三维荧光二阶校正法用于未知混合物中苯酚含量的测定

将三维荧光光谱技术与秩消失因子分析、广义秩消失因子分析和交替三线性分解3种二阶校正方法相结合,建立了测定未知混合物中苯酚含量的三维荧光二阶校正新方法。设定在激发波长240~280 nm和发射波长280~360 nm范围内测定未知混合物中苯酚的三维荧光光谱,构建三维响应数据阵,运用基于三线性分解的二阶校正算法进行解析。结果表明,当模拟样品的组分数为2时,秩消失因子分析、广义秩消失因子分析和交替三线性分解3种方法测定苯酚的预测均方根误差分别为0.33,1.18和0.15,平均回收率分别为101.6%,115.6%和101.9%;当组分数为3时,3种方法的预测均方根误差则分别为1.61,1.80和0.51,平均回收率分别为134.2%,133.9%和107.1%;将其分别应用于实际样品中苯酚的测定,结果满意,且交替三线性分解法的测定结果优于秩消失因子分析法和广义秩消失因子分析法。     

The Application of Perdeuterated Polycyclic Aromatic Hydrocarbons (PAH) as Internal Standards for the Liquid Chromatographic Determination of PAH in a Petroleum Crude Oil and Other Complex Mixtures

Abstract

A sequential liquid chromatographic (LC) procedure for the determination of polycyclic aromatic hydrocarbons (PAH) in a petroleum crude oil and other complex mixtures is described. The procedure includes normal-phase LC on an aminosilane column to isolate fractions containing isomeric PAH and reversed-phase LC on a polymeric C₁₈ column to separate the individual PAH isomers. Appropriate perdeuterated PAH are added to the sample so that each isomeric fraction will contain one internal standard. The perdeuterated PAH are excellent internal standards for this sequential LC procedure. Perdeuterated PAH have normal-phase and reversed-phase LC retention characteristics similar to those of the parent PAH. In the normal-phase LC separation, the perdeuterated PAH elute in the same fraction as the parent PAH. In the reversed-phase LC separation, the perdeuterated PAH elute first and are generally resolved from the parent PAH. The optimized spectrofluorometric detection of each PAH analyte is accomplished by programming appropriate sets of excitation and emission wavelengths to correspond with the elation time of each analyte on the polymeric C₁₈ column. The analytical results obtained from this procedure for the analysis of a shale oil sample [Standard Reference Material (SRM) 1580] and a petroleum crude oil (SRM 1582) are compared to values obtained by gas chromatography - mass spectrometry.     

On the improvement of solid-phase extraction room-temperature phosphorimetry for the analysis of polycyclic aromatic hydrocarbons in water samples

This article presents considerable improvements in SPE-RTP methodology for the analysis of polycyclic aromatic hydrocarbons in water samples. Bulky glassware and vacuum pump were removed from the previous extraction procedure [E.D. Hagestuen, A.D. Campiglia, Talanta 49 (1998) 547] by processing 10 ml of sample with syringes and stainless steel filter holders. The oven-drying step was substituted by air sample drying, which employed positive pressure to remove water excess from the extraction membrane. As a result, analysis times from 8 to 10 min per sample were obtained. No costs in levels of detection were observed. Limits of detection at the pg ml(-1) level were estimated for phenanthrene, pyrene, benzo(k)fluoranthene, benzo(a)pyrene, and chrysene. The feasibility of identifying single components in PAH mixtures was investigated. Binary and tertiary mixtures were resolved by appropriate choice of excitation and emission wavelengths. The advantage of using excitation-emission matrix analysis was demonstrated for a six-component mixture.     

加速溶剂萃取-磁固相萃取净化-气相色谱-质谱法测定土壤中16种多环芳烃和23种有机氯残留

建立了加速溶剂萃取（ASE）、磁固相萃取净化（MSPE）、气相色谱-质谱（GC-MS）测定土壤中多环芳烃和有机氯残留的方法。ASE萃取溶剂为丙酮-正己烷（1：1，v/v），萃取温度为100℃，萃取压力为11.032 MPa，加热时间为5 min，静态萃取时间为5 min，循环萃取3次，冲洗体积为60%萃取池体积，氮气吹扫100 s。然后采用室温制备法自制ZIF-8/nZVI磁性材料用于净化萃取液，将净化液浓缩定容后进行GC-MS测定。多环芳烃和有机氯的线性范围为5~200 μg/kg，线性相关系数（r²）均大于0.99；目标物的检出限（LOD，S/N=3）为0.04~1.21 μg/kg。所建方法成功用于土壤样品中16种多环芳烃和23种有机氯的测定，在3个加标水平下得到的加标回收率为63.9%~112.1%，相对标准偏差（RSD）为0.4%~26.2%。研究结果表明，该方法具有灵敏度高、重现性好、回收率高等特点，适用于土壤中多环芳烃和有机氯残留的检测。     

Quantitative analysis of polycyclic aromatic hydrocarbons using high-performance liquid chromatography-photodiode array-high-resolution mass spectrometric detection platform coupled to electrospray and atmospheric pressure photoionization sources

Polycyclic aromatic hydrocarbons (PAHs) are common pollutants present in atmospheric aerosols and other environmental mixtures. They are of particular air quality and human health concerns as many of them are carcinogenic toxins. They also affect absorption of solar radiation by aerosols, therefore contributing to the radiative forcing of climate. For environmental chemistry studies, it is advantageous to quantify PAH components using the same analytical technics that are commonly applied to characterize a broad range of polar analytes present in the same environmental mixtures. Liquid chromatography coupled with photodiode array and high-resolution mass spectrometric detection (LC-PDA-HRMS) is a method of choice for comprehensive characterization of chemical composition and quantification of light absorption properties of individual organic compounds present in the environmental samples. However, quantification of non-polar PAHs by this method is poorly established because of their imperfect ionization in electrospray ionization (ESI) technique. This tutorial article provides a comprehensive evaluation of the quantitative analysis of 16 priority pollutant PAHs in a standard reference material using the LC–MS platform coupled with the ESI source. Results are further corroborated by the quantitation experiments using an atmospheric pressure photoionization (APPI) method, which is more sensitive for the PAH detection. The basic concepts and step-by-step practical guidance for the PAHs quantitative characterization are offered based on the systematic experiments, which include (1) Evaluation effects of different acidification levels by formic acid on the (+)ESI-MS detection of PAHs. (2) Comparison of detection limits in ESI+ versus APPI+ experiments. (3) Investigation of the PAH fragmentation patterns in MS² experiments at different collision energies. (4) Calculation of wavelength dependent mass absorption coefficient (MAC_λ) of the standard mixture and its individual PAHs using LC-PDA data. (5) Assessment of the minimal injected mass required for accurate quantification of MAC_λ of the standard mixture and of a multi-component environmental sample.     

Simultaneous determination of YM-64227, a phosphodiesterase type 4 inhibitor, and its five metabolites in dog plasma by high-performance liquid chromatography with fluorescence detection

We developed and validated a reversed-phase high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of YM-64227 [4-cyclohexyl-1-ethyl-7-methylpyrido(2,3-d)pyrimidin-2-(1H)-one], a novel and selective phosphodiesterase type 4 inhibitor, and its fi ve hydroxylated metabolites in dog plasma. The plasma samples were extracted with tert-butyl methyl ether under alkali conditions. The analytes were well separated on a phenyl ethyl column (5 microm, 250 x 4.6 mm i.d.), opreating at 40 degrees C and using an acetonitrile-acetic acid gradient at a fl ow rate of 1.0 mL/min. The fluorescence signal was monitored at an excitation and emission wavelength of 330 and 400 nm, respectively. No interfering peak was observed at the retention time of YM-64227, its metabolites or the internal standard. The validated quantitation range of the method was 0.4-200 ng/mL for all analytes using 0.5 mL of the plasma sample. The recovery of analytes in the extraction process was more than 65.5%. The intra- and inter-assay precision was less than 5.1 and 12.6%, respectively, and the intra- and inter-assay accuracy ranged from -8.1 to 11.8% and -8.0 to 9.9%, respectively. Using this assay, the plasma concentration of YM-64227 and metabolites can be determined after the oral administration of YM-64227 to beagle dogs.     

Design of a portable gas chromatography with a conducting polymer nanocomposite detector device and a method to analyze a gas mixture

A portable chromatography device and a method were developed to analyze a gas mixture. The device comprises a chromatographic column for separating components of a sample of the gas mixture. It has an air pump coupled to the inlet of a chromatographic column for pumping air and an injector coupled to the inlet of chromatographic column for feeding the sample using the air as a carrier gas. A detector is arranged downstream from and coupled to the outlet of the chromatographic column. The detector is a nanostructure semiconductive microfiber. The device further comprises an evaluation unit arranged and configured to evaluate each detected component to determine the concentration. The designed portable system was used for simultaneous detection of amines. The possibility of applying dispersive liquid–liquid microextraction for the determination of analytes in trace levels is demonstrated. The reproducibility of this method is acceptable, and good standard deviations were obtained. The relative standard deviation value is less than 6% for all analytes. Finally, the method was successfully applied to the extraction and determination of analytes in water samples.     

超声萃取-高效液相色谱法测定沉积物中多环芳烃

提出了高效液相色谱法测定沉积物中多环芳烃(PAH′s)含量的方法。样品中多环芳烃用正己烷-丙酮(1+1)混合溶液超声提取,离心分离后,所得萃取液经蒸发浓缩,然后过装有1g无水硫酸钠和2g硅胶的层析柱净化。以Varian PAHs色谱柱为分离柱,不同比例配成的甲醇和水为流动相梯度洗脱,用荧光检测器检测。方法的检出限(3S/N)在0.34～1.52ng.g-1之间。方法用于沉积物中多环芳烃的测定,测定结果的相对标准偏差(n=5)在3.2%～10.6%之间。用标准加入法测定方法的回收率,结果在57.1%～103.4%之间     

Laser-Induced fluorescence detection in conventional-size liquid chromatography with a frequency-doubled argon-ion laser

Laser-induced fluorescence (LIF) detection in conventional-size column liquid chromatography is achieved at 257 nm with a frequency-doubled argon-ion laser. Short-wavelength excitation offers two important advantages: firstly, a wide variety of analytes can be excited, and secondly, the Raman scatter of the eluent does not interfere with the fluorescence of the analytes. A standard mixture of polynuclear aromatic hydrocarbons was studied, both with LIF detection and with a commercially available sensitive conventional fluorescence detector. The improvement in the detection limits ranges from about a factory of 4 to 30; the LIF detection limits are typically at the 50 ng l^?1 level, which corresponds to an injected amount of 0.5 pg.     

Simultaneous spectrofluorometric determination of piroxicam and pyridoxine using generalized rank annihilation method.

The application of generalized rank annihilation method (GRAM) to the analysis of fluorescence excitation-emission matrices of mixtures of piroxicam and pyridoxine is described. The input of GRAM consists of two bilinear data matrices, i.e. one for unknown and one for the calibration sample. The excitation wavelength range was from 290 to 340 nm and the emission was recorded from 370 to 560 nm. Piroxicam and pyridoxine were determined in the concentration ranges 0.33 - 4.00 microg ml(-1) and 0.66 - 8.00 microg ml(-1), respectively. To check the accuracy of the proposed method, several binary synthetic mixtures and one real sample were analyzed successfully. No matrix effect was observed in mixture analysis, so a single external calibration sample was used for each analyte. The ability of GRAM to quantify the studied compounds and the comparability of GRAM results were evaluated by comparing them with those of PLS regression as a standard first-order calibration.     

Simultaneous determination of potassium guaiacolsulfonate, guaifenesin, diphenhydramine HCl and carbetapentane citrate in syrups by using HPLC-DAD coupled with partial least squares multivariate calibration

A simple and rapid analytical procedure was proposed for the determination of chromatographic peaks by means of partial least squares multivariate calibration (PLS) of high-performance liquid chromatography with diode array detection (HPLC-DAD). The method is exemplified with analysis of quaternary mixtures of potassium guaiacolsulfonate (PG), guaifenesin (GU), diphenhydramine HCI (DP) and carbetapentane citrate (CP) in syrup preparations. In this method, the area does not need to be directly measured and predictions are more accurate. Though the chromatographic and spectral peaks of the analytes were heavily overlapped and interferents coeluted with the compounds studied, good recoveries of analytes could be obtained with HPLC-DAD coupled with PLS calibration. This method was tested by analyzing the synthetic mixture of PG, GU, DP and CP. As a comparison method, a classsical HPLC method was used. The proposed methods were applied to syrups samples containing four drugs and the obtained results were statistically compared with each other. Finally, the main advantage of HPLC-PLS method over the classical HPLC method tried to emphasized as the using of simple mobile phase, shorter analysis time and no use of internal standard and gradient elution.     

Determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using zirconium containing chemical modifiers.

A method for direct determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using Zr, Ir, etylenediamine acetic acid (EDTA), Zr + EDTA, Ir + EDTA, Zr + Ir and Zr + Ir + EDTA as chemical modifiers in 0.5% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent was developed. The effects of mass and mass ratio of modifiers on analytes in sample solutions were studied. The optimum masses and mass ratios of modifiers: 20 microg of Zr, 4 microg of Ir, 100 microg of EDTA and 20 microg of Zr + 4 microg of Ir + 100 microg of EDTA, were used to enhance the analyte signals. Pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, and detection limits of analytes in samples were compared in the presence or absence of a modifier. The detection limits and characteristic masses of analytes in a 0.5% (m/v) dissolved sample (dilution factor of 200 ml g(-1)) obtained with Zr + Ir + EDTA are 8.0 ng g(-1) and 1.2 pg for Cd, 61 ng g(-1) and 4.3 pg for Cr, 32 ng g(-1) and 23 pg for Cu, and 3.4 ng g(-1) and 19 pg for Pb, respectively. The Zr + Ir + EDTA modifier mixture was found to be preferable for the determination of analytes in sediment and soil-certified and standard reference materials. Depending on the sample type, the percent recoveries of analytes were increased from 81 to 103% by using the proposed modifier mixture; the results obtained are in good agreement with the certified values.     

A simple,low-cost,remote fiber-optic micro volume fluorescence flowcell for capillary flow-injection analysis

A small volume flowcell for fluorescence detection in capillary flow injection (CFI) analysis has been created by using a low cost, commercially available fluidic device. Fluorescence detection is achieved using an optical fiber to deliver excitation light to the sample flowing through the device and another optical fiber to collect fluorescence emission. The flowcell is a standard fluidic cross with a swept volume of 721 nL. Optical fibers were oriented at right angles using standard sleeves and ferrules to set their position near the cross intersection. Multiple excitation sources were used including a low power UV laser and blue and UV light emitting diodes (LED). The full emission spectrum detection limits, using the laser, for fluorescein and bovine serum albumin (BSA) were 0.30 ppb and 2.1 x 10(-4)% (w/w), respectively. Two fluidic crosses were used in series for multi-wavelength fluorescence excitation using fiber-optically coupled LED.     

Determination of some hydroxybenzoic acids and catechins in white wine samples by liquid chromatography with luminescence detection

A liquid chromatographic method with luminescence detection for the determination of eight phenolic compounds is reported. The method involves postcolumn derivatization with terbium(III). This derivatization is based on the reaction between phenolics and terbium(III) to form luminescent chelates, which were determined at lamda ex 295 and lamda em 545 nm using the fluorescence mode. The long wavelength emission of lanthanide chelates can minimize interferences from background sample matrix, which usually emit at shorter wavelengths. Also, the chromatographic separation allows the individual determination of phenolics, which cannot be done using the direct measurement of the fluorescence of their corresponding terbium chelates. Dynamic ranges of the calibration graphs and detection limits, obtained with standard solutions of analytes were (microg/mL): gallic acid (0.9-40, 0.3), protocatechuic acid (0.05-7, 0.016), catechin (0.2-40, 0.07), vanillic acid (0.25-40, 0.08), p-hydroxybenzoic acid (0.8-40, 0.25), syringic acid (0.17-40, 0.05), epicatechin (0.3-40, 0.09) and salicylic acid (0.07-12, 0.02). The precision was established at two concentration levels of each analyte and expressed as the percentage of RSD with values ranging between 1.0 and 6.5%. The practical usefulness of the method was demonstrated by the analysis of white wine samples, which were diluted two-fold and directly injected into the chromatographic system. The recovery values obtained ranged between 93.3 and 108.0%.     

Flow-through fluorescence-based optosensor with on-line solid-phase separation for the simultaneous determination of a ternary pesticide mixture

A rapid and selective method was developed for the simultaneous determination of 3 widely used pesticides, carbendazim (CBZ), carbofuran (CF), and benomyl (BNM). The method utilized a single continuous-flow, solid surface fluorometric multioptosensor implemented with a previous separation of the analytes on a minicolumn, placed just before the sensor, that was packed with the same solid support (C18 silica gel) as the flow-through cell. The separation was achieved because of the different kinetics of retention/elution of the pesticides on the solid support in the minicolumn, enabling the sequential arrival of the analytes at the sensing zone. With a single injection of the mixture, 2 of them were more strongly retained in the minicolumn (CF and BNM) while the other (CBZ) passed through the system towards the sensing material where it developed its fluorescence transitory signal. Then, CF and BNM were successively eluted from the solid support using 2 different eluting solutions, and they sequentially reached the sensing zone and developed their respective signals. A multiwavelength fluorescence detection mode was used, recording the signals of each pesticide at its maximum excitation/emission wavelength; therefore, the sensitivity was increased. The system was calibrated using a sample volume of 2000 microL. The linear dynamic range was 80-1400, 250-2400, and 150-2000 ng/mL with detection limits of 15, 68, and 35 ng/mL and relative standard deviation values of 3.5, 3.2, and 2.4% for CBZ, CF, and BNM, respectively. A recovery study was applied to spiked environmental water samples, and recoveries ranged from 96 to 104%.     

High-performance liquid chromatographic determination of peptides in biological fluids by automated pre-column fluorescence derivatization with fluorescamine

Peptides containing a free alpha- or epsilon-amino group react with fluorescamine under mild alkaline conditions to generate a highly fluorescent but unstable reaction product and, consequently, practical high-performance liquid chromatographic (HPLC) approaches to analysis have typically involved the use of postcolumn derivatization. An automated precolumn approach is reported in which peptides are reacted with fluorescamine just prior to HPLC analysis by a commercially available autoinjector with derivatization capabilities. The autoinjector added base and fluorescamine reagent solutions to a sample vial containing peptide analytes, and the derivatization reaction was allowed to proceed for 5 min at room temperature prior to injection into the HPLC system. The derivatized peptides were analyzed by reversed-phase HPLC with fluorescence detection (excitation at 390 nm; emission 470-nm cut-off filter) on an octylsilica column. Optimization of the precolumn reaction conditions and the use of narrower HPLC columns (2 mm I.D.) resulted in a typical on-column detection limit of 30-50 fmol of peptide, which was substantially lower than that in previously reported post-column methods. This approach was applied to the HPLC of several naturally occurring and synthetic peptides containing alpha- and epsilon-amino groups. In combination with solid-phase extraction, prior to automated precolumn fluorescence derivatization and chromatographic analysis, the methodology was used for the determination of a synthetic growth hormone-releasing peptide in plasma samples.     

A simple and rapid high performance liquid chromatographic method with fluorescence detection for the estimation of fexofenadine in rat plasma--application to preclinical pharmacokinetics

A sensitive high performance liquid chromatographic (HPLC) method involving fluorescence detection was developed for the determination of fexofenadine (FEX), known to have low oral bioavailability, in rat plasma. In order to understand the effect of various chromatographic factors on the separation of analytes and to simultaneously optimize the resolution and analysis run time, a response surface method was used. The chromatographic separation was achieved using a Supelco C(18)-DB (250 mm x 4.6mm I.D./5 microm particle size) column with mobile phase comprising of ammonium acetate buffer and acetonitrile (63:37, v/v), delivered isocratically at a flow rate of 1.0 mL min(-1). Diphenhydramine was used as an internal standard (I.S.). The statistical evaluation of the method was examined and the method was found to be precise and accurate with a linearity range of 1-500 ng mL(-1) (r>0.9980). The intra- and inter-day precision studies showed good reproducibility with coefficients of variation (C.V.) less than 12.26%. The advantages of our method are small sample volume (100 microL), short time of analysis (13 min) and a simple sample extraction and clean-up as compared to the previously published methods. The established method provides a reliable bioanalytical methodology to carry out FEX pharmacokinetics in rat plasma.     

High-performance liquid chromatographic method for the determination of pindolol in human plasma

A sensitive, simple and highly reliable high-performance liquid chromatographic method using fluorescence detection is reported for the determination of pindolol in plasma. This method involves a single extraction of pindolol from alkalinized plasma into methyl tert.-butyl ether followed by a back-extraction into dilute hydrochloric acid. Injection of the dilute acid phase directly onto an octyl (LC-8) bonded-phase column provides the final separation, and detection of pindolol is achieved by monitoring the intrinsic fluorescence of pindolol at 315 nm following excitation at 255 nm. The method is sensitive enough to measure with confidence pindolol plasma concentrations of 2 ng/ml using a 2-ml sample. No internal standard is required. This method has been applied to the analysis of 1500 human plasma samples by two different laboratories.     

Laser-induced dispersed fluorescence detection of polycyclic aromatic compounds in soil extracts separated by capillary electrochromatography

Polycyclic aromatic hydrocarbons (PAHs) and nitrogen containing aromatic compounds (NCACs) are characterized in soil extracts and laboratory standards by capillary electrochromatography (CEC) with laser-induced dispersed fluorescence (LIDF) detection using a liquid-nitrogen cooled charge-coupled device detector. The LIDF detection technique provides information on compound identity and, when coupled with the high separation efficiencies of the CEC technique, proves useful in the analysis of complex mixtures. Differences in fluorescence spectra also provide a means of identifying co-eluting compounds by using deconvolution algorithms. Detection limits range from 0.5 to 96x10(-10) M for selected PAHs and 0.9-3.7x10(-10) M for selected NCACs. Soil extracts are also injected onto the CEC column to evaluate chromatographic method performance with respect to complex samples and the ability to withstand exposure to environmental samples.     

Polymers imprinted with PAH mixtures—comparing fluorescence and QCM sensors

Molecular imprinting with binary mixtures of different polycyclic aromatic hydrocarbons (PAH) is a tool for design of chemically highly sensitive layers for detection of these analytes. Sensor responses increase by one order of magnitude compared with layers imprinted with one type of template. Detection limits, e.g. for pyrene, reach down to 30 ng L(-1) in water, as could be observed with a naphthalene and pyrene-imprinted polyurethane. Comparing sensor characteristics obtained by QCM and fluorescence reveals different saturation behaviours indicating that, first, single PAH molecules occupy the interaction centres followed by gradual excimer incorporation at higher concentrations finally leading to substantial quenching, when all accessible cavities are occupied. The plateau in the mass-sensitive measurements suggests that up to 80% of the cavities generated in the MIP are re-occupied. Displacement measurements between chrysene and pyrene revealed that for imprinted layers with very high pyrene sensitivities the signals of both PAH are additive, whereas in materials with lower pyrene uptake the two analytes replace each other in the interaction sites of the polymer.