Check out our New Publishers' Select for Free Articles

Analytical and Bioanalytical Chemistry (v.394, #5)

Science outreach: an important endeavor for active scientists by Susan V. Olesik (pp. 1233-1236).

is the Dow Professor in the Department of Chemistry of Ohio State University. For the development of WOW, she received the 2008 American Chemical Society National Award for Encouraging Disadvantaged Students into Careers in the Chemical Sciences. The WOW program also received the 2008 Stanley C. Israel Regional Award for Advancing Diversity in the Chemical Sciences Her research interests are separation science with foci of carbon-based stationary phases, enhanced-fluidity liquid mobile phases, and unique polymer separations.

Quality assurance challenge 8 by Manfred Reichenbächer; Jürgen W. Einax (pp. 1237-1240).

Solution to quality assurance challenge 7 by Manfred Reichenbächer; Jürgen W. Einax (pp. 1241-1245).

Francisco J. Arregui (Ed.): Sensors based on nanostructured materials by Rosario Pereiro (pp. 1247-1248).

Marek Trojanowicz (Ed.): Advances in flow analysis by Qun Fang (pp. 1249-1250).

European Symposium on Atomic Spectrometry (ESAS): electrothermal atomization, vaporization and laser sampling by Björn Meermann (pp. 1251-1252).

Advances in analytical separations by Uwe Karst; Martin Vogel (pp. 1253-1253).

(right) has held the Chair of Analytical Chemistry at the University of Münster since 2005. His research interests include hyphenated techniques and speciation analysis. (left) has had a faculty position at the University of Münster since 2006. His research interests include liquid chromatography/mass spectrometry and biochemical detection schemes for liquid chromatography.

High-temperature liquid chromatography of steroids on a bonded hybrid column by Lateefa A. Al-Khateeb; Roger M. Smith (pp. 1255-1260).

A hybrid stationary phase, XTerra MS C18, has been evaluated for the high-temperature reversed-phase liquid chromatography of selected hydrophobic steroids. The effects on the retention and efficiency at temperatures up to 130°C and eluent compositions from methanol–water mixtures to superheated water were studied. The thermodynamic data of the separations were determined. It was shown that increasing the temperature enabled the percentage of methanol to be reduced. High mobile-phase flow rates could be used, but for these non-polar analytes, the retention times with superheated water as the eluent were still high.

Keywords: High-temperature liquid chromatography; Superheated water; Steroids; Hybrid stationary phase; XTerra MS C18 stationary phase

Synthesis, characterisation and chromatographic evaluation of polyether dendrimer stationary phases by Gerard P. O’Sullivan; Norma M. Scully; Jean-Marie Prat; Jeremy D. Glennon; Benjamin Dietrich; Volker Friebolin; Klaus Albert (pp. 1261-1272).

Supercritical carbon dioxide has attracted attention as a potential replacement for traditional organic solvents due to its simplified workup procedures and reduced environmental impact—providing a green chemistry approach for organic solvent-free functionalisation. In addition to the environmental benefits, the enhanced diffusivity observed in supercritical solvents can often enhance reaction rates. We have applied these valuable features to the preparation of silica-bonded stationary phases and examined their potential in liquid chromatography. We report the successful preparation and characterisation of polyether silica based on Frechet dendrimers—this significantly enhances the range of stationary-phase chemistries that can be prepared in supercritical fluids. First- and second-generation polyether silicas were prepared, characterised, end-capped and evaluated for use as stationary phases for liquid chromatography. Figure SRM1649 on 2nd generation polyether silica

Keywords: Polyether stationary phases; Frechet dendrimer; Supercritical carbon dioxide; Silica functionalisation

Parameter selection for peak alignment in chromatographic sample profiling: objective quality indicators and use of control samples by Sonja Peters; Ewoud van Velzen; Hans-Gerd Janssen (pp. 1273-1281).

In chromatographic profiling applications, peak alignment is often essential as most chromatographic systems exhibit small peak shifts over time. When using currently available alignment algorithms, there are several parameters that determine the outcome of the alignment process. Selecting the optimum set of parameters, however, is not straightforward, and the quality of an alignment result is at least partly determined by subjective decisions. Here, we demonstrate a new strategy to objectively determine the quality of an alignment result. This strategy makes use of a set of control samples that are analysed both spiked and non-spiked. With this set, not only the system and the method can be checked but also the quality of the peak alignment can be evaluated. The developed strategy was tested on a representative metabolomics data set using three software packages, namely Markerlynx™, MZmine and MetAlign. The results indicate that the method was able to assess and define the quality of an alignment process without any subjective interference of the analyst, making the method a valuable contribution to the data handling process of chromatography-based metabolomics data.

Keywords: Chromatographic profiling; Metabolomics; Peak alignment; Quality control; Control samples

Selection of adequate optimization criteria in chromatographic separations by P. F. Vanbel; P. J. Schoenmakers (pp. 1283-1289).

Computer-assisted optimization of chromatographic separations is still a fruitful activity. In fact, advances in computerized data handling should make the application of systematic optimization strategies much easier. However, in most contemporary applications, the optimization criterion is not considered to be a key issue (Vanbel, J Pharm Biomed, 21:603–610, 1999). In this paper, an update of the importance of selecting adequate criteria in chromatographic separation is presented.

Keywords: Optimization criteria; HPLC separation; Two-dimensional chromatography; Multicriteria decision techniques; Chemometrics

Genotyping of single nucleotide polymorphism in MDM2 genes by universal fluorescence primer PCR and capillary electrophoresis by Yen-Ling Chen; Ya-Sian Chang; Jan-Gowth Chang; Shou-Mei Wu (pp. 1291-1297).

Single nucleotide polymorphism (SNP) 309 in the promoter region of the murine double minute 2 (MDM2) gene plays an important role in human tumorigenesis. We established a simple and effective CE method for SNP detection in the MDM2 gene. We designed one universal fluorescence-based nonhuman-sequence primer and one fragment-oriented primer, which were combined in one tube, and proceeded with the polymerase chain reaction (PCR). The amplicons were analyzed by capillary electrophoresis using single-strand conformation polymorphism method. PCR fragments generated from this two-in-one PCR displayed either T/T or G/G homozygosity or T/G heterozygosity. A total of 304 samples were blindly genotyped using this developed method, which included the DNA from 138 healthy volunteers, 43 chronic myeloid leukemia (CML) patients, and 123 colorectal cancer (CRC) patients. The results were confirmed by DNA sequencing and showed good agreement. The SSCP-CE method was feasible for SNP screening of MDM2 in large populations.

Keywords: Universal fluorescence primer PCR; CE; MDM2 gene

A miniaturised isotachophoresis method for magnesium determination by Jeff E. Prest; Sara J. Baldock; Peter R. Fielden; Nicholas J. Goddard; Bernard J. Treves Brown (pp. 1299-1305).

The use of malonic acid as a complexing agent has enabled a new method to be devised to allow the determination of magnesium to be made using miniaturised isotachophoresis. Using a leading electrolyte of 10 mmol L⁻¹ caesium hydroxide and 2 mmol L⁻¹ malonic acid at pH 5.1 gave the method a high specificity towards magnesium. Investigations using a poly(methyl methacrylate) chip device with an integrated conductivity detector showed that no interference from calcium, strontium, barium and sodium should occur. The method was found to be linear over the range of magnesium concentrations from 0.625 to 75 mg L⁻¹ and the limit of detection was calculated to be 0.45 mg L⁻¹. Separations were demonstrated with water samples but the procedure should also be applicable to more complex sample matrices such as inorganic explosive residues, blood or urine.

Keywords: Isotachophoresis; Miniaturisation; Microdevice; Magnesium; Metal analysis

Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of carbamate insecticide residues in fruits by Apichai Santalad; Supalax Srijaranai; Rodjana Burakham; Jeremy D. Glennon; Richard L. Deming (pp. 1307-1317).

A cloud-point extraction (CPE) method using Triton X-114 non-ionic surfactant was developed for the extraction and preconcentration of carbamate insecticide residues (i.e., methomyl, propoxur, carbofuran, carbaryl, isoprocarb, and promecarb) in fruit samples. The optimum conditions of CPE were 1.5% (w/v) Triton X-114, 7.0% (w/v) NaCl and 20 min equilibrated at 45 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 270 nm, under gradient separation using methanol and 0.1% (v/v) acetic acid. Under the study conditions, six carbamate insecticides were successfully separated within 27 min. Good reproducibility was obtained with the relative standard deviation of <3% for retention time and <9% for peak area. Limits of detection in the studied fruit samples were in the range of 0.1–1.0 mg kg⁻¹. No carbamate insecticides were detected in the studied fruit samples. The high recoveries of the spiked fruit samples were obtained in the range 80.0–107%. The CPE method has been shown to be a potential useful methodology for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environmental friendly.

Keywords: Cloud-point extraction; Triton X-114; Carbamate insecticides; Fruits; High-performance liquid chromatography

Development of an analytical procedure for the determination of emerging and priority organic pollutants in leafy vegetables by pressurized solvent extraction followed by GC–MS determination by Diana Calderón-Preciado; Claudio Jiménez-Cartagena; Gustavo Peñuela; Josep Maria Bayona (pp. 1319-1327).

A new multiresidue method for the determination of 13 emerging and priority pollutants in lettuce, including pesticides, pharmaceuticals, personal care products, polycyclic aromatic hydrocarbons (PAHs), and phenolic estrogens, has been developed using matrix solid-phase dispersion combined to pressurized fluid extraction (PFE) followed by gas chromatography coupled to mass spectrometry determination. A sequential optimization strategy based on solvent optimization first, followed by experimental design, was performed in order to maximize target analyte extraction with the aid of response surface methodology. Firstly, a full factorial design was applied to choose the significant variables in PFE; extraction time and temperature were found to have the biggest overall effect on response for most of analytes. They were later optimized performing a central composite design and the variable response of these factors was modeled for all analytes. It was found that marked differences in physicochemical nature exerted a strong influence on extraction conditions and yield. Therefore, the effect of parameters on the response was rather different for some compounds. To overcome this conflicting behavior, a multiple response simultaneous optimization was applied using the desirability function to achieve global optimal operating conditions. The optimal conditions were attained at 13.5 min (two extraction cycles) and 104 °C in the PFE by using hexane acetone mixture (1:1). Limit of detection and limit of quantitation values were found to be between 6.6 and 58 and 7.6 and 61.7 μg kg⁻¹, respectively.

Keywords: Matrix solid-phase dispersion; Pressurized solvent extraction; Multiresidue analysis; Multivariate optimization; Emerging pollutants; Vegetable

Determination of tetracycline residues in soil by pressurized liquid extraction and liquid chromatography tandem mass spectrometry by Vicente Andreu; Pablo Vazquez-Roig; Cristina Blasco; Yolanda Picó (pp. 1329-1339).

An optimized extraction and cleanup method for the analysis of chlortetracycline (CTC), doxycycline (DC), oxytetracycline (OTC) and tetracycline (TC) in soil is presented. Soil extraction in a pressurized liquid extraction system, followed by extract clean up using solid-phase extraction (SPE) and tetracycline determination by liquid chromatography tandem mass spectrometry (LC-MS/MS) provided appropriate efficiency and reproducibility. Different dispersing agents and solvents for soil extraction and several SPE cartridges for cleanup were compared. The best extraction results were obtained using ethylenediamine tetraacetic acid-treated sand as dispersing agent, and water at 70 °C. The most effective cleanup was obtained using Strata-X^TM sorbent in combination with a strong anion exchange cartridge. Recoveries ranged from 71% to 96% and precision, as indicated by the relative standard deviations, was within the range of 8–15%. The limits of quantification (LOQs) by using LC-MS/MS, based on signal-to-noise ratio (S/N) of 10, ranged from 1 μg kg⁻¹ for TC to 5 μg kg⁻¹ for CTC. These results pointed out that this technique is appropriate to determine tetracyclines in soils. Analysis of 100 samples taken in the Valencian Community revealed that, in soil, up to 5 μg kg⁻¹ CTC, 15 μg kg⁻¹ OTC, 18 μg kg⁻¹ TC, and 12 μg kg⁻¹ DC could be detected. Detection of the analytes in several samples, which typify great part of the Spanish agricultural soils, should be outlined as most important result of this study.

Keywords: Antibacterials; Tetracyclines; LC-MS/MS; Pressurized liquid extraction; Environmental analysis; Soil

Electrochemistry meets enzymes: instrumental on-line simulation of oxidative and conjugative metabolism reactions of toremifene by Wiebke Lohmann; Uwe Karst (pp. 1341-1348).

The metabolism of the selective estrogen receptor modulator toremifene was simulated in an on-line electrochemistry/enzyme reactor/liquid chromatography/mass spectrometry system. To simulate the oxidative phase I metabolism, toremifene was oxidized in an electrochemical (EC) flow-through cell at 1,500 mV vs. Pd/H₂ to its phase I metabolites, some of which are reactive quinoid species. In the presence of glutathione-S-transferase (GST), these quinoid compounds react with glutathione, which is also the common detoxification mechanism in the body. While reacting with glutathione, the chlorine atom is eliminated from the toremifene moiety. Due to higher conversion rates, GST supplied in continuous flow proved to be more efficient than using immobilized GST on magnetic microparticles. In the absence of GST, not all GSH adducts are formed, proving the necessity of a phase II enzyme to simulate the complete metabolic pathway of xenobiotics in an on-line EC/LC/MS system. Figure Mass voltammogram of toremifene

Keywords: Electrochemistry; Liquid chromatography; Mass spectrometry; Drug metabolism; Toremifene; Glutathione-S-transferase; Detoxification

Analytical study proving alprazolam degradation to its main impurity triazolaminoquinoleine through Maillard reaction by A. L. Huidobro; C. Barbas (pp. 1349-1359).

Triazolaminoquinoleine is rapidly formed in formulations of alprazolam tablets in presence of excipients, and its generation is speeded up with increasing temperature and humidity. The present paper deals with detailed quantitative and qualitative studies into the nonactive constituents of the formulation in order to determine the excipient (or the mixture) responsible for the degradation. Our studies have demonstrated that reducing carbohydrate excipients play a fundamental role in the generation of triazolaminoquinoleine, with lactose as the main one responsible, through a Maillard reaction. In order to demonstrate the validity of the proposed degradation mechanism, p-nitrobenzaldehyde has been employed as a model of reaction of the nucleophylic attack of amino-opened structure of alprazolam to an aldehyde to generate the first intermediate involved in Maillard reaction, a Schiff base. This model enables the identification of all the intermediates by mass spectrometry and/or nuclear magnetic resonance techniques, with the outcome of this experiment leading to a full understanding of the generation pathway. Calcium carbonate has been proposed as a possible tablet diluent replacing lactose in the pharmaceutical formulation. Figure Apparence of the samples after degradation treatment. Synthetic mixtures leaving one excipient out of the pharmaceutical formulation. Excipient missing for sample 3 is Lactose.

Keywords: Alprazolam; Triazolaminoquinoleine; Lactose; Reducing sugars; Excipient incompatibility; Degradation pathway; Maillard reaction

Analysis of glutathione adducts of patulin by means of liquid chromatography (HPLC) with biochemical detection (BCD) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) by Nils Helge Schebb; Helene Faber; Ronald Maul; Ferry Heus; Jeroen Kool; Hubertus Irth; Uwe Karst (pp. 1361-1373).

A novel method for the identification of glutathione/electrophile adducts that are inhibiting glutathione-S-transferase (GST) activity was developed and applied for the analysis of the mycotoxin patulin. The method is based on high-performance liquid chromatography (HPLC) coupled to a continuous-flow enzyme reactor serving as biochemical detector (BCD) in parallel to electrospray mass spectrometric detection (ESI-MS). This HPLC-BCD technique combines a separation step and the detection of the inhibition and is therefore ideally suited for the analysis of the activity of single patulin/glutathione adducts within a complex mixture of adducts. Two out of at least 15 detected patulin–glutathione adducts showed strong GST inhibition. In ESI-MS, the inhibitory active adducts were characterized by [M + H]⁺ ions with m/z 462.1138 and m/z 741.2011, respectively. They could be identified as a dihydropyranone adduct containing one molecule glutathione and a ketohexanoic acid bearing two glutathione molecules.OnlineAbstractFigure

Keywords: HPLC-BCD; Patulin–glutathione adducts; Glutathione-S-transferase inhibition; ESI(+)-MS/MS; Fragmentation reactions

Silver nanofractals: electrochemical synthesis, XPS characterization and application in LDI-MS by N. Cioffi; L. Colaianni; R. Pilolli; C. D. Calvano; F. Palmisano; P. G. Zambonin (pp. 1375-1383).

Silver nanofractals (Ag-NFs) have been electrosynthesized and characterized by means of morphological and spectroscopic analytical techniques. In particular, X-ray photoelectron spectroscopy has been used to assess the nanomaterial surface chemical state. Ag-NFs show interesting perspectives in bioanalytical applications, particularly as non-conventional desorption and ionization promoters in laser desorption ionization mass spectrometry.

Keywords: Silver fractal; Electrosynthesis; X-ray photoelectron spectroscopy; Laser desorption ionization; Bioanalytical applications

Masking effect of anti-androgens on androgenic activity in European river sediment unveiled by effect-directed analysis by Jana M. Weiss; Timo Hamers; Kevin V. Thomas; Sander van der Linden; Pim E. G. Leonards; Marja H. Lamoree (pp. 1385-1397).

This study shows that the androgen receptor agonistic potency is clearly concealed by the effects of androgen receptor antagonists in a total sediment extract, demonstrating that toxicity screening of total extracts is not enough to evaluate the full in vitro endocrine disrupting potential of a complex chemical mixture, as encountered in the environment. The anti-androgenic compounds were masking the activity of androgenic compounds in the extract with relatively high anti-androgenic potency, equivalent to 200 nmol flutamide equivalents/g dry weight. A two-step serial liquid chromatography fractionation of the extract successfully separated anti-androgenic compounds from androgenic compounds, resulting in a total androgenic potency of 3,820 pmol dihydrotestosterone equivalents/g dry weight. The fractionation simplified the chemical identification analysis of the original complex sample matrix. Seventeen chemical structures were tentatively identified. Polyaromatic hydrocarbons, a technical mixture of nonylphenol and dibutyl phthalate were identified to contribute to the anti-androgenic potency observed in the river sediment sample. With the GC/MS screening method applied here, no compounds with AR agonistic disrupting potencies could be identified. Seventy-one unidentified peaks, which represent potentially new endocrine disrupters, have been added to a database for future investigation.

Keywords: Androgenicity; Androgen receptor (AR); Effect-directed analysis (EDA); Sediment; Polycyclic aromatic hydrocarbons (PAHs); MODELKEY

Solid-phase microextraction gas chromatography-mass spectrometry determination of fragrance allergens in baby bathwater by J. Pablo Lamas; Lucia Sanchez-Prado; Carmen Garcia-Jares; Maria Llompart (pp. 1399-1411).

A method based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) has been optimized for the determination of fragrance allergens in water samples. This is the first study devoted to this family of cosmetic ingredients performed by SPME. The influence of parameters such as fibre coating, extraction and desorption temperatures, salting-out effect and sampling mode on the extraction efficiency has been studied by means of a mixed-level factorial design, which allowed the study of the main effects as well as two-factor interactions. Excluding desorption temperature, the other parameters were, in general, very important for the achievement of high response. The final procedure was based on headspace sampling at 100 °C, using polydimethylsiloxane/divinylbenzene fibres. The method showed good linearity and precision for all compounds, with detection limits ranging from 0.001 to 0.3 ng mL⁻¹. Reliability was demonstrated through the evaluation of the recoveries in different real water samples, including baby bathwater and swimming pool water. The absence of matrix effects allowed the use of external standard calibration to quantify the target compounds in the samples. The proposed procedure was applied to the determination of allergens in several real samples. All the target compounds were found in the samples, and, in some cases, at quite high concentrations. The presence and the levels of these chemicals in baby bathwater should be a matter of concern. Baby exposure to fragrance allergens and other cosmetic ingredients through the daily bath

Keywords: Fragrance allergens; Allergens; Cosmetics; Personal care products; Solid-phase microextraction; Water analysis; Multifactor optimization; Factorial design

Assessing indoor air exposures using passive sampling with bioanalytical methods for estrogenicity and aryl hydrocarbon receptor activity by Karen Kennedy; Miroslava Macova; Frederic Leusch; Michael E. Bartkow; Darryl W. Hawker; Bin Zhao; Michael S. Denison; Jochen F. Mueller (pp. 1413-1421).

Passive air sampling was undertaken using polyurethane foam passive air samplers at three types of locations, including indoors (six offices) at buildings in the central business district (CBD) and at a private suburban home (indoor and outdoor) located 9 km from the CBD in Brisbane, Queensland, Australia. Estrogenic (E-SCREEN—MCF7-BOS) and aryl hydrocarbon receptor (AhR) (CAFLUX—H4G1.1c2) activity were assessed for samples collected from each of these locations. The samples were tested either as crude extracts (“untreated”) or were subjected to H₂SO₄ silica gel (“treated”) for each location in order to determine whether chemicals, which are not resistant to this treatment like polycyclic aromatic hydrocarbons, potentially account for the observed activity. In most cases, H₂SO₄ treatment resulted in a statistically significant reduction of potency for both endpoints, suggesting that chemicals less resistant to treatment may be responsible for much of the detected biological activity in these locations. Estrogenic potency measurements (<0.22–185 pg m⁻³) were highest in the indoor offices, followed by the indoor suburban home and finally the outdoor suburban home (which was not estrogenic). Total AhR activity for crude extracts (1.3–10 pg m⁻³) however was highest for the outdoor suburban home site. Levels of polycyclic aromatic hydrocarbons were monitored indoors and outdoors at the suburban home. At that location, polycyclic aromatic hydrocarbon air concentrations were on average approximately two times higher outdoor than indoor, while AhR potency was five times higher outdoor than indoor. No significant correlation was found between the estrogenic and AhR activity (P = 0.88) for the sites in this study.

Keywords: Aryl hydrocarbon receptor activity; Estrogenicity; Bioanalytical methods; Indoor air; Passive air sampling

Novel approach for interlaboratory transfer of real-time PCR methods: detecting bovine meat and bone meal in feed by Marta Prado; Olivier Fumière; Ana Boix; Aline Marien; Gilbert Berben; Christoph von Holst (pp. 1423-1431).

The availability of robust methods for the species-specific detection of meat and bone meal (MBM) in compound feedingstuffs is an important prerequisite to enforce current and upcoming European legislation on the use of processed animal proteins in animal nutrition. Among possible methods, those based on DNA turned out to be a reliable tool for this aim, since DNA is a quite thermostable molecule able to resist severe heat treatments applied in the manufacturing of animal meals. The application of such methods by control laboratories implies that the method has been validated including an assessment of its robustness. Successful transferability between laboratories is considered an important robustness criterion of the method. However, corresponding guidelines regarding the design of such a study relevant to this field are missing. Here, we demonstrate the feasibility of an alternative concept that was applied to check for the transferability of a qualitative assay for the detection of banned MBM in feedingstuffs at trace level based on real-time PCR. The concept was based on an experimental nested design applying analysis of variance (ANOVA) that was conducted independently in two laboratories and which allows for establishing major factors influencing the result of analysis. Statistical assessment of the results confirmed the importance of the DNA extraction/purification step utilised, whereas the PCR step turned out to be a minor factor regarding the overall variability of the results. Furthermore, blind samples comprised of compound feed adulterated with MBM at 0.1 % and blank compound feed were correctly classified as "positive" or "negative" samples, thus confirming fitness of purpose for the method. This approach can be of interest for other research groups working in the development of real-time PCR methods and in their use by control laboratories. Nested design of the study to check for the transferability of the real-time PCR method

Keywords: Real-time PCR; Transferability; Meat and bone meals (MBM); Bovine; DNA; Feed

Chemical analysis of acoustically levitated drops by Raman spectroscopy by Rudolf Tuckermann; Ljiljana Puskar; Mahta Zavabeti; Ryo Sekine; Don McNaughton (pp. 1433-1441).

An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid–base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension. Figure We have systematically investigated the analytical potential of Raman spectroscopy of samples in acoustically levitated drops.

Keywords: Raman spectroscopy; Acoustic levitation; Drop evaporation; Crystallization; Microtitration

Chemical analysis of acoustically levitated drops by Raman spectroscopy by Rudolf Tuckermann; Ljiljana Puskar; Mahta Zavabeti; Ryo Sekine; Don McNaughton (pp. 1433-1441).

Keywords: Raman spectroscopy; Acoustic levitation; Drop evaporation; Crystallization; Microtitration

Pollen discrimination and classification by Fourier transform infrared (FT-IR) microspectroscopy and machine learning by R. Dell’Anna; P. Lazzeri; M. Frisanco; F. Monti; F. Malvezzi Campeggi; E. Gottardini; M. Bersani (pp. 1443-1452).

The discrimination and classification of allergy-relevant pollen was studied for the first time by mid-infrared Fourier transform infrared (FT-IR) microspectroscopy together with unsupervised and supervised multivariate statistical methods. Pollen samples of 11 different taxa were collected, whose outdoor air concentration during the flowering time is typically measured by aerobiological monitoring networks. Unsupervised hierarchical cluster analysis provided valuable information about the reproducibility of FT-IR spectra of the same taxon acquired either from one pollen grain in a 25 × 25 μm² area or from a group of grains inside a 100 × 100 μm² area. As regards the supervised learning method, best results were achieved using a K nearest neighbors classifier and the leave-one-out cross-validation procedure on the dataset composed of single pollen grain spectra (overall accuracy 84%). FT-IR microspectroscopy is therefore a reliable method for discrimination and classification of allergenic pollen. The limits of its practical application to the monitoring performed in the aerobiological stations were also discussed. Figure Traditional and innovative methods for the identification of airborne pollen grains

Keywords: FT-IR microspectroscopy; Allergic pollen; Supervised and unsupervised learning methods; Aerobiological monitoring networks

Selective extraction of phospholipids from dairy products by micro-solid phase extraction based on titanium dioxide microcolumns followed by MALDI-TOF-MS analysis by Cosima D. Calvano; Ole N. Jensen; Carlo G. Zambonin (pp. 1453-1461).

A new micro-solid phase extraction (µ-SPE) procedure based on titanium dioxide microcolumns was developed for the selective extraction of phospholipids (PLs) from dairy products before matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. All the extraction steps (loading, washing, and elution) have been optimized using a synthetic mixture of PLs standard and the procedure was subsequently applied to food samples such as milk, chocolate milk and butter. The whole method demonstrated to be simpler than traditional approaches and it appears very promising for a rapid PLs screening and characterization also in biological matrices.

Keywords: Phospholipid; TiO₂ ; MALDI; SPE; Milk

Determination of filbertone in spiked olive oil samples using headspace-programmed temperature vaporization-gas chromatography–mass spectrometry by José Luis Pérez Pavón; Miguel del Nogal Sánchez; María Esther Fernández Laespada; Bernardo Moreno Cordero (pp. 1463-1470).

A sensitive method for the fast analysis of filbertone in spiked olive oil samples is presented. The applicability of a headspace (HS) autosampler in combination with a gas chromatograph (GC) equipped with a programmable temperature vaporizer (PTV) and a mass spectrometric (MS) detector is explored. A modular accelerated column heater (MACH^TM) was used to control the temperature of the capillary gas chromatography column. This module can be heated and cooled very rapidly, shortening total analysis cycle times to a considerable extent. The proposed method does not require any previous analyte extraction, filtration and preconcentration step, as in most methods described to date. Sample preparation is reduced to placing the olive oil sample in the vial. This reduces the analysis time and the experimental errors associated with this step of the analytical process. By using headspace generation, the volatiles of the sample are analysed without interference by the non-volatile matrix, and by using injection in solvent-vent mode at the PTV inlet, most of the compounds that are more volatile than filbertone are purged and the matrix effect is minimised. Use of a liner packed with Tenax-TA® allowed the compound of interest to be retained during the venting process. The limits of detection and quantification were as low as 0.27 and 0.83 µg/L, respectively, and precision (measured as the relative standard deviation) was 5.7%. The method was applied to the determination of filbertone in spiked olive oil samples and the results revealed the good accuracy obtained with the method.

Keywords: Olive oil; Filbertone; Programmed temperature vaporizers

Phosphoester hydrolysis by cerium(IV)-thiacalix[4]arene complexes and its application to immunoassay by Hiroaki Matsumiya; Hiroko Nakamura; Masataka Hiraide (pp. 1471-1476).

Thiacalix[4]arenetetrasulfonate was treated with Ce(IV) in water at pH 9.5 to give novel phosphoester-hydrolyzing complexes. The dinuclear Ce(IV) complex promoted the hydrolysis of p-nitrophenyl phosphate with a turnover frequency of 6.8 h⁻¹ at 50 °C, showing fourfold higher activity than the mononuclear complex. The dinuclear complex was readily immobilized onto an antibody by simply mixing them in water, hence its phosphatase-like activity was applied to the color-developing reaction in immunoassay. The model assay using an antibody labeled with the dinuclear complex allowed the detection of as little as 10 ng mL⁻¹ of a tumor marker, Bence–Jones protein, in a 96-well microtiter plate format. Analysis of urine for Bence–Jones protein was performed by the proposed method.

Keywords: Thiacalixarene; Cerium; Phosphoester hydrolysis; Immunoassay; Bence–Jones protein

Determination of ultrafiltrable and exchangeable copper in plasma: stability and reference values in healthy subjects by Souleiman El Balkhi; Joël Poupon; Jean-Marc Trocello; Angélique Leyendecker; France Massicot; Martine Galliot-Guilley; France Woimant (pp. 1477-1484).

The knowledge of copper (Cu) distribution in blood contributes to a better understanding of copper metabolism and to a better approach and follow up of related diseases such as Wilson’s disease (WD). Many tests can be used to investigate patients who may have WD but they show many drawbacks and do not allow real patient monitoring. Knowing that the Cu overload can result from the free and easily exchangeable form of copper in plasma, a two-step method (ultrafiltration–determination by ETAAS) was carried out to determine these two fractions. The ultrafiltration procedure and the instrumental determination showed good repeatability, and a very low limit of detection was obtained (0.7 nmol/L). In vitro stability of both ultrafiltrable copper (CuUF) and exchangeable copper (CuEXC) was studied. Plasma was ultrafiltered in 44 presumably healthy subjects to determine CuUF and CuEXC and to set reference values ranges. The method was applied on a few patients showing good correlation between both parameters and the clinical and biological features of the patients. Figure Ultrafiltrable fraction of plasma copper is very instable in vitro. A 50% loss occurs within 6 hours after blood sampling

Keywords: Free copper; Ultrafiltration; Wilson’s disease; Labile-bound-copper

Calibration possibilities and modifier use in ETV ICP OES determination of trace and minor elements in plant materials by Albena Detcheva; Peter Barth; Juergen Hassler (pp. 1485-1495).

The possibilities for universal calibration based on multi-element aqueous standard solutions and graphite laboratory reference materials (graphite standards) for the electrothermal vaporization inductively coupled plasma optical emission spectrometric (ETV ICP OES) determination of Al, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Sr, Ti, V, and Zn in plant materials were investigated. A commercially available state-of-the-art ETV device was coupled with an Echelle ICP spectrometer equipped with a charge-injection-device (CID) camera for spectral detection. The transition area between transport tube and ETV graphite tube and the gas streams for inner gas, bypass gas, and modifier gas were optimized to achieve best transport efficiencies. The influence of four gaseous modifiers (CCl₄, CHCl₃, CCl₂F₂, and C₃H₈) added to the inner gas was studied. Five reference materials (RM P-Alfalfa, Lucerne; NIES CRM No.9 “Sargasso”; CTA-VTL-2 Virginia Tobacco Leaves; NIST SRM 1515 Apple Leaves; IAEA-V-10 Hay Powder) were used for method validation. If certified reference materials are not available, calibration against graphite standards or dried aqueous standard solutions is possible. Three carbonization procedures as sample pretreatment for the plant materials were investigated. Figure Picture of the ETV system (sample changer and graphite-tube furbace) used in this work

Keywords: Electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV ICP OES); Solid sampling; Plant materials; Calibration; Matrix modifiers

Continuous electrochemical monitoring of nitric oxide production in murine macrophage cell line RAW 264.7 by Michaela Pekarova; Jana Kralova; Lukas Kubala; Milan Ciz; Antonin Lojek; Cenek Gregor; Jan Hrbac (pp. 1497-1504).

In this study, we realized the continual and long-term electrochemical detection of NO production by stimulated macrophages using modified porphyrinic microsensor. The NO release from RAW 264.7 cells stimulated by lipopolysaccharide started 5 h after the lipopolysaccharide administration. After reaching its maximum at the sixth hour, the stable level of NO production was observed between the seventh and 12th hour of the experiment. This phase was followed by a gradual decline in NO production. A close correlation between the NO signal detected with microelectrode and nitrite accumulation, which had been determined in supernatants removed from stimulated cells, was observed. This finding was utilized for the calibration of the electrochemical experiment. The presence of iNOS enzyme, which constitutes a main requirement for NO production by stimulated macrophages, was confirmed by Western blot analysis of iNOS protein expression at key time points of the corresponding electrochemical experiment. The capability of our microsensor to instantaneously monitor the changes in the NO production by stimulated RAW 264.7 cells was demonstrated by the immediate decrease in the signal due to NO as a response to the addition of iNOS inhibitor into the cell culture medium.

Keywords: Nitric oxide; Macrophages; RAW 264.7; Nitric oxide sensor; Nitrites; iNOS expression

Rapid amplification of genetically modified organisms using a circular ferrofluid-driven PCR microchip by Yi Sun; Yien-Chian Kwok; Peter Foo-Peng Lee; Nam-Trung Nguyen (pp. 1505-1508).

The use of genetically modified organisms (GMOs) as food and in food products is becoming more and more widespread. Polymerase chain reaction (PCR) technology is extensively used for the detection of GMOs in food products in order to verify compliance with labeling requirements. In this paper, we present a novel close-loop ferrofluid-driven PCR microchip for rapid amplification of GMOs. The microchip was fabricated in polymethyl methacrylate by CO₂ laser ablation and was integrated with three temperature zones. PCR solution was contained in a circular closed microchannel and was driven by magnetic force generated by an external magnet through a small oil-based ferrofluid plug. Successful amplification of genetically modified soya and maize were achieved in less than 13 min. This PCR microchip combines advantages of cycling flexibility and quick temperature transitions associated with two existing microchip PCR techniques, and it provides a cost saving and less time-consuming way to conduct preliminary screening of GMOs. Figure Schematic of the circular ferrofluid-driven PCR microchip

Keywords: Genetic modified organism (GMO); Ferrofluid; PCR microchip; PMMA

Sections

Personal tools

Analytical and Bioanalytical Chemistry (v.394, #5)

Sections

Personal tools

Local resources

Analytical and Bioanalytical Chemistry (v.394, #5)