Analytical and Bioanalytical Chemistry (v.393, #3)
Reinhard Renneberg and Fred Lisdat (eds.): Biosensing for the 21st century by Gerald Urban (777-778).
New sample preparation technologies by Stig Pedersen-Bjergaard; Knut Einar Rasmussen (779-779).
is Professor of Pharmacy at the School of Pharmacy, University of Oslo, Norway, and Professor of Analytical Chemistry at the Faculty of Pharmaceutical Sciences, University of Copenhagen, Denmark. His research interest is development of new and miniaturized sample-preparation technologies for drugs and related substances in biological fluids and in environmental samples. Major research is focused on micro extraction techniques combined with new concepts for transport of analytes across liquid membranes. is Professor of Pharmacy at the School of Pharmacy, University of Oslo, Norway. His research interest also is development of new and miniaturized sample-preparation technologies for drugs and related substances in biological fluids and in environmental samples. Dr Rasmussen’s major research is focused on micro extraction techniques combined with new concepts for transport of analytes across liquid membranes.
Recent developments in solid-phase microextraction by Sanja Risticevic; Vadoud H. Niri; Dajana Vuckovic; Janusz Pawliszyn (781-795).
The main objective of this review is to describe the recent developments in solid-phase microextraction technology in food, environmental and bioanalytical chemistry applications. We briefly introduce the historical perspective on the very early work associated with the development of theoretical principles of SPME, but particular emphasis is placed on the more recent developments in the area of automation, high-throughput analysis, SPME method optimization approaches and construction of new SPME devices and their applications. The area of SPME automation for both GC and LC applications is particularly addressed in this review, as the most recent developments in this field have allowed the use of this technology for high-throughput applications. The development of new autosamplers with SPME compatibility and new-generation metal fibre assemblies has enhanced sample throughput for SPME-GC applications, the latter being attributed to the possibility of using the same fibre for several hundred extraction/injection cycles. For LC applications, high-throughput analysis (>1,000 samples per day) can be achieved for the first time with a multi-SPME autosampler which uses multi-well plate technology and allows SPME sample preparation of up to 96 samples in parallel. The development and evolution of new SPME devices such as needle trap, thin-film microextraction and cold-fibre headspace SPME have offered significant improvements in performance characteristics compared with the conventional fibre-SPME arrangement. Figure Photo of a high-throughput multi-fibre SPME PAS autosampler
Keywords: Solid-phase microextraction; Food analysis; Environmental analysis; Bioanalytical analysis; High throughput
Two new techniques for sample preparation in bioanalysis: Microextraction in packed sorbent (MEPS) and use of a bonded monolith as sorbent for sample preparation in polypropylene tips for 96-well plates by Lars G. Blomberg (797-807).
Analytical methods providing high throughput are required for the ever increasing number of samples in bioanalysis. Currently, the method of choice in bioanalysis is LC-MS-MS. This method is quite rapid and thereby the focus has been directed to sample preparation as being a bottleneck in total analysis systems. It has become necessary to develop sample preparation techniques to a new improved level. This development has been based on a systematic and scientific approach. The key factors in this development have been miniaturization, integration, and automation of the techniques. This review provides a short overview of recent developments. Special emphasis is on two techniques: microextraction in packed syringe (MEPS) and use of a monolithic acrylamide plug as sorbent in polypropylene tips primarily intended for use with 96-well plate systems.
Keywords: Sample preparation; Micro-extraction; Monolithic sorbent; High throughput; Automation; Mass spectrometry; Quantitative analysis; Bioanalysis
Critical review on recent developments in solventless techniques for extraction of analytes by C. Nerín; J. Salafranca; M. Aznar; R. Batlle (809-833).
The most recent contributions on solventless extraction techniques have been reviewed. This paper deals with those techniques that use solid phases, such as solid-phase microextraction, liquid phases, such as single-drop microextraction and hollow-fibre liquid-phase microextraction, and subcritical fluids, such as subcritical water extraction. In all cases, the most recent publications have been critically studied. Direct extraction and derivatization processes to facilitate the extraction of analytes in different areas have been included. Hyphenated approaches, if available, are also included in this review. Comparison of techniques organized by analytes and matrices also enhances this critical overview of solventless techniques.
Keywords: Microextraction techniques; SPME; In-tube; SPDE; LPME; HFLPME; SWE; Analysis
A review of recent advances in electrochemically modulated extraction methods by Courtney J. Collins; Damien W. M. Arrigan (835-845).
The use of electrochemistry and electrical behavior as a control and manipulation factor in analyte extractions is reviewed. Electromodulated extractions of ionic and neutral analytes are possible using this general approach. Extractions based on solid–liquid, liquid–liquid and membrane behaviors have been demonstrated and reported together with analyte extractions from real matrices and interfacing with instrumental detection methods. The electromodulation strategy offers great opportunities for selectivity in sample preparation.
Keywords: Sample preparation; Electrochemistry; Solid-phase extraction; Membrane extraction; Liquid–liquid extraction
Advances in the determination of degradation intermediates of personal care products in environmental matrixes: a review by Víctor Matamoros; Eric Jover; Josep M. Bayona (847-860).
In this review, recent methods developed for the determination of degradation intermediates of personal care products in environmental matrixes focusing on the extraction and determination steps are discussed. The five classes of personal care products evaluated are stimulants, fragrances, sunscreens, antimicrobials, and insect repellents. Methods are critically reviewed in terms of the analytical steps involved in the analysis, sample pretreatment, separation, and detection as well as the different confirmation strategies employed. Preconcentration from aqueous matrixes was performed by solid-phase extraction, liquid–liquid extraction, or solid-phase microextraction, allowing the simultaneous extraction of parent compounds and their degradation intermediates. Following the extraction and cleanup steps, the identification and quantification of degradation intermediates of personal care products at environmental levels (i.e., parts per trillion to parts per billion range) is usually performed by using mass spectrometry techniques such as single quadrupole mass spectrometry and more recently by time-of-flight mass spectrometry or tandem mass spectrometry. The main scope of this review is to critically evaluate the current state of the art of the analytical techniques used and to identify the research needs in the determination of degradation intermediates of personal care products in environmental matrixes.
Keywords: Personal care products; Metabolites; Degradation intermediates; Sample preparation
Fiber-packed needle-type sample preparation device designed for gas chromatographic analysis by Yoshihiro Saito; Ikuo Ueta; Mitsuhiro Ogawa; Akira Abe; Kentaro Yogo; Shingoro Shirai; Kiyokatsu Jinno (861-869).
A miniaturized sample preparation technique that uses a fine-fiber-packed needle as the extraction medium is reviewed, especially in relation to its application to the analysis of volatile organic compounds by gas chromatography. When the needle was packed longitudinally with a bundle of fine filaments (12 µm o.d.) which were also surface-coated with polymeric materials, successful sample preconcentration was obtained. Improved sensitivity was also established by introducing simultaneous derivatization reactions into the extraction process in the fiber-packed needle. The storage performance of the needle clearly demonstrated the potential of the technique for typical on-site sampling during environmental analysis. In this short review, the fiber-packed extraction needle developed by the authors is summarized along with applications that use the fiber-packed needle as a miniaturized extraction device.
Keywords: Sample preparation; Miniaturization; Fiber-packed needle; Derivatization; Gas chromatography
Ionic liquids in sample preparation by Rui Liu; Jing-fu Liu; Yong-guang Yin; Xia-lin Hu; Gui-bin Jiang (871-883).
Due to their unique properties, their good extractabilities for various target analytes, and the fact that many compounds are highly soluble in them, room-temperature ionic liquids (ILs) are used as promising alternatives to the traditional organic solvents employed in sample preparation. ILs have been used as extraction solvents for a wide range of analytes, from environmental contaminates to biomacromolecules and nanomaterials, and as dissolution solvents for various detection techniques. In this paper, the main applications of ILs in sample preparation are reviewed, and the problems and challenges in this area are described.
Keywords: Ionic liquids; Sample preparation; Environmental analysis; Bioanalysis; Nanomaterials
Sample pretreatment techniques for oligopeptide analysis from natural sources by Anna Poliwoda; Piotr P. Wieczorek (885-897).
The analysis of oligopeptides in samples of food, tissues, and body fluids attracts considerable attention. The complexity of such samples requires efficient sample preparation (i.e., concentration and cleanup) procedures to remove interfering endogenous compounds and inorganic or organic salts. The methods of sample pretreatment that enable effective and selective isolation and/or preconcentration of oligopeptides from complex sample matrices have been reviewed. In each case, examples of application were presented and discussed, taking into account selectivity, enrichment, method automation, cleanup, and environmental aspects of the developed methods.
Keywords: Body fluids; Oligopeptides; Sample preparation
Selective sample preparation for the analysis of (fluoro)quinolones in baby food: molecularly imprinted polymers versus anion-exchange resins by Myriam Díaz-Alvarez; Esther Turiel; Antonio Martín-Esteban (899-905).
In this work, an analytical method for simultaneous analysis of several quinolones (cinoxacin, oxolinic acid, nalidixic acid, and flumequine) and fluoroquinolones (norfloxacin, enrofloxacin, enoxacin, ciprofloxacin, and danofloxacin) in baby-food samples is described for the first time. The method is based on isolation of these analytes by ultrasound-assisted extraction procedure followed by a solid-phase extraction sample clean-up step and final determination of the analytes by HPLC using UV detection. For the extraction step, 2 g baby food was mixed with methanol in a centrifuge tube and one single extraction cycle of 15 min at room temperature was carried out. After centrifugation, supernatant was collected and two different solid-phase extraction procedures were developed and evaluated for sample clean-up. The first was based on use of strong anion-exchange cartridges whereas the second was based on use of a ciprofloxacin-imprinted polymer. Both sample clean-up procedures had their own advantages and drawbacks, and the analytical performance and applicability of each procedure was established and properly discussed. The anion-exchange resin-based method enabled simultaneous determination of quinolones and fluoroquinolones, reaching limits of detection ranging from 0.03 to 0.11 μg g−1. In contrast, the use of a ciprofloxacin-imprinted polymer did provide selectivity towards fluoroquinolones, leading to chromatograms free from co-extractives reaching limits of detection one order of magnitude lower than those obtained by the first approach.
Keywords: Baby food; (Fluoro)quinolones; Ultrasound-assisted extraction; Sample clean-up; Anion exchanger; Molecularly imprinted polymer
Multiresidue screening of endocrine-disrupting chemicals and pharmaceuticals in aqueous samples by multi-stir bar sorptive extraction–single desorption–capillary gas chromatography/mass spectrometry by Els Van Hoeck; Francesca Canale; Chiara Cordero; Sien Compernolle; Carlo Bicchi; Pat Sandra (907-919).
A multiresidue method for screening endocrine-disrupting chemicals (EDCs) and pharmaceuticals in aqueous samples is presented. Four 10-mL aliquots of water were taken for stir bar sorptive extraction (SBSE) and they were treated in the following way. In sample one, in situ derivatization was performed with acetic acid anhydride to improve the extraction efficiencies and chromatographic analysis of phenolic compounds. For the same reasons, aliquot two was treated with ethyl chloroformate to improve amine and acid extraction and analysis, and aliquot three with tetraethylborate to enhance organotin compound extraction and analysis. Methanol was added to sample four to stop adsorption of apolar solutes on the wall. After SBSE, the four stir bars, together with a plug of glass wool impregnated with bis(trimethylylsilyl)trifluoroacetamide (BSTFA) to derivatize hydroxyl functionalities, were introduced into the same thermal desorption tube, heat-desorbed, and analyzed simultaneously by capillary GC/MS. The figures of merit of the method were evaluated with an EDC model mixture. In scan-mode MS, the limits of detection (LODs) were in the range 1–500 ng/L, while the LODs dropped by a factor of 50–100 when ion monitoring MS was applied to the targets. The performance of the method was illustrated by analysing some real-world water samples.
Keywords: Capillary GC/MS; Stir bar sorptive extraction; In situ derivatization; Water analysis; Multi-shot mode; Endocrine-disrupting chemicals
Electromembrane extraction of basic drugs from untreated human plasma and whole blood under physiological pH conditions by Astrid Gjelstad; Knut Einar Rasmussen; Stig Pedersen-Bjergaard (921-928).
The present work describes the first systematic study of electromembrane extraction (EME) from biological matrices under physiological conditions. Six basic drugs with protein binding in the range of 20–97% were extracted from untreated human plasma and whole blood through a supported liquid membrane (SLM) consisting of 1-ethyl-2-nitrobenzene impregnated in the walls of a hollow fiber, and into an acidified aqueous solution inside the lumen of the fiber. The electrical potential difference over the membrane reduced the protein binding of the drugs and transported the free drug fraction over the membrane. Recoveries in the range 25–65% were obtained with 10-min extraction time and an applied voltage of only 10 V over the SLM. Interday precision better than 20% RSD and linearity in the range 0.5–10 µg/mL were obtained for nortriptyline and methadone. Extraction from untreated whole blood was also demonstrated with recoveries in the range 19–51%.
Keywords: Sample preparation; Supported liquid membranes; Electromembrane extraction; Basic drugs; Physiological conditions
Ion-pair hollow-fiber liquid-phase microextraction of the quaternary ammonium surfactant dicocodimethylammonium chloride by Sofie Hultgren; Niklas Larsson; Bo F. Nilsson; Jan Åke Jönsson (929-937).
A two-phase hollow-fiber (HF) liquid-phase microextraction (LPME) method was developed for determination of a quaternary ammonium compound surfactant, dicocodimethylammonium chloride, in aqueous samples. The porous HF was fixed on a metal rod support and was impregnated with approximately 6.6 μL of organic extractant, which was immobilized in the HF pores. Surfactant extraction was facilitated by addition of carboxylic acid to the sample forming neutral ion pairs with the quaternary ammonium compound. After extraction, the analyte was transferred from the organic extractant in the fiber pores by dissolving the 1-octanol into 100 μL methanol. The methanol extract was analyzed by liquid chromatography–mass spectrometry. The method was optimized (with optimized parameters in brackets) with regard to type of organic extractant (1-octanol), fiber length (2 cm), choice and concentration of anionic carrier (600 μg L−1 octanoate), procedure of transfer to methanol (15-min sonication), sample volume (250 mL), extraction time (17 h), pH (10), and ionic strength (50 mM carbonate). Aspects influencing repeatability in LPME of (quaternary ammonium) surfactants are discussed. The enrichment factor achieved in 250-mL carbonate buffer was around 400. Due to matrix effects, the enrichment factors achieved when industrial process water was analyzed were 120 or about 30% of that in carbonate buffer. Detection limits of 0.3 μg L−1 in carbonate buffer and 0.9 μg L−1 in industrial process water were obtained. If the studied compound is seen as a model substance representing quaternary dialkylated dimethylated ammonium surfactants in general, the developed method may be applied to other quaternary ammonium surfactants.
Keywords: Liquid-phase microextraction; Quaternary ammonium compound; Cationic surfactant; Ion-pair extraction; Liquid chromatography; Mass spectrometry
Determination of seven arsenic compounds in urine by HPLC-ICP-DRC-MS: a CDC population biomonitoring method by Carl P. Verdon; Kathleen L. Caldwell; Mark R. Fresquez; Robert L. Jones (939-947).
A robust analytical method has been developed and validated by use of high-performance liquid chromatography inductively coupled plasma mass spectrometry with Dynamic Reaction Cell™ (DRC) technology that separates seven arsenic (As) species in human urine: arsenobetaine (AB), arsenocholine, trimethylarsine oxide (TMAO), arsenate (As(V)), arsenite (As(III)), monomethylarsonate, and dimethylarsinate. A polymeric anion-exchange (Hamilton PRP® X-100) column was used for separation of the species that were detected at m/z 75 by ICP-DRC-MS (PerkinElmer™ SCIEX® ELAN DRCII™) using 10% hydrogen–90% argon as the DRC gas. The internal standard (As) is added postcolumn via an external injector with a sample loop. All analyte peaks were baseline-separated except AB and TMAO. Analytical method limits of detection for the various species ranged from 0.4 to 1.7 μg L−1 as elemental As. As(III) conversion to As(V) was avoided by adjusting the urine sample to
Keywords: Arsenic; Speciation; High-performance liquid chromatography; Inductively coupled plasma mass spectrometry; Urine; Biomonitoring
Determination of viable Escherichia coli using antibody-coated paramagnetic beads with fluorescence detection by F. Ceyda Dudak; İsmail H. Boyacı; Agnese Jurkevica; Mahmud Hossain; Zoraida Aquilar; H. Brian Halsall; Carl J. Seliskar; William R. Heineman (949-956).
A rapid and convenient assay system was developed to detect viable Escherichia coli in water. The target bacteria were recovered from solution by immunomagnetic separation and incubated in tryptic soy broth with isopropyl-β-d-thiogalactopyranoside, which induces formation of β-galactosidase in viable bacteria. Lysozyme was used to lyse E. coli cells and release the β-galactosidase. β-Galactosidase converted 4-methylumbelliferyl-β-d-galactoside to 4-methylumbelliferone (4-MU), which was measured by fluorescence spectrophotometry using excitation and emission wavelengths of 355 and 460 nm, respectively. Calibration graphs of 4-MU fluorescence intensity versus E. coli concentration showed a detection range between 8 × 104 and 1.6 × 107 cfu mL−1, with a total analysis time of less than 3 h. The advantage of this method is that it detects viable cells because it is based on the activity of the enzyme intrinsic to live E. coli.
Keywords: Escherichia coli ; Immunoassay; Paramagnetic bead; β-Galactosidase; Fluorescence
Toxicity identification fractionation of environmental estrogens in waste water and sludge using gas and liquid chromatography coupled to mass spectrometry and recombinant yeast assay by Marc P. Fernandez; Tania-Noelia Noguerol; Silvia Lacorte; Ian Buchanan; Benjamin Piña (957-968).
We developed a toxicity identification fractionation (TIF) procedure to determine estrogenic compounds in wastewaters and sludge. The procedure consisted in fractionation of samples through a C18 solid-phase extraction cartridge, in which Fraction I contained nonylphenol (NP) and its mono (NPEO1) and diethoxylate (NPEO2) and the markers of faecal exposure, Fraction II contained bisphenol A (BPA) and synthetic and natural hormones, and Fraction III contained the hormone conjugates. These three fractions were analyzed in parallel using gas or liquid chromatography coupled to mass spectrometry and recombinant yeast assay (RYA). Water samples collected daily throughout a whole week contained from 0.45 to 7.22 μg L−1 of NP > NPEO1 > NPEO2 and were responsible for the estrogenicity of these samples. Fractions II and III were not estrogenic and that was due to the low ng L−1 level of hormones and hormone conjugates found, respectively. The biological treatment sewage treatment plant (STP) was capable to eliminate from 52 to 100% of the compounds, with bisphenol A being the least removed. Only alkylphenols were accumulated in sludge with concentrations from 8.69 to 26.3 mg kg−1 dw of NPEO1 > NPEO2 > NP. The integrated procedure herein proposed can be used as a screening method to evaluate estrogenic compounds in STPs and to survey faecal elimination.
Keywords: Estrogenic endocrine-disrupting compounds; Wastewater; Sludge; Toxicity identification fractionation; GC-MS; LC-MS
A method for the quantification of biomarkers of exposure to acrylonitrile and 1,3-butadiene in human urine by column-switching liquid chromatography–tandem mass spectrometry by T. Schettgen; A. Musiol; A. Alt; E. Ochsmann; T. Kraus (969-981).
1,3-Butadiene and acrylonitrile are important industrial chemicals that have a high production volume and are ubiquitous environmental pollutants. The urinary mercapturic acids of 1,3-butadiene and acrylonitrile—N-acetyl-S-(3,4-dihydroxybutyl)cysteine (DHBMA) and MHBMA (an isomeric mixture of N-acetyl-S-((1-hydroxymethyl)-2-propenyl)cysteine and N-acetyl-S-((2-hydroxymethyl)-3-propenyl)cysteine) for the former and N-acetyl-S-2-cyanoethylcysteine (CEMA) for the latter—are specific biomarkers for the determination of individual internal exposure to these chemicals. We have developed and validated a fast, specific, and very sensitive method for the simultaneous determination of DHBMA, MHBMA, and CEMA in human urine using an automated multidimensional LC/MS/MS method that requires no additional sample preparation. Analytes are stripped from urinary matrix by online extraction on a restricted access material, transferred to the analytical column, and subsequently determined by tandem mass spectrometry using labeled internal standards. The limits of quantification (LOQs) for DHBMA, MHBMA, and CEMA were 10 µg/L, 2 µg/L, and 1 µg/L urine, respectively, and were sufficient to quantify the background exposure of the general population. Precision within series and between series for all analytes ranged from 5.4 to 9.9%; mean accuracy was between 95 and 115%. We applied the method on spot urine samples from 210 subjects from the general population with no occupational exposure to 1,3-butadiene or acrylonitrile. A background exposure of the general population to acrylonitrile was discovered that is basically influenced by individual exposure to passive smoke as well as active smoking habits. Smokers showed a significantly higher excretion of MHBMA, whereas DHBMA levels did not differ significantly. Owing to its automation, our method is well suited for application in occupational or environmental studies. Figure Boxplots of the results from LC/ESI-MS/MS analysis of urinary excretion of CEMA reveal a strong correlation with nicotine metabolite cotinine, indicating that exposure to passive smoke as well as active smoking is the main source of exposure to acrylonitrile in the general population
Keywords: Biomarkers of exposure; Carcinogen; Passive smoke; Mass spectrometry
Study of toxicity of imidazolium ionic liquids to watercress (Lepidium sativum L.) by Sylwia Studzińska; Bogusław Buszewski (983-990).
The sensitivity of Lepidium sativum L. germination to three imidazolium ionic liquids was investigated in solutions and soils artificially contaminated with mixtures of those compounds. In case of aquatic solutions, the toxic character of analyzed compounds is connected with their hydrophobicity. The seedling growth is increasing with the decrease in ionic liquid hydrophobicity. The novelty of those studies is the application of high-performance liquid chromatography, which was used for the determination of ionic liquid quantity absorbed by cress. There was almost linear relationship between decrease in root germination and amount of ionic liquid uptaken by cress. Furthermore, the systematic studies on the influence of total organic carbon content in soil on the toxicity of ionic liquids to cress were performed for the first time. Hazardous effects appeared to be closely connected with organic matter: with the decrease of total organic carbon quantity, the inhibition of plant growth was more significant. Visual effects of ionic liquid toxic activity to garden cress are similar as in the case of nutrient deficit in plants. Figure Visual phytotoxicity effects observed during the test; leaf chromatosis: light green and yellow (up photos), violet (lower photos)
Keywords: Imidazolium ionic liquids; Lepidium sativum L.; Toxicity tests; Hydrophobicity; Organic matter in soil; High-performance liquid chromatography
Investigation of genetic variants of α-1 acid glycoprotein by ultra-performance liquid chromatography–mass spectrometry by Lívia Budai; Oliver Ozohanics; Krisztina Ludányi; László Drahos; Tibor Kremmer; Judit Krenyacz; Károly Vékey (991-998).
Genetic variants of human plasma alpha-1 acid glycoprotein (AGP) have been studied in cancer, compared with a group of healthy control. AGP has four genetic variants: AGP F1, F2, and S variants correspond to the ORM1 gene whereas AGP A corresponds to the ORM2 gene. The proportion of ORM1 and ORM2 variants were studied in plasma using a novel UPLC–MS method. Plasma total AGP level was 0.5 ± 0.2 g L−1 and the proportions of the ORM1 and ORM2 variants were 76.3 ± 8.2% and 23.7 ± 8.2%, respectively. In cancer plasma AGP levels increased fourfold and the proportion of ORM1 variants increased to 88.7 ± 6.8%. Changes in the proportion of genetic variants due to cancer were clearly significant, as shown by statistical analysis. Three different cancer types have been studied, lymphoma, melanoma, and ovarian cancer. The results did not show any difference depending on cancer type. The results indicate that, in accordance with prior expectations, the ORM1 variant is predominantly responsible for the acute-phase property of AGP.
Keywords: Alpha-1 acid glycoprotein; Cancer; Genetic variant; Peptide marker; UPLC–MS
Fluorometry of singlet oxygen generated via a photosensitized reaction using folic acid and methotrexate by Kazutaka Hirakawa (999-1005).
A method for the fluorometry of singlet oxygen (1O2) using less fluorescent folic acid and its analogue, methotrexate (MTX), was examined. Folic acid and MTX were decomposed into a strongly fluorescent pteridine compound via a photosensitized reaction by 1O2-generating photosensitizers in a deuterium oxide solution. The fluorescence intensity increased in proportion to the irradiation time or the number of photons absorbed by the photosensitizer. This method using the fluorescence enhancement of these folic acid analogues can be applied to determine the quantum yield of 1O2 generated through a photosensitized reaction in deuterium oxide. The background fluorescence of MTX is quite smaller than that of folic acid, indicating that MTX can be used for the more sensitive detection of 1O2. Figure (DOC 37.0 KB)
Keywords: Singlet oxygen; Fluorometry; Folic acid; Methotrexate; Photosensitizer
How critical is the use of commercially available enzymes for selenium speciation? by Petra Cuderman; Vekoslava Stibilj (1007-1013).
The aim of this work was to check whether commercially available enzymes are pure enough to be used for selenium speciation analysis and the contribution that impurities could make to Se determination in real samples. For this purpose, twelve commercially available enzymes with different origins and classifications (protease, amylase, cellulase, lipase) were analysed. After the dissolution of the enzyme in water, the Se species were separated by ion exchange chromatography, with inductively coupled plasma mass spectrometry used as the detection system. The results showed that the Se content was significant in several cases. The highest value was obtained for β-amylase from barley, 3100 ng Se per g of enzyme. Speciation analysis showed that Se-methionine, selenite, selenate and some unknown compounds were present in several enzymes. In general, the Se species identified represented a small fraction of the total Se. For instance, only 17% of the total Se was determined for β-amylase from barley. On the other hand, about 100% of the total Se was identified in protease from Streptomyces griseus. Upon comparing the results from different lots of the same enzyme, not all of them were found to be comparable. Thus, the presence of selenium species in commercially available enzymes could be due to the preparation procedure used for the enzyme; they could be present as degradation products. Therefore, when determining selenium species in samples with low Se contents, attention should be paid to enzyme purity in relation to selenium compounds when an enzyme is used for hydrolysis.
Keywords: Protease; Amylase; Cellulase; Lipase; Selenium compounds; HPLC-ICP-MS
Multivariate optimization and simultaneous determination of hydride and non-hydride-forming elements in samples of a wide pH range using dual-mode sample introduction with plasma techniques: application on leachates from cement mortar material by Mesay Mulugeta; Grethe Wibetoe; Christian J. Engelsen; Alemayehu Asfaw (1015-1024).
Analytical methods have been developed for the simultaneous determination of hydride-forming (As, Sb) and non-hydride-forming (Cr, Mo, V) elements in aqueous samples of a wide pH range (pH 3–13). The methods used dual-mode (DM) sample introduction with ICP-AES and ICP-MS instruments. The effect of selected experimental variables, i.e., sample pH and concentrations of HNO3, thiourea, and NaBH4, were studied in a multivariate way using face-centered central composite design (FC-CCD). Compromised optimum values of the experimental parameters were identified using a response optimizer. The statistically found optimum values were verified experimentally. The methods provided improved sensitivities for the hydride-forming elements compared with the respective conventional nebulization (Neb) systems by factors of 67 (As) and 64 (Sb) for ICP-AES and 36 (As) and 54 (Sb) for ICP-MS. Slight sensitivity improvements were also observed for the non-hydride-forming elements. The limits of detection (LOD) of As and Sb were lowered, respectively, to 0.8 and 0.9 μg L−1 with the DM-ICP-AES system and to 0.01 and 0.02 μg L−1 with the DM-ICP-MS system. The short-term stabilities of both methods were between 2.1 and 5.4%. The methods were applied for the analysis of leachates of a cement mortar material prepared in the pH range 3–13. The elemental concentration of the leachates determined by the two DM methods were statistically compared with the values obtained from Neb-ICP-MS analysis; the values showed good agreement at the 95% confidence level. Quantitative spike recoveries were obtained for the analytes from most of the leachates using both DM methods. Figure Schematic of the dual-mode sample introduction system used in combination with ICP-AES and ICP-MS for the simultaneous determination of hydride and non-hydride-forming elements
Keywords: Dual-mode sample introduction; ICP-AES; ICP-MS; Multivariate optimization; pH-dependent leaching
Development of a nondestructive method for underglaze painted tiles—demonstrated by the analysis of Persian objects from the nineteenth century by Ina Reiche; Stefan Röhrs; Joseph Salomon; Birgit Kanngießer; Yvonne Höhn; Wolfgang Malzer; Friederike Voigt (1025-1041).
The paper presents an analytical method developed for the nondestructive study of nineteenth-century Persian polychrome underglaze painted tiles. As an example, 9 tiles from French and German museum collections were investigated. Before this work was undertaken little was known about the materials used in pottery at that time, although the broad range of colors and shades, together with their brilliant glazes, made these objects stand out when compared with Iranian ceramics of the preceding periods and suggested the use of new pigments, colorants, and glaze compositions. These materials are thought to be related to provenance and as such appropriate criteria for art-historical attribution. The analytical method is based on the combination of different nondestructive spectroscopic techniques using microfocused beams such as proton-induced X-ray emission/proton-induced γ-ray emission, X-ray fluorescence, 3D X-ray absorption near edge structure, and confocal Raman spectroscopy and also visible spectroscopy. It was established to address the specific difficulties these objects and the technique of underglaze painting raise. The exact definition of the colors observed on the tiles using the Natural Color System®© helped to attribute them to different colorants. It was possible to establish the presence of Cr- and U-based colorants as new materials in nineteenth-century Persian tilemaking. The difference in glaze composition (Pb, Sn, Na, and K contents) as well as the use of B and Sn were identified as a potential marker for different workshops. Figure UV fluorescence and visible spectroscopy are two of the non-destructive analytical methods used to investigate the coloring agents of underglaze painted tiles. Imaging of the uranium-containing areas was carried out by UV photography and identification of the chemical species by visible spectroscopy.
Keywords: Archaeometry/fine arts; X-ray spectroscopy; Raman spectroscopy; UV–VIS; Colored glaze; Uranium
Characterization of volatile and semivolatile compounds in waste landfill leachates using stir bar sorptive extraction–GC/MS by L. Badoil; D. Benanou (1043-1054).
Stir bar sorptive extraction in combination with thermal desorption coupled online to capillary gas chromatography–mass spectrometry was applied to investigate volatile and semivolatile fractions in two waste leachate samples: old and fresh ones. The present study helps to improve our knowledge of waste leachate organic composition. The aim is to then make use of this knowledge afterwards in order to generate more reliable and specific treatment processes for waste leachates and thus to respect the environmental statute law regarding their rejection. The volatile and semivolatile compounds appeared to be mainly anthropogenic in origin. Moreover, lactic acid and cyclic octaatomic sulfur could potentially be used as microbiological activity indicators, since they occur during organic matter degradation processes within waste leachates. Figure TDU-CGC-MS analytical equipment
Keywords: Stir bar sorptive extraction; Volatile and semivolatile organic compounds; Waste landfill leachate; Capillary gas chromatography/mass spectrometry
Preparation of highly selective solid-phase extractants for Cibacron reactive dyes using molecularly imprinted polymers by Yahya S. Al-Degs; Adnan S. Abu-Surrah; Khalid A. Ibrahim (1055-1062).
Selective polymeric extractants were prepared for preconcentration of Cibacron reactive red dye, a dye that is often applied with Cibacron reactive blue and Cibacron reactive yellow for dyeing of fabrics. The best extractant was fabricated (in chloroform) using methacrylic acid (as monomer), ethylene glycol dimethacrylate (as crosslinker), AIBN (as initiator for polymerization), and red dye as template molecule, with a molar stoichiometric ratio of 8.0:40.0:2.5:0.63, respectively. The structure of the molecularly imprinted polymer (MIP) was robust, and resisted dissolution up to 260 °C. Compared with the un-imprinted polymer, the imprinted product has a large specific surface area which improved its adsorption capacity. The effect of imprinting was obvious from the adsorption capacity measured at pH 4 for red dye (the imprinted molecule), which was increased from 24.0 to 79.3 mg g−1 after imprinting. Equilibrium adsorption studies revealed that the dye-imprinted-polymer enables efficient extraction of red dye even in the presence of blue and yellow dyes which have similar chemical natures to the red dye. The selectivity coefficients S red dye/dye, were 13.9 and 17.1 relative to the yellow and blue dyes, respectively. The MIP was found to be effective for red dye preconcentration, with a preconcentration factor of 100, from tap water and treated textile wastewater. The factors affecting extraction of red dye by the MIP were studied and optimized. Under the optimized extraction conditions, red dye was selectively quantified in the presence of other competing dyes at a concentration of 20 μg L−1 from different water systems with satisfactory recoveries (91–95%) and RSD values (∼5.0%).
Keywords: Reactive dyes; Separation; Molecularly imprinted polymers; Solid-phase extraction
Molecularly imprinted solid-phase extraction for the determination of fenitrothion in tomatoes by Leandro Alves Pereira; Susanne Rath (1063-1072).
Organophosphorus insecticides are widely employed in agriculture, and residues of them can remain after harvesting or storage. Pesticide residue control is an important task for ensuring food safety. Common chromatographic methods used in the determination of pesticide residues in food require clean-up and concentration steps prior to quantitation. While solid-phase extraction has been widely employed for this purpose, there is a need to improve selectivity. Due to their inherent biomimetic recognition systems, molecularly imprinted polymers (MIP) allow selectivity to be enhanced while keeping the costs of analysis low. In this work, a MIP that was designed to enable the selective extraction of fenitrothion (FNT) from tomatoes was synthesized using a noncovalent imprinting approach. The polymer was prepared using methacrylic acid as functional monomer and ethyleneglycol dimethacrylate as crosslinking monomer in dichloromethane (a porogenic solvent). The polymer was characterized by Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and nitrogen sorption porosimetry. The pore structure and the surface area were evaluated using the BET adsorption method. To characterize the batch rebinding behavior of the MIP, the adsorption isotherm was measured, allowing the total number of binding sites, the average binding affinity and the heterogeneity index to be established. A voltammetric method of quantifying FNT during the molecularly imprinted solid-phase extraction (MISPE) studies was developed. The polymer was placed in extraction cartridges which were then used to clean up and concentrate FNT in tomato samples prior to high-performance liquid chromatographic quantitation. The material presented a medium extraction efficiency of 59% (for analyses performed with three different cartridges on three days and a fortification level of 5.0 μg g−1) and selectivity when used in the preparation of tomato samples, and presented the advantage that the polymer could be reused several times after regeneration. Figure
Keywords: Imprinted polymers; Bulk polymerization; Organophosphorus insecticide; Molecularly imprinted solid-phase extraction
Determination of organochlorine pesticides in propolis by gas chromatography–electron capture detection using double column series solid-phase extraction by Fang Chen; Lanzhen Chen; Qiang Wang; Jinhui Zhou; Xiaofeng Xue; Jing Zhao (1073-1079).
A rapid and reliable method was developed and applied for the simultaneous determination of 17 organochlorine pesticides (OCPs) in propolis. After extraction with hexane and acetone (1:1, v/v), four sorbents (florisil, silica, graphitized carbon, and tandem graphitized carbon plus florisil) were assayed for the clean-up step. The elution solvents hexane and ethyl acetate (1:1, v/v), hexane and dichloromethane (3:7, v/v), and ethyl acetate and hexane (2:8, v/v) were studied. The results showed that the combination of the tandem graphitized carbon and florisil cartridge with the elution solvent of 6mL of ethyl acetate and hexane (2:8, v/v), which was capable of eliminating matrix interference and providing colorless eluates, was the most efficient clean-up procedure for propolis extracts when testing for OCPs. The analytical technique employed was gas chromatography with electron capture detection (GC–ECD). The correlation coefficients from linear regression for the analyzed concentrations (5∼100 μg/kg) were >0.9961. The limits of detection (LODs) varied between 0.8 μg/kg for 4,4′-DDE and 11.4 μg/kg for endosulfan II, and the limits of quantitation (LOQs) ranged from 2.6 to 38.1 μg/kg. The average recoveries varied between 62.6 and 109.6%. Relative standard deviations (RSD%) ranged from 0.8 to 9.4%. Sample analysis indicated that 4,4′-DDE was detected more often in propolis than other pesticides, such as β-HCH, δ-HCH and heptachlor. Figure GC-ECD chromatogram of a standard solution with 0.1 mg/L of OCPs
Keywords: Propolis; Organochlorine pesticides (OCPs); Solid-phase extraction (SPE); Gas chromatography–electron capture detection (GC–ECD)
Capillary waveguide fluoroimmunosensor with improved repeatability and detection sensitivity by Aristidis E. Niotis; Christos Mastichiadis; Panagiota S. Petrou; Ion Christofidis; Athanasia Siafaka-Kapadai; Konstantinos Misiakos; Sotirios E. Kakabakos (1081-1086).
An optical capillary waveguide fluoroimmunosensor based on glass capillaries internally coated with an ultrathin poly(dimethylsiloxane) (PDMS) film is presented. The evaluation of the capillaries developed was done in comparison with aminosilanized [3-(aminopropyl)triethoxysilane, APTES] glass and poly(methylpentene) (PMP) capillaries by immobilizing rabbit γ-globulins on the internal capillary wall. Following reaction with (R)-phycoerythrin-labelled antibody, the capillary was scanned with a laser beam and the fluorescence waveguided through the capillary wall was detected by a photomultiplier placed at one of its ends. The capillaries developed provided considerably improved protein coating homogeneity (intracapillary coefficients of variation 2.9–6.6%) and repeatability (intercapillary coefficients of variation 2.1–5.0%) compared with APTES-treated ones (7.9–13.4 and 8.5–15.2%, respectively). With use of these capillaries in a sandwich-type immunosensor for the determination of rabbit γ-globulins, the assay detection limit was improved eightfold (4.4 ng/mL) compared with that obtained using PMP capillaries (35.3 ng/mL), whereas the assay repeatability was improved threefold (intra-assay coefficients of variation 5.9–13.1%) compared with APTES-treated capillaries (15.6–36%). Optoelectronic set-up used to scan the capillaries (left) and representative fluorescence scannings of dual-band poly(methylpentene) (PMP), PDMS-modified glass and APTES treated glass capillaries
Keywords: Capillary fluoroimmunosensor; Poly(dimethylsiloxane) emulsion; Ultrathin poly(dimethylsiloxane) film; Protein adsorption homogeneity; (3-Aminopropyl)triethoxysilane; Poly(methylpentene) capillary