Sensitive and selective determination of metabolically formed trans-dihydrodiols and phenols of benzo[a]pyrene in water and urine samples by HPLC with amperometric detection

A method has been developed to separate hydroxylated metabolites of the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene, i. e. trans-4,5-, 7,8-, 9,10-dihydrodiol and 1-, 3-, 7-, and 9-phenol, by HPLC with amperometric detection employing an isocratic methanol/water eluent (70:30, v/v) containing 0.5 g/L sulfuric acid and 1 g/L lithium perchlorate. Compared with the usually applied fluorescence (λ_ex = 265 nm, λ_em = 460 nm) and ultraviolet (λ = 265 nm) detection, the amperometric technique is about 2–12 times more sensitive for the determination of all metabolites investigated. The method was applied to the determination of the seven metabolites of benzo[a]pyrene in different water samples and in urine after solid-phase extraction (SPE). The results obtained by HPLC with amperometric detection after SPE enrichment from an aqueous extract of a soil sample and from the urine of a rat intragastrically treated with benzo[a]pyrene agreed well with the values determined with fluorescence and/or UV detection.     

Determination of polycyclic aromatic hydrocarbons in water by solid-phase microextraction and liquid chromatography.

This study describes the determination of polycyclic aromatic hydrocarbons (PAHs) in water using high-performance liquid chromatography (HPLC) coupled with fluorescence detection (FLD). Because individual PAHs are generally present in water only at trace levels, a sensitive and accurate determination technique is essential. The separation and detection of five PAHs were run completely within 25 min by the HPLC/FLD system with an analytical C18 column, a fluorescence detection, and acetonitrile-water gradient elution. Calibration graphs were linear with very good correlation coefficients (r > 0.9998), and the detection limits were in the range of 2-6 ng/l for five PAHs. Solid phase microextraction (SPME) was performed for sample pretreatment prior to HPLC-FLD determination, and the governing parameters were investigated. Compared to conventional methods, SPME has high recovery, saves considerable time, and reduces solvents waste. The extraction efficiencies of five PAHs were above 88% and the extraction times were 35 min in one pretreatment procedure. One particular discovery is that 1.5 M sodium monochloroactate (ClCH2COONa) can improve the extraction yield of PAH compounds more than other inorganic salts. The SPME-HPLC-FLD technique provides a relatively simple, convenient, practical procedure, which was here successfully applied to determine five PAHs in water from authentic water samples.     

Sensitive and selective determination of metabolically formed trans-dihydrodiols and phenols of benzo[a]pyrene in water and urine samples by HPLC with amperometric detection

A method has been developed to separate hydroxylated metabolites of the carcinogenic polycyclic aromatic hydrocarbon benzo[a]pyrene, i. e. trans-4,5-, 7,8-, 9,10-dihydrodiol and 1-, 3-, 7-, and 9-phenol, by HPLC with amperometric detection employing an isocratic methanol/water eluent (70:30, v/v) containing 0.5 g/L sulfuric acid and 1 g/L lithium perchlorate. Compared with the usually applied fluorescence (λ_ex = 265 nm, λ_em = 460 nm) and ultraviolet (λ = 265 nm) detection, the amperometric technique is about 2–12 times more sensitive for the determination of all metabolites investigated. The method was applied to the determination of the seven metabolites of benzo[a]pyrene in different water samples and in urine after solid-phase extraction (SPE). The results obtained by HPLC with amperometric detection after SPE enrichment from an aqueous extract of a soil sample and from the urine of a rat intragastrically treated with benzo[a]pyrene agreed well with the values determined with fluorescence and/or UV detection. Received: 20 December 1996 / Revised: 10 March 1997 / Accepted: 30 April 1997     

Selective immunoclean-up followed by liquid or gas chromatography for the monitoring of polycyclic aromatic hydrocarbons in urban waste water and sewage sludges used for soil amendment

A selective clean-up procedure using immunoaffinity solid-phase extraction was applied for the trace-level determination of polycyclic aromatic hydrocarbons (PAHs) in urban waste water and sewage sludges used for soil amendment. Anti-pyrene antibodies have been immobilized on a silica-based sorbent and the cross-reactivity of the antibodies towards structurally related compounds were allowed to extract the whole class of priority PAHs. The selectivity of the antibodies provided clean extracts from sludges and, therefore, the identification and quantification were shown to be easier using either liquid chromatography (LC) with UV diode array and fluorescence detection in series or gas chromatography-mass spectrometry (GC-MS), although some loss of up to 50% was observed for the clean-up. The identification of the PAHs by matching of UV and MS spectra was greatly improved. The procedure, including immunoclean-up and LC coupled to diode array and fluorescence detection, was validated using certified reference materials with native PAHs of concentrations in the range of 0.57-2.16 mg/kg (dry sludges).     

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 Aztreonam by liquid Chromatography with UV and Amperometric Detection

Abstract

A comparative study of UV and amperometric detection of aztreonam after HPLC separation is presented. At pH 2.0 and a detection potential of +1.15 V (vs. Ag/AgCl), the detection limits with amperometric detection are about two times higher (3–5 ng) than those obtained with UV detection (1–3 ng) for aztreonam and its main decomposition products, the E-isomer and open-ring aztreonam. With the advantage of specificity for the aminothiazole group of the aztreonam molecule, amperometry can be used as an alternative or complementary mode to UV detection for the determination of aztreonam in injectable formulations and in human serum.     

Headspace single drop microextraction combined with HPLC for the determination of trace polycyclic aromatic hydrocarbons in environmental samples

A new method by combining headspace single drop microextraction (HS-SDME) with HPLC fluorescence detection for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in environmental samples was developed. Aqueous solution of saturated beta-cyclodextrin was used as extraction solvent and five PAHs were employed as target analytes. The factors affecting the extraction efficiency were studied in detail and the optimal extraction conditions were established. Beta-cyclodextrin was found to play two important roles, one is the improvement of extraction efficiency of target analytes and the other is the enhancement of their fluorescence intensities in HPLC fluorescence detection. The detection limits for the target analytes were found to be in the range of 0.004-0.247ng/ml and the relative standard deviations (R.S.D.s) of 5.1-7.1% were obtained. The proposed method was applied to the analysis of trace PAHs in environmental samples with satisfactory results.     

Multiwalled carbon nanotubes/cryogel composite, a new sorbent for determination of trace polycyclic aromatic hydrocarbons

A new cost-effective sorbent, multiwalled carbon nanotubes/poly (vinyl alcohol) cryogel composite (MWCNTs/PVA), was prepared under frozen conditions for the extraction and preconcentration of trace polycyclic aromatic hydrocarbons (PAHs) in water samples. This was followed by high performance liquid chromatography (HPLC) with fluorescence detection. The proposed method provided a high enrichment factor with an extremely high extraction efficiency (89–98%) of three spiked levels of three standard PAHs with relative standard deviations of less than 8%. The low detection limits of the method were 5, 8 and 5 ng L^{− 1} for benzo(a)anthracene, benzo(b)fluoranthene and benzo(a)pyrene, respectively. This method was successfully applied for the determination of the three PAHs in real water samples where they were found in the range of 7 to 22 ng L^{− 1}. The major advantages of MWCNTs/PVA over the commercial C₁₈ is that it can be operated at a higher loading flow rate without sorbent clogging and requires a shorter time for completion without any loss of extraction efficiency.     

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.     

Exploration of coordination polymer as sorbent for flow injection solid-phase extraction on-line coupled with high-performance liquid chromatography for determination of polycyclic aromatic hydrocarbons in environmental materials

The copper(II) isonicotinate (Cu(4-C5H4N-COO)2(H2O)4) coordination polymer was prepared, characterized and explored as sorbent for flow injection solid-phase extraction on-line coupled with high-performance liquid chromatography (HPLC) for determination of trace polycyclic aromatic hydrocarbons (PAHs) in environmental matrices. Naphthalene, phenanthrene, anthracene, fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene and benzo(ghi)perylene with various shape, size and hydrophobicity were used as model analytes. The porosity of the coordination polymer allows these guest PAHs molecules to diffuse into the buck structure, and the shape and size of the pores lead to shape- and size-selectivity over the guests. The precolumn packed with the coordination polymer was shown to be promising for solid-phase extraction of PAHs in environmental samples with subsequent HPLC separation and UV detection. With extraction of 50 ml of sample solution, the enhancement factors for the PAHs studied ranged from 200 to 2337, depending on the shape, size and hydrophobic property of the PAHs. The detection limits (S/N = 3) of 2-14 ng l(-1) and the sample throughput of 3 samples h(-1) were obtained. The developed method was applied to the determination of trace PAHs in a certified reference material (coal fly ash) and local water samples.     

Analysis of 27 polycyclic aromatic hydrocarbons by matrix solid-phase dispersion and isotope dilution gas chromatography-mass spectrometry in sewage sludge from the Spanish area of Madrid

A method for the determination of 27 polycyclic aromatic hydrocarbons (PAHs) in sludge from wastewater treatment plants (WWTPs) located in urban, industrial or rural zones is presented. PAHs were extracted by matrix solid-phase dispersion (MSPD) assisted by sonication. Purification of extracts was carried out by solid-phase extraction with C(18) and PAHs were eluted with acetonitrile. PAHs were determined by isotope dilution gas chromatography with electron impact mass spectrometric detection in the selected ion-monitoring mode (GC-MS-SIM), using deuterated PAHs as internal standards. The limits of detection ranged from 0.03 ng/g for acenaphthylene to 0.45 ng/g for benzo[b]naphtho[2,1-d]thyophene. After optimization, the method was validated with a certified reference sludge. The proposed analytical method was applied to determine PAH levels in sewage sludge samples collected from 19 water treatment plants located in the province of Madrid (Spain). In most of the examined samples, phenanthrene was the main compound with a mean concentration of 1062 ng/g. PAHs were detected in all of the samples, with total concentrations between 390 and 6390 ng/g dry weight for the 27 PAHs analyzed and from 310 to 5120 ng/g dry weight for the sum of the 10 PAHs considered in the draft European Union directive.     

高效液相色谱法测定黄浦江表层沉积物中的痕量多环芳烃

建立了高效液相色谱-二极管阵列检测器(PDA)测定上海市黄浦江表层沉积物中16种多环芳烃(PAHs)的方法。在保留时间定性分析的基础上,利用PDA获取的紫外扫描光谱图对目标组分进行了准确的定性,并通过异构体紫外光谱图中特征峰的差异有效地识别了样品中的4种异构体,即苯并［b］荧蒽、 苯并［k］荧蒽、 苯并［a］芘和苯并［e］芘。通过检测波长的优化,减少了干扰物的影响,提高了检测灵敏度;针对分离度较差的两种目标组分(苯并［b］荧蒽和苯并［k］荧蒽)的定量进行了分析讨论。该方法对16种PAHs的检出限(以干基计)介于1.1～18.3 ng/g之间,具有较高的方法灵敏度。黄浦江表层沉积物测定结果表明,除二氢苊外的15种PAHs都被检出,含量为10.1～253.0 ng/g。     

Amperometric detection of unithiol complexes of heavy metals in high-performance liquid chromatography

It was demonstrated that Pb(II), Cd(II), Hg(II), Ni(II), Co(II), and Cu(II) can be indirectly determined as their unithiol complexes by amperometric detection under static and HPLC conditions. Factors affecting the Chromatographic separation and amperometric detection of metal complexes of unithiol were studied. Two designs of flow electrochemical cells (thin-layer and wall-jet cells) and three electrode materials (platinum, graphite, and glassy carbon) were compared. The best sensitivity was attained for an amperometric detector with wall-jet flow cell and a graphite indicator electrode. The detection limits for Hg(II), Pb(II), and Cd(II) were 0.9, 0.3, and 0.1 μg/mL, respectively. The Chromatographic determination of heavy metals in a sample of waste water was carried out using the amperometric detector     

直观推导式演进特征投影法解析多环芳烃的重叠色谱峰

用高效液相色谱法(HPLC)测定多环芳烃时,因芴、苊和菲,茚(1,2,3-cd)芘和苯并(g,h,i)苝的色谱峰严重重叠而影响测定结果。本研究用高效液相色谱-二极管阵列检测器(DAD)和荧光检测器(FLD)测定多环芳烃,在激发波长λex=230nm,发射波长λem=300～500nm范围内采集重叠峰的HPLC-FLD二维色谱数据,再用直观推导式演进特征投影法(HELP)解析它们的重叠色谱峰,分辨结果令人满意。该方法对重叠组分的分辨下限为0.02mg/L。结果表明,用二维色谱荧光数据解析色谱重叠峰,灵敏度更高,可用于环境样品中多环芳烃的测定。     

Determination of trace amounts of Galaxolide® (HHCB) by HPLC

An analytical method for the determination of trace amounts of Galaxolide^® (HHCB) by HPLC is presented. It is based on the separation of HHCB in different samples by a C18-column and a gradient elution by water and acetonitrile, both containing some acetic acid. The detection is carried out with a combination of a fast scanning UV detector and a fast scanning fluorescence detector. The fluorescence detection limit is 5 μg/L HHCB without sample pretreatment. HHCB adsorbed on solids or suspended solids can be extracted by ethanol.     

Polycyclic aromatic hydrocarbons in waste waters and sewage sludge: Extraction and clean-up for HPLC analysis with fluorescence detection

Summary A modified solid-phase extraction technique using sonication of the adsorbent material instead of the elution normally applied has been compared with two conventional liquid-liquid extraction procedures for the determination of the 16 EPA PAHs in municipal waste waters by means of HPLC coupled with fluorescence detection. Liquid-liquid extraction with cyclohexane proved to be the most efficient and simplest procedure. Clean-up of the waste-water extracts was not considered necessary, because of the high chromatographic resolution of the column and the selectivity of the fluorescence detector. Different organic solvents were also compared for ultrasonic extraction of PAHs from sewage sludge. The best results were obtained by use of acetonitrile. Clean-up of sewage-sludge extracts was not found necessary for accurate quantification of the major PAH components with fluorescence detection. The precision of the whole analytical procedure from extraction to the final determination of PAHs was satisfactory for both waste-water and sewage-sludge samples.     

Development of capillary electrophoresis methods for quantitative determination of taurine in vehicle system and biological media

CE methods have been developed for the determination of taurine in pharmaceutical formulation (microemulsion) and in biological media such as sweat. The CE system with end-column pulsed amperometric detection has been found to be an interesting method in comparison with UV and fluorescence detection for its simplicity and rapidity. A gold-disk electrode of 100 mm diameter was used as the working electrode. The effects of a field decoupler at the end of the capillary, separation voltage, injection and pressure times were investigated. A detection limit of 4 x 10(-5) mol/L was reached using integrated pulsed amperometric detection, a method successfully applied to taurine analysis of the biological samples such as sweat. For taurine analysis of oil-in-water microemulsion, fluorescence detector was the favored method, the detection limit of which was 4 x 10(-11) mol/L.     

On-line concentration and fluorescence determination HPLC for polycyclic aromatic hydrocarbons in seawater samples and its application to Japan Sea

An on?line concentration and fluorescence determination HPLC for polycyclic aromatic hydrocarbons (PAHs) in seawater was proposed. An online concentration column packed with octadecyl polyvinyl alcohol polymer, a pump and a column switching valve were introduced in the conventional HPLC with a fluorescence detector. Only 1.0-100?mL seawater sample was introduced into the concentration column at 1.0?mL?min(-1) without any other pretreatment except filtration. Then the trapped PAHs totally flew into the separation column and eluted separately to be detected fluorogenically. The proposed method had good linearity with correlation coefficients (r) ranged from 0.951 to 0.998, and limits of detection ranged from 0.002 to 0.50?ng?L(-1) for 15 PAHs as 100?mL seawater was loaded. The sensitivity of the method was 10 to 100 times higher than those reported by other works. The proposed method was applied to the determination of PAHs in the seawater samples collected in the Japan Sea with satisfactory results and to check the present benzo[a]pyrene concentration at the beaches in Noto peninsula, Japan polluted with C-heavy oil spilled from the tanker in 1997.     

Determination of polycyclic aromatic hydrocarbons in limpet samples

Summary An HPLC method with UV and programmed fluorescence detection has been optimized and used to evaluate the levels of contamination of PAHs in lightly contaminated biota samples. A specific stationary phase was used that offers high selectivity for PAH separation. The proposed method was applied to limpet samples from Fuerteventura (Canary Island) with good results.     

Analysis of delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine by ion chromatography and pulsed amperometric detection

A novel high-performance liquid chromatography (HPLC) method is presented for the detection and trace level determination of the tripeptide delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine (ACV). The tripeptide, an intermediate in penicillin production, is derived from fungal fermentation. The technique relies on ion-exchange separation of the tripeptide on an anion-exchange column followed by detection by reduction on a gold electrode using pulsed amperometry. The sensitivity of direct determination of ACV is increased by employing pulsed amperometric detection (PAD) over direct ultraviolet detection. Choice of the working electrode and optimisation of electrode potentials was based on cyclic voltammograms recorded for the tripeptide in the mobile phase. A linear regression equation was obtained over the range 0-100 micrograms ml-1. The detection limit in fermentation broths was found to be 0.1 micrograms ml-1 whereas in buffer the detection limit was found to be 10 ng ml-1. A good correlation coefficient was observed when ACV concentrations determined by ion chromatography-PAD were compared with measurements obtained by pre-column derivatisation with fluoromethylorthochloroformate followed by HPLC separation on a reversed-phase C18 silica column with UV detection. The procedure has been applied to the measurement of natural levels of ACV in fermentation broths of selected strains of Aspergillus nidulans and Penicillin chrysogenum.