Browsing by Subject "GAS-CHROMATOGRAPHY"

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  • Shikov, Alexander N.; Laakso, Into; Pozharitskaya, Olga N.; Seppänen-Laakso, Tuulikki; Krishtopina, Anna S.; Makarova, Marina N.; Vuorela, Heikki; Makarov, Valery (2017)
    The lipids from gonads and polyhydroxynaphthoquinone pigments from body walls of sea urchins are intensively studied. However, little is known about the body wall (BW) lipids. Ethanol extract (55 degrees C) contained about equal amounts of saturated (SaFA) and monounsaturated fatty acids (MUFA) representing 60% of total fatty acids, with myristic, palmitic and eicosenoic acids as major SaFAs and MUFAs, respectively. Non-methylene-interrupted dienes (13%) were composed of eicosadienoic and docosadienoic acids. Long-chain polyunsaturated fatty acids (LC-PUFA) included two main components, n6 arachidonic and n3 eicosapentaenoic acids, even with equal concentrations (15 mu g/mg) and a balanced n6/n3 PUFA ratio (0.86). The UPLC-ELSD analysis showed that a great majority of the lipids (80%) in the ethanolic extract were phosphatidylcholine (60 mu g/mg) and phosphatidylethanolamine (40 mu g/mg), while the proportion of neutral lipids remained lower than 20%. In addition, alkoxyglycerol derivativeschimyl, selachyl, and batyl alcoholswere quantified. We have assumed that the mechanism of action of body wall lipids in the present study is via the inhibition of MAPK p38, COX-1, and COX-2. Our findings open the prospective to utilize this lipid fraction as a source for the development of drugs with anti-inflammatory activity.
  • Ruiz-Jimenez, Jose; Lan, Hangzhen; Leleev, Yevgeny; Hartonen, Kari; Riekkola, Marja-Liisa (2020)
    Several calibration approaches were evaluated for the quantitation of volatile organic compounds in air using miniaturized exhaustive and non-exhaustive sampling techniques, such as in-tube extraction (ITEX) and solid phase microextraction (SPME) Arrow. Eleven compounds, 2-ethyl-hexanol, hexanal, nonanal, toluene, ethyl-benzene, methyl isobutyl ketone, acetophenone, p-cymene, alpha-pinene, trimethylamine and triethylamine, all them found in the natural air samples, were selected as model analytes. Liquid injection, liquid standard addition to the sorbent bed and gas phase standards provided by an automatic permeation system, were evaluated in the case of ITEX packed with laboratory-made 10% polyacrylonitrile (PAN) material. Two different approaches, based on sampling of gas phase compounds from the permeation system and from sample vial containing gas phase standards, were evaluated for SPME Arrow with two different coatings, commercial divinylbenzene-poly(dimethylsiloxane) (DVB-PDMS) and laboratory-made mesoporous Mobil Composition of Matter No. 41 (MCM-41). In addition, interface model approach was used for the calculation of the real concentration of the target analytes in the sample from the total amount of analytes injected into the GC-MS in the case of SPME Arrow. Similar results were obtained with the different approaches used for the quantitation by ITEX and SPME Arrow. However, the use of gas phase standards with sample matrix similar to the natural samples, allowed the permeation system to provide the most reliable results for the quantitation of the target analytes. For this approach, linearity (expressed as r(2) values) ranged between 0.991 and 0.999. The limit of detection ranged from 0.5 mu g/m(3) (trimethylamine, MCM-41) to 2.2 x 10(-4) mu g/m(3) (methyl isobutyl ketone, MCM-41). In addition, the use of the fully automated permeation system provided good reproducibility values that were between 1.4% (acetophenone, MCM-41) and 7.8% (methyl isobutyl ketone, 10% PAN). The linear ranges were at least 3 order of magnitude for all the studied analytes with the exception of the calibration curve developed for trimethylamine with SPME Arrow (linear ranges between LOQ and 4.9 mu g/m(3) (DVB-PDMS) and LOQ and 9.8 mu g/m(3) (MCM-41)). (C) 2019 Elsevier B.V. All rights reserved.
  • Mesihää, Samuel; Ketola, Raimo A.; Pelander, Anna; Rasanen, Ilpo; Ojanpera, Ilkka (2017)
    Gas chromatography coupled to atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-APCI-QTOFMS) was evaluated for the identification of new psychoactive substances (NPS). An in-house high mass resolution GC-APCI-QTOFMS test library was developed for 29 nitrogen-containing drugs belonging mostly to synthetic stimulants. The library was based on 12 intra-day measurements of each compound at three different collision energies, 10, 20 and 40 eV. The in-house library mass spectra were compared to mass spectra from a commercial library constructed by liquid chromatography-electrospray ionization (LC-ESI) QTOFMS. The reversed library search scores between the in-house GC-APCI library and the commercial LC-ESI library were compared once a week during a 5-week period by using data measured by GC-APCI-QTOFMS. The protonated molecule was found for all drugs in the full scan mode, and the drugs were successfully identified by both libraries in the targeted MS/MS mode. The GC-APCI library score averaged over all collision energies was as high as 94.4/100 with a high repeatability, while the LC-ESI library score was also high (89.7/100) with a repeatability only slightly worse. These results highlight the merits of GC-APCI-QTOFMS in the analysis of NPS even in situations where the reference standards are not immediately available, taking advantage of the accurate mass measurement of the protonated molecule and product ions, and comparison to existing soft-ionization mass spectral libraries.
  • Szukalska, Marta; Szyfter, Krzysztof; Florek, Ewa; Rodrigo, Juan P.; Rinaldo, Alessandra; Mäkitie, Antti A.; Strojan, Primoz; Takes, Robert P.; Suarez, Carlos; Saba, Nabil F.; Braakhuis, Boudewijn J. M.; Ferlito, Alfio (2020)
    Simple Summary The risk of developing cancer is always higher for tobacco smokers than for non-smokers. Electronic cigarettes (e-cigarettes) have become increasingly popular in the last decade and are considered less harmful than traditional tobacco products, due to the lower content of toxic and carcinogenic compounds. However, this is still a controversial issue. This paper contains a review of previous reports on the composition of e-cigarettes and their impact on the pathogenesis and risk of head and neck cancer (HNC). The authors reviewed articles on both toxic and carcinogenic compounds contained in e-cigarettes and their molecular and health effects on the upper respiratory tract in comparison to traditional tobacco cigarettes. In conclusion, the studies discussed in the review strongly suggest that more long-term studies are needed to better address the safety of e-cigarettes. E-cigarettes have become increasingly popular in the last decade and are considered less harmful than traditional tobacco products due to the lower content of toxic and carcinogenic compounds. However, this is still a controversial issue. This paper contains a review of previous reports on the composition of e-cigarettes and their impact on the pathogenesis and risk of head and neck cancer (HNC). The objective of the review was to compare the molecular and health effects of e-cigarette use in relation to the effects of traditional cigarette smoking in the upper respiratory tract, and to assess the safety and effect of e-cigarettes on HNC risk. A review for English language articles published until 31 August 2020 was made, using a PubMed (including MEDLINE), CINAHL Plus, Embase, Cochrane Library and Web of Science data. The authors reviewed articles on both toxic and carcinogenic compounds contained in e-cigarettes and their molecular and health effects on the upper respiratory tract in comparison to tobacco cigarettes. The risk of developing head and neck squamous cell carcinoma (HNSCC) remains lower in users of e-cigarettes compared with tobacco smokers. However, more long-term studies are needed to better address the safety of e-cigarettes.
  • Feijo Barreira, Luis Miguel; Duporte, Geoffroy; Rönkkö, Tuukka; Parshintsev, Jevgeni; Hartonen, Kari; Schulman, Lydia; Heikkinen, Enna; Jussila, Matti; Kulmala, Markku; Riekkola, Marja-Liisa (2018)
    Biogenic volatile organic compounds (BVOCs) emitted by terrestrial vegetation participate in a diversity of natural processes. These compounds impact both on short-range processes, such as on plant protection and communication, and on high-range processes, by e.g. participation on aerosol particle formation and growth. The biodiversity of plant species around the Earth, the vast assortment of emitted BVOCs, and their trace atmospheric concentrations contribute to the high remaining uncertainties about the effects of these compounds on atmospheric chemistry and physics, and call for the development of novel collection devices that can offer portability with improved selectivity and capacity. In this study, a novel solid-phase microextraction (SPME) Arrow sampling system was used for the static and dynamic collection of BVOCs from the boreal forest, and samples were subsequently analysed on-site by gas chromatography-mass spectrometry (GC-MS). This system offers higher sampling capacity and improved robustness than the traditional equilibrium-based SPME techniques, such as SPME fibers. Field measurements were performed in summer 2017 at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiälä, Finland. Complementary laboratory tests were also performed to compare the SPME-based techniques under controlled experimental conditions and to evaluate the effect of temperature and relative humidity on their extraction performance. The most abundant monoterpenes and aldehydes were successfully collected. A significant improvement on sampling capacity was observed with the new SPME Arrow system when compared to SPME fibers, with collected amounts being approximately 2 times higher for monoterpenes and 7-8 times higher for aldehydes. BVOC species exhibited different affinities for the type of sorbent materials used (PDMS/Carbon WR vs. PDMS/DVB). Higher extraction efficiencies were obtained with dynamic collection prior to equilibrium regime, but this benefit during the field measurements was small probably due to the natural agitation provided by the wind. An increase in temperature and relative humidity caused a decrease in the amounts of analytes extracted under controlled experimental conditions, even though the effect was more significant for PDMS/Carbon WR than for PDMS/DVB. Overall, results demonstrated the benefits and challenges of using SPME Arrow for the sampling of BVOCs in the atmosphere.
  • Lan, Hangzhen; Holopainen, Jani; Hartonen, Kari; Jussila, Matti; Ritala, Mikko; Riekkola, Marja-Liisa (2019)
    Comprehensive and time-dependent information (e.g., chemical composition, concentration) of volatile organic compounds (VOCs) in atmospheric, indoor, and breath air is essential to understand the fundamental science of the atmosphere, air quality, and diseases diagnostic. Here, we introduced a fully automated online dynamic in-tube extraction (ITEX)-gas chromatography/mass spectrometry (GC/MS) method for continuous and quantitative monitoring of VOCs in air. In this approach, modified Cycle Composer software and a PAL autosampler controlled and operated the ITEX preconditioning, internal standard (ISTD) addition, air sampling, and ITEX desorption sequentially to enable full automation. Air flow passed through the ITEX with the help of an external pump, instead of plunger up-down strokes, to allow larger sampling volumes, exhaustive extraction, and consequently lower detection limits. Further, in order to evaluate the ITEX system stability and to develop the corresponding quantitative ITEX method, two laboratory-made permeation systems (for standard VOCs and ISTD) were constructed. The stability and suitability of the developed system was validated with a consecutive 19 day atmospheric air campaign under automation. By using an electrospun polyacrylonitrile nanofibers packed ITEX, selective extraction of some VOCs and durability of over 1500 extraction and desorption cycles were achieved. Especially, the latter step is critically important for on-site long-term application at remote regions. This ITEX method provided 2-3 magnitudes lower quantitation limits than the headspace dynamic ITEX method and other needle trap methods. Our results proved the excellence of the fully automated online dynamic ITEX-GC/MS system for tracking VOCs in the atmospheric air.
  • Pereira, Pedro A. B.; Trivedi, Drupad K.; Silverman, Justin; Duru, Ilhan Cem; Paulin, Lars; Auvinen, Petri; Scheperjans, Filip (2022)
    We aimed to investigate the link between serum metabolites, gut bacterial community composition, and clinical variables in Parkinson's disease (PD) and healthy control subjects (HC). A total of 124 subjects were part of the study (63 PD patients and 61 HC subjects). 139 metabolite features were found to be predictive between the PD and Control groups. No associations were found between metabolite features and within-PD clinical variables. The results suggest alterations in serum metabolite profiles in PD, and the results of correlation analysis between metabolite features and microbiota suggest that several bacterial taxa are associated with altered lipid and energy metabolism in PD.
  • Mesihää, Samuel; Rasanen, Ilpo; Pelander, Anna; Ojanperä, Ilkka (2020)
    A method was developed for quantitative estimation of illicit psychostimulants in blood, with an emphasis on new psychoactive substances, based on gas chromatography nitrogen chemiluminescence detection coupled with atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (GC-NCD-APCI-QTOFMS). Quantitative estimation relied on the NCD's N-equimolar response to nitrogen, using amphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and methylenedioxypyrovalerone as external calibrators for prim-, sec- and tert- amines, respectively. After spiking with 38 stimulants at 3 concentration levels, the donor blood samples were submitted to liquid-liquid extraction at a basic pH followed by acylation with trifluoroacetic anhydride. All but 3 psychostimulants could be analyzed with a limit of quantification (LOQ) of 0.05 mg/L. At LOQ, the coefficient of variation (CV) values for between-day accuracy was 62.3-143.3% (mean, 93.5%; median, 88.5%) and precision 6.6-22.4% (mean, 15.8%; median, 16.1%). In addition, 11 post-mortem blood samples, containing 0.08-2.4 mg/L of amphetamine (n = 5), methamphetamine (n = 4) or MDMA (n = 4), were analyzed by the GC-NCD-APCI-QTOFMS method, and the results were compared with an established electron ionization GC-MS method with appropriate calibration. The agreement between the 2 methods was 62.5-117.3%. Regarding identification, the APCI source permitted detection of the intact precursor ion, or the respective acylation product, for all of the measured compounds. The GC-NCD-APCI-QTOFMS method developed here enables instant quantitative estimation of illicit psychostimulants in blood at reasonable accuracy, without the necessity of possessing the true reference standards for each analyte.
  • Mesihaa, Samuel; Rasanen, Ilpo; Ojanpera, Ilkka (2018)
    Gas chromatography (GC) hyphenated with nitrogen chemiluminescence detection (NCD) and quadrupole time-of-flight mass spectrometry (QTOFMS) was applied for the first time to the quantitative analysis of new psychoactive substances (NPS) in urine, based on the N-equimolar response of NCD. A method was developed and validated to estimate the concentrations of three metabolites of the common stimulant NPS alpha-pyrrolidinovalerophenone (alpha-PVP) in spiked urine samples, simulating an analysis having no authentic reference standards for the metabolites and using the parent drug instead for quantitative calibration. The metabolites studied were OH-alpha-PVP (M1), 2 ''-oxo-alpha-PVP (M3), and N,N-bis-dealkyl-PVP (2-amino-1-phenylpentan-1-one; M5). Sample preparation involved liquid-liquid extraction with a mixture of ethyl acetate and butyl chloride at a basic pH and subsequent silylation of the sec-hydroxyl and prim-amino groups of M1 and M5, respectively. Simultaneous compound identification was based on the accurate masses of the protonated molecules for each compound by QTOFMS following atmospheric pressure chemical ionization. The accuracy of quantification of the parent-calibrated NCD method was compared with that of the corresponding parent-calibrated QTOFMS method, as well as with a reference QTOFMS method calibrated with the authentic reference standards. The NCD method produced an equally good accuracy to the reference method for alpha-PVP, M3 and M5, while a higher negative bias (25%) was obtained for M1, best explainable by recovery and stability issues. The performance of the parent-calibrated QTOFMS method was inferior to the reference method with an especially high negative bias (60%) for M1. The NCD method enabled better quantitative precision than the QTOFMS methods To evaluate the novel approach in casework, twenty post-mortem urine samples previously found positive for alpha-PVP were analyzed by the parent calibrated NCD method and the reference QTOFMS method. The highest difference in the quantitative results between the two methods was only 33%, and the NCD method's precision as the coefficient of variation was better than 13%. The limit of quantification for the NCD method was approximately 0.25 mg/mL in urine, which generally allowed the analysis of alpha-PVP and the main metabolite M1. However, the sensitivity was not sufficient for the low concentrations of M3 and M5. Consequently, while having potential for instant analysis of NPS and metabolites in moderate concentrations without reference standards, the NCD method should be further developed for improved sensitivity to be more generally applicable. (c) 2018 Elsevier B.V. All rights reserved.
  • Ojanpera, Ilkka; Mesihää, Samuel; Rasanen, Ilpo; Pelander, Anna; Ketola, Raimo A. (2016)
    A novel platform is introduced for simultaneous identification and quantification of new psychoactive substances (NPS) in blood matrix, without the necessity of using authentic reference standards. The instrumentation consisted of gas chromatography (GC) coupled to nitrogen chemiluminescence detection (NCD) and atmospheric pressure chemical ionization quadrupole time-of-flight mass spectrometry (APCI-QTOFMS). In this concept, the GC flow is divided in appropriate proportions between NCD for single-calibrant quantification, utilizing the detector's equimolar response to nitrogen, and QTOFMS for accurate mass-based identification. The principle was proven by analyzing five NPS, bupropion, desoxypipradrol (2-DPMP), mephedrone, methylone, and naphyrone, in sheep blood. The samples were spiked with the analytes post-extraction to avoid recovery considerations at this point. All the NPS studies produced a protonated molecule in APCI resulting in predictable fragmentation with high mass accuracy. The N-equimolarity of quantification by NCD was investigated by using external calibration with the secondary standard caffeine at five concentration levels between 0.17 and 1.7 mg/L in blood matrix as five replicates. The equimolarity was on average 98.7 %, and the range of individual equimolarity determinations was 76.7-130.1 %. The current analysis platform affords a promising approach to instant simultaneous qualitative and quantitative analysis of drugs in the absence of authentic reference standards, not only in forensic and clinical toxicology but also in other bioanalytical applications.
  • Ketola, Raimo A.; Ojanperä, Ilkka (2019)
    Concentration distributions for 183 drugs and metabolites frequently found in post-mortem (PM) femoral venous blood were statistically characterized based on an extensive database of 122 234 autopsy cases investigated during an 18-year period in a centralized laboratory. The cases represented all causes of death, with fatal drug poisonings accounting for 8%. The proportion of males was 74% with a median age of 58 years compared with 26% females with a median age of 64 years. In 36% of these cases, blood alcohol concentration was higher than or equal to 0.2 parts per thousand, the median being 1.6 parts per thousand. The mean, median, and upper percentile (90th, 95th, 97.5th) drug concentrations were established, as the median PM concentrations give an idea of the "normal" PM concentration level, and the upper percentile concentrations indicate possible overdose levels. A correspondence was found between subsets of the present and the previously published PM drug concentrations from another laboratory that grouped cases according to the cause of death. Our results add to the knowledge for evidence-based interpretation of drug-related deaths.