Rapid and sensitive determination of polycyclic aromatic hydrocarbons in atmospheric particulates using fast high-performance liquid chromatography with on-line enrichment system

A method using on-line enrichment and fast high-performance liquid chromatography (HPLC) with fluorescence detection has been developed and validated for the determination of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate samples. The evaporation step for sample preparation can be eliminated since this system allows the injection of 1000microL of sample solution. PAH recoveries were between 87% and 120% for spiked atmospheric particulate samples. The limit of detection was 0.02-0.23ng/mL (signal/noise ratio=3.3). There was good linear correlation between HPLC peak area and PAH concentration, with a linear range of 0.4-40ng/mL and correlation coefficients >0.997. Furthermore, compared to conventional approaches that include an evaporation step, the method proposed is acceptable for detecting PAHs in atmospheric particulate samples.     

Stereoselective determination of demethyl- and didemethyl-citalopram in rat plasma and brain tissue by liquid chromatography with fluorescence detection using precolumn derivatization

A rapid and sensitive HPLC enantioselective method with fluorescence detection was developed to determine (-)-(R) and (+)-(S) enantiomers of the metabolites of citalopram, demethyl- and didemethyl-citalopram in plasma and brain tissue. This assay involves pre-column chiral derivatization with (-)-(R)-1-(1-naphthyl)ethyl isocyanate followed by separation on a normal-phase silica column. The developed liquid-liquid extraction procedure permits quantitative determination of analytes with recoveries ranged between 81 and 88% with intra- and inter-day relative standard deviations less than 10.5%. Linearity was obtained over the concentration range 5-1000 ng/mL and 100-10,000 ng/g for spiked drug-free plasma and brain tissue, respectively, with detection limits lower than 2.1 ng/mL and 42.8 ng/g.     

Determination of polynuclear aromatic hydrocarbons in water by flotation enrichment and HPLC

A method of concentration and determination of several polynuclear aromatic hydrocarbons (PAHs) in water by flotation enrichment and HPLC is described. Triton X-100 was used as the foaming agent to extract the PAHs from water by passage of nitrogen. Reversed-phase liquid chromatography with coupled fluorescence detection was applied to separate and determine these PAHs. Various factors which may affect the recovery of PAHs from water, including pH, temperature and the concentration of Triton X-100 added, are discussed. This simplified method of concentrating PAHs from water has been applied to determine PAHs in water from Lake Erie. The method has practical value for the determination of PAHs in large volumes of water.     

Determination of uranium in seawater by flow-injection preconcentration on dodecylamidoxime-impregnated resin and spectrophotometric detection

A flow injection method has been developed for the determination of uranium in seawater combining the on-line preconcentration with spectrophotometric detection. An aliquot (10 mL) of the seawater sample adjusted to pH 5.5 was injected into the analytical system and uranium was adsorbed on the column packed with styrene-divinylbenzene copolymer resin (Bio-Beads SM-2) modified with dodecylamidoxime which showed high selectivity to uranium. Uranium was then eluted with 0.01 M hydrochloric acid and detected spectrophotometrically after the reaction with Chlorophosphonazo III. Interference from calcium and strontium was masked with cyclohexanediaminetetraacetic acid added to the chromogenic reagent solution. The sample throughput, the detection limit (3σ), and the preconcentration factor were 23 per hour, 0.13 μg/L, and 20, respectively, when the sample injection volume was kept at 10 mL. The precision at the 2 μg/L level was less than 4% (RSD). The proposed method was applied to the determination of uranium in the seawater samples collected off the Boso peninsula, Japan and the uranium concentration was found to be ca. 3 μg/L, which is close to the literature data. The yield of the recovery test ranged from 95% to 99%.     

An HPLC method for the determination of ethacridine lactate in human urine

An HPLC method was developed and validated for the determination of ethacridine lactate in human urine. Solid-phase extraction cartridges were used to extract urine samples. Separation was carried out on a C(18) column maintained at 30 degrees C with methanol-0.05% sodium dodecylsulfonate (70:30, v/v, pH 3) as mobile phase at a flow rate of 1.0 mL/min. Detection was at UV 272 nm. The calibration curve was linear in the concentration range of 4-4000 ng/mL, with linear correlation coefficient r equal to 0.9998. The limit of detection for the assay was 1.1 ng/mL. The within-day accuracy ranged from 94.8 to 101.6% and precision from 2.3 to 5.4%. The between-day accuracy ranged from 96.8 to 102.6% and precision from 4.0 to 5.3%. The absolute recovery was 95.4-101.2%. Urine samples were stable for at least 15 days if stored in the dark at -20 degrees C. This simple and accurate method allows the sensitive determination of ethacridine lactate in human urine. It was successfully applied to assess the urine level of ethacridine lactate in women received intra-amniotic injection.     

Solid-phase extraction clean-up procedure for the analysis of PAHs in lichens

A clean-up procedure based on a solid-phase extraction column was optimized for determination of polycyclic aromatic hydrocarbons (PAHs) in lichen extracts to remove co-extracted compounds from the matrix in the final extract. Several kinds of solid phases were evaluated: normal phase (-NH₂ and alumina), strong anion exchange and reversed phase. The -NH₂ columns were the most effective by using a packed solid bed of 500?mg. The lichen raw extract was loaded on the column previously conditioned with dichloromethane and hexane. Hexane (0.5?mL) was used as rinsing solvent, and PAHs were quantitatively eluted (80–97%) using 2?mL of hexane–dichloromethane (65–35) as eluting solvent. In these conditions, even the heaviest PAHs were quantitatively eluted. The optimized SPE method provides a short time and low-solvent-consumption sample clean-up compared with other conventional methods based on column chromatography. The analytical procedure, dynamic sonication-assisted extraction, followed by the optimized solid-phase extraction clean-up, was used to determine the 16 EPA priority PAHs from native lichens collected from the Aragon valley in central Pyrenees. The PAH concentrations in lichen samples ranged from 352 to 1654?ng?g^?1, and the minimum concentration value was established as the regional reference PAH levels in the area.     

Hplc Assay for Phenelzine Sulfate Drug Substance and the Decomposition Product Phenethyl Alcohol Using Short Wavelength UV Detection

Abstract

An HPLC procedure for the determination of phenelzine sulfate in the presence of its oxidation decomposition products expressed as phenethyl alcohol has been developed. The method uses a mobile phase consisting of 20:80 acetonitrile - 0.05 M sodium dihydrogen phosphate (pH 2.5) containing 0.02 M heptane sulfonic acid sodium salt, pumped at a flow rate of 1.0 mL/min. through a 100 mm × 4.6 mm i. d. octadecylsilane column (5 um) with UV detection at 209 nm. As little as 0.005% decomposition of phenelzine, expressed as phenethyl alcohol (134.5 pg on column), can also be detected at 209 nm. Peak height or area versus concentration of phenelzine base is linear over the range of 7.5 to 22.5 mg (r²=0.9982 for height and 0.9991 for area; n=5). Analysis of spiked samples of phenelzine gave mean percent recoveries of 101.31 ± 0.78%. Precision of the method ranged from 0.33 ? 1.42% and 0.53 ? 0.85% using peak height and peak area data, respectively.     

快速溶剂提取-高效液相色谱法测定PM2.5中16种多环芳烃

建立大气细颗粒物(PM2.5)中16种多环芳烃(PAHs)的快速溶剂提取-直接进样-高效液相色谱测定方法.PM2.5经玻璃纤维滤膜收集,采样后的滤膜直接用乙腈经快速溶剂萃取仪提取,以乙腈和水作为流动相,提取液通过ZORBAX Eclipse PAH液相色谱柱分离,紫外串联荧光检测器检测.16种PAHs分离效果良好,在0.025~5.000μg/mL范围内线性相关系数r≥0.9998,方法加标回收率为78.3%~113.2%,相对标准偏差为0.5%~9.5%,检出限为0.007~0.062 ng/m3.本方法操作简便、快速、准确、灵敏,适于PM2.5中16种PAHs的同时测定.     

Multiwalled carbon nanotubes as adsorbents of solid-phase extraction for determination of polycyclic aromatic hydrocarbons in environmental waters coupled with high-performance liquid chromatography

Multiwalled carbon nanotubes (MWCNTs) were used as a novel kind of solid-phase extraction adsorbents in this work as well as an analytical method based on MWCNTs solid-phase extraction (SPE) combined with high-performance liquid chromatography (HPLC) was established for the determination of polycyclic aromatic hydrocarbons (PAHs), some of which belong to typical persistent organic pollutants (POPs) owing to their carcinogenicity and endocrine disrupting activity. Several conditions that probably affected the extraction efficiency including the eluent volume, sample flow rate, sample pH and the sample volume were optimized in detail. The characteristic data of analytical performance were determined to investigate the sensitivity and precision of the method, and the method was applied to the determination of PAHs in environmental water samples such as river water sample, tap water sample and wastewater sample from the constructed wetland effluent. The experimental results indicated that there were excellent linear relationship between peak area and the concentration of PAHs over the range of 0.04-100 microg L(-1), and the precisions (RSD) were 1.7-4.8% under the optimal conditions. The detection limits of proposed method for the studied PAHs were 0.005-0.058 microg L(-1) (S/N=3). The recoveries of PAHs spiked in environmental water samples ranged from 78.7 to 118.1%. It was concluded that MWCNTs packed cartridge coupled with HPLC was an excellent alternative for the routine analysis of PAHs at trace level.     

加速溶剂萃取-固相萃取净化-气相色谱/质谱法测定土壤中的多环芳烃

建立了加速溶剂萃取-固相萃取净化-气相色谱/质谱法同时测定土壤中16种多环芳烃的方法。土壤样品经正己烷-丙酮提取,经无水Na₂SO₄脱水、氮吹浓缩后,弗罗里土小柱净化,采用气相色谱/质谱检测,内标法定量。结果表明:该方法在质量浓度0.4～10μg/mL范围内线性良好,相关系数(r²)大于0.9962,检出限为4.8～25μg/kg,定量限为19.2～100μg/kg;在0.05,0.15,0.40 mg/kg 3个加标水平下的平均回收率为55.4%～129.0%,相对标准偏差为1.5%～11%。采用该方法检测土壤样品,除苊烯、苊、芴3种多环芳烃未检出外,其他13种多环芳烃均有检出,其含量范围在6.6～86μg/kg。     

固相萃取-亲水相互作用液相色谱法同时测定环境水样中3种酰胺类化合物

基于亲水相互作用液相色谱(Hydrophilic Interaction Liquid Chromatography,HILIC)技术,建立了同时测定环境水样中丙烯酰胺、N,N-二甲基甲酰胺和N,N-二甲基乙酰胺的液相色谱分析方法.水样采用石墨化碳黑固相萃取柱净化,上样1.0 mL,并最终用1.0 mL乙腈洗脱,洗脱液进样色谱分析.选择Waters HILIC色谱柱,以乙腈/水作为流动相,等度洗脱,二极管阵列检测器200 nm条件下检测.在优化的分析条件下,3种酰胺类化合物在11 min内实现基线分离.所有目标化合物浓度在0.05～ 100 mg/L范围内线性良好,相关系数均大于0.9999;检出限达0.01 mg/L.加标回收率为84.1％～106％;相对标准偏差1.8％～10.4％.本方法具有简便快捷、灵敏准确等特点,能够满足环境水样中痕量酰胺类污染物检测的要求.     

Enrichment of polycyclic aromatic hydrocarbons in seawater with magnesium oxide microspheres as a solid-phase extraction sorbent

The enrichment of polycyclic aromatic hydrocarbons (PAHs) in water samples with magnesium oxide (MgO) microspheres was evaluated, and four 3-5-ring PAHs were used as probes to validate the adsorption capacity of the material. Factors affecting the recovery of PAHs were investigated in detail, including the type and concentration of organic modifiers, elution solvents, particle size of the adsorbent, volume and flow rate of the samples, and the lifetime of MgO cartridges. The recoveries of four PAHs extracted from 20 mL of seawater spiked with standard PAHs ranged from 85.8% to 102.0% under the optimised conditions. The limits of detection varied from 1.83 ng L⁻¹ to 16.03 ng L⁻¹, indicating that the analytical method was highly sensitive. Additionally, the proposed method was successfully used to enrich PAHs in seawater. Compared to conventional methods, the proposed method consumed less organic modifier (5% acetone), and cheaper sorbents with comparable extraction efficiency were employed.     

Detection of glucocorticoid residues in pig liver by high-performance liquid chromatography with on-line electrogenerated [Cu(HIO6)2](5-)--luminol chemiluminescence detection

A novel method was developed for the simultaneous determination of glucocorticoid residues such as triamcinolone (TR), prednisolone (PR), hydrocortisone (HC), cortisone (CO), methylprednisolone (MP), dexamethasone (DE) and triamcinolone acetonide (TA) by high-performance liquid chromatography (HPLC) coupled with chemiluminescence (CL) detection. The procedure was based on the enhancement effect of glucocorticoids on the chemiluminescence reaction between luminol and the complex of trivalent copper and periodate ([Cu(HIO6)2]5-), which was on-line electrogenerated by constant current electrolysis. The HPLC separation used a Nucleosil RP-C18 column (250 mmx4.6 mm i.d., 5 microm, pore size, 100 A) with a mobile phase consisting of acetonitrile and 1.0 mmol L(-1) ammonium acetate (pH 6.8, 40:60,v/v) at a flow rate of 0.8 mL min(-1). The effects of several parameters on the HPLC resolution and CL emission were studied systematically. Liver samples were hydrolyzed with Helix pomatia juice followed by a solid-phase extraction procedure. Under optimum conditions, the limits of detection (LOD) at a signal-to-noise of 3 ranged from 0.08 to 1.0 ng g(-1) and the limits of quantification (LOQ) at a signal-to-noise of 10 ranged from 0.27 to 3.33 ng g(-1) for seven glucocorticoids. The relative standard deviations (RSD) of intra- and inter-day precision were below 6.8%. The average recoveries for glucocorticoids (spiked at the levels of 5-50 ng g(-1)) in pig liver ranged from 88 to 106%, and the relative standard deviations of the quantitative results were from 2.0 to 6.9%. The proposed method had been successfully applied to the determination of glucocorticoid residues in pig liver.     

High performance liquid chromatographic method for the determination and pharmacokinetic studies of oxyresveratrol and resveratrol in rat plasma after oral administration of Smilax china extract

A sensitive and simple HPLC method has been developed and validated for the determination of oxyresveratrol (trans-2,4,3',5'-tetrahydroxystilbene, OXY) and resveratrol (trans-3,5,4'-trihydroxystilbene, RES) in rat plasma. The plasma samples were extracted with ethyl acetate and analyzed using HPLC on an Aglient Zorbax SB-C(18) column (250 x 4.6 mm, 5 microm) at a wavelength 320 nm, with a linear gradient of (A) acetonitrile and (B) 0.5% aqueous acetic acid (v/v), at a flow rate of 1.0 mL/min. The method was linear over the range of 0.1265-25.3 microg/mL for OXY and 0.117-23.4 microg/mL for RES. The extraction recovery for OXY, RES and internal standard ranged from 71.1 to 88.3%. The intra- and inter-day precisions were better than 10%, and the accuracy ranged from 89 to 108%. The validated method was used to study the pharmacokinetic profiles of OXY and RES in rat plasma after oral administration of Smilax china root extract.     

Comparison of two sample clean‐up methodologies for the determination of polycyclic aromatic hydrocarbons in edible oils

An off‐line high‐performance normal‐phase liquid chromatography procedure with a silica column followed by reversed‐phase high‐performance liquid chromatography (HPLC) with fluorescence detection for the determination of polycyclic aromatic hydrocarbons (PAHs) in edible oils is reported. The method was validated using certified reference materials and compared with a standardized method widely used in the food industry, consisting in low pressure column chromatography with alumina as stationary phase followed by reversed phase HPLC determination. The limits of detection were lower than 1 ng/g and good selectivity was achieved for both methods. There were no significant differences in accuracies and precisions obtained for each approach. The advantages and disadvantages of the two methods are discussed.     

Quantitative determination of DRF-1042 in human plasma by HPLC: validation and application in clinical pharmacokinetics

A simple and sensitive high-performance liquid chromatography (HPLC) method has been developed and validated for the determination of DRF-1042, a novel orally active camptothecin (CPT) analog, in human plasma. The sample preparation was a simple deproteinization with acidified methanol yielding almost 100% recovery of DRF-1042. An isocratic reverse-phase HPLC separation was developed on a Supelcosil-LC318 column (250 x 4.6 mm, 5 microm) with mobile phase consisting of 1% v/v triethylamine acetate, pH 5.5 and acetonitrile (80:20, v/v) at a fl ow rate of 1.0 mL/min. The eluate was monitored with a fluorescence detector set at excitation and emission wavelengths of 370 and 430 nm, respectively. The standard curves were linear (r(2) > 0.999) in the concentration ranges 5.0-2004 ng/mL. The lower limit of quantification (LLQ) of the assay was 5 ng/mL. The mean measured quality control (QC) concentrations (range 5 ng/mL to 40 microg/mL) deviated from the nominal concentrations in the range of -10.5-0.08 and -14.5-7.97%, inter- and intra-day, respectively. The inter- and intra-day precisions in the measurement of QC samples at four tested concentrations, were in the range 0.64-5.89% relative standard deviation (RSD) and 0.33-14.7% RSD, respectively. The method was found to be suitable for measurement of plasma concentrations above the calibration curve after serial dilutions. Stability of DRF-1042 was confirmed in a battery of studies, viz., on bench-top, in the auto-sampler, in the stock solutions, after four quick freeze-thaw cycles, up to one month at -20 degree C in human plasma and up to 2 months in the ex vivo samples. The method is simple, sensitive and reliable and has been successfully implemented to investigate the clinical pharmacokinetics of DRF-1042 in cancer patients in a phase I clinical trial.     

Determination of fleroxacin in pure and tablet forms by liquid chromatography and derivative UV-spectrophotometry

Derivative UV-spectrophotometric and liquid chromatographic (LC) methods for fleroxacin determination were validated. In the spectrophotometric assay, first-, second-, third-, and fourth-order measurements were applied with the use of peak-zero and peak-peak techniques. The linear correlation between amplitude of the peak and concentration of the examined drug ranged from 2.0 to 12.0 micro/mL. An isocratic LC analysis was performed on a Purospher ODS column with an acidic mobile phase containing tetrabutylammonium hydroxide. Measurements were made at a wavelength of 285 nm with 4-aminobenzoic acid (PABA) as internal standard. The calibration curve was linear (r = 0.9999) in the studied range of concentration (1.0-10.0 microg/mL). The accuracy (mean recovery, about 100%), precision (relative standard deviation < 1%), selectivity, and sensitivity of the elaborated methods were satisfactory.     

HPLC‐DAD method for the simultaneous determination of zofenopril and hydrochlorothiazide in oral pharmaceutical formulations

An HPLC method with DAD detection was developed and validated for the simultaneous determination of zofenopril and hydrochlorothiazide in tablets. The separation was carried out through a gradient elution using an Agilent LiChrospher C18 column (250×4.0 mm id, 5 μm) and a mobile phase consisting of (A) water–TFA (99.9:0.1 v/v) and (B) acetonitrile–TFA (99.1:0.1 v/v) delivered at a flow‐rate of 1.0 mL/min. 8‐Chlorotheophylline was used as internal standard. Calibration curves were found to be linear for the two drugs over the concentration ranges of 5.0–40 and 1.0–20 μg/mL for zofenopril and hydrochlorothiazide, respectively. Linearity, precision, accuracy, specificity and robustness were determined in order to validate the proposed method, which was further applied to the analysis of commercial tablets. The proposed method is simple and rapid, and gives accurate and precise results.     

Indirect fluorometric determination of diclofenac sodium.

A simple and easy method of analysis for diclofenac sodium is reported. A spectrofluorometric method for the microdetermination of diclofenac sodium has been developed through its reaction with cerium(IV) in an acidic solution and measurement of the fluorescence of the Ce(III) ions produced. Under the optimum experimental conditions for the oxidation reaction, 1.0 M H2SO4 with 90 min of heating time (100 degrees C), the range of application is 124.3-600 ng mL(-1) and the limit of detection is 72.7 ng mL(-1). The proposed method was applied to the determination of diclofenac sodium in pharmaceutical tablets. The results of the analysis show a good agreement with those obtained by the official USP 27 HPLC method.     

HPLC-F analysis of melatonin and resveratrol isomers in wine using an SPE procedure

An original analytical method has been developed for the determination of the antioxidants trans-resveratrol (t-RSV) and cis-resveratrol (c-RSV) and of melatonin (MLT) in red and white wine. The method is based on HPLC coupled to fluorescence detection. Separation was obtained by using a RP column (C8, 150 mm x 4.6 mm id, 5 mum) and a mobile phase composed of 79% aqueous phosphate buffer at pH 3.0 and 21% ACN. Fluorescence intensity was monitored at lambda = 386 nm while exciting at lambda = 298 nm, mirtazapine was used as the internal standard. A careful pretreatment of wine samples was developed, using SPE with C18 cartridges (100 mg, 1 mL). The calibration curves were linear over the following concentration ranges: 0.03-5.00 ng/mL for MLT, 3-500 ng/mL for t-RSV and 1-150 ng/mL for c-RSV. The LOD values were 0.01 ng/mL for MLT, 1 ng/mL for t-RSV and 0.3 ng/mL for c-RSV. Precision data, as well as extraction yield and sample purification results, were satisfactory. Thus, the method seems to be suitable for the analysis of MLT and resveratrol isomers in wine samples. Moreover, wine total polyphenol content and antioxidant activity were evaluated.