Naphthalene,a polycyclic aromatic hydrocarbon,in the fish samples from the Bangsai river of Bangladesh by gas chromatograph–mass spectrometry

Naphthalene, a polycyclic aromatic hydrocarbon (PAH), was detected and quantified in the selected varieties of fishes collected from the Bangsai river, one of the contaminated rivers located at Savar near the Dhaka Export Processing Zone (DEPZ), Bangladesh, during the period October 2009. Naphthalene, a carcinogenic compound, was analyzed by GC–MS as it was in the mixture of dichloromethane–hexane (1:1) crude extract of the flesh of fish samples collected from the aforesaid river. A suitable and reliable procedure for the extraction of naphthalene from the fish sample has been developed. A multi-layer clean-up (silica gel) column was used, followed by glass fiber filter (GFF) paper to eliminate the interfering organic compounds as well as the lipids and fat. It was observed that PAHs deposition on the samples takes place in different morphological parts of the biological materials. The PAH, naphthalene, was found in almost all of the fish samples and the concentration of which was in the range 0.030–1.004 μg/g. Recovery studies with fortified samples indicated that the recovery efficiency for naphthalene was about 79.14%. This concentration is within the range of values reported for other comparable regions of the world.     

Analytical development for analysis of pharmaceuticals in water samples by SPE and GC–MS

An analytical procedure involving solid-phase extraction (SPE) and gas chromatography–mass spectrometry (GC–MS) has been developed for determination of pharmaceutical compounds (aspirin, caffeine, carbamazepine, diclofenac, ketoprofen, naproxen, ibuprofen, clofibrate, clofibric acid, and gemfibrozil) in a variety of aqueous samples (wastewater and surface water). After filtration, samples were extracted and concentrated using C₁₈ or HLB cartridges, depending on the type of compound. Sample storage conditions were checked and optimized to ensure preservation of the pharmaceutical substance, taking into consideration environmental sampling conditions. For most of the pharmaceuticals monitored, recovery was in the range 53 to 99% and the variability was below 15% for the complete procedure, with limits of detection ranging from 0.4 to 2.5 ng L⁻¹, depending on the compound. The methods were successfully applied to monitoring of pharmaceutical contamination of the Seine estuary. Concentrations varied from several dozens of nanograms per liter for surface waters to several hundreds of nanograms per liter for wastewaters.     

Separation of free iodide from other I-species in human serum – Quantification in serum pools and individual samples

A method for the determination of free iodide in human serum has been developed. Iodide from pooled serum samples has been separated from the organic matter by SEC, subsequently freeze-dried and analyzed by ion chromatography. Investigations for recovery and precision have been carried out and provided sufficient results. For quality assurance ICP-MS has been taken additionally as a total I-detector. The iodide results of ICP-MS agree well with IC values. Iodine containing SEC- fractions from iodide-spiked samples has shown no increased I-values except that in the iodide fractions, proving that there has been no iodide conversion into other I-species (and vice versa) during the whole procedure. Free iodide from two serum pools of different healthy persons has been determined as 2.25 and 2.43 microg I(-)/l, respectively. The values are related to total iodine levels determined by ICP-MS. For comparative reasons a table of individual iodine and iodide values is presented.     

Using GC × GC-FID profiles to estimate the age of weathered gasoline samples

Predicting the amount of time that a petroleum mixture has been exposed to weathering effects has applications in areas of environmental and other forensic investigations, such as aiding in determining the cause and intent of a fire. Historically, research on the evaporation rates of hydrocarbon mixtures has focused on forensic oil spill identification and predicting if a fresh sample could be weathered to give an observed composition in an aged sample. Relatively little attention has focused on approaching the problem from the other direction: estimating exposure time based on the observed composition of a weathered sample at a given time and assuming a prior composition. Here, we build upon our previous research into the weathering of model mixtures by extending our work to gasoline. Samples of gasoline with varying octane ratings and from several vendors were weathered under controlled conditions and their composition monitored over time by two-dimensional gas chromatography (GC × GC). A variety of chemometric models were explored, including partial least squares (PLS), nonlinear PLS (PolyPLS) and locally weighted regression (LWR). A hierarchical application of multivariate techniques was able to predict the time for which a sample had been exposed to evaporative weathering. Partial least squares discriminant analysis could predict whether a sample was relatively fresh (<12 h exposure time) or highly weathered (>20 h exposure time). Subsequent regression models for these classes were evaluated for accuracy using the root mean square error of prediction. LWR was the most successful, whereby fresh and highly weathered samples were predicted to within 30 min and 5 h of exposure, respectively.     

Separation of Flavonoids from the Leaves of Oroxylum indicum by HSCCC

A high-speed counter-current chromatography system (HPCCC) capable of rapid processing has been employed to separate seven flavonoids from a methanolic extract of the leaves of Oroxylum indicum by a one-step isocratic elution using a chloroform–methanol–water (9.5:10:5) two-phase system. LC, MS and NMR have identified the components from the extract as chrysin, baicalein, baicalein-7-O-glucoside, baicalein-7-O-diglucoside, chrysin-7-O-glucuronide, baicalein-7-O-glucuronide, and a chrysin-diglucoside. Baicalein-7-O-glucuronide and chrysin-7-O-glucuronide have been separated from this plant by HSCCC for the first time. The present study also reports a new chrysin-diglucoside from the leaf extract. The results demonstrate that HSCCC is a powerful separation tool and can contribute to identifying and quantifying plant ingredients.     

Determination of selected polycyclic aromatic hydrocarbons and oxygenated polycyclic aromatic hydrocarbons in aerosol samples by high-performance liquid chromatography and liquid chromatography–tandem mass spectrometry

Fine and ultrafine particles are probably responsible for numerous health effects, but it is still unclear whether and to what extent the particle itself or organic compounds adsorbed or condensed on the particle are responsible for the effects observed. One important class of particle-bound substances are the polycyclic aromatic hydrocarbons (PAH) and their oxygenated derivatives. To improve the tools used for chemical characterization of particulate matter analytical methods for the determination of PAH and oxygenated PAH in aerosol samples of different origin have been developed and optimized. PAH on high-volume filters and on soot aerosols were analyzed by using accelerated solvent extraction for extraction and high-performance liquid chromatography with fluorescence detection for separation and quantification. Total PAH concentrations were in the range 0.3–9.3 ng m^–3. For analysis of selected oxygenated PAH on high-volume filters a liquid chromatography–tandem mass spectrometric method was developed and optimized. Preliminary investigations showed that oxygenated PAH at pg m^–3 concentrations can be determined.     

At-line microextraction by packed sorbent-gas chromatography–mass spectrometry for the determination of UV filter and polycyclic musk compounds in water samples

An at-line analysis protocol is presented that allows the determination of four UV filters, two polycyclic musk compounds and caffeine in water at concentration level of ng L⁻¹. The fully automated method includes analytes enrichment by Microextraction by packed sorbent (MEPS) coupled directly to large volume injection-gas chromatography–mass spectrometry. Two common SPE phases, C8 and C18, were examined for their suitability to extract the target substances by MEPS. The analytes were extracted from small sample volumes of 800 μL with recoveries ranging from 46 to 114% for the C8-sorbent and 65–109% for the C18-sorbent. Limits of detection between 34 and 96 ng L⁻¹ enable the determination of the analytes at common environmental concentration levels. Both sorbents showed linear calibration curves for most of the analytes up to a concentration level of 20 ng mL⁻¹. Carryover was minimized by washing the sorbents 10 times with 100 μL methanol. After this thorough cleaning, the MEPS are re-used and up to 70 analyses can be performed with the same sorbent. The fully automated microextraction GC–MS protocol was evaluated for the influence of matrix substances typical for wastewater. Dilution of samples prior to MEPS is recommended when the polar caffeine is present at high concentration. Real water samples were analyzed by the MEPS-GC–MS method and compared to standard SPE.     

Simultaneous determination of UV filters and polycyclic musks in aqueous samples by solid-phase microextraction and gas chromatography–mass spectrometry

A simple, precise and accurate method for the simultaneous determination of four UV filters and five polycyclic musks (PCMs) in aqueous samples was developed by solid-phase microextraction coupled with gas chromatography–mass spectrometry (SPME-GC–MS). The operating conditions affecting the performance of SPME-GC–MS, including fiber thickness, desorption time, pH, salinity, extraction time and temperature have been carefully studied. Under optimum conditions (30 μm PDMS fiber, 7 min desorption time, pH 7, 10% NaCl, 90 min extraction time at 24 °C), the correlation coefficients (r²) of the calibration curves of target compounds ranged from 0.9993 to 0.9999. The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.2 to 9.6 ng L⁻¹ and 0.7 to 32.0 ng L⁻¹, respectively. The developed procedure was applied to the determinations of four UV filters and five PCMs in river water samples and internal standard was used for calibration to compensate the matrix effect. Good relative recoveries were obtained for spiked river water at low, medium and high levels. The proposed SPME method was compared with traditional SPE procedure and the results found in river water using both methods were in the same order of magnitude and both are quite agreeable.     

A Novel Derivatization Method for Separation of Sarcosine from Isobaric l-Alanine in Human Urine by GC–MS

Sarcosine, an isomer of l-alanine, has been recently proposed as a potential biomarker for prostate cancer risk and aggressiveness, while some studies debated its importance. As both sarcosine and l-alanine are present in human urine, it is a great challenge to separate and accurately quantify these isobaric (i.e., same m/z) compounds by chromatographic separation and mass spectrometric detection. In this study, we developed a novel 1,3-dipolar cycloaddition derivatization method that resolves sarcosine from l-alanine and allows accurate quantification of sarcosine in human urine by gas chromatography–mass spectrometry (GC–MS). This novel derivatization approach was specific to sarcosine only, while the common silylanization method resulted in overlapped derivates of both sarcosine and l-alanine. The derivatization conditions, including reagent amount, reaction temperature and time, were optimized. The method developed here has excellent precision (relative standard deviation <4.7 %, n = 5), good linearity (slope = 0.2408; r ² = 0.9996, 0.1–100 μg mL^?1), and a low limit of detection in human urine (0.15 ng mL^?1). Application of this analytical method to urine samples spiked with standard sarcosine indicates that it is a robust and powerful alternative for resolving and quantifying sarcosine from l-alanine isomer in human urine by GC–MS.     

Insight of unresolved complex mixtures of saturated hydrocarbons in heavy oil via GC×GC-TOFMS analysis

The saturated hydrocarbon fraction of a heavily biodegraded crude oil from Liaohe oilfield was analyzed by using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The "humps", which was termed as unresolved complex mixtures (UCMs) in conventional gas chromatographic analysis, was separated for identification of the individual compound. Main compounds of UCMs were identified according to the combined information of characteristics of GC×GC chromatogram and time-of-flight mass spectra. It’s found that UCMs are mainly composed of great number of ring compounds with extremely low concentration. The ring compounds are separated according to their boiling point diversity in the first dimension column, then to their polarity or ring number variety in the second dimension column. In the sample there are two groups of UCMs, i.e., the first group compounds with boiling point lower that of C24 and the second group compounds with boiling point higher than that of C24. The first group of UCMs mainly consists of monocyclic, bicyclic and tricyclic ring compounds. The first group of UCMs is mainly composed of saturated hydrocarbons, in which the percentage of ring compounds with signal-to-noise ratio above 100 is about 75% of the total quantity of saturated hydrocarbon, while its mass is over 80% of the total saturated hydrocarbon. The second group of UCMs is mainly composed of tetracyclic and pentacyclic ring compounds, in which the percentage of UCM compounds with signal-to-noise ratio over 100 is about 17% of the total quantity of saturated hydrocarbon, and its mass is about 0.5% of the total saturated hydrocarbon. The results of this study are helpful for heavy oil developing and genesis mechanism understanding.     

Characteristics Identification of Neutral Constituents in Cigarette Particulate Matter by GC × GC -TOF MS

建立了全二维气相色谱-飞行时间质谱( GC×GC - TOF MS)分析卷烟主流烟气中中性化学成分的方法.以较长的弱极性柱HP-5 MS(50 m×0.2 mm i.d.×0.33 μm)作为第一维柱,较短的薄液膜中等极性柱DB-17MS(1.7 m×0.1 mm i.d.×0.1 μm)作为第二维柱,对优质烟叶单料卷烟烟气的中性成分进行定性分析,经过人工纠错等分析初步鉴定出匹配度大于700的1 464种成分,重点讨论了中性香味羰基化合物全二维点阵的谱图特征,为烟气和复杂体系的深入研究提供了方法学基础.     

Separation of microamounts of yttrium from strontium in the two‐phase water/nitrobenzene system

A rapid and very effective separation of carrierfree 90 Y in the aqueous phase of the water/nitrobenzene system from an 90 Y/90 Sr generator is proposed. After a twostage extraction separation, the radionuclide impurity of 90 Sr in the final aqueous phase containing carrierfree 90 Y is approximately 10 16%, while the chemical yield of 90 Y in this phase is practically 100%.     

Development of an analytical method for the determination of the residues of four pyrethroids in meat by GC–ECD and confirmation by GC–MS

The development of an analytical method for the determination of four selected pyrethroid insecticides at residue level in beef meat is presented. Acetone and petroleum ether at 40-60 degrees C were chosen as extraction solvents. A two-step clean-up was performed using an Extrelut NT3-C(18) system followed by a Florisil column, with disposable, ready-to-use cartridges. Instrumental analysis was carried out on a gas chromatograph equipped with an electron capture detector (GC-ECD), using matrix-matched and internal standard calibration techniques. Confirmatory analysis by GC-MS was performed. Recoveries at the EU Maximum Residue Limit (MRL), 0.5 x MRL and 1.5 x MRL levels and the repeatabilities were widely satisfactory. The main advantage of the method was the reduction of analysis time as compared with previously published works. The applicability of the method to different matrices and pesticide classes will be investigated.     

Separation of metallic impurities from uranium by anion exchange on Dowex 1×8 resin

The separation of metallic impurities from uranium by anion exchange with a Dowex 1×8 resin has been investigated. The following elements can be quantitatively separated from 400 mg uranium using a 1 cm diameter 15 or 30 cm long column. The elements Ag, Al, Ba, Ca, Cr, Cs, K, Mg, Mn, Na, Ni, Rb, REE, Sc, Th, Ti and Y can be separated by eluting the elements with conc. HCl. Uranium is retained by the resin. Al, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, REE and V can be separated by eluting with 0.01 N H₂SO₄. Uranium is retained by the resin. Cd and Zn can be separated by first eluting uranium with 0.5 N HCl and then eluting Cd and Zn with 1 N NH₃. Hf, Zr and V can be separated by eluting with 5 N HCl but some uranium contamination is unavoidable.     

Development of an analytical procedure for the determination of polybrominated diphenyl ethers in environmental water samples by GC–ICP-MS

Polybrominated diphenyl ethers (PBDEs) are flame retardants, which due to their widespread use are frequently present as pollutants in the environment. In the EU Water Framework Directive (WFD) six PBDE congeners (BDE 28, BDE47, BDE 99, BDE 100, BDE 153 and BDE 154) are listed as priority substances. The uncertainty of the analytical method used for their determination in water samples at environmental quality standard (EQS) level (0.5 ng L⁻¹ for the ΣPBDEs) should be equal or less than 50% and the limit of quantification (LOQ) for ΣPBDEs below 0.15 ng L⁻¹. To meet these requirements, an analytical procedure for the determination of these six PBDEs in environmental water samples by gas chromatography–inductively coupled plasma mass spectrometry (GC–ICP-MS) was developed. The acidification of water samples to pH 2 maintained the stability of PBDEs for at least 20 days. The use of Tris–citrate buffer enabled efficient desorption of PBDEs from suspended particulate matter (SPM) and humic acids (HA), and their further quantitative solvent extraction into 2 mL of iso-octane. When 300 mL of water sample was used for analysis and the organic phase concentrated to 25 μL, the expanded uncertainty for determination of PBDEs at EQS level was found to be around 40% (a coverage factor for a confidence level of 95%, k = 2), and the LOQ for the ΣPBDEs 0.109 ng L⁻¹. Finally, to demonstrate the applicability of the newly developed GC–ICP-MS procedure, PBDEs were determined in river and sea water samples.     

Positional and Quantitative Characterization of the Hydroxyethyl Groups in Hydroxyethyl Starch by GC/MS or NMR

Hydroxyethyl starches (HES) have been used medically as plasma volume expanders. They are composed of a starch backbone and substituted hydroxyethyl groups. The backbone is ?(1,4)-glycosidic-linked anhydroglucose units, which has branches formed by ?(1,6)-glycosidic bonds. Hydroxyethylation can take place at the C-2, C-3 and C-6 sites of the glucose rings, as well as at the hydroxyl groups of the substituted hydroxyethyl groups. Variation of the position and quantity of the substituted …     

Micro-pyrolysis of technical lignins in a new modular rig and product analysis by GC–MS/FID and GC × GC–TOFMS/FID

A new offline-pyrolysis rig has been designed to allow multifunctional experiments for preparative and analytical purposes. The system conditions can be set and monitored, e.g. temperature, its gradients and heat flux. Some special features include (1) high heating rates up to 120 °C/s with pyrolysis temperatures up to 850 °C at variable pyrolysis times and (2) the selection of different atmospheres during pyrolysis. A complete mass balance of products and reactants (gas, liquids and solids) by gravimetric methods and sequential chromatographic analyses was obtained.The pyrolytic behaviour and the decomposition products of lignin-related compounds were studied under different conditions: heating rates (from 2.6 °C/s up to 120 °C/s), pyrolysis temperatures at 500 °C and 800 °C in different atmospheres (N₂, H₂, and mixtures of N₂ and acetylene). Kraft lignin, soda lignin, organosolv lignin, pyrolytic lignin from pine bio-oil, residues from biomass hydrolysis and fermentation were studied.The obtained pyrolysis products were classified into three general groups: coke, liquid phase and gas phase (volatile organic compounds (VOC) and permanent gases). The liquid fraction was analysed by GC–MS/FID. In addition, comprehensive two-dimensional GC was applied to further characterise the liquid fraction. VOCs were semi-quantified by a modified headspace technique using GC–MS/FID analysis. The micro-pyrolysis rig proved to be an efficient and useful device for complex pyrolysis applications.     

Spectrophotometric determination of thorium in standard samples and monazite sands based on the floated complex of thorium with N-hydroxy-N,N′-diphenylbenzamidine and thorin

A selective and sensitive spectrophotometric method for the determination of Th(IV) has been based on the reaction with thorin and subsequent extraction of the red-orange coloured complex with N-hydroxy-N,N'-diphenylbenzamidine (HDPBA) in benzene as floated complex at pH 2.2. The complex in ethanol exhibits a maximum absorbance at 495 nm, with a molar absorptivity of 6.0x10(4) l mol(-1) cm(-1), with a Sandell's sensitivity of 3.9x10(-3) microg cm(-2). The method follows Beer's law up to 3.0 microg Th(IV) ml(-1). None of the common cations and anions tested interfere. The detection limit of the method is 0.04 microg Th(IV) ml(-1), the RSD (n=10) is 1.4%. The method has been successfully employed for the determination of thorium in various standard and monazite samples.