Gy. Záray

Multiresidue analysis of pollutants as their trimethylsilyl derivatives, by gas chromatography-mass spectrometry

This paper reports a multiresidue analysis procedure which permits the identification and quantification of sixty-three water-soluble pollutants. Subsequent to their solid-phase extraction (SPE) enrichment, analyses of species have been carried out from one solution, by a single injection, as their trimethylsilyl-oxime ether/ester derivatives, by gas chromatography-mass spectrometry, within 31min. Based on our optimized extraction, derivatization and mass fragmentation studies separation have been performed in the total ion current mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Including various pharmaceuticals, benzoic acid, its substituted species, different aromatic carboxylic acids, cholic acids, unsaturated and saturated fatty acids, aliphatic dicarboxylic acids, as well as synthetic pollutants of various origins (2,4-di-tert-butylphenol, different phthalates). Standard compounds were added to 500 mL effluent wastewater samples, at three concentrations (1-5 microg/L, 5-10 microg/L and 10-20 microg/L). Recoveries, using the Waters Oasis cartridges performing extractions at pH 2, pH 4 and pH 7 proved to be the optimum at pH 4 (average recoveries (94.5%), except for cholesterol (10%), paracetamol (18%) and 2,5-dihydroxybenzoic acid (25%). Carbamazepine could be recovered at pH 7, only. Responses, obtained with derivatized standards proved to be linear in the range of 4-80 microg/L levels. Limit of quantitation values varied between 0.92 ng/L (4-hydroxyphenylacetic acid) and 600 ng/L (dehydrocholic acid) concentrations. One of the most important messages of this work is the confirmation of the origin of blank values. It was shown that contaminants, mainly 2,4-di-tert-butylphenol, different phthalates and fatty acids, are sourced both from the reagents and mainly from the SPE procedure, independent on the cartridge applied. Reproducibilities, characterized with the relative standard deviations (RSDs) of measurements, varied between 0.71% and 10%, with an average of 4.38% RSD. The practical utility of the method was shown by the identification and quantification of the pollutant contents of Hungarian influent and effluent wastewaters (for six consecutive months and that of the Danube River for 2 months).

A study of some techniques for direct solids sampling in plasma spectrometry

Abstract The capabilities and limitations of three techniques for direct solids sampling in atomic spectrometry are discussed and results obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES) for the analysis of real samples reported. First, the use of electroerosion with a medium-voltage spark at high repetition rate combined to ICP-AES for the direct analysis of metals is described. Detection limits are down to the smg g level and matrix effects are low, as is shown by the example of aluminium. Both are explained from an investigation of the produced analyte vapor by electron probe microanalysis. As a second technique, direct insertion of the sample into the plasma is studied. It is used for the direct determination of volatile elements but also of Ti in Al3O3. A suitable sample preparation technique and volatilization studies including the use of thermochemical aids are reported. Direct sample insertion also can be used for metal analyses, provided the trace elements to be determined are separated from the matrix. In aluminium, trace elements at the sub- μg g level have been determined after sorption of the elements on cellulose collectors. As a third technique, the use of slurry atomization for the analysis of powders of a small grain size has been investigated. The optimization of a Babington nebulizer and capabilities of the technique are illustrated by initial results for TiO2 and Al2O3 powders.

The role of the acquisition methods in the analysis of the non-steroidal anti-inflammatory drugs in Danube River by gas chromatography-mass spectrometry

In this paper authors describe a GC-MS acquisition study, relating to the most common, non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, naproxen, ketoprofen and diclofenac. As novelties to the field, for the trimethylsilyl (TMS) oxime ester derivatives of NSAIDs, at first, a tandem mass spectrometric (MS/MS) acquisition method has been developed, and, also for the first time, the three acquisition techniques, the full scan (FS), the selective ion monitoring (SIM) and the currently optimized MS/MS ones, have been compared: all three in parallel, under strictly the same derivatization/instrumental conditions, both from model solutions and from the Danube River samples. Critical evaluation of the three acquisition protocols was collated on their analytical performances and validated with the same characteristics like the six point calibration curve, the relative standard deviation percentages (RSD%) of parallel tests, the limit of quantitation (LOQ) and the instrumental limit of quantitation (ILQ) values. Data of six point calibration (r(2)>or=0.997) and RSD% (average: 5.8 RSD%) values proved to be independent on the acquisition methods, while, LOQ and ILQ values furnished considerable differences. Decreasing LOQ data, (expressed in ng/L concentrations) were obtained in the FS, SIM, MS/MS line for ibuprofen (1.0, 0.43, 0.41), naproxen (1.1, 1.0, 0.42), ketoprofen (2.6, 1.0, 0.49) and diclofenac (1.4, 0.41, 0.21), respectively. The same trend was determined in terms of the ILQ values. The practical utility of the optimized MS/MS technique was confirmed by the quantitation of the NSAID contents of the Danube River samples, determined by all three acquisition techniques. Results obtained confirmed the primary importance of the MS/MS acquisition method, even in comparison to the SIM one: avoiding the extreme overestimation of the ibuprofen (approximately 100%) and ketoprofen (approximately 400%) concentrations in the Danube River samples.

Graphite furnace for alternative combination with d.c. arc or inductively coupled plasma. Introduction and analysis of solid samples

SummaryA graphite furnace and d.c. arc combined source with the use of halogenating atmosphere in the furnace is described. The construction makes possible the introduction and analysis of both liquid and solid samples at minimum risk of contamination. Spectrographic detection resulted in background equivalent mass values below 10 ng for 22 from 36 elements applied in solution (Ar + CCl4 atmosphere and NaCl matrix). The intensity-time profiles indicated high rates of distillation of the impurities (including B, Cr, Hf, Mo, Ti, V, W and Zr) from silicon carbide and silicon nitride samples in the first 40 s of heating under chlorination (CCl4 vapour). Two versions of the exit part of the furnace are described for coupling to an ICP source; one of them has been used for the determination of titanium in alumina (spectrometric detection). Standardization with solution standards for solid sample analysis was unsuccessful. Based on the analytical curve obtained with variable amounts of solid standards (5–20 mg), a detection limit of 0.32 μg/g Ti was found for 20 mg alumina.

Derivatization and fragmentation pattern analysis of natural and synthetic steroids, as their trimethylsilyl (oxime) ether derivatives by gas chromatography mass spectrometry: analysis of dissolved steroids in wastewater samples.

This paper reports the extension of our multiresidue analysis (MA) procedure with 18 natural and synthetic steroids; permitting the identification and quantification, in total of 81 pollutants from one solution, by a single injection, as their trimethylsilyl (TMS)-oxime ether/ester derivatives, by gas chromatography-mass spectrometry (GC-MS), within 31 min. As a novelty to the field, basic researches, such as fragmentation pattern analysis and derivatization optimization studies were performed for androsterone, transdehydroandrosterone, transandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxy-progesterone-acetate, stigmasterol and β-sitosterol. Results confirmed that (i) the TMS oxime-ether derivatives of the keto steroids provide from 1.40 times (gestodene) up to 4.25 times (norethisterone) higher responses compared to their TMS-ether ones, and (ii) the distribution of syn/anti oximes is characteristic to the ketosteroid species examined. Based on our optimized mass fragmentation, solid phase extraction (SPE) and derivatization studies separations have been performed in the total ion current (TIC) mode, identification and quantification of compounds have been carried out on the basis of their selective fragment ions. Responses, obtained with derivatized standards proved to be linear (hydroxysteroids), or have been calculated from calibration curves (ketosteroids) in the range of 1.88-750ng/L levels. Limit of quantitation (LOQ) values varied between 1.88ng/L and 37.5ng/L concentrations. The most important practical messages of this work are the high androsterone (0.744-4.28μg/L), transandrosterone (0.138-4.00μg/L), coprostanol (2.11-302μg/L), cholesterol (0.308-41μg/L), stigmasterol (1.21-8.40μg/L) and β-sitosterol (1.12-11.0μg/L) contents of influent wastewaters. β-Estradiol (100ng/L) and estriol (54ng/L) were found in one influent sample, only. Reproducibilities, characterized with the relative standard deviation percentages (RSD%) of measurements, varied between 1.73 RSD% (β-estradiol) and 5.4 RSD% (stigmasterol), with an average of 4.82 RSD%.

The role of the acquisition methods in the analysis of natural and synthetic steroids and cholic acids by gas chromatography-mass spectrometry.

An exhaustive GC-MS acquisition study was performed, for the simultaneous analysis of natural and synthetic steroids and cholic acids (in order to insert them into the last tierce of our multiresidue analysis system), such as androsterone, β-estradiol, transdehydroandro-sterone, transdehyroandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, progesterone, cholesterol, medroxyprogesterone-acetate, lithocholic acid, stigmasterol, cholic acid, chenodeoxycholic acid, β-sitosterol, ursodeoxycholic acid, 3-hydroxy-7-ketocholic acid and dehydrocholic acid, in total 26 compounds. As novelties to the field, for the trimethylsilyl (TMS) oxime ether/ester derivatives of steroids and cholic acids, at first, a tandem mass spectrometric (MS/MS), multiple reaction monitoring (MRM) type acquisition method has been developed in a single run; also for the first time, the three acquisition techniques, the full scan (FS), the selective ion monitoring (SIM), in our case the multiple ion monitoring (MIM) and the currently optimized MRM methods, have been compared; all three, in parallel, under strictly the same derivatization/instrumental conditions, both in matrix free solutions and municipal wastewater from two Hungarian wastewater treatment plants (WWTPs). Critical evaluation of the three acquisition protocols was collated on their analytical performances and validated under the same conditions. The data of six point calibration curves for FS, MIM and MRM methods, showed that both R² (0.9995, 0.9858, 0.9975) and RSD (5.3, 5.8, 5.0), for two parallel derivatizations, each injected three times, proved to be independent of the acquisition processes. Whereas, for the method limit of quantification (LOQ) and the instrument limit of quantification (ILQ) values showed considerable differences. LOQ data, were decreasing in the FS, MIM, MRM line (expressed in ng/L), for all steroids and cholic acids. The same trend was determined in terms of the ILQ values. The practical utility of the optimized acquisition techniques was confirmed by the quantitation of the steroids and cholic acids contents of wastewater samples. Results confirmed the importance of the MRM acquisition method, even in comparison to the MIM one: with particular interest in selected cases: avoiding the extreme overestimation of the β-estradiol (156-1325%) and that of the ethinylestradiol (582-831%) concentrations in the wastewater samples.

Reference concentrations of trace elements in urine of the budapestian population

Reference values in biological specimens are crucial to estimate the type and magnitude of environmental and occupational exposure: Because of its importance in the excretion of noxious substances and to the noninvasive mode of its collection, urine is a useful specimen for monitoring studies. Thus, the concentrations of six trace elements (Al, Co, Mo, Nb, Ni, and Ti) were determined in 100 urine samples of the Budapestian population by inductively coupled plasma-mass spectrometry. The obtained creatinine adjusted concentrations (medians) are (in μg/g) 9.9, 0.6, 53.5, 0.4, 1.5, and 8.5 for Al, Co, Mo, Nb, Ni, and Ti, respectively.

The role of harmonized, gas and liquid chromatography mass spectrometry in the discovery of the neolignan balanophonin in the fruit wall of Cirsium vulgare

In order to identify and quantify fruit-lignans of Cirsium vulgare - authors introduced a special analysis system: with particular attention to the lignans enrichment/separation course. These synchronized, germination and enzymatic hydrolysis processes were followed by complementary gas and liquid chromatography, coupled with special mass selective detections (GC-MS, LC-MS/MS, LC-TOF/MS) and confirmed by nuclear magnetic resonance (NMR) spectroscopy. Mass fragmentations and NMR evidences, proved that the two main medicinal lignan constituents of the fruits of Cirsium vulgare are the neolignan-type, free balanophonin and the butyrolactone-type tracheloside. As novelty to the field, these two lignans of different chemical structures could be quantitatively extracted, separately from each others, without impurities. Balanophonin and tracheloside do accumulate in the fruits of C. vulgare, separately: balanophonin was found, in enormous high concentrations, in the fruit wall (23.2-24.9 mg/g), while in embryo part tracheloside was determined (20.3mg/g), exclusively. Consequently, the optimum source of balanophonin proved to be the fruit wall, while tracheloside, - providing trachelogenin upon enzymatic hydrolysis, - could be obtained from the embryo parts of fruits. As further novelties of the study balanophonin was identified and quantified at the first time with on-line chromatographic technique, in free form, without authentic standard compound.

DIRECT ANALYSIS OF SILICON CARBIDE POWDER BY TOTAL REFLECTION X-RAY FLUORESCENCE SPECTROMETRY

Three silicon carbide powders having different grain size distributions were analyzed by total reflection X-ray fluorescence (TXRF) spectrometry with the application of slurry sampling. For the elements investigated (Fe, Ti, V, Cu, Ni, and Ca) the line-to-background ratios show a maximum value at a surface concentration of 12.5 μg/mm2. For the realization of this surface concentration, a 25-μL aqueous slurry with a concentration of 1% (m/V) and pH of 10 was dropped onto the hydrophobic quartz carrier plate. For quantification of the intensity data, gallium was added as an internal standard to the slurries. Under these experimental conditions, the analytical data of the fine-grained powders (80–90% of the powder particles were less than 1.5 μm) are in good agreement with concentrations determined in various laboratories by inductively coupled plasma atomic emission spectrometry (ICP-AES), ICPmass spectroscopy (MS), electrothermal vaporization- (ETV)-ICP-AES, slurry sampling graphite furnace atomic absorption spectroscopy (GF-AAS), and neutron activation methods. Powders with a mean grain size greater than 1.5 μm deviate much more from the reference data. Calculated limits of detection (LODs) range from 2 to 25 μg/g. The precision expressed as relative standard deviation (RSD) varies between 4 and 14% for Fe, Ti, and V, whose concentrations in the fine-grained silicon carbide samples exceed by a minimum of tenfold their limits of detection; however the precision is very poor for Cu (66.6%) and Ni (62.3%), which have concentrations near the limits of the detection.

Elemental analysis of Dikerogammarus villosus samples for river water monitoring

Dikerogammarus villosus (amphipod crustacean) samples were collected from the River Danube. The applicability of artificial substrates (gravel and clay filled containers translocated at the bottom of the river) and the effect of the applied colonization periods of short (3 weeks) and long (up to 30 weeks) terms were tested. Ag, As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn concentrations of the amphipods were measured by inductively coupled plasma mass spectrometry (ICP-MS) after the digestion of some milligram samples. It was established that the artificial substrates did not influence the bioaccumulative processes of the elements investigated, and the short-term colonization period turned out to be sufficient for biomonitoring.