new stationary phase chemistries and morphologies. In recent years, these technologies have also found increasing application for phenolic analysis. This review seeks to provide an updated overview of the application of recent advances in HPLC to phenolic separation, with the emphasis on how these methodologies can contribute to improve performance in HPLC analysis of phenolics.     

固相萃取-微乳液相色谱法测定环境水体中的3种酚类化合物

建立了固相萃取-微乳液相色谱法同时测定环境水体中的苯酚、双酚A (BPA)、2,4-二氯苯酚3种酚类化合物的检测方法。水样加酸酸化后,经C18固相萃取小柱富集净化,用微乳液相色谱法测定3种目标物的含量。在Inertsil C18色谱柱(150 mm×4.6 mm, 5 μm)上以微乳(3.0%十二烷基硫酸钠(SDS)-6.0%正丁醇-0.8%正庚烷-90.2%(水+0.5%HAc))和乙腈作为流动相进行梯度洗脱,流速1.0 mL/min,检测波长280 nm。结果表明,苯酚、双酚A、2,4-二氯苯酚的检出限(S/N=3)依次为0.74、8.0、8.0 μg/L,线性范围在0.1~10 mg/L范围内,相关系数(r)均大于0.999。将3种酚类化合物定量加到空白水样中,苯酚、双酚A、2,4-二氯苯酚的加标回收率分别为82.7%、87.8%、82.6%,其RSD均小于5%(n=6)。对环境水样的酚类化合物分析也取得了良好的加标回收率,其值均在85.7%~113.2%之间。结果表明,该方法准确可靠、灵敏度高,适用于环境水体中酚类化合物的检测。     

Ultra‐high performance supercritical fluid chromatography of lignin‐derived phenols from alkaline cupric oxide oxidation

Traditional chromatographic methods for the analysis of lignin‐derived phenolic compounds in environmental samples are generally time consuming. In this work, an ultra‐high performance supercritical fluid chromatography method with a diode array detector for the analysis of major lignin‐derived phenolic compounds produced by alkaline cupric oxide oxidation was developed. In an analysis of a collection of 11 representative monomeric lignin phenolic compounds, all compounds were clearly separated within 6 min with excellent peak shapes, with a limit of detection of 0.5–2.5 μM, a limit of quantification of 2.5–5.0 μM, and a dynamic range of 5.0–2.0 mM (R² > 0.997). The new ultra‐high performance supercritical fluid chromatography method was also applied for the qualitative and quantitative analysis of lignin‐derived phenolic compounds obtained upon alkaline cupric oxide oxidation of a commercial humic acid. Ten out of the previous eleven model compounds could be quantified in the oxidized humic acid sample. The high separation power and short analysis time obtained demonstrate for the first time that supercritical fluid chromatography is a fast and reliable technique for the analysis of lignin‐derived phenols in complex environmental samples.     

Fast and comprehensive analysis of secondary metabolites in cocoa products using ultra high‐performance liquid chromatography directly after pressurized liquid extraction

Fast methods for the extraction and analysis of various secondary metabolites from cocoa products were developed and optimized regarding speed and separation efficiency. Extraction by pressurized liquid extraction is automated and the extracts are analyzed by rapid reversed‐phase ultra high‐performance liquid chromatography and normal‐phase high‐performance liquid chromatography methods. After extraction, no further sample treatment is required before chromatographic analysis. The analytes comprise monomeric and oligomeric flavanols, flavonols, methylxanthins, N‐phenylpropenoyl amino acids, and phenolic acids. Polyphenols and N‐phenylpropenoyl amino acids are separated in a single run of 33 min, procyanidins are analyzed by normal‐phase high‐performance liquid chromatography within 16 min, and methylxanthins require only 6 min total run time. A fourth method is suitable for phenolic acids, but only protocatechuic acid was found in relevant quantities. The optimized methods were validated and applied to 27 dark chocolates, one milk chocolate, two cocoa powders and two food supplements based on cocoa extract.     

Determination of Plumbagin in Plant Extracts and Polyherbal Formulations by High-Performance Liquid Chromatography with Fluorescence Detection

Plumbagin, a naturally occurring naphthoquinone derivative, is known to possess various pharmacological activities. A rapid, sensitive, and specific high-performance liquid chromatographic method using fluorescence detection is reported for the determination of plumbagin in two Plumbago species and five polyherbal formulations. The method employed a reverse phase C18 column with isocratic elution using 65:35 pH 3.2 methanol and 0.1% aqueous o-phosphoric acid at a flow rate of 1.0 mL/min. Plumbagin displayed maximal fluorescence with excitation at 264 nm and emission at 605 nm. A linear calibration relationship was obtained for 1 to 10 µg/mL plumbagin with limits of detection and quantitation of 8 ng/mL and 30 ng/mL, respectively. The relative standard deviation values for intraday and interday precision were less than 2%. The recoveries were greater than 97% with relative standard deviations less than 3%. This is the first study to employ high-performance liquid chromatography with fluorescence detection for the determination of plumbagin. The method was rapid, sensitive, and accurate for the analysis of plants and polyherbal formulations.     

顶空气相色谱法测定离子交换树脂中8种有机溶剂残留

建立了功能食品加工用离子交换树脂中甲基异丙基甲酮、丁酸甲酯、3-戊酮、1,3-二乙基苯、1,4-二乙基苯、1,2-二氯乙烷、间二氯苯、甲基丙烯酸甲酯8种有机残留物的顶空气相色谱检测方法,研究了不同类型树脂中的有机残留物种类及含量,为食品和药品中安全使用离子交换树脂提供依据.优化了样品的提取溶剂和顶空气相色谱条件,样品经...     

Evaluation of Formaldehyde in Foundry Waste Sands Using Liquid Chromatography

Abstract

The industrial manufacturing of metallic objects results in a high level of foundry waste sands that may contain toxic compounds such as formaldehyde. The formaldehyde content of foundry waste sands was evaluated by liquid chromatography. Samples were collected during various steps of the industrial processes. Results showed that the phenolic alkaline process generated waste sands with higher formaldehyde content than the furanic process; the highest value was 7.6 × 10^?3% (w/w). In this work, formaldehyde content decreased with time in all of the samples studied, revealing that most formaldehyde was released to the occupational environment.     

酚醛树脂分子量及分布场解吸质谱表征方法研究

酚醛树脂分子量及分布的表征方法有很多,如蒸气压渗透法(VPO)、气相色谱、高压液相色谱和凝胶渗透色谱等,但由于酚醛树脂存在众多异构体,这些方法均有一定限制性.场解吸质谱(FD-MS)方法的特点是只给出样品固有组分的分子峰,不产生碎片离子峰,用于酚醛树脂的表征,可以直接得出树脂所有固有组分的分子离子峰值,及树脂不同缩合度组分的相对含量,非常适用于组份繁多的酚醛树脂的的分子量及分布表征研究.以苯酚、甲酚及甲醛等原料分别制备了Resole型苯酚-甲醛树脂、Novolac型苯酚-甲醛树脂、Novolac型甲酚树脂及混酚-甲醛树脂,利用FD-MS对制备的几种不同类型酚醛树脂的分子量及分布进行了研究.结果表明,通过FD-MS谱图分析还可以得到树脂缩聚程度、原料种类、树脂特性等信息,对于鉴别及剖析各种类型酚醛树脂方便有效.     

液-液萃取气相色谱法测定地表水中痕量苯酚

建立了液-液萃取气相色谱法测定地表水中痕量苯酚的方法。用盐酸调节水样至pH2左右,以二氯乙烷-乙酸乙酯(体积比为2∶1)混合溶液为萃取剂,以CD-5色谱柱进行分离,氢火焰离子化检测器检测苯酚的含量。苯酚的质量浓度在1.00~20.0μg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数r=0.999 3,检出限为0.03μg/L。样品加标回收率为93.0%~97.0%,测定结果的相对标准偏差小于2%(n=7)。该方法检出限低,精密度和准确度高,操作简便,适用于地表水中微量苯酚的分析。     

Determination of eleven priority EPA phenolics at ng L−1 levels by on-line solid-phase extraction and liquid chromatography with UV and electrochemical detection

Summary The eleven priority, EPA phenolic pollutants were determined by liquid chromatography followed by two detectors in series; UV and electrochemical. Three different adsorbents, Envi-Carb (a carbon black) and two functionalized polymeric resins, Bond Elut PPL and another synthesized in our laboratory with an ocarboxybenzoyl moiety, were compared for solid-phase extraction (SPE) to detect lower concentrations of the eleven phenolics in natural waters. Higher recoveries were obtained using the functionalized polymeric adsorbents compared with Envi-Carb. When real samples were analysed, the synthetic adsorbent gave lower interference than Bond Elut PPL and phenol was determined at low levels with no humic and fulvic acid inter-ference when Na₂SO₃ was added. The linearity range for most compounds in tap water was 0.05–20 μg L⁻¹ and the limits of detection were <35 ng L⁻¹. Repeatability and reproducibility between days for real samples spiked at 0.1 μg L⁻¹, expressed as relative standard deviation, were <8% and 10%, respectively.     

Chemical Fingerprint and Quantitative Analysis of Cirsium setosum by LC

A reverse phase liquid chromatography method with diode array detection was developed to evaluate the quality of Cirsium setosum through establishing chromatographic fingerprint and simultaneous determination of six phenolic compounds, namely chlorogenic acid, caffeic acid, rutin, linarin, luteolin and apigenin. The chromatographic separation was performed on an Agilent SB-C₁₈ column (250 × 4.6 mm, 5.0 μm) with a gradient elution program using a mixture of acetonitrile and 0.5% aqueous acetic acid (v/v) as mobile phase within 25 min at 326 nm wavelength. The correlation coefficients of similarity were determined from the LC fingerprints, and they shared a close similarity. The LC with electrospray ionization mass spectrometry experiment was performed to further confirm the identity of phenolic compounds. The six phenolic compounds showed good regression (R ² > 0.9995) within test ranges and the recovery of the method was in the range of 95.8–102.8%. In addition, the content of those six phenolic compounds in C. setosum growing in different locations of China was determined to establish the effectiveness of the method. The results indicated that the developed method by having a combination of chromatographic fingerprint and quantification analysis could be readily utilized as a quality control method for C. setosum and its related traditional Chinese medicinal preparations.     

Differentiation of Mint (Mentha haplocalyx Briq.) from different regions in China using gas and liquid chromatography

In this study, complex substances such as Mint (Mentha haplocalyx Briq.) samples from different growing regions in China were analyzed for phenolic compounds by high‐performance liquid chromatography with diode array detection and for the volatile aroma compounds by gas chromatography with mass spectrometry. Chemometrics methods, e.g. principal component analysis, back‐propagation artificial neural networks, and partial least squares discriminant analysis, were applied to resolve complex chromatographic profiles of Mint samples. A total of 49 aroma components and 23 phenolic compounds were identified in 79 Mint samples. Principal component analysis score plots from gas chromatography with mass spectrometry and high‐performance liquid chromatography with diode array detection data sets showed a clear distinction among Mint from three different regions in China. Classification results showed that satisfactory performance of prediction ability for back‐propagation artificial neural networks and partial least squares discriminant analysis. The major compounds that contributed to the discrimination were chlorogenic acid, unknown 3, kaempherol 7‐O‐rutinoside, salvianolic acid L, hesperidin, diosmetin, unknown 6 and pebrellin in Mint according to regression coefficients of the partial least squares discriminant analysis model. This study indicated that the proposed strategy could provide a simple and rapid technique to distinguish clearly complex profiles from samples such as Mint.     

A Novel Method for Determination of Ethoxyl Content in Ethyl Cellulose by Headspace Gas Chromatography

This paper reported a headspace gas chromatographic (HS-GC) method for the determination of ethoxyl in ethyl cellulose. A 0.5 mL sample of hydroiodic acid (57%) was added to ～20 mg samples in a closed headspace test vial (20mL) for 30 min at 120°C, for the quantitative cleavage of ethoxyl with hydroiodic acid (HI) to form ethyl iodide. After the reaction, the excess amount of HI in the vial was neutralized by injecting a sodium hydroxide solution, and then the ethyl iodide in the vial was determined by headspace gas chromatography using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD <0.5%) and accuracy (recovery = 98.6 ± 0.5%) for the quantification of ethoxyl content in ethyl celluloses. The present method is simple and accurate, which can be used for the efficient determination of ethoxyl substitution in ethyl cellulose related research.     

Optimization strategy and validation of one chromatographic method as approach to determine the phenolic compounds from different sources

We have designed a novel working strategy to optimize a unique chromatographic method consisting of diode array detection for the analysis of the most representative phenolic compounds from different food sources. The simultaneous inclusion of standard phenolic compounds, phenolic compounds isolated from food sources and representative real extracts as an ultimate test in analysis has allowed to establish, for the first time, a unique liquid gradient to serve as an excellent medium for the investigation of phenolics in samples from different food sources. Under the optimized conditions, 21 commercially available phenolic compounds and 25 commercially unavailable phenolic structures were analyzed in less than 30 min. The chromatographic method was designed as an alternative for the provisional identification of these compounds before their full characterization. The optimized chromatographic method was carefully validated for precision and accuracy. A high reproducibility in the retention time (<2%), peak area and calibration slope (<5%) as well as recoveries higher than 95% were obtained in all cases. Consequently, the currently described method was successfully employed to study the phenolic compounds in the most representative food samples.     

柱前衍生化高效液相色谱法测定氯氮平中肼含量

建立了柱前衍生高效液相色谱法准确测定氯氮平中游离肼的含量.该方法以对二甲氨基苯甲醛为衍生试剂,将游离肼衍生化为对二甲氨基苄连氮,然后进行高效液相色谱测定.采用Inertsil ODS-3色谱柱(250 mm×4.6 mm,5 μm)分离,以体积分数0.1％磷酸水溶液和乙腈为流动相进行梯度洗脱,检测波长为480 nm,流...     

Alkaline hydrolysis of cured phenol–formaldehyde resins at high temperatures

Hydrolysis of cured phenolic resin, either straight or oil- or epoxy-modified, in dilute caustic at 280–320°C, gives novolac resins in 70–80% recovery. Infrared analysis indicates these novolacs have the same composition as conventional novolacs made by the acid-catalyzed phenol–formaldehyde condensation. Like the conventional novolacs, these recovered resins are soluble in oxygen-containing solvents and form crosslinked infusible thermoset materials when heated with 10% hexamethylenetetramine. Molecular weights of the recovered novolacs, determined by high-pressure liquid chromatography, are dependent on both time and temperature of the hydrolysis. The weight-average molecular weight varied from 270 to 770. The Lowry index values indicate that the molecular weight distribution is narrower for the recovered novolacs than that normally obtained for conventional novolacs. The recovered novolacs have higher melting temperatures than the corresponding commercial novolacs. This is believed to be due to the lower free phenol content of the recovered novolacs.