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Ilkka Ojanpera - One of the best experts on this subject based on the ideXlab platform.
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comparison between drug screening by immunoassay and ultra high performance liquid chromatography high Resolution Time of flight mass spectrometry in post mortem urine
Drug Testing and Analysis, 2015Co-Authors: Mira Sundstrom, Anna Pelander, Ilkka OjanperaAbstract:Immunoassay is currently the most common approach for urine drug screening. However, the continuous emergence of new psychoactive substances (NPS) and their low urinary concentrations have challenged the scope and sensitivity of immunoassays. Consequently, specialized toxicology laboratories rely more and more on mass spectrometry (MS) based techniques. Ultra-high performance liquid chromatography/high-Resolution Time-of-flight mass spectrometry (UHPLC-HR-TOF-MS) is an especially attractive technique for comprehensive drug screening. The objective was to compare the performances of immunoassay and UHPLC-HR-TOF-MS in terms of scope, flexibility, sensitivity, and reliability of substance identification. A total of 279 post-mortem urine samples were analyzed using a method representative of each technique. The immunoassay method was an Emit II Plus enzyme immunoassay for the following drug groups: amphetamines, benzodiazepines, buprenorphine, cannabis, and opiates. The UHPLC-HR-TOF-MS method was a recently published method covering hundreds of drugs: conventional drugs of abuse, abused prescription drugs, and NPS of various classes. UHPLC-HR-TOF-MS produced a lower number of false positive (FP) results for the drug groups covered by immunoassay. Many of the false negative (FN, n = 40) and FP (n = 22) immunoassay results were obviously due to the higher cut-off concentrations and interfering matrix, respectively. Moreover, the wider scope of UHPLC-HR-TOF-MS allowed detection of NPS and prescription drugs. UHPLC-HR-TOF-MS gave FP results related to a few particular substances. The future option of adjusting all compound-specific reporting parameters individually would allow the method's sensitivity and specificity to be fully exploited. Copyright © 2014 John Wiley & Sons, Ltd.
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a high sensitivity ultra high performance liquid chromatography high Resolution Time of flight mass spectrometry uhplc hr tofms method for screening synthetic cannabinoids and other drugs of abuse in urine
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Mira Sundstrom, Anna Pelander, Verena Angerer, Melanie Hutter, Stefan Kneisel, Ilkka OjanperaAbstract:The continuing emergence of designer drugs imposes high demands on the scope and sensitivity of toxicological drug screening procedures. An ultra-high performance liquid chromatography/high-Resolution Time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method was developed for screening and simultaneous confirmation of both designer drugs and other drugs of abuse in urine samples in a single run. The method covered selected synthetic cannabinoids and cathinones, amphetamines, natural cannabinoids, opioids, cocaine and other important drugs of abuse, together with their main urinary metabolites. The database consisted of 277 compounds with molecular formula and exact monoisotopic mass; retention Time was included for 192 compounds, and primary and secondary qualifier ion exact mass for 191 and 95 compounds, respectively. Following a solid-phase extraction, separation was performed by UHPLC and mass analysis by HR-TOFMS. MS, and broad-band collision-induced dissociation data were acquired at m/z range 50–700. Compound identification was based on a reverse database search with acceptance criteria for retention Time, precursor ion mass accuracy, isotopic pattern and abundance of qualifier ions. Mass resolving power in spiked urine samples was on average FWHM 23,500 and mass accuracy 0.3 mDa. The mean and median cut-off concentrations determined for 75 compounds were 4.2 and 1 ng/mL, respectively. The range of cut-off concentrations for synthetic cannabinoids was 0.2–60 ng/mL and for cathinones 0.7–15 ng/mL. The method proved to combine high sensitivity and a wide scope in a manner not previously reported in drugs of abuse screening. The method’s feasibility was demonstrated with 50 authentic urine samples.
F J Lopez - One of the best experts on this subject based on the ideXlab platform.
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gas chromatography coupled to high Resolution Time of flight mass spectrometry to analyze trace level organic compounds in the environment food safety and toxicology
Trends in Analytical Chemistry, 2011Co-Authors: Felix Hernandez, Tania Portoles, E Pitarch, F J LopezAbstract:Abstract Gas chromatography coupled to high-Resolution Time-of flight mass spectrometry (GC-HR-TOF-MS) is a powerful analytical technique with excellent capabilities due to its high sensitivity in full-spectrum-acquisition mode together with its resolving power and accurate-mass measurements. These features make this technique very attractive in qualitative analysis, especially for wide-scope screening of a large number of organic contaminants and residues at trace levels. Full-spectrum MS allows data processing, in principle, of an unlimited number of compounds in samples, as no analyte-specific information is required before the injection. Also, as all data remain available, retrospective analysis is always possible without the need to reinject the sample – an important advantage of full-spectrum MS techniques. Despite these advantages, GC-HR-TOF-MS has rarely been applied, so we expect promising results in different applied fields in the years ahead. We discuss in detail the characteristics and the potential of GC-HR-TOF-MS. We describe different analytical strategies from wide-scope target screening to investigation of unknowns in biology, the environment and food safety. Recent instrumental developments (e.g., high-speed analog-to-digital converter or soft ionization sources) and advances in software for processing the huge amount of data available open up new prospects, making GC-TOF-MS one of the most promising techniques to investigate the presence of organic compounds in different fields.
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target and nontarget screening of organic micropollutants in water by solid phase microextraction combined with gas chromatography high Resolution Time of flight mass spectrometry
Analytical Chemistry, 2007Co-Authors: Felix Hernandez, Tania Portoles, E Pitarch, F J LopezAbstract:The potential of gas chromatography coupled to high-Resolution Time-of-flight mass spectrometry (GC/TOF-MS) for screening of organic pollutants in water has been explored. After optimization of the solid-phase microextraction (SPME) step, where parameters such as fiber selection and addition of salt were studied, this extraction technique was applied to the analysis of different types of water samples. Investigation of 60 target organic pollutants, including pesticides, octyl/nonyl phenols, pentachlorobenzene, and polycyclic aromatic hydrocarbons (PAHs) was carried out by evaluating the presence of up to five representative m/z ions per analyte, measured at high mass accuracy, and the attainment of their Q/q (Q, quantitative ion; q, confirmative ion) intensity ratio. This strategy led to the detection of 4-t-octylphenol, simazine, terbuthylazine, chlorpyrifos, terbumeton, and terbutryn in several water samples at low part-per-billion levels. Full spectrum acquisition data generated by the TOF-MS analyzer ...
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target and nontarget screening of organic micropollutants in water by solid phase microextraction combined with gas chromatography high Resolution Time of flight mass spectrometry
Analytical Chemistry, 2007Co-Authors: Felix Hernandez, Tania Portoles, E Pitarch, F J LopezAbstract:The potential of gas chromatography coupled to high-Resolution Time-of-flight mass spectrometry (GC/TOF-MS) for screening of organic pollutants in water has been explored. After optimization of the solid-phase microextraction (SPME) step, where parameters such as fiber selection and addition of salt were studied, this extraction technique was applied to the analysis of different types of water samples. Investigation of 60 target organic pollutants, including pesticides, octyl/nonyl phenols, pentachlorobenzene, and polycyclic aromatic hydrocarbons (PAHs) was carried out by evaluating the presence of up to five representative m/z ions per analyte, measured at high mass accuracy, and the attainment of their Q/q (Q, quantitative ion; q, confirmative ion) intensity ratio. This strategy led to the detection of 4-t-octylphenol, simazine, terbuthylazine, chlorpyrifos, terbumeton, and terbutryn in several water samples at low part-per-billion levels. Full spectrum acquisition data generated by the TOF-MS analyzer also allowed subsequent investigation of the presence of polybrominated diphenyl ethers and several fungicides in samples after MS data acquisition, without the need to reanalyze the water samples. In addition, nontarget analysis was also tested by application of a deconvolution software. Several organic pollutants that did not form a part of the list of contaminants investigated were identified in the water samples, thanks to the excellent sensitivity of TOF-MS in full spectrum acquisition mode and the valuable accurate mass information provided by instrument. Bisphenol A, the antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT), its metabolite 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO), the polycyclic musk galaxolide, and the UV filter benzophenone were some of the compounds present in the water samples analyzed. SPME in combination with GC/TOF-MS has been proved to be an attractive and powerful approach for the rapid screening of multiclass organic pollutants in water, with very little sample manipulation and no solvent consumption. This combination provides to the analyst with information-rich MS data that facilitates the reliable identification of many different organic compounds in samples.
Mira Sundstrom - One of the best experts on this subject based on the ideXlab platform.
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comparison between drug screening by immunoassay and ultra high performance liquid chromatography high Resolution Time of flight mass spectrometry in post mortem urine
Drug Testing and Analysis, 2015Co-Authors: Mira Sundstrom, Anna Pelander, Ilkka OjanperaAbstract:Immunoassay is currently the most common approach for urine drug screening. However, the continuous emergence of new psychoactive substances (NPS) and their low urinary concentrations have challenged the scope and sensitivity of immunoassays. Consequently, specialized toxicology laboratories rely more and more on mass spectrometry (MS) based techniques. Ultra-high performance liquid chromatography/high-Resolution Time-of-flight mass spectrometry (UHPLC-HR-TOF-MS) is an especially attractive technique for comprehensive drug screening. The objective was to compare the performances of immunoassay and UHPLC-HR-TOF-MS in terms of scope, flexibility, sensitivity, and reliability of substance identification. A total of 279 post-mortem urine samples were analyzed using a method representative of each technique. The immunoassay method was an Emit II Plus enzyme immunoassay for the following drug groups: amphetamines, benzodiazepines, buprenorphine, cannabis, and opiates. The UHPLC-HR-TOF-MS method was a recently published method covering hundreds of drugs: conventional drugs of abuse, abused prescription drugs, and NPS of various classes. UHPLC-HR-TOF-MS produced a lower number of false positive (FP) results for the drug groups covered by immunoassay. Many of the false negative (FN, n = 40) and FP (n = 22) immunoassay results were obviously due to the higher cut-off concentrations and interfering matrix, respectively. Moreover, the wider scope of UHPLC-HR-TOF-MS allowed detection of NPS and prescription drugs. UHPLC-HR-TOF-MS gave FP results related to a few particular substances. The future option of adjusting all compound-specific reporting parameters individually would allow the method's sensitivity and specificity to be fully exploited. Copyright © 2014 John Wiley & Sons, Ltd.
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a high sensitivity ultra high performance liquid chromatography high Resolution Time of flight mass spectrometry uhplc hr tofms method for screening synthetic cannabinoids and other drugs of abuse in urine
Analytical and Bioanalytical Chemistry, 2013Co-Authors: Mira Sundstrom, Anna Pelander, Verena Angerer, Melanie Hutter, Stefan Kneisel, Ilkka OjanperaAbstract:The continuing emergence of designer drugs imposes high demands on the scope and sensitivity of toxicological drug screening procedures. An ultra-high performance liquid chromatography/high-Resolution Time-of-flight mass spectrometry (UHPLC-HR-TOFMS) method was developed for screening and simultaneous confirmation of both designer drugs and other drugs of abuse in urine samples in a single run. The method covered selected synthetic cannabinoids and cathinones, amphetamines, natural cannabinoids, opioids, cocaine and other important drugs of abuse, together with their main urinary metabolites. The database consisted of 277 compounds with molecular formula and exact monoisotopic mass; retention Time was included for 192 compounds, and primary and secondary qualifier ion exact mass for 191 and 95 compounds, respectively. Following a solid-phase extraction, separation was performed by UHPLC and mass analysis by HR-TOFMS. MS, and broad-band collision-induced dissociation data were acquired at m/z range 50–700. Compound identification was based on a reverse database search with acceptance criteria for retention Time, precursor ion mass accuracy, isotopic pattern and abundance of qualifier ions. Mass resolving power in spiked urine samples was on average FWHM 23,500 and mass accuracy 0.3 mDa. The mean and median cut-off concentrations determined for 75 compounds were 4.2 and 1 ng/mL, respectively. The range of cut-off concentrations for synthetic cannabinoids was 0.2–60 ng/mL and for cathinones 0.7–15 ng/mL. The method proved to combine high sensitivity and a wide scope in a manner not previously reported in drugs of abuse screening. The method’s feasibility was demonstrated with 50 authentic urine samples.
B M Lerner - One of the best experts on this subject based on the ideXlab platform.
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a high Resolution Time of flight chemical ionization mass spectrometerutilizing hydronium ions h 3 o tof cims for measurements ofvolatile organic compounds in the atmosphere
Atmospheric Measurement Techniques, 2016Co-Authors: Bin Yuan, A Koss, C Warneke, J B Gilman, B M LernerAbstract:Abstract. Proton transfer reactions between hydronium ions (H3O+) and volatile organic compounds (VOCs) provide a fast and highly sensitive technique for VOC measurements, leading to extensive use of proton-transfer-reaction mass spectrometry (PTR-MS) in atmospheric research. Based on the same ionization approach, we describe the development of a high-Resolution Time-of-flight chemical ionization mass spectrometer (ToF-CIMS) utilizing H3O+ as the reagent ion. The new H3O+ ToF-CIMS has sensitivities of 100–1000 cps ppb−1 (ion counts per second per part-per-billion mixing ratio of VOC) and detection limits of 20–600 ppt at 3σ for a 1 s integration Time for simultaneous measurements of many VOC species of atmospheric relevance. The ToF analyzer with mass Resolution (m∕Δm) of up to 6000 allows the separation of isobaric masses, as shown in previous studies using similar ToF-MS. While radio frequency (RF)-only quadrupole ion guides provide better overall ion transmission than ion lens system, low-mass cutoff of RF-only quadrupole causes H3O+ ions to be transmitted less efficiently than heavier masses, which leads to unusual humidity dependence of reagent ions and difficulty obtaining a humidity-independent parameter for normalization. The humidity dependence of the instrument was characterized for various VOC species and the behaviors for different species can be explained by compound-specific properties that affect the ion chemistry (e.g., proton affinity and dipole moment). The new H3O+ ToF-CIMS was successfully deployed on the NOAA WP-3D research aircraft for the SONGNEX campaign in spring of 2015. The measured mixing ratios of several aromatics from the H3O+ ToF-CIMS agreed within ±10 % with independent gas chromatography measurements from whole air samples. Initial results from the SONGNEX measurements demonstrate that the H3O+ ToF-CIMS data set will be valuable for the identification and characterization of emissions from various sources, investigation of secondary formation of many photochemical organic products and therefore the chemical evolution of gas-phase organic carbon in the atmosphere.
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a high Resolution Time of flight chemical ionization mass spectrometer utilizing hydronium ions h 3 o tof cims for measurements of volatile organic compounds in the atmosphere
Atmospheric Measurement Techniques Discussions, 2016Co-Authors: Bin Yuan, A Koss, C Warneke, J B Gilman, B M LernerAbstract:Proton transfer reactions between hydronium ions (H3O C / and volatile organic compounds (VOCs) provide a fast and highly sensitive technique for VOC measurements, leading to extensive use of proton-transfer-reaction mass spectrometry (PTR-MS) in atmospheric research. Based on the same ionization approach, we describe the development of a high-Resolution Time-of-flight chemical ionization mass spectrometer (ToF-CIMS) utilizing H3O C as the reagent ion. The new H3O C ToF-CIMS has sensitivities of 100- 1000 cps ppb 1 (ion counts per second per part-per-billion mixing ratio of VOC) and detection limits of 20-600 ppt at 3 for a 1 s integration Time for simultaneous measurements of many VOC species of atmospheric relevance. The ToF an- alyzer with mass Resolution (m=1m) of up to 6000 allows the separation of isobaric masses, as shown in previous stud- ies using similar ToF-MS. While radio frequency (RF)-only quadrupole ion guides provide better overall ion transmission than ion lens system, low-mass cutoff of RF-only quadrupole causes H3O C ions to be transmitted less efficiently than heav- ier masses, which leads to unusual humidity dependence of reagent ions and difficulty obtaining a humidity-independent parameter for normalization. The humidity dependence of the instrument was characterized for various VOC species and the behaviors for different species can be explained by compound-specific properties that affect the ion chemistry (e.g., proton affinity and dipole moment). The new H3O C ToF-CIMS was successfully deployed on the NOAA WP-3D research aircraft for the SONGNEX campaign in spring of 2015. The measured mixing ratios of several aromatics from the H3O C ToF-CIMS agreed within 10 % with independent gas chromatography measurements from whole air samples. Initial results from the SONGNEX measurements demon- strate that the H3O C ToF-CIMS data set will be valuable for the identification and characterization of emissions from var- ious sources, investigation of secondary formation of many photochemical organic products and therefore the chemical evolution of gas-phase organic carbon in the atmosphere.
Yingning Peng - One of the best experts on this subject based on the ideXlab platform.
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super Resolution Time delay estimation in multipath environments
IEEE Transactions on Circuits and Systems, 2007Co-Authors: Dongxu Shen, Yingning PengAbstract:The super-Resolution Time delay estimation in multipath environment is very important for many applications. Conventional super-Resolution approaches can only deal with signals with wideband and flat spectra. In this paper, we propose a novel super-Resolution Time delay estimation method that can treat signals with narrowband spectra. In our method, the Time delay estimation is first transformed into the frequency domain, in which the problem is converted into the parameter estimation of sinusoidal signals with lowpass envelopes. Then a MUSIC-type algorithm taking account of the envelope variation is applied to achieve the super-Resolution estimation. Time delay estimation in active and passive systems are considered. Simulation results confirm that the proposed estimators provide better performance than the classical correlation approach and the conventional MUSIC algorithm for separating closely spaced signals with narrowband spectra.
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super Resolution Time delay estimation in multipath environments
Wireless Communications and Networking Conference, 2004Co-Authors: Dongxu Shen, Yingning PengAbstract:The problem of super-Resolution Time delay estimation in multipath environments is addressed in this paper. Two cases, active and passive systems, are considered. The Time delay estimation is first converted into a sinusoidal parameter estimation problem. Then the sinusoidal parameters are estimated by generalizing the multiple signal classification (MUSIC) algorithm for single-experiment data. The proposed method, referred to as the MUSIC-type algorithm, approximates the Cramer-Rao bound (CRB) in terms of the mean square errors (MSKs) for different signal-to-noise ratios (SNRs) and separations of multipath components. Simulation results show that the MUSIC-type algorithm performs better than the classical correlation approach and the conventional MUSIC method for the closely spaced components in multipath environments.
