Extraction and Gas-Chromatographic Determination of Phenol and Cresols in Soil

The effects of the acidity of an aqueous solution, the time of moistening a soil sample, and the time of ultrasonic desorption on the extraction of phenols from soils were studied. The optimum conditions were found. A procedure was developed for the gas-chromatographic determination of 0.05–50 mg/kg of phenol and o- and p-cresols in soil with an error of 10–25%. The time of analysis was 40 min.     

A simple and rapid electrophoretic method to characterize simple phenols, lignans, complex phenols, phenolic acids, and flavonoids in extra-virgin olive oil

We have devised a simple and rapid capillary electrophoretic method which provides the analyst with a useful tool for the characterization of the polyphenolic fraction of extra-virgin olive oil. This method that uses a capillary with 50 microm id and a total length of 47 cm (40 cm to the detector) with a detection window of 100 x 200 microm, and a buffer solution containing 45 mM of sodium tetraborate pH 9.3 offers valuable information about all the families of compounds present in the polar fraction of the olive oil. The detection was carried out by UV absorption at 200, 240, 280, and 330 nm in order to facilitate the identification of the compounds. Concretely, the method permits the identification of simple phenols, lignans, complex phenols (isomeric forms of secoiridoids), phenolic acids, and flavonoids in the SPE-Diol extracts from extra-virgin olive oil in a short time (less than 10 min) and provides a satisfactory resolution. Peak identification was done by comparing both migration time and spectral data obtained from olive oil samples and standards (commercial or isolated (by HPLC-MS) standards), with spiked methanol-water extracts of olive oil with HPLC-collected compounds and commercially available standards at several concentration levels, studying the information of the electropherograms obtained at several wavelengths and also using the information previously reported.     

Supercritical fluid extraction of phenol compounds from olive leaves

A clean, highly selective supercritical fluid extraction (SFE) method for the isolation of phenols from olive leaf samples was examined. Total phenol extracts were determined using the Folin-Ciocalteu reagent. Dried, ground, sieved olive leaf samples (30 mg) are subjected to SFE, using carbon dioxide modified with 10% methanol at 334 bar, 100 degrees C (CO(2) density 0.70 g ml(-1)) at a liquid flow-rate of 2 ml min(-1) for 140 min. Diatomaceous earth is used to reduce the void volume of the extraction vessel. The influence of extraction variables such as modifier content, pressure, temperature, flow-rate, extraction time, and collection/elution variables, were studied. Supercritical fluid extracts were screened for acid compounds such as carboxylic acids and phenols using Electrospray-MS (in the negative ionization mode). SFE was found to produce higher phenol recoveries than sonication in liquid solvents such as n-hexane, diethyl ether and ethyl acetate. However, the extraction yield obtained was only 45%, using liquid methanol.     

Micro-magnetic particles frit for capillary electrochromatography

This paper presents a new method for making frit using soft-ferrite-based micro-magnetic particles (MMPs) in a micro-space, such as in a capillary tube. The MMPs-frit was made by injecting an aliquot of 10 microm (outer diameter; o.d.)-MMPs-suspension in methanol (ca. 1mg/ml) into a capillary tube (75 microm inner diameter (i.d.) x 375 microm o.d. x ca. 35 cm length) that was already sandwiched between a pair of cylindrical Neodium (Nd-Fe-B) magnets (1.5 mm o.d. x 1.5 mm height, 280 mT) at a position where the frit was made. The MMPs were trapped in the capillary tube as a frit due to the attraction of the magnets placed at surface on the capillary tube. With regard to durability, the frit was stable for methanol flow with a flow rate of 400 microl/min at room temperature. Using such a frit, a capillary column (20 cm long) was prepared by injecting a 5 microm (o.d.)-ODS-particle suspension in methanol (ca. 0.4 mg/microl) into the capillary tube. The MMPs-frits-ODS-packed column was stable for methanol for a flow pressure less than 20MPa. When comparing the present column with a conventional sintered-frits-ODS-packed column for the purposes of separating five kinds of biogenic amines by means of an on-column derivatization capillary electrochromatography (CEC), the performance of the MMPs-frits capillary column was almost equivalent to that of the sintered-frits-ODS-packed column.     

Use of lignins as components of background electrolyte in capillary electrophoresis

The electrophoretic behavior of two lignins of different compositions, i.e., spruce dioxane lignin and lignosulfonate, is studied. The lignins are shown to affect the electrophoretic behavior of negatively charged analytes, such as carboxylic acids and phenols; their migration time increases. The addition of lignins improves the analytical parameters of phenol quantification by capillary electrophoresis. By means of a simple non-modified capillary, a mixture of six phenols was separated (simple phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, and perchlorophenol) with the high resolution (up to 20) and efficiency [(1–5) × 10⁵ TPM]. The separation of six phenols takes 10 min, the lower limit of the analytical range makes 1 μg/mL, the relative standard deviation does not exceed 3%. The potency for the determination of simple phenol and m-cresol is shown on an example of the Verrukatsid medication within 7 min.     

Changing the Electrophoretic Mobility of Phenols Using Ionenes as Additives in the Buffer Electrolyte

Water-soluble polymers of the ionene class with increased hydrophobicity (2-10-, 6-9-, and 3-X-ionenes) are used as modifiers in capillary electrophoresis in the determination of p-nitrophenol, phenol, and resorcinol. It is shown that 2-10-ionene provides the highest selectivity of phenol separation among all of the selected ionenes. The application of this polymer increases the selectivity of determination compared to commercially available 3-6-ionene (Polybrene) and poly(diallyldimethylammonium chloride). Under optimum conditions (a phosphate buffer solution, pH 11, U = –15 kV, l _cap = 50 cm), the separation efficiency of more than 40000 theoretical plates per capillary has been achieved with an analysis time of about 8 min. Using a stacking procedure, the efficiency of more than 250000 theoretical plates per capillary has been achieved. Changes have been introduced into the design of the capillary cartridge of a Kapel'-103R instrument. As a result, it has been possible to increase the field strength up to 1180 V/cm and, thus, to decrease the analysis time down to 2.5 min. The sensitivity of the instrument is mainly determined by the quality of the equipment used. The limits of detection of phenols are about 40 g/mL for a Kapel'-103R instrument and 0.05–0.1 g/mL for a Hewlett-Packard HP^3D CE.     

Determination of bisphenol A and 10 alkylphenols in serum using SDS micelle capillary electrophoresis with gamma-cyclodextrin.

A new micelle capillary electrophoresis based on cyclodextrin micellar electrokinetic chromatography (MEKC) for the determination of bisphenol A and 10 alkylphenols in rat serum is reported. Several surfactants and dextrins were studied. Bisphenol A and alkylphenols were separated using a 50 microm x 50 cm capillary with 20 mM borate phosphate buffer (pH 8.0) containing 20 mM sodium dodecylsulfate and 5 mM gamma-cyclodextrin as carrier. The method could determine 0.6-2000 microg/mL of phenols in 100 microL serum by photometric detection at 214 nm. Using 2.0 mL serum, 1.0 ng/mL of phenols could be determined. The relative standards deviations were 6.3-7.7% at 10 microg/mL in serum. The recoveries were 91.8-93.0% with 10 microg/mL serum samples.     

Separation of related opiate compounds using capillary electrochromatography

Capillary electrophoretic separations have been investigated for six controlled narcotic analgesic compounds having related structures. Owing to the similar charge-to-mass ratios of these compounds, capillary zone electrophoresis failed to provide a satisfactory separation, whereas a baseline-resolved separation was achieved in 10 min using micellar electrokinetic chromatography. Column efficiencies of 40,000-150,000 plates/m were obtained with a 50 cm long, 50 microm inner diameter (ID) capillary using 50 mM sodium dodecyl sulfate (SDS) in a 50 mM borate solution containing 12% isopropanol. In contrast, separation of this mixture by capillary electrochromatography proved to be significantly superior. The capillary was 15 cm long, with an ID of 75 microm, and was packed with 1.5 microm nonporous octadecyl silica (ODS) particles. The mobile phase consisted of 80% 10 mM tris(hydroxymethyl)aminomethane (Tris) and 20% acetonitrile, and contained 5 mM SDS. A complete separation was obtained in 2.5 min with an efficiency of 250,000-500,000 plates/m.     

铬酸钴催化剂上苯酚和甲醇气相邻位烷基化反应

研究了具有尖晶石结构的铬酸钴及负载钾的铬酸钴催化剂上苯酚和甲醇气相邻位烷基化反应. 结果表明, 相对较高的反应温度有利于提高催化剂的反应活性和2,6-二甲酚的选择性; 随着质量空速的降低, 苯酚的转化率和2,6-二甲酚的选择性逐渐增加, 邻甲酚的选择性逐渐降低, 这表明2,6-二甲酚是邻甲酚进行连续反应的结果. 另外, 钾的引入能明显提高邻甲酚的选择性, 降低苯酚的转化率和2,6-二甲酚的选择性, 原因可能主要是由于负载钾后铬酸钴催化剂上的较强的酸中心数目明显减少所致.     

Chiral separation of benzoporphyrin derivative mono- and diacids by laser induced fluorescence-capillary electrophoresis

A method for the separation of benzoporphyrin derivative mono- and diacid (BPDMA, BPDDA) enantiomers by laser induced fluorescence-capillary electrophoresis (LIF-CE) has been developed. By using 300 mM borate buffer, pH 9.2, 25 mM sodium cholate and 10% acetronitrile as electrolyte, +10 kV electrokinetic sampling injection of 2 s and an applied +20 kV voltage across the ends of a 37 cm capillary (30 cm to the detector, 50 microm ID), all six BPD stereoisomers were baseline-separated within 20 min. Formation constants, free electrophoretic and complexation mobilities with borate and cholate were determined based on dynamic complexation capillary electrophoresis theory. The BPD enantiomers can be quantitatively determined in the range of 10(-2)-10(-5) mg mL(-1). The correlation coefficients (r2) of the least-squares linear regression analysis of the BPD enantiomers are in the range of 0.9914-0.9997. Their limits of detection are 2.18-3.5 x 10(-3) mg mL(-1). The relative standard deviations for the separation were 2.90-4.64% (n = 10). In comparison with high-performance liquid chromatography (HPLC), CE has better resolution and efficiency. This separation method was successfully applied to the BPD enantiomers obtained from a matrix of bovine serum and from liposomally formulated material as well as from studies with rat, dog and human microsomes.     

pH-mediated dual-cloud point extraction as a preconcentration and clean-up technique for capillary electrophoresis determination of phenol and m-nitrophenol

pH-mediated dual-cloud point extraction (dCPE) technique for capillary electrophoresis (CE) determination of phenol and m-nitrophenol is proposed in this paper. This technique for the preconcentration and clean-up of the two analytes includes two steps through simple pH-mediation. The analytes are transferred into surfactant-rich phase in the first step (under acidic condition) with Triton X-114 as the extractant because the two analytes become hydrophobic in acidic solution. They were back-extracted into alkaline aqueous phase in the second cloud point step. Because the concentration of Triton X-114 in the final aqueous solution after dCPE is only around critical micelle concentration, its adsorption on the inner wall of capillary and its possible influence on electrophoretic separation are eliminated. Baseline separation of phenol and m-nitrophenol is realized in a 60 cm x 75 microm i.d. capillary at 18 kV using 50 mM boric acid solution (pH 9.5). The preconcentration factors are 24.0 for phenol and 22.5 for m-nitrophenol. The detection limits of phenol and m-nitrophenol are 2.0 x 10(-6) mol L(-1) and 2.5 x 10(-6) mol L(-1), respectively. The proposed method was successfully applied to the determination of two analytes in spiked natural water samples.     

Micellar electrokinetic chromatography method for the determination of sulfamethoxazole, trimethoprim and their main metabolites in human serum

A complete analytical procedure, including sample clean-up and a micellar electrokinetic chromatographic method, is presented for the determination of sulfamethoxazole, trimethoprim, and their main metabolites by using 20 mmol L(-1) borate buffer (pH 9.3), 25 mmol L(-1) sodium dodecylsulfate, and 5% v/v acetonitrile as electrolyte. The separation was carried out at 30 kV and 20 degrees C in a fused silica capillary (60.2 cm x 75 microm inner diameter) fitted with a window in the capillary cartridge of 100 x 800 microm. The detector response was linear from the limit of quantification to 3 mg L(-1) for the individual components. The limits of quantification ranged from 0.13 up to 0.24 mg L(-1). The method was applied to human serum, previously spiked at different concentrations of all the analytes, and recoveries between 95% and 108% were obtained.     

Simultaneous determination of phytoestrogens in different medicinal parts of Sophora japonica L. by capillary electrophoresis with electrochemical detection

A high-performance capillary electrophoresis with electrochemical detection (CE-ED) method has been developed for the determination of phytoestrogens from the pericarps and seeds of Sophora japonica L. in this work. Genistin, genistein, rutin, kaempferol and quercetin are important bioactive constituents in these plants. The effects of several factors such as the acidity and concentration of running buffer, the separation voltage, the applied potential and the injection time on the CE-ED procedure were investigated. Under the optimum conditions, the five analytes could be well separated within 18 min in a 75 cm length capillary (i.d. 25 microm) at the separation voltage of 16 kV in a 50 mmol L(-1) borax running buffer (pH 9.0). A 300 microm diameter carbon disk electrode was used as the working electrode positioned carefully opposite the outlet of the capillary in a wall-jet configuration at the potential of +950 mV (vs SCE). Detection limits (S/N = 3) ranged from 1.1 x 10(-7) to 2.8 x 10(-7) g mL(-1) for all fi ve analytes. This method was successfully used to analyse dried Flos sophorae immaturus, pericarps and seeds of dried Fructus sophorae after a relatively simple extraction procedure, and the assay results were satisfactory.     

Accelerated solvent extraction combined with dispersive liquid–liquid microextraction before gas chromatography with mass spectrometry for the sensitive determination of phenols in soil samples

A method combining accelerated solvent extraction with dispersive liquid–liquid microextraction was developed for the first time as a sample pretreatment for the rapid analysis of phenols (including phenol, m‐cresol, 2,4‐dichlorophenol, and 2,4,6‐trichlorophenol) in soil samples. In the accelerated solvent extraction procedure, water was used as an extraction solvent, and phenols were extracted from soil samples into water. The dispersive liquid–liquid microextraction technique was then performed on the obtained aqueous solution. Important accelerated solvent extraction and dispersive liquid–liquid microextraction parameters were investigated and optimized. Under optimized conditions, the new method provided wide linearity (6.1–3080 ng/g), low limits of detection (0.06–1.83 ng/g), and excellent reproducibility (<10%) for phenols. Four real soil samples were analyzed by the proposed method to assess its applicability. Experimental results showed that the soil samples were free of our target compounds, and average recoveries were in the range of 87.9–110%. These findings indicate that accelerated solvent extraction with dispersive liquid–liquid microextraction as a sample pretreatment procedure coupled with gas chromatography and mass spectrometry is an excellent method for the rapid analysis of trace levels of phenols in environmental soil samples.     

Capillary Zone Electrophoresis of Eleven Priority Phenols with Amperometric Detection

A scheme for separation and detection of eleven priority phenols using capillary zone electrophoresis (CZE) coupled with amperometric detection is described. With a capillary of I.D. 50 μm and length 62.5 cm at 9 kV and an electrophoretic buffer of 20 mM CHES (pH 10.1), complete separation of the eleven compounds was achieved in less than 17 min. Amperometric detection was carried out using a carbon fiber microelectrode of diameter 9 μm inserted into the end of the detection capillary. Linearity over two orders of magnitude was generally obtained for the eleven priority phenols. With an electrode potential+1.10 V (vs. Ag/AgCl reference), the concentration limits of detection were in the sub-ppm (10^?6 M) level. This method was successfully applied to analysis of priority phenols in industrial waste water.     

毛细管电泳安培法检测酚类化合物

使用自行设计组装的毛细管电泳柱端安培检测系统 ,对四个酚类化合物进行了分离检测。研究了工作电极、缓冲液及其 p H值、检测电压和分离电压对分离检测的影响。在优化条件下 ,4个酚在 5× 1 0 -6～ 5× 1 0 -4 mol/L范围内峰高与浓度成良好的线性关系 ,检测下限为 8.5× 1 0 -7mol/L     

Comparison of gas chromatography-mass spectrometry and capillary electrophoresis in analysis of phenolic compounds extracted from solid matrices with pressurized hot water

Self-constructed pressurized hot water extraction (PHWE) equipment was used in dynamic mode to extract spiked phenolic compounds (phenol, 3-methylphenol, 4-chloro-3-methylphenol and 3,4-dichlorophenol) from sea sand and soil. Phenols were analyzed by both gas chromatography-mass spectrometry (GC-MS) and capillary zone electrophoresis (CZE) to compare the techniques and to find out if CZE is a suitable tool for analysis of phenols extracted from environmental matrix. Good recoveries of phenols spiked in sea sand were achieved at all PHWE temperatures (50, 100, 200, 300 C). GC-MS studies showed that phenols were selectively extracted from soil at 50 C but various other compounds (e.g. polyaromatic hydrocarbons) were extracted along with the phenols at 300 degrees C. In the case of CZE, phenols extracted from the soil, at 300 C were separated with good resolution at pH 9.7, and co-extracted compounds did not interfere with the analysis. The analytical values obtained by GC-MS and CZE were generally of similar magnitude.     

Tryptic digest mapping by gradient capillary electrochromatography

A high performance liquid chromatography (HPLC) system complemented with T-split, capillary detection cell and a high voltage power supply was used for peptide mapping by gradient electrochromatography and nanoliquid chromatography (nano-LC). With capillary columns of 100 microm ID, 6 cm packed with octadecylated 1.5 microm silica particles, the typical analysis time was approximately 10-15 min. The resolution of a tryptic digest of cytochrome c obtained by electrochromatography at 100 kV/m was superior compared to the analysis by nano-LC. Bubble formation caused by Joule heating at currents up to 100 microA was successfully suppressed by using a resistor capillary of 25 microm ID connected to the outlet of the packed column.     

Gas-chromatographic headspace analysis of phenol and cresols in soils by direct acetylation

A quick, simple and selective procedure has been developed for the determination of phenol, o-cresol, m-cresol, and p-cresol in soil samples. The method is based on the gas chromatographic headspace analysis of phenols as acetate derivatives. These acetates were prepared directly in the wetted soil samples by acetic anhydride in the presence of KHCO_3˙ With this procedure sample handling is reduced to a minimum as desorption and derivatization of the analytes are developed from the wetted samples inside the vial of the head space sampler. The acetate esters were analyzed using a 60 m × 0.56 mm DIIDP capillary column (di-isodecyl-phthalate), using 2-chlorophenol as an internal standard. The detection limit was between 0.03–0.08 μg g⁻¹ for the different species considered. Soil samples having carbon contents lower than 5 % can be analyzed by the proposed procedure.     

Fast supercritical fluid chromatography hydrocarbon group-type separations of diesel fuels using packed and monolithic columns

Two approaches for decreasing diesel hydrocarbon group-type separation times by normal phase supercritical fluid chromatography (SFC) are compared. Short (10-15 cm) columns with small 3 microm diameter packing are compared with monolithic Chromolith bare silica columns under high carbon dioxide flow rates approaching 5 ml min(-1). Elution times are reduced up to 13-fold on a 10 cm Chromolith column and 7-fold on the short packed columns compared with conventional length columns run at typical flow rates. Short packed columns, with their higher surface area and retention characteristics, offer higher resolutions compared with Chromolith columns. Diesel samples are separated into saturates, mono-, di-, tri-, and polyaromatics in as little as 2 min on a 10 cm packed silica column. Diesel group-type results on a 15 cm titania-silica coupled column compare favorably with results from longer columns.