Two methods for the speciation analysis of mercury in fish involving microwave-assisted digestion and gas chromatography-atomic emission spectrometry

In this paper a novel approach for the speciation analysis of mercury (methyl mercury and mercury II) in fish tissue using gas chromatography-microwave induced plasma atomic emission spectromertry is described. Focused microwave-assisted digestion which has been used previously in speciation analysis only for the determination of organotin and organoselenium compounds, was applied for sample preparation, a technique which enables mild, quick and complete dissolution of the sample. The important parameters for the digestion of fish tissues were optimised for the given analytical problem. Since no experience was available for the further treatment of the produced sample solution two different derivatisation/injection procedures were examined:

1. (1) ethylation with sodium tetraethylborate, extraction into hexane and injection with a cooled injection system and

2. (2) hydride generation with sodium tetrahydroborate together with purge-and-trap injection. The latter reaction has not been used previously for the determination of mercury species in fish samples.

The optimum parameters for both procedures were evaluated and the methods were validated by analysis of a standard reference material (CRM 464). The 3σ detection limits were (1) 3.0 pg g⁻¹ and (2) 12.5 pg g⁻¹.     

Methods for the analysis of thiodiglycol sulphoxide, a metabolite of sulphur mustard, in urine using gas chromatography-mass spectrometry.

Two methods have been developed for the analysis of thiodiglycol sulphoxide, a metabolite of sulphur mustard, in urine. The first method recovers thiodiglycol sulphoxide from urine by extraction from a solid absorbent tube and clean up on Florisil. In the second method thiodiglycol sulphoxide is reduced to thiodiglycol with acidic titanium trichloride prior to extraction. This method detects thiodiglycol, thiodiglycol sulphoxide, and their acid-labile esters, as the single analyte thiodiglycol. In both cases the recovered analytes were converted to the bis(pentafluorobenzoyl) derivative of thiodiglycol and detected by gas chromatography-mass spectrometry using negative ion chemical ionisation. The limits of detection were 1 ng per 0.5-ml sample of urine. Urine from five normal human subjects showed low background levels of thiodiglycol sulphoxide in the range 2-8 ng/ml. However, a sixth subject was found to be excreting levels of thiodiglycol sulphoxide as high as 36 ng/ml. The first method has been used in toxicokinetic studies of sulphur mustard and the second method is intended to be used for the retrospective confirmation of mustard poisoning in casualties of chemical warfare.     

Determination of butyltin, methyltin and tetraalkyltin in marine food products with gas chromatography-atomic absorption spectrometry

Extraction methods were developed for the determination of butyltin, methyltin and tetraalkyltin in marine food products. Alkyltins were complexed with either diphenylthiocarbazone (dithizone) or tropolone from enzymatically hydrolysed samples. Tetraalkyltins were extracted with hexane. Butyl or methyl derivatives of the alkyltins were made by Grignard reaction for analysis by gas chromatography-atomic absorption spectrometry. Many of the examined marine food products contained ppb levels of alkyltins. Tetramethyltin and tetraethyltin levels were less than the method detection limits of 0.8 and 0.7 ng/g (as Sn), respectively.     

气相色谱-质谱法分析硫芥子气及相关化合物

用气相色谱－质谱法对含硫芥子气类化合物进行了分析。探讨了长链芥子气的电子轰击电离的质谱规律，并对待测化合物的色谱保留数据进行了研究，在给定条件下，各种待测含硫芥子气在气相色谱柱中能有效的分离和鉴定。     

Determination of butyltin species in sewage and sludge by gas chromatography-atomic absorption spectrometry.

A method for the extraction and determination of butyltin compounds in sewage and sludge is reported. Sewage and sludge samples are acidified and shaken for 2 h. The various butyltin species are extracted quantitatively by tropolone (cycloheptatrienone) in toluene, followed by ethylation to their tetraalkyl-substituted forms, BuSnEt3, Bu2SnEt2, Bu3SnEt and Et4Sn, all of which can be separated and determined by a gas chromatographic-atomic absorption spectrometric technique. The non-pesticidal octyltin species and acid-leachable SnIV species can also be determined by this method. Detection limits expressed as Sn are 40 ng dm-3 and 2 ng g-1 dry mass for sewage and sludge, respectively. Analyses of some samples from Canadian treatment plants are given.     

An indirect flame emission spectrometry method for the determination of sulphur and sulphur compounds. II

Microchimica Acta - An accurate and simple indirect method of flame-emission spectrometric determination of small quantities of elemental sulphur and many sulphur compounds, without their prior...     

Complementary use of gas chromatography-mass spectrometry, gas chromatography-atomic emission detection and nuclear magnetic resonance for identification of pharmaceutically related impurities of unknown structures

The complementary use of gas chromatography-mass spectrometry (GC-MS), gas chromatography-atomic emission detection (GC-AED) and nuclear magnetic resonance (NMR) spectroscopy is demonstrated by the identification of four major by-products in a sample from an exploratory attempt to synthesise 1.3-dichloro-5-(difluoromethoxy)benzene. GC-MS was used for straightforward identification of the target compound and one of the impurities. By employing GC-AED, the sample was screened for heteroatoms in the analysed molecules and determination of the partial empirical formula of one sample component was carried out. The combined spectroscopic data obtained from the MS and AED experiments facilitated structure elucidation of two of the additional by-products. Finally, identification of the last unknown component could be obtained by combining spectral information from GC-MS, GC-AED and NMR data acquired after isolation of the impurity from the sample.     

Liquid chromatography-tandem mass spectrometry analysis of estrogenic compounds in coastal surface water of the Baltic Sea

An analytical method has been developed for the determination of five naturally occurring estrogens (estradiol, estriol, estrone, genistein, daidzein), one synthetic hormone (ethynylestradiol) and three xenoestrogens (4-nonylphenol (NP), 4-tert-octylphenol (4-tert-OP), bisphenol A (BPA)) in coastal marine waters. The procedure includes a solid-phase extraction of approx. fifty litres of water samples on the solid-phase copolymer Oasis HLB followed by a clean-up on silica. Twenty-five percent aliquots were used for the analytical determination of the analytes using high performance liquid chromatography coupled with electrospray-ionisation tandem mass spectrometry (HPLC-ESI-MS/MS). Calculated extraction recoveries between 52 (4-tert-octylphenol) and 91% (nonylphenol) were obtained for the method developed. Matrix interferences occurring during electrospray ionisation were quantified by spiking the extracts prior to the measurements. Method detection limits ranged from 0.02 (estrone) to 1 ng L(-1) (estriol). The method was applied to determine environmental estrogens in coastal waters of the Baltic Sea. The analyses showed the presence of five compounds at levels between 0.10 (estrone) and 17 ng L(-1) (ethynylestradiol).     

Determination of sulphur in petroleum products after sulphur dioxide generation and of sulphur dioxide in air by chemiluminescent flame emission

The determination of sulphur in petroleum products by combustion, concentration of the sulphur dioxide in sodium tetrachtoromercurate solutions and cool flame molecular emission is described. Improvements in burner design and optimization of analytical conditions result in a minimum detectable amount of 6 ng of sulphur. The absorption of sulphur dioxide from air samples and its determination by a similar method gives a detection limit of 1.3 μg SO₂ m^-3.     

The accurate determination of total sulphur and disulphide and polysulphide compounds in petroleum products by metal reduction and flame emission spectrometry

Conditions for the determination of total sulphur and disulphide/polysulphide in petroleum products are described. The sulphur is reduced by heating with sodium or Devarda's alloy under reflux with subsequent liberation of H₂S and measurement of the chemiluminescent S₂ emission intensity in a hydrogen—argon diffusion flame. The precision and accuracy are good. Applications to light distillates and waxy residues are discussed.     

An indirect flame emission spectrometry method for the determination of traces of sulphur. I

Summary An accurate and simple indirect method of flame emission spectrometric determination of small quantities of elemental sulphur is described. The method is based on the reduction of elemental sulphur by means of sodium borohydride and oxidation of the resulting boron-sulphur compounds to sulphate by means of hydrogen peroxide. The determinations can be carried out in the presence of methanol, acetone, dimethylformamide, toluene and benzene. The detection limit of the reported method is 1 ppm of sulphur.

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Indirekte etnissionsspektroskopische Bestimmungsmethode für Spuren elementaren Schwefels. I.

Zusammenfassung Eine genaue und einfache, indirekte, emissionsspektroskopische Methode zur Bestimmung geringer Mengen elementaren Schwefels wurde ausgearbeitet. Sie besteht in der Reduktion des elementaren Schwefels mit Hilfe von Natriumborhydrid und in der Oxydation der entstehenden Bor-Schwefel-Verbindung zu Sulfat mit Hilfe von Wasserstoffperoxid. Die Analyse wurde in Methanol, Aceton, Dimethylformamid, Toluol und Benzol durchgeführt. Die Erfassungsgrenze beträgt 1 ppm Schwefel.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Characterization of nodularin variants in Nodularia spumigena from the Baltic Sea using liquid chromatography/mass spectrometry/mass spectrometry

Nodularin is a potent hepatotoxic cyclic pentapeptide produced by planktonic cyanobacterium Nodularia spumigena. Bloom and culture samples of the cyanobacterium collected and isolated from the Gulf of Gdańsk, southern Baltic Sea, were analyzed. Hybrid quadrupole-time-of-flight liquid chromatography/mass spectrometry/mass spectrometry (TOF-LC/MS/MS) with ionspray (ISP) and collision-induced dissociation (CID) were used to characterize nodularin and its analogues. The identification process was based on the comparison of recorded product ion spectra with the previously reported FAB-MS/CID (high-energy) mass spectra of the corresponding nodularin variants. Amino acid structures and sequences were derived from the fragmentation pattern of the [M+H](+) ions. Apart from unmodified nodularin with an arginine residue (NOD-R), three demethylated variants have been found. The sites of demethylation were located on aspartic acid [Asp(1)]NOD, the Adda residue [DMAdda(3)]NOD, and dehydrobutyric acid [dhb(5)]NOD. In two other nodularin variants an additional methyl group is located in the Adda [MeAdda]NOD and Glu [Glu(4)(OMe)]NOD residues. The linear NOD and the geometrical isomer of NOD-R, reported earlier in N. spumigena from New Zealand, have also been detected. Two of the total eight nodularin variants characterized in the present study, [dhb(5)]NOD and [MeAdda]NOD, have not been described earlier.     

Solid phase extractive preconcentration coupled to gas chromatography-atomic emission detection for the determination of chlorophenols in water samples

Solid-phase extraction (SPE) followed by derivatization and gas chromatography-atomic emission detection (GC-AED) was evaluated for the determination of five chlorophenols (CPs) in water samples. The derivatization was based on the esterification of phenolic compounds with ferrocenecarboxylic acid. The determination of the derivatized phenols was performed by GC-AED in the iron selective detection mode at 302 nm. The described method was tested on spiked water samples.The overall method gave detection limits of 1.6-3.7 ng L⁻¹ and recoveries of 90.9-104.5% for the examined mono- to trichlorophenols in 10 mL water samples. The CPs extracted from a 10 mL water sample with SPE were concentrated into 100 μL of organic solvent, a preconcentration factor of 100. The method was applied to lake and tap water samples, and CP contents between 6 and 51 ng L⁻¹ in lake water and between below the detection limit and 8 ng L⁻¹ in tap water were found for different CPs. The method is quick, simple and gives excellent recoveries, limits of detection and standard deviations.     

Selective and sensitive trace analysis of sulfur mustard with thermal desorption and two-dimensional gas chromatography-mass spectrometry

An improved method is presented for the trace analysis of sulfur mustard (HD) in biological samples, such as blood and tissue from laboratory animals. Using the internal standard method and liquid-liquid extraction with ethyl acetate, up to 400 microL of the extract was injected by thermal desorption from Tenax and analyzed by two-dimensional GC-MS/EI in SIM mode. The analysis was compared with a direct GC injection. Reversed thermal desorption was used as a tool for handling heavily contaminated (fat) samples, thus preventing contamination of the injection system and pre-column. A successful analytical configuration has been set up for the bioanalysis of HD at the low, toxicologically relevant pM level. A detection limit of 10 pg mL(-1) blood or pg g(-1) tissue of sulfur mustard (S/N=3) was established by using this configuration.     

Analysis of odour compounds from scented consumer products using gas chromatography-mass spectrometry and gas chromatography-olfactometry

Scented consumer products are being bought in increasing amounts and gaining more popularity. There is, however, relatively little information available about their ingredients, emissions and allergenic potential. Frequently, a mixture of different fragrance substances and not solely an individual substance contributes to the overall desired smell. The aim of this study was to investigate the odorous volatile organic compounds (OVOCs) in consumer products containing fragrances. Over 44 products were selected: various scented candles, printing products with different scent types and other products types particularly meant to be used indoors. Measurements were carried out in a desiccator. Air samples were collected on thermal desorption tubes to determine the released fragrance substances by means of gas chromatography-mass spectrometry (GC-MS). Moreover, gas chromatography-olfactometry (GC-O) was used to obtain sensory data and to ensure no important odorant was overlooked. Using both methods it was possible to distinguish between odour active and inactive compounds and subsequently to identify almost 300 different odorants across all scented products. Besides the advantage of differentiation, as the human nose is a very sensitive detector, GC-O was found to be a useful tool for detecting traces and chosen target compounds. One focus in this study lay on the 26 EU-regulated fragrance allergens to prove their relevance in scented consumer goods. In total, 18 of them were identified, with at least one substance being present in almost every product. Benzyl alcohol, cinnamaldehyde, citronellol, eugenol, linalool and limonene were the prevalently detected allergens. Particularly linalool and limonene were observed in over 50% of the products. In addition, eugenol appeared to be one of the most frequently detected compounds in trace-level concentrations in the candle emissions.     

Selective detection of volatile nickel,vanadium, and iron porphyrins in crude oils by gas chromatography-atomic emission spectroscopy

This report describes the selective detection of volatile nickel, vanadium, and iron metalloporphyrins in crude oil samples. An atomic emission detector (AED) was used for simultaneous detection of these metals using the Ni 301.2 nm, V 292.4 nm, and Fe 302.1 nm emission lines. Detection limits for these metals range from 0.05 to 5 pg/sec. The presence of volatile forms of these metals in several crude oil samples has been confirmed.     

Multiresidue method for the analysis of multiclass pesticides in agricultural products by gas chromatography-tandem mass spectrometry

A multiresidue method is described for determining 55 organophosphorus and organochlorinated compounds and pyrethroids commonly used in crop protection. Pesticide residues are extracted from samples with a mixture of ethyl acetate and sodium sulfate, obtaining a final preconcentration of I mg sample (ml extract)(-1). No additional clean-up steps are necessary. Analysis is performed by gas chromatography by using a combination of positive chemical ionisation (PCI) and electron impact (EI) ionisation modes and tandem mass spectrometry (GC-PCI/EI-MS-MS). Good sensitivity and selectivity of the method are obtained with limits of detection (LODs) ranging from 0.07 to 4.21 microg kg(-1) in all the cases, except for methamidophos, permethrin, cypermethrin and difenconazol. Average recoveries between 52 and 114% are obtained and good linearity is observed in the studied ranges (r > or = 0.994). The RSD values are < or = 29% in all the cases. The method has been applied to the analysis of 178 vegetable samples, as a part of the monitoring programme of the Association of Producers and Exporters of Fruits and Vegetables of Almería (COEXPHAL) and quality control systems applied during the assays have demonstrated a good performance and stability with time.     

Identification of radiolytic products from N-nitrosodimethylamine and N-nitrosopyrrolidine by gas chromatography and mass spectrometry

The radiolytic products of N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR) dissolved in dichloromethane (DCM) were identified after gamma irradiation. The UV spectra of NDMA and NPYR indicated that irradiation reduced the typical peak of NDMA at 258 nm and NPYR at 260 nm.The major radiolytic components identified in irradiated NDMA were ethyl acetate and 2-dimethyl propanol. The irradiated NPYR dissolved in DCM and produced 2-butanone and 2-methyl-6-propyl piperidine as the major radiolytic components. 2-Methyl-6-propyl piperidine was the component detected in the greatest concentration in irradiated NPYR.     

Permethylation of barbiturates. Separation and characterization of the reaction products by gas chromatography-mass spectrometry

A Series of barbiturates (I) has been permethylated with the methylsulfinylmethide carbanion and methyl iodide and the products (II to IV) separated, quantified and characterized by g.c.-m.s. The ratios and fragmentation patterns of II to IV are highly dependent upon the nature of the R-groups. All fragment ions have been confirmed by accurate mass measurements or perdeuteriomethylation.