Showing papers in "International Journal of Environmental Analytical Chemistry in 1992"

Determination of Alkylphenol Ethoxylates and Their Acetic Acid Derivatives in Drinking Water by Particle Beam Liquid Chromatography/Mass Spectrometry

Abstract: Particle beam liquid chromatography/mass spectrometry (PB/LC/MS) was used to analyze finished drinking water for non-volatile organic compounds. 500 liters of finished water were extracted with an on-line continuous liquid/liquid extractor with dichloromethane at pH 7.4. PB/LC/MS was an excellent tool to detect and identify ng/L concentrations of alkylphenol polyethoxylates (n = 3−8), materials which went undetected by on-column gas chromatography/mass spectrometry. In addition, alkylphenol polyethoxylate carboxylates with 2–7 degrees of ethoxylation could be detected without chemical derivatization.

The Determination of Quickly Reacting Aluminium in Natural Waters by Kinetic Discrimination in a Flow System

Abstract: Different aluminium species react with oxine at different rates, a behaviour that we have used as the basis of an analytical method. The reaction is performed in a FIA system and is terminated by extraction of the excess oxine, together with the aluminium trioxinate formed, into chloroform. The reaction time is 2.3 sec, much shorter than that used normally. After separation, the amount of aluminium trioxinate in the organic phase is determined spectrophotometrically. The system has been validated using model substances with known complexation constants. Al3+, AlOH2+, probably Al(OH)2 +, aluminium sulphato complexes and, to some extent, some of its weakest organic complexes are included in the measured fraction, whereas fluoro complexes, citrato complexes and Al13O4(OH)7+ 24 are excluded. Complexes with fulvic and humic acid cause a reduction of the signal. The detection limit is at best about 5 μg/L (ca. 0.2 μM), and we can make 60 measurements per hour. Results from measurements made on natural ...

Nitrogen isotope composition of ammonium and nitrate in bulk precipitation and forest throughfall

Abstract: The stable nitrogen isotope composition of ammonium (NH+ 4) and nitrate (NO− 3) ions in bulk precipitation and forest throughfall was determined at Walker Branch watershed, a low elevation site (340 m) in northeastern Tennessee, and in cloud water from Whitetop Mountain, a high elevation site (1680 m) in southwestern Virginia. Tests of the method used indicated that sample processing did not introduce significant isotopic fractionation in measurements of nitrogen isotope composition. Mean δ15N values for NH+ 4 and NO− 3 in solutions of artificial rain were within 0.3%o of the mean δ15N values of nitrogen compounds used to make the solutions. Over a one-year period on Walker Branch watershed, the measured mean (± SD) δ15N value for NH+ 4 in bulk precipitation and throughfall (− 3.4 ± 2.1%o) was significantly less than that for NO− 3(+ 2.3 ± 2.4%o). The same relative pattern was observed in cloud water from Whitetop Mountain: mean (± SD) δ15N in cloud water NH+ 4 was −5.5 ± 3.2%o; i.e., isotopicall...

Rapid Screening of a Large Group of Polar Pesticides in River Water by On-Line Trace Enrichment and Column Liquid Chromatography

Abstract: Column liquid chromatography on a reversed-phase (C-18) analytical column using a linear acetonitrile-water gradient and diode-array detection is used in an on-line early-warning system of over 50 pesticides in surface water. It allows the separation of most compounds with detection limits of about 1–5 μg/1 after preconcentration of 30 ml of sample. Problems encountered for co-eluting pesticides with similar spectra and pesticides with weak ultraviolet absorption over 230 nm, are discussed. If the system is combined with on-line trace enrichment on a styrene-divinylbenzene copolymer (PLRP-S) precolumn, the overall resolution is only slightly affected, and the qualitative information obtained remains about the same. Chromatograms of spiked (2–10 μg/1) surface (river Rhine) water containing 54 test compounds are shown. Preliminary studies show the stability of several pesticides in water to be rather low. Some degradation products have been detected in 1-month-old methanolic and aqueous solutions.

A Method for Micro-Determination of Total Microcystin Content in Waterblooms of Cyanobacteria (Blue-Green Algae)

Abstract: Microcystins as cyanobacterial (blue-green algal) toxins are found from toxic waterblooms in freshwater lakes and reservoirs for drinking water all over the world. In this paper, we demonstrated a micro-determination method for total microcystin content in waterblooms of toxic cyanobacteria. This method based on a quantitative analysis of 2-methyl-3-methoxy-4-phenylbutyric acid(MMPB) as an oxidation product of microcystins by gas chromatography(GC) with a flame ionization detector or high performance liquid chromatography(HPLC) with a fluorescence monitor. In the case of GC analysis, methyl ester of MMPB in the pmol range of concentration was determined. On the other hand, in the HPLC analysis, MMPB in the fmol range of concentration was determined by labeling with 2-(2,3-naphthalimino)ethyl trifluoromethanesulfonate as a fluorescent reagent. These results pointed out that this micro-analysis is able to be applied to the monitoring of microcystins in drinking water, reservoirs and freshwater lakes.

Trace Element Speciation in Soils and Sediments Using Sequential Chemical Extraction Methods

Abstract: Several commonly used sequential chemical extraction procedures of heavy metals in soils and sediments are compared, and their advantages and disadvantages are discussed focusing on selected case studies. In particular, problems caused by handling of anoxic samples, and of specific phases (e.g. organic fractions and sulfides) are addressed. Eventually, recommendations for the improvement of extraction selectivity as well as the reduction of readsorption effects are given.

Congener Specific Analysis of 140 Chlorobiphenyls in Technical Mixtures on Five Narrow-Bore GC Columns

Abstract: The separation of 140 chlorobiphenyl (CB) congeners from technical polychlorinated biphenyl (PCB) mixtures was investigated on five narrow-bore (0.22–0.25 mm I.D.) gas chromatography (GC) columns with stationary phases representing a broad range of polarities: dimethylsiloxane (0.15 μm SIL-5, 50 m), 5% diphenyl dimethylsiloxane (0.26 μm SIL-8, 50 m), 14% cyanopropylphenyl 1% vinyl dimethylsiloxane (0.26 μm SIL-19, 50 m), bis-cyanopropyl phenylsiloxane (0.20 μm SIL-88, 50 m) and 1,2-dicarba-closo-dodecarborane dimethylsiloxane (0.1 μm HT-5, 25 m). Technical PCB mixtures (Aroclors) and authentic standards (totally 66 CBs) were injected on the narrow-bore columns and analyzed by GC-ECD and GC-MS. Peak assignments were based on experimental data together with published retention data and data on the quantitative composition of Aroclors. Structural principles for retention of CBs on polar stationary GC phases were developed. Surprisingly, the general performance of the classical column for PCB analysi...

Soil Type and Herbicides Adsorption

Abstract: Herbicides behaviour in soils greatly depends on adsorption through its influence on degradation and movement. The adsorption intensity depends on both the chemical structure of pesticides, the nature of soil constituents and soil physico-chemical factors such as the pH. In this paper, the role played by these factors is analysed and used to evaluate the possible use of soil surveys for assessing adsorption behaviour of pesticides in soils. The analysis is based on adsorption measurements of three herbicides (atrazine, terbutryn and 2,4-D) by several soils differing in their mineralogical composition, organic matter content and pH. Using statistical analysis, it is shown that some relations can be defined between soil types and adsorption behaviour. These relations are strongly dependent on the electrical state of the herbicide molecule (cationic, anionic and neutral).

Determination of Individual Chlorobiphenyls (CBs), Including Non-Ortho, and Mono-Ortho Chloro Substituted CBs in Marine Mammals from Scottish Waters

Abstract: Twenty individual chlorobiphenyls (CBs) have been determined in marine mammals. The more toxic non-ortho and mono-ortho CBs have been separated from di and tri-ortho CBs using a pyrenyl silica HPLC column prior to the final determination by capillary GC. The comparative metabolism of the biologically active CBs in whale, porpoise, dolphin and seal tissue is described. An estimate of the TCDD toxic equivalence concentration (TEC) for the non ortho and mono ortho CBs is made.

High resolution PCB analysis of kanechlor, phenoclor and sovol mixtures using multidimensional gas chromatography

Abstract: Kanechlor-300, -400, -500 and -600, Phenoclor DP-3, -4, -5 and -6 and Sovol mixtures were analyzed for their chlorobiphenyl (CB) composition using high-resolution one-dimensional and multidimensional gas chromatography-electron capture detection (MDGC-ECD) techniques. The congener patterns of tested Kanechlor and Phenoclor mixtures resembled Aroclor 1016, 1242, 1254 and 1260. However, differences in the percentage contribution of minor constituents were noticed among these mixtures, which could be due to variations in the boiling-point fractionation of these commercial products. CB pattern of Sovol was different from the rest of the mixtures tested. It showed a composition in between ca. 30%, 40%, 50% and 60% overall chlorine levels. MDGC-ECD study showed the presence of hitherto unnoticed non-CB compounds coeluting with CBs in some commercial PCBs. The use of these mixtures as quantitation standards should be considered with caution. CB patterns of Sovol and a water extract of the Gulf of Finlan...

A new method for the characterization of organic carbon in aquatic systems

Abstract: Some problems in organic carbon characterization are briefly discussed. A new chromatographic multi-method for the direct characterization of organic matter in original waters with the simultaneous determination of UV-Vis, fluorescence, DOC, TIC, and organically bound nitrogen (DON) is described. Some applications with UV-Vis and DOC (“CODOC”) detection are presented.

Mobility of Heavy Metals in Soil Profiles

Abstract: Mobility is a concept frequently used in soil science to estimate the risk of contamination of other environmental compartments. However some confusion exists over the definition of mobility, originating from the fact that this term is used in different fields. Consequently many operational parameters have appeared in relation to mobility estimation. This leads to great difficulties in comparatively interpreting practical data obtained under different conditions, and especially the biological significance of mobility. A standardization of the definition of mobility, taking into account the time scale, should be recommended. Practical results obtained in reconstituted soil-vegetation systems are discussed, with a particular emphasis on the “mobility” of Cd, Cu and Zn. Several definitions were used to estimate the movement of heavy metals in the studied systems, i.e. the metal exports by plants or by gravitational water and the distribution of metals in the soil profile; this led to opposite conclu...

Gas Chromatographic Trace-Level Determination of Volatile Organic Sulfides and Selenides and of Methyl Iodide in Atlantic Surface Water

Abstract: The concentration of the sulfur compounds dimethyl sulfide (DMS), dimethyl disulfide (DMDS), and carbon disulfide (CS2) as well as of methyl iodide (CH3I) was determined in surface sea water of the Atlantic Ocean from 30°S to 45°N during an expedition with the German research vessel 'FS Polarstern' using a purge and trap/gas chromatographic system equipped with a flame photometric and an electron capture detector. The most abundant sulfur compound was DMS with a mean concentration of 55 ng S/l. DMDS and CS2 could be detected in 14 and 56 out of a total number of 100 sea water samples with concentrations up to 14.7 ng S/l and up to 10.7 ng S/l, respectively. This is the first time that DMDS could be quantified in a number of sea water samples. CH3I was determined in all samples with a mean of 0.6 ng I/l. In three Atlantic sea water samples dimethyl selenide (DMSe) was detected for the first time (concentration range, 1–5 ng Se/l). Its presence was verified by means of an atomic emission detector. ...

Liquid Chromatographic Determination of Polar Pollutants in Surface Water Using Membrane Extraction Disks for On-Line Trace Enrichment

Abstract: Membrane extraction disks loaded with alkyl-bonded silica, copolymer or ion-exchange material have been tested for the on-line trace enrichment of polar pesticides from surface water. To this end, a new membrane extraction disk holder has been designed, which can be used in the forward flush and backflush mode. The basic compounds carbendazim, chloridazon, simazine and 4-chloroaniline were used as test compounds. They are preconcentrated from acidic solution using one or two membrane extraction disk holders in series (operated in the reversed-phase and ion-pair mode), and analysed by gradient liquid chromatography with polymer PLRP-S as the stationary phase and aqueous acetonitrile mixtures (pH 3) as the eluent. Data on the efficiency and repeatability of the on-line procedure are reported. Preconcentration of 30 ml of surface (river Rhine) water allows the UV detection of the four pollutants at the 0.1 μg 1−1 level.

A Comparison of Ultrasonic Extraction and Soxhlet Extraction of Polycyclic Aromatic Hydrocarbons from Sediments and Air Particulate Material

Abstract: The extraction of polycyclic aromatic hydrocarbons (PAH) from sediments and from an urban dust standard reference material (SRM 1649) was compared using two methods; ultrasonication and Soxhlet extraction. Sample weights ranging from 0.5 g to 5 g were extracted using ultrasonication. The yield of organic material from sediment samples using ultrasonication with two solvents was 2.53 ± 0.10% while the Soxhlet method yielded 2.41 ± 0.14% of the initial sample weight. Sequential ultrasonic extraction with two solvents was much more rapid (45 minutes) than Soxhlet extraction (two days) and resulted in equal extraction efficiency. The levels of PAH extracted by ultrasonication from the urban dust standard reference material varied by no more than 15% from the certified values.

Calibrants and Calibration for Chlorobiphenyl Analysis

Abstract: Guidelines are given for the preparation of calibration solutions and the calibration of the capillary gas chromatograph for the determination of chlorobiphenyls (CBs) and ways in which errors may be reduced to produce comparable data in the analysis of environmental samples. Results from a Community Bureau of Reference (BCR) intercomparison exercise indicate that calibration remains a key factor in obtaining reliable data.

Derivatization of humic compounds : an analytical approach for bound organic residues

Abstract: Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of 13C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more. 14C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of 14C anilazine r...

Effect of Liquid Animal Manure Application on the Solubilization of Heavy Metals from Soil

Abstract: The effect of liquid animal manure on heavy metal solubilization in soil has been studied in the laboratory; three different types of experiments were carried out: 1) aerobic and anaerobic incubation of soil/manure mixtures 2) desorption of heavy metals from soil, as affected by manure liquid fraction 3) gel permeation chromatography of soil/manure aqueous extracts to identify components responsible for heavy metal solubilization. Alf three different approaches showed that complexation involving high molecular weight dissolved organic matter from the soil/manure matrix is (together with pH) the most important driving force for heavy metal solubilization. As a consequence, chemical and microbial processes (e.g. nitrification) that influence dissolved organic matter concentrations in the soil solution, determine the degree of heavy metal solubilization in manured soil.

Isotopic composition as an indicator of origin of lead accumulations in surface soils

Abstract: Surface accumulation of lead in urban soils is a well-known phenomenon but its marked accumulation in remote, upland areas is less well documented. Such enrichments (up to 500 mg/kg) could be a potential hazard to grazing sheep. Lead isotope ratios determined by thermal ionization mass spectrometry are reported for three soil profiles from remote, upland areas with highly enriched surface concentrations of lead. Isotope ratios in recent rainwater samples from six widely dispersed sites in Scotland are also discussed. Lead in current rainwater samples has very low isotope ratios indicating its likely origin from petrol-derived sources. The ratios in soil surface horizons are not as low as those in current rainwater samples which suggests that lead accumulated over many decades is derived from both petrol-derived sources and also from other industrial emissions such as smelting and steel production.

Binding of organic pollutants to soil organic matter

Abstract: Binding of organic pollutants to water-soluble, low-molecular weight humic substances increases their mobility in soil and their leaching, whereas binding to high-molecular weight humic substances results in unextractable residues. Water-soluble pollutants in leachate may be bound to low-molecular weight humic material, or may be free water-soluble conversion products that are slowly released from a soil-bound form, as shown for a conversion product of the insecticide aldrin. Unextractable soil-bound 4-chloroaniline was isolated by supercritical methanol extraction 16 years after application of the phenylurea herbicide buturon to soil. Biodegradation and bioavailability of unextractable soil-bound residues are greatly reduced as compared to the free compounds. For some chlorinated anilines and phenols, biomineralization and plant uptake was shown to be highest for residues bound in fulvic acids and lowest for those in humic acids. Model experiments demonstrate that chlorinated anilines form coval...

Composition of PCB Isomers and Congeners in Technical Chlorofen Formulation Produced in Poland

Abstract: The composition of Chlorofen, a technical formulation of polychlorinated biphenyls (PCBs) produced in Poland, has been investigated using GC-ECD and GC-MS techniques. Chlorofen was a highly chlorinated mixture (63.6% Cl), mainly composed of PCB members with 5 to 9 chlorine atoms which comprised 99.55% of total PCBs. The average number of Cl per molecule in Chlorofen was 7.3, and the average molecular weight was 405.4. It was found that Chlorofen contained at least 59 PCB congeners with the major components such as IUPAC No. 153 of hexa-, 176, 180, 187 of hepta-, 194, 195, 198, 201/196 of octa- and 206 of nonachlorobiphenyls. Additionally, three components of highly toxic non-ortho chlorine substituted coplanar PCBs (IUPAC Nos 77, 126 and 169) were also quantified at a concentration of 0.52, 0.25 and 0.43 μg g−1, respectively, the latter (169), showing a greater content than in Aroclor and Kanechlor formulations.

Separation of Toxic Congeners from PCB Mixtures on Two Series Coupled Narrow-Bore Columns (50 m SIL-8 AND 25 m HT-5)

Abstract: The complete separation of the toxic non-ortho-substituted polychlorinated biphenyls (PCBs) PCB-77, PCB-126 and PCB-169 from the technical PCB mixtures Askarel and Aroclors (A1232, A1242, A1248, A1254, A1260 and A1262) was obtained on two series coupled narrow-bore columns: 50 m × 0.25 mm, 0.26 μm 5% diphenyldimethylsiloxane (CP-SIL-8) and 25 m × 0.2 mm, 0.1 μm 5% 1,2-dicarba-closo-dodecarborane dimethylsiloxane (HT-5). The high upper temperature limit for these GC-phases (>300°C) allowed for fast temperature programming and short analysis time (60 min). In addition to the non-ortho-substituted PCBs most of the toxic mono-ortho-substituted PCBs were completely separated from other PCBs (PCB-74, PCB-81, PCB-105, PCB-118, PCB-123, PCB-157 and PCB-189). Only four toxic PCBs were eluted with interference: PCB-60/PCB-56, PCB-114/PCB-134, PCB-167/PCB-128 and PCB-156/PCB-202. These could be analyzed satisfactorily on a CP-SIL-19 column i.e. 50 m × 0.25 mm, 0.20 μm 14% cyanopropylphenyl 1% vinyldimethyls...

Persistent Organochlorine Insecticide Residues in Some Paddy, Upland and Urban Soils of India

Abstract: A wide variety of agricultural soils from different regions of India such as paddy, wheat, mustard, potato, cotton, tea, tomato, sugarcane, grape and urban soils were surveyed for the residual levels of persistent organochlorine insecticide residues in 1988 and 1989. DDT and HCH concentrations were found to be higher in upland soils and lower in paddy field soils. These results indicate the large application of HCH and DDT compounds for agricultural purposes in India. In urban soil DDT levels were higher than HCHs reflecting the use of the former insecticide in relatively large amounts for vector control. Among DDT compounds, p,p′-DDE showed higher percentage in paddy and upland soils. On the other hand, p,p′-DDT contributed to higher levels in urban soils. The β-HCH was detected as the dominant isomer in both agricultural and non agricultural soils. The levels and percentage compositions of DDTs and HCHs revealed the extent of environmental contamination caused by the continuous usage of persist...

Trace analysis of heavy metals in aerosols over the Atlantic Ocean from Antarctica to Europe

Abstract: The particulate heavy metal concentrations of Tl, Cu, Cd, Pb, Zn, Ni, Cr, and Fe were determined in the atmosphere over the Atlantic Ocean from 77°S (Antarctica) to 54°N (Europe) using the analytical method of isotope dilution mass spectrometry. The samples were collected on board of the German polar research vessel “Polarstern” during four different expedition legs from September 1987 to March 1990. Analyses of the crustal reference element Fe resulted in the calculation of enrichment factors EF(Fe), which were used for interpretation of crustal influences on heavy metal contents as well as for contamination control. The variations in concentration of the dominant crust element Fe run up to five orders of magnitude (0.22–36200 ng m−3). The region between the equator and 20°N was strongly influenced by crustal material transported by the north-eastern trades out of the Sahara. EF(Fe) values around unity and the highest measured concentrations of the dominant crustal elements Fe (36200 ng m−3), Cr...

Determination of Chromium in Environmental and Biological Samples by Atomic Absorption Spectroscopy: A Review

Abstract: The technique most widely used for chromium determination in biological and environmental samples is atomic absorption spectrometry with flame (FAAS) or graphite furnace (GFAAS). In this regard, there are many articles in the literature dealing with the effect of the interferences upon chromium solutions of different oxidation state. These effects are not well established and the results are contradictory. With the aim of joining all this information, we review the state of the art in chromium determination with AAS in environmental and biological samples. The first part of the paper is related with the different sample pretreatment methods proposed for natural and seawaters, sediments, soils, plant materials, biological materials, sewage sludges and urban particulate matter. The second part deals with the instrumental parameters and interference effects which affect chromium measurements by FAAS and GFAAS. The last part presents different certified reference materials available for the quality c...

Preliminary Study on Degradation of Ionic Alkyllead Species in Water

Abstract: Laboratory experiments are reported, aimed at monitoring the degradation of ionic alkyllead compounds in water in the dark, in daylight and with UV irradiation. A stepwise dealkylation in aqueous media is not supported by the simulations. It appears that trialkyllead (triAL) degradation does not give rise to appreciable formation of dialkyllead (diAL) but directly yields inorganic lead; on the other hand, dialkyllead species appear too stable to be involved as short-lived intermediates. Generally ethyllead compounds are observed to be more sensitive towards degradation than the corresponding methyllead compounds. The results are consistent with existing literature evidence.

Use of Extraction Disks for Trace Enrichment of Various Pesticides from River and Sea Water Samples

Abstract: C-18 Empore extraction disks were used for the isolation and trace enrichment of different groups of pesticides from river water and artificial sea water at concentration levels of 0.2, 5 and 20 μg/l [chlorotriazines, (atrazine and simazine), their dealkylated metabolites, (deethyl- and deisopropylatrazine), organophosphorus (parathion-ethyl), phenylurea (linuron), anilide (propanil), carbamate (aldicarb and carbofuran) and carbamate transformation products (aldicarb sulfoxide, aldicarb sulfone and 3-hydroxy-7-phenol carbofuran]. The extraction disks allowed high flow rates thus 51 samples could be processed within 2h. 30 min. For most of the pesticides the recoveries, as determined by liquid chromatography with diode array detection (LC-DAD), varied from 74 up to 125% with coefficients of variations (CV) of 5-10%, whereas for the carbamate transformation products the recoveries were in the range of 30-35% having a CV of 17-21%. At spiking level of 0.2 μg/l the dealkylated triazine metabolites an...

Measurement and Control of Mercury Species in Flue Gases from Liquid Waste Incineration

Abstract: New measurement methods have been developed for speciation of mercury and its compounds under flue gas conditions. Total mercury can be collected by a silver denuder or by a gold-coated diffusion screen. Mercury halides can be selectively preconcentrated by a potasium chloride denuder. The use of a microwave-induced plasma source combined with optical emission spectrometry for continuous monitoring of total mercury is investigated. Incineration of municipal and industrial wastes is the most relevant mercury emission source. Therefore, first experiments have been carried out with solid adsorbents in order to evaluate attempts towards reduction of mercury emissions from such sources.

Trace element analysis of food spices by INAA. II : Solanaceae, Liliaceae, Zingiberaceae and Apiaceae families

Abstract: Extensive use of food spices in oriental and Latin American cooking, pharmacy, and perfumery entails the evaluation of trace element contents in them. Instrumental neutron activation analysis (INAA) was used to determine the concentration of 18 trace elements (essential, toxic and non-essential) in six different spices consumed in Rawalpindi/Islamabad area. Turmeric powder and ginger powder were found to contain relatively high amounts of essential elements and low amounts of toxic elements. The comparison of our values with Canadian and Egyptian data shows variation in trace element contents of red pepper, turmeric, coriander and ginger. The estimated dietary intake through food spices show that these may be considered appreciable sources of trace element intake due to their extensive use. With the present studies the investigation of trace element contents of 13 food spices has been completed.

Polycyclic Aromatic Sulfur Heterocycles. I. Use of Hydrogen Peroxide Oxidation for the Group Separation of Polycyclic Aromatic Hydrocarbons and Their Sulfur Analogs

Abstract: Some of the reasons for the difficulty of devising a generally valid analytical procedure for polycyclic aromatic sulfur heterocycles (PASHs) are discussed. A procedure for the separation of polycyclic aromatic hydrocarbons and PASHs which has been used for many years is investigated. It is shown that the oxidation with hydrogen peroxide in acetic acid/benzene produces not only the desired sulfones of the PASHs but that also the aromatic rings of polycyclic compounds of all types are oxidized. Low or zero recovery of the analytes is therefore often found. A large number of reagents was tested for the reduction of aromatic sulfones to PASHs in order to find a substitute for lithium aluminum hydride. None was discovered that cleanly affects this conversion. It is strongly recommended that oxidation with hydrogen peroxide not be used for any samples in which aromatic compounds are to be analyzed.