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Analytical and Bioanalytical Chemistry (v.388, #3)
Navigating a scientific job market and how the library can help by Wil Weston (pp. 507-509).
is currently the Engineering Librarian at San Diego State University and a doctorial student in higher education administration at the University of New Orleans. His research interests are in student services and library consortia.
High-pressure liquid chromatography in lab-on-a-chip devices
by Steffen Ehlert; Ulrich Tallarek (pp. 517-520).
Extraction across supported liquid membranes by use of electrical fields
by Stig Pedersen-Bjergaard; Knut Einar Rasmussen (pp. 521-523).
Nuclear magnetic resonance of mass-limited samples using small RF coils by Andrew Webb (pp. 525-528).
Figure Schematic diagram of a typical arrangement used for hyphenating chemical microseparations (e.g. capillary HPLC, CE, or CEC) with microcoil NMR detection
Enhancing high-throughput technology and microfluidics with FTIR spectroscopic imaging
by Sergei G. Kazarian (pp. 529-532).
Coupling of capillary electroseparation techniques with mass spectrometric detection
by Christian W. Klampfl; Wolfgang Buchberger (pp. 533-536).
The natural fingerprint of stable isotopes—use of IRMS to test food authenticity
by Hilmar Förstel (pp. 541-544).
Recent progress in analytical instrumentation for glycemic control in diabetic and critically ill patients by Venkata Radhakrishna Kondepati; H. Michael Heise (pp. 545-563).
Implementing strict glycemic control can reduce the risk of serious complications in both diabetic and critically ill patients. For this reason, many different analytical, mainly electrochemical and optical sensor approaches for glucose measurements have been developed. Self-monitoring of blood glucose (SMBG) has been recognised as being an indispensable tool for intensive diabetes therapy. Recent progress in analytical instrumentation, allowing submicroliter samples of blood, alternative site testing, reduced test time, autocalibration, and improved precision, is comprehensively described in this review. Continuous blood glucose monitoring techniques and insulin infusion strategies, developmental steps towards the realization of the dream of an artificial pancreas under closed loop control, are presented. Progress in glucose sensing and glycemic control for both patient groups is discussed by assessing recent published literature (up to 2006). The state-of-the-art and trends in analytical techniques (either episodic, intermittent or continuous, minimal-invasive, or noninvasive) detailed in this review will provide researchers, health professionals and the diabetic community with a comprehensive overview of the potential of next-generation instrumentation suited to either short- and long-term implantation or ex vivo measurement in combination with appropriate body interfaces such as microdialysis catheters.
Keywords: Blood glucose sensors; Self-monitoring of blood glucose (SMBG); Continuous glucose monitoring; Diabetes mellitus; Critically ill patients; Artificial pancreas
Biosensors based on screen-printing technology, and their applications in environmental and food analysis by Madalina Tudorache; Camelia Bala (pp. 565-578).
This review summarizes scientific research activity on biosensors, especially screen-printed, electrode-based biosensors. The basic configurations of biosensors based on screen-printing technology are discussed and different procedures for immobilization of the biorecognition component are reviewed. Theoretical aspects are exemplified by practical environmental and food-analysis applications of screen-printed, electrode-based biosensors.
Keywords: Biosensor; Screen-printed electrode; Environment; Food
Use of single-drop microextraction for determination of fentanyl in water samples by Pradeep Kumar Gupta; Laxmi Manral; Kumaran Ganesan; Devendra Kumar Dubey (pp. 579-583).
Fentanyl is a very potent synthetic narcotic analgesic. Because of its strong sedative properties, it has become an analogue of illicit drugs such as heroin. Its unambiguous detection and identification in environmental samples can be regarded as strong evidence of its illicit preparation. In this paper we report application of single-drop microextraction (SDME) for analysis of water samples spiked with fentanyl. Experimental conditions which affect the performance of SDME, for example the nature of the extracting solvent, sample stirring speed, extraction time, ionic strength, and solution pH, were optimized. The method was found to be linear in the concentration range 0.10–10 ng mL−1. The limits of quantitation and detection of the method were 100 pg mL−1 and <75 pg mL−1, respectively. This technique is superior to other sample-preparation techniques because of the simple experimental set-up, short analysis time, high sensitivity, and minimum use of organic solvent.
Keywords: Fentanyl; Narcotic analgesic; Water; Sample preparation; SDME; GC–MS
Multitechnique mass-spectrometric approach for the detection of bovine glutathione peroxidase selenoprotein: focus on the selenopeptide by Guillaume Ballihaut; Sandra Mounicou; Ryszard Lobinski (pp. 585-591).
Glutathione peroxidase (isolated from bovine erythrocytes) and its behaviour during alkylation and enzymatic digestion were studied by various hyphenated techniques: gel electrophoresis–laser ablation (LA) inductively coupled plasma (ICP) mass spectrometry (MS), size-exclusion liquid chromatography–ICP MS, capillary high-performance liquid chromatography (capHPLC)–ICP MS, matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) MS, electrospray MS, and nanoHPLC–electrospray ionization (ESI) MS/MS. ESI TOF MS and MALDI TOF MS allowed the determination of the molecular mass but could not confirm the presence of selenium in the protein. The purity of the protein with respect to selenium species could be evaluated by LA ICP MS and size-exclusion chromatography (SEC)–ICP MS under denaturating and nondenaturating conditions, respectively. SEC–ICP MS and capHPLC–ICP MS turned out to be valuable techniques to study the enzymolysis efficiency, miscleavage and artefact formation during derivatization and tryptic digestion. For the first time the parallel ICP MS and ESI MS/MS data are reported for the selenocysteine-containing peptide extracted from the gel; capHPLC–ICP MS allowed the sensitive detection of the selenopeptide regardless of the matrix and nanoHPLC–electrospray made possible its identification. Figure Eye catching image
Keywords: Glutathione peroxidase; Selenoprotein; Speciation; Capillary high-performance liquid chromatography–inductively coupled plasma mass spectrometry; Electrospray mass spectrometry
History of individuals of the 18th/19th centuries stored in bones, teeth, and hair analyzed by LA–ICP–MS—a step in attempts to confirm the authenticity of Mozart’s skull by Christina Stadlbauer; Christian Reiter; Beatrix Patzak; Gerhard Stingeder; Thomas Prohaska (pp. 593-602).
A cranium stored in the Stiftung Mozarteum in Salzburg/Austria which is believed to be that of Mozart, and skeletal remains of suspected relatives which have been excavated from the Mozart family grave in the cemetery in Salzburg, have been subjected to scientific investigations to determine whether or not the skull is authentic. A film project by the Austrian television ORF in collaboration with Interspot Film on this issue was broadcast at the beginning of the “Mozart year 2006”. DNA analysis could not clarify relationships among the remains and, therefore, assignment of the samples was not really possible. In our work this skull and excavated skeletal remains have been quantified for Pb, Cr, Hg, As, and Sb content by laser ablation-inductively coupled plasma-mass spectrometry (LA–ICP–MS) to obtain information about the living conditions of these individuals. A small splinter of enamel (less than 1 mm3) from a tooth of the “Mozart cranium” was also available for investigation. Quantification was performed by using spiked hydroxyapatite standards. Single hair samples which are recorded to originate from Mozart have also been investigated by LA–ICP–MS and compared with hair samples of contemporary citizens stored in the Federal Pathologic–Anatomical Museum, Vienna. In general, Pb concentrations up to approximately 16 μg g−1 were found in the bone samples of 18th century individuals (a factor of 7 to 8 higher than in recent samples) reflecting elevated Pb levels in food or beverages. Elevated Pb levels were also found in hair samples. The amount of Sb in the enamel sample of the “Mozart cranium” (approx. 3 μg g−1) was significantly higher than in all the other tooth samples investigated, indicating possible Sb ingestion in early childhood. Elevated concentrations of elements in single hair samples gave additional information about possible exposure of the individuals to heavy metals at a particular point in their life.
Keywords: LA–ICP–MS; Bone; Hair; Mozart
Determination of lead in blood by laser ablation ICP-TOF-MS analysis of blood spotted and dried on filter paper: a feasibility study by James V. Cizdziel (pp. 603-611).
Screening programs for pediatric lead (Pb) poisoning routinely collect blood by finger stick onto specially designed filter paper (FP) for subsequent laboratory testing. Here, laser ablation inductively coupled plasma time-of-flight mass spectrometry is evaluated as a novel method for the determination of Pb in blood spotted onto FP cards. The method requires no sample pretreatment and may be particularly suitable for rapidly screening a large number of samples. Signal intensity from the ICP-MS strongly correlated (r 2 = 0.996) with Pb target values for five blood cards from a laboratory proficiency testing program. Better precision was obtained by replicate ablation line scans (<15% rsd) compared to a grid of 25 individual ablation spots (>30% rsd). Because <2% of the sample is consumed in the laser ablation analysis, selected samples can also be analyzed by traditional techniques or archived. Lead isotope ratios determined during the same total-Pb analysis appear to be effective for discerning contamination extraneous to the blood sample. Determining that an elevated result was due to contamination may negate the need for retesting with invasive pediatric venipuncture. Some elements monitored along with Pb exhibited signal profiles conducive to potential quantitation (Ca, V, Fe, Cu Zn), whereas others did not (Cr, Mn, Co, Ni, Cd, Hg, Tl, U). Copper, Ca, and V were inversely correlated with Pb (r = −0.89, −0.90, and −0.92, respectively). Scanning electron microscope images revealed surface modality differences between FP spotted with fresh whole blood and reconstituted freeze-dried blood reference material. Figure Image of spotted filter paper blood specimen showing ablation line scans
Keywords: Blood lead levels; Laser ablation; Filter paper blood spots; Time-of-flight mass spectrometry; Lead isotope ratios
Analytical performance of the AtheNA MultiLyte® ANA II assay in sera from lupus patients with multiple positive ANAs by Raymond E. Biagini; Christine G. Parks; Jerome P. Smith; Deborah L. Sammons; Shirley A. Robertson (pp. 613-618).
The purpose of this study was to evaluate the precision and accuracy of a commercial multiplexed kit for the measurement of 9 anti-nuclear antibodies (ANAs; anti-SS/A, anti-SS/B, anti-Sm, anti-RNP, anti-Jo-1, anti-Scl-70, anti-dsDNA, anti-Centromere B, and anti-Histone), and to compare these results to a subset of ANAs measured by enzyme-linked immunosorbent assays (ELISA) and immunodiffusion (ID). Sera were obtained from 22 systemic lupus erythematosus (SLE) patients, twelve controls and five others (commercial source) with various autoimmune diseases. ANA results from the AtheNA MultiLyte® ANA II Assay (AtheNA) were compared to ELISA results (controls) and patients (ID). The AtheNA interassay coefficients of variation (CVs, N = 39, performed in duplicate; replicated 3×) ranged from 6.2% to 16.7% (mean = 9.8%), while the intra-assay CVs ranged from 5.8% to 14.3% (mean = 10.8%). Compared to results for SLE cases and controls, the sensitivity of AtheNA ranged from 85.7% to 100% (mean = 97.1%), while diagnostic specificity ranged from 16.7% to 100% (mean = 71.6%). There was significant agreement (P values ranging from 0.0001 to 0.03) when analytes coanalyzed by AtheNA and ELISA/ID were evaluated using Cohen’s kappa (κ values ranging from 0.376 to 1.000). No false positive ANA results were observed for either the control or commercial source autoimmune disease sera. These results indicate that the AtheNA assay is a precise and accurate alternative for performing multiple ELISAs or IDs in the diagnosis of autoimmune diseases, especially when the number of sera to be tested is large, such as in clinical screening or epidemiologic studies. It also appears that the AtheNA assay identifies positive ANA specificities which are missed by ID techniques, suggesting that it may have greater analytical sensitivity for some ANAs. Figure Schematic Diagram of Multiplexed Measurement of 9 Anti-Nuclear Antibodies Using the AtheNA Multilyte Assay
Keywords: AtheNA MultiLyte® ANA system; Antinuclear antibodies; Autoimmune diseases; Systemic lupus erythematosus; ELISA
Fiber-packed needle for dynamic extraction of aromatic compounds by Mitsuhiro Ogawa; Yoshihiro Saito; Ikuo Ueta; Kiyokatsu Jinno (pp. 619-625).
A fiber-packed needle was developed as a novel extraction device for gas-chromatographic analysis of trace organic compounds in aqueous samples. In the extraction device, a bundle of the polymer-coated filaments as the sorbent material was longitudinally packed into a specially designed needle. The extraction was made by pumping the aqueous sample solution into the needle extraction device, and the subsequent desorption process was carried out with a flow of desorption solvent through the needle in a heated gas chromatograph injector. The needle device showed an excellent thermal stability for repeated use without any deterioration of extraction performance, and no carryover effect was observed after the optimization of the desorption conditions. Additionally, the extraction efficiency of the fiber-packed needle could be enhanced by optimizing the number of packed filaments. The selectivity for various compounds could be also tuned using an appropriate combination of the fibrous medium and the coating polymer. The relative standard deviation for run to run was from 3.88 to 4.55% (n = 5), and that for needle to needle was 7.21% (n = 3), clearly suggesting a good repeatability of the needle extraction technique developed. Upon successful optimization of the extraction conditions, a rapid extraction of trace organic compounds from an aqueous sample matrix was successfully demonstrated, where each extraction process was completed within 10 min.
Keywords: Heat-resistant fiber; Needle extraction device; Rapid extraction; Aqueous sample; Gas chromatography; Aromatic compounds
Analytical development for analysis of pharmaceuticals in water samples by SPE and GC–MS by Anne Togola; Hélène Budzinski (pp. 627-635).
An analytical procedure involving solid-phase extraction (SPE) and gas chromatography–mass spectrometry (GC–MS) has been developed for determination of pharmaceutical compounds (aspirin, caffeine, carbamazepine, diclofenac, ketoprofen, naproxen, ibuprofen, clofibrate, clofibric acid, and gemfibrozil) in a variety of aqueous samples (wastewater and surface water). After filtration, samples were extracted and concentrated using C18 or HLB cartridges, depending on the type of compound. Sample storage conditions were checked and optimized to ensure preservation of the pharmaceutical substance, taking into consideration environmental sampling conditions. For most of the pharmaceuticals monitored, recovery was in the range 53 to 99% and the variability was below 15% for the complete procedure, with limits of detection ranging from 0.4 to 2.5 ng L−1, depending on the compound. The methods were successfully applied to monitoring of pharmaceutical contamination of the Seine estuary. Concentrations varied from several dozens of nanograms per liter for surface waters to several hundreds of nanograms per liter for wastewaters.
Keywords: Pharmaceuticals; Wastewater; Surface water; SPE; GC–MS
Identification of human hepatocellular carcinoma-related proteins by proteomic approaches by Ming-Hui Yang; Yu-Chang Tyan; Shiang-Bin Jong; Ying-Fong Huang; Pao-Chi Liao; Ming-Chen Wang (pp. 637-643).
Hepatocellular carcinoma (HCC) is the most common malignant liver tumor. Analysis of human serum from HCC patients using two-dimensional gel electrophoresis (2DE) combined with nano-high-performance liquid chromatography electrospray ionization tandem mass spectrometry (nano-HPLC–ESI-MS/MS) identified fourteen different proteins differentially expressed between HCC patients and the control group. Twelve proteins were up-regulated and two down-regulated. By using nano-HPLC–MS/MS system to analyze proteome in human serum, 317 proteins were identified, twenty-nine of which to high confidence levels (protein matched at last two unique peptide sequences). Of these twenty-nine proteins, six were present only in HCC patients and may serve as biomarkers for HCC.
Keywords: Proteomics; Hepatocellular carcinoma; Serum; Protein biomarker; Mass spectrometry
Noninvasive monitoring of intracellular pH change induced by drug stimulation using silica nanoparticle sensors by Jiaofeng Peng; Xiaoxiao He; Kemin Wang; Weihong Tan; Yan Wang; Yi Liu (pp. 645-654).
We have synthesized and applied a nanoparticle-based pH sensor for noninvasive monitoring of intracellular pH changes induced by drug stimulation. The pH sensor is a two-fluorophore-doped nanoparticle sensor (2DFNS) that contains a pH-sensitive indicator (fluorescein isothiocyanate, FITC) and a reference dye (tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate, RuBPY). The nanoparticles have an average diameter of 42 ± 3 nm and can easily be taken up by cells for noninvasive intracellular pH measurement. The 2DFNS exhibited excellent pH sensitivity, reversibility, and a dynamic range of pH 4–7 for biological studies. We have used 2DFNS to monitor pH changes in living cells by drug stimulation. Both lysosomal pH changes in murine macrophages stimulated by chloroquine and intracellular acidification in apoptotic cancer cells were monitored in real time and with high pH sensitivity. Hela cells underwent intracellular acidification with a drop in pH from 7.2 to 6.5 after 8 h of treatment with 2 μmol/L dexamethasone, and this intracellular pH drop in the apoptotic cells was not influenced by the addition of zinc ions. The application of 2DFNS to intracellular pH measurements yields some important advantages: excellent pH sensitivity, little environmental effect on the pH dye, excellent quantification, high stability and excellent reversibility. Figure Scanning images of macrophages loaded with 2DFNS at different times after exposure to 200 μmol/L chloroquine. Images a and b represent fluorescence images of FITC and RuBPY in 2DFNS internalized by a macrophage, respectively. Images labeled c are bright-field images of the macrophage, and those labeled d show a and b merged
Keywords: Silica nanoparticle; Two-fluorophore-doped nanoparticle sensor (2DFNS); Intracellular pH; Noninvasive monitoring
Automated single-nucleotide polymorphism analysis using fluorescence excitation–emission spectroscopy and one-class classifiers by Yun Xu; Richard G. Brereton (pp. 655-664).
We have developed a new method of highly automated SNP (single nucleotide polymorphism) analysis for identification of genotypes. The data were generated by the Taqman reaction. A total of 18 half-plates were analysed for different genes, each consisting of 48 wells, including six synthetic DNA samples, three background samples, and 39 human DNA samples. Fluorescence spectra were obtained from each well. The characteristics of the spectra depended on whether the genotype originated from one of three classes—homozygotic wild-type, mutant, or heterozygote. The main problems are: (1) spectral variation from one half-plate to another is sometimes very substantial; (2) the spectra of heterozygotic samples vary substantially; (3) outliers are common; and (4) not all possible alleles are represented on each half-plate so the number of types of spectra can vary, depending on the gene being analysed. We solved these problems by using a signal-standardisation technique (piecewise direct standardisation, PDS) and then built two one-class classifiers based on PCA models (PCA data description) to identify the two types of homozygote. The remaining samples were tested to see whether they could be approximated well by a linear combination of the spectra of two types of homozygote. If they could, they were identified as heterozygotic; if not, they were identified as outliers. The results are characterised by very low false-positive errors and 2 to 6% overall false-negative errors. Figure Principal components scores after piecewise Direct Standardisation
Keywords: Single nucleotide polymorphism; Taqman reaction; One-class classification; Piecewise direct standardisation
Porous imprinted polymer membranes prepared by phase separation in compressed liquid CO2 by Quanqiu Zhang; Takayuki Kusunoki; Qun Xu; Hongying Wang; Takaomi Kobayashi (pp. 665-673).
Phase separation of poly(acrylonitrile–co-methacrylic acid) in compressed liquid CO2 resulted in formation of a porous imprinted membrane which preferentially adsorbed uracil (URA). The cross-section of the membrane was observed by SEM, which revealed its porous structure. The mechanical strength of the membrane indicated formation of a rigid matrix with high tensile strength (4.4 N mm−2). The imprinted membranes bound highly selectively to URA (12.8 μmol g−1) but binding to dimethyluracil (DMURA), thymine, and cytosine was less (0.7, 0.8, and 0.9 μmol g−1, respectively). When DMURA was similarly used to prepare an imprinted membrane in liquid CO2 there was less binding of DMURA to the imprinted membrane obtained. The URA-imprinted membranes were evaluated by IR spectroscopy before and after URA extraction. The results indicated that hydrogen bonding was the mechanism of binding of URA to the imprinted membrane. Competitive binding studies were performed with binary mixtures of URA and its analogues. The URA-imprinted membrane enabled good separation of URA from cytosine, DMURA, and thymine, with separation factors of 3.0, 3.8, and 2.5, respectively. It was confirmed that the compressed liquid CO2 contributed to efficient formation of template substrate sites in the URA-imprinted membrane.
Keywords: Molecularly imprinted membrane; Molecular recognition; Compressed CO2 ; Membrane adsorbent; URA
Comparison of a novel ultra-performance liquid chromatographic method for determination of retinol and α-tocopherol in human serum with conventional HPLC using monolithic and particulate columns by I. Citová; L. Havlíková; L. Urbánek; D. Solichová; L. Nováková; P. Solich (pp. 675-681).
Retinol and α-tocopherol are biologically active compounds often monitored in blood samples because of their evident importance in human metabolism. In this study a novel ultra-performance liquid chromatographic (UPLC) method used for determination of both vitamins in human serum has been compared with conventional HPLC with particulate and monolithic C18 columns. In UPLC a sub-two-micron particle-hybrid C18 stationary phase was used for separation, in contrast with a five-micron-particle packed column and a monolithic column with a highly porous structure. Methanol, at flow rates of 0.48, 1.5, and 2.5 mL min−1, respectively, was used as mobile phase for isocratic elution of the compounds in the three methods. Detection was performed at 325 nm and 290 nm, the absorption maxima of retinol and α-tocopherol, respectively. Analysis time, sensitivity, mobile-phase consumption, validation data, and cost were critically compared for these different chromatographic systems. Although cost and mobile-phase consumption seem to make UPLC the method of choice, use of the monolithic column resulted in almost the same separation and performance with a slightly shorter analysis time. These methods are alternatives and, in routine laboratory practice, more economical means of analysis of large numbers of biological samples than use of a traditional particulate column.
Keywords: UPLC; Retinol; α-Tocopherol; Human serum; Monolithic column
Raman spectroscopy of natron: shedding light on ancient Egyptian mummification by Howell G. M. Edwards; Katherine J. Currie; Hassan R. H. Ali; Susana E. Jorge Villar; A. Rosalie David; John Denton (pp. 683-689).
The mummification ritual in ancient Egypt involved the evisceration of the corpse and its desiccation using natron, a naturally occurring evaporitic mineral deposit from the Wadi Natrun, Egypt. The deposit typically contains sodium carbonate, sodium bicarbonate and impurities of chloride and sulfate as its major elemental components. It is believed that the function of the natron was to rapidly remove the water from the cadaver to prevent microbial attack associated with subsequent biological tissue degradation and putrefaction. Several specimens of natron that were recently collected from the Wadi Natrun contained coloured zones interspersed with the mineral matrix that are superficially reminiscent of extremophilic cyanobacterial colonisation found elsewhere in hot and cold deserts. Raman spectroscopy of these specimens using visible and near-infrared laser excitation has revealed not only the mineral composition of the natron, but also evidence for the presence of cyanobacterial colonies in several coloured zones observed in the mineral matrix. Key Raman biosignatures of carotenoids, scytonemin and chlorophyll have been identified. Figure The mummification ritual in ancient Egypt involved the evisceration of the corpse and its desiccation using natron, a naturally occurring evaporitic mineral deposit from the Wadi Natrun, Egypt. The deposit typically contains sodium carbonate, sodium bicarbonate and impurities of chloride and sulfate as its major elemental components. It is believed that the function of the natron was to rapidly remove the water from the cadaver to prevent microbial attack associated with subsequent biological tissue degradation and putrefaction. Several specimens of natron that were recently collected from the Wadi Natrun contained coloured zones interspersed with the mineral matrix that are superficially reminiscent of extremophilic cyanobacterial colonisation found elsewhere in hot and cold deserts. Raman spectroscopy of these specimens using visible and near-infrared laser excitation has revealed not only the mineral composition of the natron, but also evidence for the presence of cyanobacterial colonies in several coloured zones observed in the mineral matrix. Key Raman biosignatures of carotenoids, scytonemin and chlorophyll have been identified.
Keywords: Raman spectroscopy; Natron; Mummification; Cyanobacterial extremophile; Biological colonisation
A comparison of three solvent-free techniques coupled with gas chromatography for determining trihalomethanes in urine samples by Natalia Jakubowska; Żaneta Polkowska; Wojciech Kujawski; Piotr Konieczka; Jacek Namieśnik (pp. 691-698).
The analysis of volatile organic compounds in samples of biological fluids characterized by complex matrices is highly challenging. This paper presents a comparison of the results obtained in this field using three solvent-free techniques: thin-layer headspace with autogenous generation of liquid sorbent (TLHS) and membrane separation of the trace substances (pervaporation, PV), both of which are coupled to direct aqueous injection gas chromatography–electron capture detection (TLHS–DAI–GC–ECD and PV–DAI–GC–ECD), as well as conventional static headspace analysis followed by GC analysis with ECD detection (HS–GC–ECD). Basic validation parameters of the HS–GC–ECD, TLHS–DAI–GC–ECD and PV–DAI–GC–ECD procedures were calculated for water and urine samples. The calibration curves for all procedures were linear within the concentration range examined. The intermediate precisions of the procedures were good and reached about 10% (for all analytes) for HS–GC–ECD and TLHS–DAI–GC–ECD. The poorest results were obtained for PV–DAI–GC–ECD: about 20% for all analytes. The lowest method detection limits were obtained for the TLHS–DAI–GC–ECD procedure: below 0.0022 μg/L for all analytes. The enrichment factors did not differ significantly between water and urine samples, indicating little or no matrix effect in all procedures.
Keywords: Trihalomethanes; Solvent-free technique; Thin-layer headspace analysis; Static headspace analysis; Pervaporation; Gas chromatography; Human urine samples
Real-time PCR detection of telomerase activity using specific molecular beacon probes by Deming Kong; Yawei Jin; Yuji Yin; Huaifeng Mi; Hanxi Shen (pp. 699-709).
Telomerase is a potentially important biomarker and a prognostic indicator of cancer. Several techniques for assessing telomerase activity, including the telomeric repeat amplification protocol (TRAP) and its modified versions, have been developed. Of these methods, real-time quantitative TRAP (RTQ-TRAP) is considered the most promising. In this work, a novel RTQ-TRAP method is developed in which a telomeric repeats-specific molecular beacon is used. The use of the molecular beacon can improve the specificity of the RTQ-TRAP assay, making the method suitable for studying the overall processivity results and the turnover rate of telomerase. In addition, the real-time, closed-tube protocol used obviates the need for post-amplification procedures, reduces the risk of carryover contamination, and supports high throughput. Its performance in synthetic telomerase products and cell extracts suggests that the developed molecular beacon assay can further enhance the clinical utility of telomerase activity as a biomarker/indicator in cancer diagnosis and prognosis. The method also provides a novel approach to the specific detection of some particular gene sequences to which sequence-specific fluorogenic probes cannot be applied directly. Figure Real-time PCR detection of telomerase activity using specific molecular beacon probes
Keywords: Telomerase activity; Molecular beacon; Real-time PCR; Specific detection
Fast ultrasound-assisted extraction of copper, iron, manganese and zinc from human hair samples prior to flow injection flame atomic absorption spectrometric detection by M. C. Yebra-Biurrun; R. M. Cespón-Romero (pp. 711-716).
A dynamic ultrasound-assisted extraction procedure utilizing diluted nitric acid was developed for the determination of copper, iron, manganese and zinc in human hair taken from workers in permanent contact with a polluted environment. The extraction unit of the dynamic ultrasound-assisted extraction system contains a minicolumn into which a specified amount of hair (5–50 mg) is placed. Once inserted into the continuous manifold, trace metals were extracted at 3 mL min−1 with 3 mol L−1 nitric acid under the action of ultrasound for 2 min for zinc and 3 min for copper, iron and manganese determination, and using an ultrasonic water-bath temperature of 70 °C for zinc and 80 °C for copper, iron and manganese determination. The system permits the direct analysis of hair and yields concentrations with relative standard deviations of <3% (n = 11). The applicability of the procedure was verified by analysing human hair samples from workers exposed to welding fumes, and its accuracy was assessed through comparison with a conventional sample dissolution procedure and the use of a certified reference material (BCR 397, human hair).
Keywords: Dynamic ultrasound-assisted extraction; Hair of occupationally exposed workers; Copper; Iron; Manganese; Zinc; Atomic absorption spectrometry
CdS quantum dots as fluorescence probes for the sensitive and selective detection of highly reactive HSe− ions in aqueous solution by Chuan-Liu Wu; Yi-Bing Zhao (pp. 717-722).
Water-soluble cadmium sulfide (CdS) quantum dots (QDs) capped by mercaptoacetic acid were synthesized by aqueous-phase arrested precipitation, and characterized by transmission electron microscopy, spectrofluorometry, and UV-Vis spectrophotometry. The prepared luminescent water-soluble CdS QDs were evaluated as fluorescence probes for the detection of highly reactive hydrogen selenide ions (HSe− ions). The quenching of the fluorescence emission of CdS QDs with the addition of HSe− ions is due to the elimination of the S2− vacancies which are luminescence centers. Quantitative analysis based on chemical interaction between HSe− ions and the surface of CdS QDs is very simple, easy to develop, and has demonstrated very high sensitivity and selectivity features. The effect of foreign ions (common anions and biologically relevant cations) on the fluorescence of the CdS QDs was examined to evaluate the selectivity. Only Cu2+ and S2− ions exhibit significant effects on the fluorescence of CdS QDs. With the developed method, we are able to determine the concentration of HSe− ions in the range from 0.10 to 4.80 μmol L−1, and the limit of detection is 0.087 μmol L−1. The proposed method was successfully applied to monitor the obtained HSe− ions from the reaction of glutathione with selenite. To the best of our knowledge, this is the first report on fluorescence analysis of HSe− ions in aqueous solution. Figure CdS quantum dots as fluorescence probes for the sensitive and selective detection of highly reactive HSe- ions in aqueous solution
Keywords: CdS quantum dots; Fluorescence; Hydrogen selenide ions; Detection; Quenching
Characterization of ganoderma spore lipid by stable carbon isotope analysis: implications for authentication by Xin Liu; Shi-Ping Xu; Jiang-Hai Wang; Jian-Ping Yuan; Lian-Xian Guo; Xin Li; Xiao-Ni Huang (pp. 723-731).
The ratios of stable carbon isotopes (13C/12C) of ganoderma fruiting body, ganoderma spore, ganoderma spore lipid (GSL) and individual fatty acids in GSL were determined by gas chromatography–stable isotope ratio mass spectrometry and elemental analysis–stable isotope ratio mass spectrometry. These values fall into a range from −26.9 to −23.3‰, suggesting that the cut log as the Ganoderma-cultivated substrate in Fujian, China, may belong to C3 plants. Eighteen fatty acids were identified and their abundances measured by gas chromatography–mass spectrometry in the six GSL samples with C16:0, C18:0, C18:1 and C18:2 as major constituents, and C16:1 is evidently enriched compared with the other edible vegetable oils. On the basis of the compositions of fatty acids and stable carbon isotopes in GSL, we have developed a novel method to detect the adulteration of GSL products with cheaper edible vegetable oils. An example of ideal blending between GSL and C4 or C3 vegetable oil is further provided to expound the discrimination procedures and corresponding sensitive indicators. Simultaneously, the carbon isotope fractionation in the biosynthesis of individual fatty acids was observed, revealing that the formation of C18:0 from C16:0 in ganodema spores had no conspicuous 13C enrichment of +0.4‰ for Ganoderma sinensis spore and +0.1‰ for G. lucidum spore; the desaturation of C18:0 to C18:1 resulted in a distinct 13C depletion of −1.4‰ for G. sinensis spore and −0.9‰ for G. lucidum spore; and the next desaturation from C18:1 to C18:2 displayed no evident 13C fractionation of −0.1‰ for G. sinensis spore and −0.2‰ for G. lucidum spore. Figure Ganoderma lucidum has been widely used in traditional Chinese medicines. Ganoderma spore lipid (GSL) extracted from the spores of G. lucidum has been approved as a health food supplement. However, because of rarity, GSL has become a target for adulteration with cheaper vegetable oils.
Keywords: Ganoderma spore lipid; Stable carbon isotope; Adulteration; Ganoderma lucidum ; Ganoderma sinensis