Advantages and limitations of HPLC in environmental analysis

Summary The application of HPLC to environmental analysis is often hindered by difficulty not experienced in other areas of analysis. Usually the components being determined are at parts per million levels or less and are usually in sample matrices that can yield many interferences. In order to develop successful methodology the prime requirements for an HPLC system are column efficiency and the sensitivity and selectivity of the detection system. In this presentation, examples are given to illustrate how HPLC can be used to advantage by comparing it to gas chromatographic (GC) methods and even TLC methods. For many classes of compounds, such as halogenated hydrocarbons (pesticides, PCB’s, dioxins), the GC methods may be preferred. However, for polycyclic aromatic hydrocarbons (PAH) HPLC with fluorescence detection has proven to be excellent for trace environmental analysis. Comparisons of HPLC with TLC for aflatoxins and with bioassays for paralytic shellfish toxins are made. Novel combinations such as headspace-HPLC analyses for SO₂ and HPLC-AA for organometallic compounds are discussed.     

Determination of bioconcentration factors of isomeric polycyclic aromatic hydrocarbons in polychaete worms by HRGC on selective liquid crystalline stationary phases

The bioconcentration factors (K_b) of parent and alkylated PAHs isolated from polychaete worms collected in coastal sediments were determined for the first time. Capillary gas chromatography using a polymeric liquid crystalline (MPMS) and SE-54 stationary phases coupled to FID, MS and concurrent elution with authentic standards permitted positive identifications of parent PAHs. The K_b values of 18 compounds were accurately determined on the liquid crystalline column and the those of mono- and dialkyl-phenathrene, -pyrene and -chrysene were determined by GC-MS on a SE-54 coated column. The experimental K_b values exhibited a moderate correlation (r=0.7–0.8) with the reported octanol-water partition coefficients (K_ow) for these compounds. Consequently, kinetic considerations, i.e. biouptake-release and enzymatic activity seem to be relevant, in addition of biota-media equilibrium. Therefore, integrated bioconcentration models are needed.     

Screening direct analysis of PAHS in atmospheric particulate matter with SPME

A direct headspace SPME method with PDMS fiber was developed for the determination of polynuclear aromatic hydrocarbons (PAHs) in atmospheric particulate matter collected in HiVol filter. The recovery obtained for PAHs lower than four congeners with the proposed method falls in the range 50-125% and DL was around 5-20 pg. The results obtained with standard reference materials (SRM 1649 and SRM 1650) for determination of PAHs showed acceptable agreement with the declared or certificated values.     

Quantification of 1-hydroxypyrene in undiluted human urine samples using magnetic solid-phase extraction coupled with internal extractive electrospray ionization mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental contaminants raising worldwide concerns due to their carcinogenic effects. In this study, 1-hydroxypyrene (1-OHP, the most widely used biomarker of internal dose of PAHs exposure) in undiluted human urine samples (10 mL) was selectively enriched by polypyrrole-coated Fe₃O₄ magnetite nanocomposites (termed as Fe₃O₄@Ppy, 1 mg) and then directly eluted by the electrospraying solvent (acetone/benzene/acetic acid (v/v/v, 90/10/1); 100 uL) biased with −3.5 kV to produce the deprotonated 1-OHP anions for mass spectrometric analysis. The method established here significantly improved the current performance for detection of urinary 1-OHP, providing the speed for a single sample analysis within 4 min, the limits of detection (LOD) of 0.0001 μg L⁻¹, the linear response range of 0.001–5.000 μg L⁻¹ (R² = 0.9994), recovery rates of 90.6–96.1%, and relative standard deviation (RSD, n = 6) values between 2.9% and 8.0%. Human samples including raw human urine collected from 10 healthy volunteers (5 smokers and 5 nonsmokers) and 7 lung cancer patients have been successfully analyzed, showing that magnetic solid-phase extraction (MSPE) coupled with internal extractive electrospray ionization mass spectrometry (iEESI-MS) is an alternative strategy for high throughput quantitative detection of urinary 1-OHP for health risk assessment of PAHs exposure.     

Origin of Polycyclic Aromatic Hydrocarbons (PAH) in Recent Sediments from the Continental Shelf of the “Golfe de Gascogne” (Atlantic Ocean) and in the Gironde Estuary

Abstract

Several aromatic series have been analysed on sediment extracts by high performance liquid chromatography coupled (HPLC) and by high resolution Shpol'skii spectroscopy. HPLC coupled to a programmable spectrofluorometer as detector has been used for the detection of the sixteen PAH priority pollutants recommended by the US Environmental Protection Agency. Relative distribution in methylated phenanthrene, chrysene, and pyrene series have been examined by high resolution spectrofluorometry in Shpol'skii matrices for the determination of the sources of aromatic matter in the sediments. These complementary studies would provide useful information on the origin of PAH in marine sediments.     

Total concentration analysis of polycylic aromatic hydrocarbons in aqueous samples with high suspended particulate matter content

The European water framework directive (WFD) requires priority pollutants to be measured in the whole water sample and not only in the dissolved phase. However, it does not give clear definitions on how to achieve this. To overcome this limitation, a new methodology of sample preparation procedure for the analysis of polycyclic aromatic hydrocarbons on the basis of extraction disks is introduced here. The automatable procedure includes a “one-step” extraction of the analytes both dissolved in the liquid phase of the sample and sorbed to suspended particulate matter. The latter is extracted concurrently with the solid-phase extraction (SPE) material within the elution step of the procedure. Separation, identification, and quantification of the analytes is performed by GC–MS. Results from surface water samples spiked with certified sediment up to 1000 mg/l are presented in this work and compared with results derived from liquid–liquid extraction (LLE). Most measured values are within or at least near certified uncertainty limits of the sediment. The SPE disk method shows much higher recoveries and better precision (relative standard deviations between 2% and 11%) than the standard LLE method. For all substances under investigation, the limits of quantification achieved range between 0.001 and 0.005 μg/l.     

Studies of the Photochemical Degradation Kinetics of BaP on Different Substrates: Formation of Oxygenated Compounds

Abstract

The rate constant for BaP decomposition induced by exposure to UV rays and rate constants for BaP1,6; 3,6; 6,12 diones formation were determined. Experiments were conducted by depositing the BaP on clean glass fiber-filter and on airborne paniculate collected by filter. The BaP half-life appears to be positively correlated with filter loading and airborne particulates protect BaP from UV degradation. Our results suggest that BaP1,6dione, BaP3,6dione, BaP6,12dione are not the main by-products of BaP photodegradation induced by UV.     

An Investigation of Filter Types,Extraction Solvents and Storage Conditions Used for PAH Measurement in Diesel Exhaust

Abstract

A device capable of collecting simultaneously eight equivalent particulate diesel exhaust samples was constructed to test the effect of filter type, extraction solvent and storage condition on the measured concentration of five PAH compounds (fluoranthene-Ft, pyrene-Py, benz(a)anthracene-BaA, benzo(k)fluoranthene-BkFT, and benzo(a)pyrene-BaP) in diesel exhaust. An experimental design was used to most efficiently test the variables. A linear model (GLM) was used to analyze the data.     

Identification and Differentiation of Isomeric Methylated Derivatives of Oxygenation Products of Polycyclic Aromatic Hydrocarbons by Gas Chromatography - Mass Spectrometry

Abstract

An isomeric pair of compounds is obtained from 4-car-boxyaldehydephenanthrene-5-carboxylic acid (1) by various methods routinely applied for the methylation of acidic oxygenation products of K-region polycyclic aromatic hydrocarbons (PAH's) prior to GC and GC/MS analysis. Differentiation of the individual cyclic and acyclic isomers, a classical general problem, proves possible by careful analysis of the mass spectral fragmentation patterns in the representative case studied here.     

Influence of surface plasmon resonance wavelength on SERS activity of naturally grown silver nanoparticle ensemble

We present experimental results to quantify and optimize the surface‐enhanced Raman scattering (SERS) activity of naturally grown silver nanoparticles. Ag nanoparticle ensembles with mean equivalent radii ranging from 10.6 to 20.3 nm were prepared under ultrahigh vacuum conditions by Volmer–Weber growth on quartz plates. A tuning of the localized surface plasmon polariton resonance wavelength from 453 to 548 nm was performed by varying the morphology of the silver nanoparticles. The dependence of the SERS activity on the plasmon resonance wavelength was investigated with a Raman set‐up containing a microsystem light source with an emission line at 488 nm. Shifted excitation Raman difference spectroscopy was applied to remove the fluorescence‐based background from the SERS spectra of pyrene in water using two slightly different emission wavelengths (487.61 and 487.91 nm) of the microsystem light source. We demonstrate that the Raman activities for all SERS substrates are available in the nanomolar range in a water sample. However, the Raman activity crucially depends on the plasmon resonance wavelength of the nanoparticle ensembles. Although for an on‐resonance ensemble the limit of detection for pyrene in water is very low and was estimated to be 2 nmol/L, it increases rapidly to several tens of nanomol for slightly off‐resonance ensembles. Hence, the highest SERS activity was obtained with a nanoparticle ensemble exhibiting a plasmon resonance wavelength at 491 nm, which almost coincides with the excitation wavelengths. Copyright © 2012 John Wiley & Sons, Ltd.