Determination of epichlorohydrin in water and sewage samples

The simple, quick and effective methods for the analysis of epichlorohydrin (ECH) in water and sewage samples with the use of gas chromatography have been presented. From among all the methods developed, the procedures for monitoring drinking-water quality and the methods which allow the determination of epichlorohydrin in sewage samples have been selected.

The limits of ECH detection have been determined by direct aqueous injection (DAI) into the chromatographic column and an analysis with the application of a flame ionization detector (FID), a mass spectrometry detector (MS), an electron capture detector (ECD) and atomic emission detection (AED) detectors. The method allows the determination of ECH in water samples at the concentration level of 0.1 mg l⁻¹. Moreover, the developed methods of water samples preparation for chromatographic analysis using the following extraction methods: headspace (HS), stripping with adsorption on solid phase, liquid–liquid extraction (LLE), solid phase extraction (SPE) and solid phase microextraction (SPME) have been evaluated. The limits of ECH detection for each procedure with the application of gas chromatography (GC) combined with various detectors have been determined and their statistical evaluation has been presented. The SPME method allowed us to determine ECH in water samples at the concentration levels of 1.0 ng l⁻¹.

The results of studies on the choice of the selective methods allowing ECH analysis in sewage samples have been demonstrated. The applied SPME method was found to be a quick and effective technique to determine micro trace amounts of ECH in samples containing high amounts of various organic compounds.     

Microwave-assisted phase-transfer catalysis for the rapid one-pot methylation and gas chromatographic determination of phenolics

Microwave-assisted phase-transfer catalysis (PTC) is reported for the first time, for the one-step extraction–derivatization–preconcentration and gas chromatographic determination of twenty phenols and ten phenolic acids. The well established phase-transfer catalytic methylation is largely accelerated when heating is replaced with the “greener” microwave irradiation. The overall procedure was thoroughly optimized and the analytes were determined by GC/MS. The method presented adequate analytical characteristics being more sensitive in analyzing phenols than phenolic acids. The limits of detection without any additional preconcentration steps (e.g. solvent evaporation) were adequate and ranged from 0.4 to 15.8 ng/mL while limits of quantitation were between 1.2 and 33.3 ng/mL. The method was applied to the determination of phenols, in spiked environmental samples and phenolic acids in aqueous infusions of commercially available pharmaceutical dry plants. The recoveries of fortified composite lake water samples and Mentha spicata aqueous infusions ranged from 89.3% to 117.3% for phenols and 93.3% to 115.2% for phenolic acids.     

Calculation of the relative acidities and oxidation potentials of para-substituted phenols. A model for alpha-tocopherol in solution

Relative acidities (Delta pK(a)) of phenols and oxidation potentials (Delta E(ox)) of the phenoxide anions have been calculated for nine para-substituted phenols using density functional theory. Solvent effects were incorporated using the conductor-like polarisable continuum method. Using the calculated Delta pK(a) and Delta E(ox) values in a thermodynamic cycle, the DeltaBDE (bond dissociation enthalpy) of the phenols were also determined with all values calculated to within 1.5 kcal mol(-1) of experiment. The Delta pK(a) and Delta E(ox) values were calculated for 6-hydroxy-2,2,5,7,8-pentamethylchroman (HPMC), a model for alpha-tocopherol for which there are no known experimental values. The acidity of this compound is raised by 2.4 pK(a) units and lowered by -0.79 V relative to phenol with a calculated Delta BDE of -14.9 kcal mol(-1). There is a negative correlation (r(2) = 0.86) between the Delta pK(a) and the Delta BDE values. A stronger and positive correlation is found between the Delta E(ox) (r(2) = 0.98) and the Delta BDE values. Using these correlations it is uncovered that hydrogen abstraction of phenols, as measured by the Delta BDE, is driven by electron transfer rather than by proton transfer.     

Predicting the activity of phenolic antioxidants: theoretical method, analysis of substituent effects, and application to major families of antioxidants.

A procedure based on density functional theory is used for the calculation of the gas-phase bond dissociation enthalpy (BDE) and ionization potential for molecules belonging to the class of phenolic antioxidants. We show that use of locally dense basis sets (LDBS) vs full basis sets gives very similar results for monosubstituted phenols, and that the LDBS procedure gives good agreement with the change in experimental BDE values for highly substituted phenols in benzene solvent. Procedures for estimating the O--H BDE based on group additivity rules are given and tested. Several interesting classes of phenolic antioxidants are studied with these methods, including commercial antioxidants used as food additives, compounds related to Vitamin E, flavonoids in tea, aminophenols, stilbenes related to resveratrol, and sterically hindered phenols. On the basis of these results we are able to interpret relative rates for the reaction of antioxidants with free radicals, including a comparison of both H-atom-transfer and single-electron-transfer mechanisms, and conclude that in most cases H-atom transfer will be dominant.     

Simple extraction method and gas chromatography-mass spectrometry in the selective ion monitoring mode for the determination of phenols in wine

The concentrations of 22 components of wine, including most of those that have been shown to possess significant biological properties, have been determined by a fast and simple analytical method based on gas chromatography with mass spectrometric detection in the selective ion monitoring mode (GC/MS-SIM). The procedure involves an easy liquid-liquid extraction and derivatization methods of flavanols, phenols and carboxylic acid, using a very small wine volume. The average recovery (Rcv) ranged from 73 to 107% and linear regression coefficients (r(2)) were in a range of 0.981or=0.999. The GC/MS-SIM technique gives good specificity and sensitivity, and can therefore be suitable for routine monitoring of the concentration of individual phenolic antioxidants during winemaking and the aging process.     

Static–dynamic sequential superheated liquid extraction of phenols and fatty acids from alperujo

Superheated liquids of different polarity have been used for sequential extraction of fatty acids and phenols from alperujo. Multivariate methodology has been used to optimise the static–dynamic extraction. Forty-two minutes are required to complete extraction (20 mg/kg of fatty acids and up to 2,200 mg/kg of hydroxytyrosol in the raw material used). The efficacy of the extraction has been demonstrated and compared with that of conventional methods (Folch and stirring-based methods for fatty acids and phenols, respectively), which needed 4.5 and 24 h for the extraction of fatty acids and phenols, respectively. The non-polar and polar extracts were injected into GC–MS and HPLC–MS–MS equipment, respectively, for individual separation–quantification of the target compounds. The simplicity of the experimental setup and the low costs of the raw material make the proposed method advisable when extraction of both fractions is required.     

Metal fractionation in olive oil and urban sewage sludges using the three-stage BCR sequential extraction method and microwave single extractions

The conventional three-stage BCR sequential extraction method was employed for the fractionation of heavy metals in sewage sludge samples from an urban wastewater treatment plant and from an olive oil factory. The results obtained for Cu, Cr, Ni, Pb and Zn in these samples were compared with those attained by a simplified extraction procedure based on microwave single extractions and using the same reagents as employed in each individual BCR fraction. The microwave operating conditions in the single extractions (heating time and power) were optimized for all the metals studied in order to achieve an extraction efficiency similar to that of the conventional BCR procedure. The measurement of metals in the extracts was carried out by flame atomic absorption spectrometry. The results obtained in the first and third fractions by the proposed procedure were, for all metals, in good agreement with those obtained using the BCR sequential method. Although in the reducible fraction the extraction efficiency of the accelerated procedure was inferior to that of the conventional method, the overall metals leached by both microwave single and sequential extractions were basically the same (recoveries between 90.09 and 103.7%), except for Zn in urban sewage sludges where an extraction efficiency of 87% was achieved. Chemometric analysis showed a good correlation between the results given by the two extraction methodologies compared. The application of the proposed approach to a certified reference material (CRM-601) also provided satisfactory results in the first and third fractions, as it was observed for the sludge samples analysed.     

Organic Compounds in High Alpine Snow

Abstract

Snow samples were taken in June 1995 at the Sonnblick Observatory located at the top of Mt. Sonn-blick (3106 m a.s.l.) in the main ridge of the Austrian Alps, as part of the project “Organic Aerosol Scavenging”. The main interest focused on the determination of aliphatic compounds and phenols. First the method for the extraction of the organic compounds was developed using standard samples prepared in the lab. The preconcentration of the samples was performed by liquid-liquid extraction with hexane and hexane/diethylether respectively. To characterize the analytical procedure, the efficiency of the extraction procedure, the reproducibility of the overall method and the detection limits were determined. Values for the recovery of the extraction method range from 57% (fatty acids) to 95% (aliphatic alcohols). Reproducibility was found to be between 3-5%, except for the fatty acids which gave a value of 16%. Detection limits were calculated for the various substances and are between 5μg/l (phenols) and 30μg/l (fatty acids). The analysis of the eight snow samples were performed using a GC-MS-FID system. The following compounds were identified as major compounds in the snow samples: 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 2-isobutyl-4-methoxy-phenol, diisobutylphenol and dibutylphthalate. The aliphatic alcohols are of biogenic origin and are present in a concentration range from 30 to 115 μg/l melted snow. The phenols show concentrations between 5 and 30 μg/l and the phthalates range up to 40 μg/l.     

Determination of carboxylic acids and phenols in water by extractive alkylation using pentafluorobenzylation,glass capillary GC and electron capture detection

A method is presented for the simultaneous determination of a wide range of carboxylic acids and phenols in water. Extractive alkylation is used with the tetrabutylammonium ion as counter ion and pentafluorobenzylbromide as alkylating agent. Extracts are analyzed by glass capillary gas chromatography and electron capture detection. Using one ml of water sample, the detection limit lies in the range of 1–10 μg/l. Application has been made to the analysis of steam condensate and domestic sewage effluent.     

Organic compounds in precipitation

Summary Precipitation samples collected in Hannover (Germany) mainly in 1989 (and in part also in 1988 and 1990) were analyzed for n-alkanes, fatty acids, aldehydes, phenols and polycyclic aromatic hydrocarbons. The analytical methods employed were: GC/FID for alkanes, GC/MS for fatty acids and phenols, HPLC for aldehydes and PAHs.     

An organic solvent-free microwave-assisted extraction of some priority pollutants of phenols in lake sediments.

Alkaline water was used for the microwave-assisted extraction of some priority pollutants of phenols in sediments, i.e. phenol (Ph), 2-chlorophenol (2CP), 2,4-dichlorophenol (2,4DCP), 4-chlorophenol (4CP), 4-dinitrophenol (4NP) and pentachlorophenol (PCP). This organic solvent-free extraction procedure was optimized by studying the parameters such as pH, volume of the alkaline water, extraction pressure and time. Under the optimized conditions, the recoveries of phenols were in the range of 80% to 110%. The extracts were then cleaned-up and concentrated by microcolumn solid phase extraction (SPE) and determined by gas chromatography-flame ionization detection system. The relative standard deviation of the overall-method for most phenol determinations was about 5.0% (n = 6). The proposed method, which needs little volume (1 mL) of ethanol for SPE, has been applied to determine these phenols in sediment samples, and the analytical results are in good agreement with those achieved by Soxhlet extraction.     

Simultaneous determination of propacetamol and paracetamol by derivative spectrophotometry

The present paper describes a procedure that phenols in air were preconcentrated in a membrane cell and their content was determined by adsorptive polarography. First, the phenols in air samples were preconcentrated in a membrane cell using 2.0 M NaOH solution, then in a pH 1.3 buffer solution p-bromophenylamine forms a diazoate with NaNO(2), and into the mixture the collected phenols were added to form azo-compound in a pH 13 buffer solution. The azo-compound can be adsorbed at the mercury electrode and yields a sensitive oscillopolarographic wave. Over the range 2.0x10(-8)-2.0x10(-5) M, the peak currents are linearly proportional to the concentration of phenols. The detection limit is 5.0x10(-9) M.     

Determination of urinary lead, cadmium and nickel in steel production workers

The determination of toxic metals in urine is an important clinical screening procedure. In this study, the aim of our investigation was to determine the concentrations of Pb, Cd, and Ni in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy and precision were studied. The method was employed for the quantitative determination of lead, cadmium and nickel in urine samples from steel production and quality control (QC) workers and healthy unexposed controls. After pre-treatment with acids, the samples were digested via a microwave oven and the samples were determined by a graphite furnace atomic absorption spectrometry (GFAAS). Quality control for these procedures was established with the concurrent analysis of Standard Trace Metals 7879 Level II and NIST SRM 2670 (Toxic Elements in Freeze Dried Urine). The results indicate that urinary lead, cadmium and nickel levels of the exposed workers are significantly higher those of the controls. The possible connection of these elements with the etiology of disease is discussed. The results also show the need for immediate improvements in workplace ventilation and industrial hygiene practices.     

Determination of the xenoestrogens 4-nonylphenol and bisphenol A by high-performance liquid chromatography and fluorescence detection after derivatisation with dansyl chloride

An easily performable and highly selective method for the determination of the xenoestrogens bisphenol A (BPA) and technical 4-nonylphenol (mixture of isomers) from environmental samples was developed. The method consists of fluorigenic labelling of the substances by dansylation followed by HPLC separation of the derivatives. Specific wavelengths (lembda(ex)=354 nm, lambda(em)=545 nm) for detection of the dansylated phenols were determined in order to reduce the signals of interfering compounds. The applicablility of the method for environmental samples was demonstrated by using sewage sludge spiked with BPA and 4-n-nonylphenol (as internal standard).     

Determination of lipids in infant formula powder by direct extraction methylation of lipids and fatty acid methyl esters (FAME) analysis by gas chromatography.

Fatty acid methyl esters (FAMEs) of pure triglyceride standards, oils, and fat from dry matrixes were formed by transesterification using sodium methoxide in methanol-hexane. FAMEs were produced by direct addition of sodium methoxide-hexane to samples and heating to simultaneously extract and transesterify acyl lipids. FAMEs were quantitated by capillary gas chromatography (GC) over a fatty acid concentration range of 0 to 1.7 mg/mL (r > or = 0.9997). Total fat was calculated as the sum of individual fatty acids expressed as triglyceride equivalents, in accordance with nutrition labeling guidelines. Saturated, polyunsaturated, and monounsaturated fats were calculated as sums of individual free fatty acids. Absolute recoveries determined from individual fatty acids in test samples ranged from 69.7 to 106%. Recoveries (relative to the C13:0 internal standard) for individual fatty acids in test samples ranged from 95 to 106%. Reproducibility was constant at each fatty acid level in the reaction mixture (n = 5, coefficient of variation [CV] < 2%). Absolute recovery determined from the sum of total fatty acids in standard reference material (SRM) 1846 (powdered infant formula) was 96.4%. Analysis of SRM 1846 gave results that agreed closely with the certified fat and fatty acid values. Analysis of commercial infant formula gave results that were comparable to those obtained with AOAC Method 996.01. The direct extraction methylation procedure is rapid, and the transesterification of acyl lipids to form FAMEs is complete within 15 min. Classical saponification and refluxing are not required. This method provides FAMEs free of interferences and easily quantitated by GC or confirmed by GC/mass spectrometry (MS). Unambiguous MS identification of individual FAMEs derived from pure standards, SRM 1846, and powdered infant formula product was obtained.     

Gas chromatographic profiling and screening for phenols as isobutoxycarbonyl derivatives in aqueous samples

An efficient method is described for the simultaneous determination of phenol and 49 substituted phenols present in aqueous samples. The method is based on the extractive two-phase isobutoxycarbonyl (isoBOC) derivatization with subsequent solid-phase extraction (SPE) for the direct analysis by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Phenolic hydroxyl groups in acidic aqueous solutions were allowed to react with isobutyl chloroformate present in the dichloromethane phase containing triethylamine. The resulting isoBOC derivatives were then recovered by SPE using Chromosorb P in normal-phase partition mode, followed by direct GC and GC-MS analysis. Using this combined procedure, linear detector responses were obtained in the concentration range of 0.5-8 microg ml(-1), with correlation coefficients varying from 0.925 to 0.999 for most of the phenols studied except for 2,4-dinitorphenol (0.789). The temperature-programmed retention index (I) sets as measured on DB-5 and DB-17 dual-capillary columns of different polarity were characteristic of each isoBOC phenol derivative and thus, useful in the screening for isomeric phenols by I matching only. The mass spectral patterns, exhibiting characteristic [M-100]+, [M-200]+ and [M-300]+ ions for the mono-, di- and trihydroxybezenes, respectively with common ions at m/z 57, facilitated their rapid structural confirmation. The present method allowed rapid screening for phenols when applied to water samples spiked with phenols.     

Analysis of steroid estrogens in water using liquid chromatography/tandem mass spectrometry with chemical derivatizations

Even in trace amounts, estrogens such as 17beta-estradiol (E2), estrone (E1), estriol (E3), and 17alpha-ethinyl estradiol (EE2) may have adverse effects on humans and the aquatic ecosystem. Therefore, it is essential to be able to measure trace amounts of steroid estrogens in water. To date, most instruments are not sensitive enough to detect these chemicals in small samples of water. Sensitivity, however, may be improved by using appropriate derivatization reagents to modify the structures of these estrogens so that their ionization efficiency is increased, making them more detectable by liquid chromatography/mass spectrometry (LC/MS). This study uses dansyl chloride, 2-fluoro-1-methylpyridinium p-toluenesulfonate (FMPTS), and pentafluorobenzyl bromide (PFBBr) as derivatization reagents to react with the phenolic estrogens to make them more detectable in water. We also test how environmental matrices (wastewater effluent, river water, and drinking water) influence the detectability of these estrogens. Both qualitative and semi-quantitative comparisons of these derivatization methods were made. We found that dansyl chloride derivatives created signal intensities one or two orders of magnitude greater than those normally found in underivatized estrogen standards. The signals derived by FMPTS were analyte-dependent, and the products derived from E1, E2, and EE2 produced 2.19 to 12.1 times the signal intensity of underivatized E1, E2, and EE2. The product derived from E3 produced weaker signals than that produced by underivatized E3. The PFBBr derivatives produced signals that were as much as 5.8 times those found in the underivatized estrogens. When these derivatization methods were applied to river water, drinking water and effluents from a sewage treatment plant (STP), the different matrices were found to significantly suppress the signals if we used electrospray ionization, though this influence became less significant if we used atmospheric pressure chemical ionization. This study suggests that PFBBr derivatization can best be used for the detection of these estrogens in complex environmental matrices such as river water and STP effluents and that the dansyl chloride derivatization is best used for clean samples such as drinking water.     

Comparison of Methods for the Preparation of Sewage Sludge Samples Prior to the Spectrophotometric Determination of Phosphorus

Abstract

Three procedures for the preparation of sewage sludge samples prior to the colorimetric determination of phosphorus as “molybdenum blue” were evaluated. Using samples of the US EPA's municipal digested sludge as a reference material, sulfuric acid/ammonium persulfate digestion, muffle furnace ignition followed by extraction of the ash with hydrochloric acid, and direct extraction of the sewage sludge with sodium bicarbonate solution were compared in terms of phosphorus recovery as determined by colorimetric measurements. On the basisof phosphorus recovery, the samples prepared by muffle furnace ignition/hydrochloric acid extraction of the ash showed the best accuracy and precision. This procedure was also superior in terms of the time and effort expended in the preparation of the sewage sludge samples.     

Analysis of selected phytotoxins and mycotoxins in environmental samples

Natural toxins such as phytotoxins and mycotoxins have been studied in food and feed for decades, but little attention has yet been paid to their occurrence in the environment. Because of increasing awareness of the presence and potential relevance of micropollutants in the environment, phytotoxins and mycotoxins should be considered and investigated as part of the chemical cocktail in natural samples. Here, we compile chemical analytical methods to determine important phytotoxins (i.e. phenolic acids, quinones, benzoxazinones, terpenoids, glycoalkaloids, glucosinolates, isothiocyanates, phytosterols, flavonoids, coumestans, lignans, and chalcones) and mycotoxins (i.e. resorcyclic acid lactones, trichothecenes, fumonisins, and aflatoxins) in environmentally relevant matrices such as surface water, waste water-treatment plant influent and effluent, soil, sediment, manure, and sewage sludge. The main problems encountered in many of the reviewed methods were the frequent unavailability of suitable internal standards (especially isotope-labelled analogues) and often absent or fragmentary method optimization and validation.     

Rapid procedure for chromatographic isolation of DOPA, DOPAC, epinephrine, norepinephrine and dopamine from a single urinary sample at endogenous levels

A three-step procedure has been investigated to extract 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), epinephrine (E), norepinephrine (NE) and dopamine (DA) from a single urinary sample with the object of obtaining extracts pure enough for specific fluorimetric assay. The procedure described in this paper results from the combination of urine purification on an aluminum oxide column, separation by ion-exchange chromatography of the DOPA-DOPAC fraction from catecholamines, and ether isolation of DOPAC from DOPA. The whole procedure is rapid and easily performed in one work day. Extraction recoveries were 72.4 +- 3.5%, 76 +- 2%, 85.7 +- 3.3%, 85.6 +- 1.4% and 92.4 +- 5.5% for DOPA, DOPAC, E, NE and DA respectively (n=6). The lowest amounts of the five catechols that could be detected in urinary samples by a combination of this extraction procedure and the methods of assay used in our laboratory were 15 ng for DOPA, 40 ng for NE, 20 ng for E, 152 ng for DA and 2.95 micrograms for DOPAC. Urinary volumes convenient for accurate estimation of each compound were 20 ml for healthy human subjects. For pathological or pharmacological purposes, 5 ml of human urine were sufficient. The daily excretion of DOPA, DOPAC, E, NE and DA found by this procedure agrees with data obtained by other authors in healthy subjects. In pathological samples, our three-step procedure led to lower amounts than methods using alumina purification only. The discrepancies between the two methods are discussed in terms of development of internal standards, relative specificity of fluorimetric assays, values of blank eluates, and the possibility of interference from unknown abnormal body metabolites or pharmacological drugs not eliminated by a single-step alumina purification.