On-line multidimensional chromatography using packed capillary liquid chromatography and capillary gas chromatography

The introduction of selected fractions from a liquid chromatograph into a gas chromatograph has been described; however, analyses were performed by off-line experiments requiring collection and reinjection of the separate fractions or by on-line procedures where disadvantageously, only a fraction of the separated peak or a well resolved component in a mixture could be introduced into a gas chromatograph. This disadvantage is overcome by the apparatus and method described in this paper, which utilizes a multidimensional chromatography system employing a high efficiency, packed capillary LC column coupled on-line to a capillary gas chromatograph. The liquid chromatograph (so designed) can act as a highly efficient clean-up or chemical class fractionation step prior to introduction into the gas chromatograph, significantly reducing sample preparation times in many applications. Thus minor components in a complex matrix can be determined without prior sample clean-up, an example of which is the determination of polychlorinated biphenyls in a complex hydrocarbon matrix.     

Nuclear-related analytical techniques: Literature retrieval from the INIS database

The applicability of the INIS database for literature retrieval on nuclear-related analytical techniques [e.g. neutron activation analysis (NAA), X-ray fluorescence (XRF), particle-induced X-ray emission (PIXE)] has been studied. There exist about 9700 documents on NAA and other forms of activation analysis, about 3500 documents on XRF and about 1200 documents on PIXE in the database collected from 1976 until July 1988. They cover a variety of elements and matrices in the fields of biology, geochemistry and the physical sciences. Some technical notes and comments on the practical use of this database are also included.     

Quantitative determination of sotolon, maltol and free furaneol in wine by solid-phase extraction and gas chromatography-ion-trap mass spectrometry

A method for the analytical determination of sotolon [4,5-dimethyl-3-hydroxy-2(5H)-furanone], maltol [3-hydroxy-2-methyl-4H-pyran-4-one] and free furaneol [2,5-dimethyl-4-hydroxy-3(2H)-furanone] in wine has been developed. The analytes are extracted from 50 ml of wine in a solid-phase extraction cartridge filled with 800 mg of LiChrolut EN resins. Interferences are removed with 15 ml of a pentane-dichloromethane (20:1) solution, and analytes are recovered with 6 ml of dichloromethane. The extract is concentrated up to 0.1 ml and analyzed by GC-ion trap MS. Maltol and sotolon were determined by selected ion storage of ions in the m/z ranges 120-153 and 79-95, using the ions m/z 126 and 83 for quantitation, respectively. Furaneol was determined by non-resonant fragmentation of the m/z 128 mother ion and subsequent analysis of the m/z 81 ion. The detection limits of the method are in all cases between 0.5 and 1 microg l(-1), well below the olfactory thresholds of the compounds. The precision of the method is in the 4-5% range for levels in wine around 20 microg l(-1). Linearity holds at least up to 400 microg l(-1), and is satisfactory in all cases. The recoveries of maltol and sotolon are constant (70 and 64%, respectively) and do not depend on the type of wine. On the contrary, in the case of furaneol, red wines show constant and high recoveries (97%), while the recoveries on white wines range between 30 and 80%. Different experiments showed that this behavior is probably due to the existence of complexes formed between furaneol and sulphur dioxide or catechols. Sensory experiments confirmed that the complexed forms found in white wines are not perceived by orthonasal olfaction, and that the furaneol determined by the method can be considered as the free and odor-active fraction.     

Porous ceramic bed supports for fused silica packed capillary columns used in liquid chromatography

Porous ceramic bed supports for fused silica packed capillary columns utilized in liquid chromatography were prepared by polymerizing solutions containing potassium silicate in-situ within a column to create a mechanically stable, rugged, and easily constructed termination. The effect of the bed support length on efficiency, and comparisons to glass wool bed supports, were considered in terms of column efficiencies and hydrodynamic variables. Results obtained indicate better performance for the ceramic bed support.     

Structure de la gouregine,alcaloïde orginal apparente aux cularines

The structure of guoregine, a new isoquinoline alkaloid from $\text{G}$$\text{u}$$\text{a}$$\text{t}$$\text{t}$$\text{e}$$\text{r}$$\text{i}$$\text{a}$$\text{o}$$\text{u}$$\text{r}$$\text{e}$$\text{g}$$\text{o}$$\text{u}$, Annonaceae, has been deduced by spectral analysis and confirmed by an X-ray structure determination. It is the first member of a new class of cularine-related alkaloids (α-$\text{g}$$\text{e}$$\text{m}$-dimetyltetradehydrocularines).     

Dwarf Kiwi (Actinidia arguta Miq.), a Source of Antioxidants for a Healthy and Sustainable Diet

The feasibility of using dwarf kiwi fruits (Actinia arguta Miq.) as a healthy and sustainable food, compared to other types of commercial kiwi fruits, was evaluated in the present study. The overall antioxidant capacity of these fruits was assessed by either extraction-dependent methods (ABTS, ORAC) or the direct method called Quick, Easy, New, CHEap, Reproducible (QUENCHER) (DPPH, FRAP, Folin–Ciocalteu), applied for the first time to analyze kiwi fruits. With this methodology, all the molecules with antioxidant capacity are measured together in a single step, even those with high molecular weight or poor solubility in aqueous extraction systems, such as antioxidant dietary fiber. The effect of kiwi extracts on physiological and induced intracellular reactive oxygen species (ROS) production on IEC-6 cells was also analyzed, as well as total phenolic content (TPC) by Fast Blue BB, flavonols, hydroxycinnamic acids, and hydroxybenzoic acids. A. arguta fruits showed the highest values in all the antioxidant assays, being remarkably higher than the other kiwi species for Q-FRAP and Q-DPPH. Dwarf kiwi showed the highest potential in reducing physiological ROS and the highest values of TPC (54.57 mgGAE/g), being hydroxybenzoic acids the main phenolic family found (2.40 mgGAE/g). Therefore, dwarf kiwi fruits are a natural source of antioxidants compared to conventional kiwi fruits, being a sustainable and healthy alternative to diversify fruits in the diet.     

Multidimensional gas chromatography for the characterization of permanent gases and light hydrocarbons in catalytic cracking process

An integrated gas chromatographic system has been successfully developed and implemented for the measurement of oxygen, nitrogen, carbon monoxide, carbon dioxide and light hydrocarbons in one single analysis. These analytes are frequently encountered in critical industrial petrochemical and chemical processes like catalytic cracking of naphtha or diesel fuel to lighter components used in gasoline. The system employs a practical, effective configuration consisting of two three-port planar microfluidic devices in series with each other, having built-in fluidic gates, and a mid-point pressure source. The use of planar microfluidic devices offers intangible advantages like in-oven switching with no mechanical moving parts, an inert sample flow path, and a leak-free operation even with multiple thermal cycles. In this way, necessary features such as selectivity enhancement, column isolation, column back-flushing, and improved system cleanliness were realized. Porous layer open tubular capillary columns were employed for the separation of hydrocarbons followed by flame ionization detection. After separation has occurred, carbon monoxide and carbon dioxide were converted to methane with the use of a nickel-based methanizer for detection with flame ionization. Flow modulated thermal conductivity detection was employed to measure oxygen and nitrogen. Separation of all the target analytes was achieved in one single analysis of less than 12 min. Reproducibility of retention times for all compounds were found to be less than 0.1% (n = 20). Reproducibility of area counts at two levels, namely 100 ppm_v and 1000 ppm_v over a period of two days were found to be less than 5.5% (n = 20). Oxygen and nitrogen were found to be linear over a range from 20 ppm_v to 10,000 ppm_v with correlation coefficients of at least 0.998 and detection limits of less than 10 ppm_v. Hydrocarbons of interest were found to be linear over a range from 200 ppb_v to 1000 ppm_v with correlation coefficients of greater than 0.999 and detection limits of less than 100 ppb_v.     

Impact of Collection Volume and DNA Extraction Method on the Detection of Biomarkers and HPV DNA in First-Void Urine

The potential of first-void (FV) urine as a non-invasive liquid biopsy for detection of human papillomavirus (HPV) DNA and other biomarkers has been increasingly recognized over the past decade. In this study, we investigated whether the volume of this initial urine stream has an impact on the analytical performance of biomarkers. In parallel, we evaluated different DNA extraction protocols and introduced an internal control in the urine preservative. Twenty-five women, diagnosed with high-risk HPV, provided three home-collected FV urine samples using three FV urine collection devices (Colli-Pee) with collector tubes that differ in volume (4, 10, 20 mL). Each collector tube was prefilled with Urine Conservation Medium spiked with phocine herpesvirus 1 (PhHV-1) DNA as internal control. Five different DNA extraction protocols were compared, followed by PCR for GAPDH and PhHV-1 (qPCR), HPV DNA, and HBB (HPV-Risk Assay), and ACTB (methylation-specific qPCR). Results showed limited effects of collection volume on human and HPV DNA endpoints. In contrast, significant variations in yield for human endpoints were observed for different DNA extraction methods (p < 0.05). Additionally, the potential of PhHV-1 as internal control to monitor FV urine collection, storage, and processing was demonstrated.