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Solid-phase Extraction Cartridges (solid-phase + extraction_cartridge)
Selected AbstractsIdentification of Major Alkaloids in Rat Urine by HPLC/DAD/ESI-MS/MS Method Following Oral Administration of Cortex Phellodendri DecoctionHELVETICA CHIMICA ACTA, Issue 2 2009Chun-Hui Ma Abstract A rapid, sensitive, and specific high-performance liquid chromatography (HPLC), diode-array detection, and mass-spectrometry techniques were developed for an identification of the constituents of Cortex Phellodendri and their metabolites in rat urine. The dose of 10,ml/kg of Cortex Phellodendri decoction was used for rats' oral administration. 0,24-h Urine was purified using a C18 solid-phase extraction cartridge, and then analyzed by an on-line MS detector. A total of 13,characteristic HPLC peaks were detected in the urine samples. Nine of them, including five alkaloids and four of their metabolites, were tentatively elucidated as magnoflorine (1), the glucuronide conjugate of demethyleneberberine (2), menisperine (3), jatrorrhizine 3- O -glucuronide (4), berberubine 9- O -glucuronide (5), jatrorrhizine (6), the monomethyl and monohydroxy catabolite of berberubine (7), palmatine (8), and berberine (9). Identification and structural elucidation of the metabolites were performed by comparing their MSn spectra data with those reported. [source] Indirect identification of isoprenoid quinones in Escherichia coli by LC-MS with atmospheric pressure chemical ionization in negative modeJOURNAL OF BASIC MICROBIOLOGY, Issue 6 2004Mengchun Gao Dr. A novel analytical method was applied for identification of isoprenoid quinones in Escherichia coli by liquid chromatography atmospheric press chemical ionization mass spectrometry in negative mode (LC-NI-APCI-MS). Extraction and clean-up of sample were carried out on Sep-Pak Plus Silica solid-phase extraction cartridges. Ubiquinone-7 (UQ-7), Ubiquinone-8 (UQ-8) and Mequinone-8 (MK-8) were determined directly using combined information on retention time, molecular ion mass, fragment ion masses and UV characteristic spectrometry without any standard reagent. It was found that UQ-8 was the major component of isoprenoid quinones in Escherichia coli under aerobic condition. Compared with UQ-8, the relative abundance of UQ-7 and MK-8 is only 15% and 14%, respectively. The average recoveries of UQ-6, UQ-10 and vitamin K1 in Escherichia coli were investigated by standard spiking experiment. The recoveries were achieved in the range from 94 to 106%, and the relative standard deviations (RSD) of the triplicate analysis of the spiked samples (UQ-6, UQ-10 and vitamin K1) ranged from 3 to 8%. The detection limits of LC-NI-APCI-MS were estimated to be 5, 40 and 0.8 ,g/g dry cell for UQ-6, UQ-10 and vitamin K1, respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrospray ionization mass spectrometric characterization and quantitation of xanthine derivatives using isotopically labelled analogues: an application for equine doping control analysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2004Mario Thevis Isotope-dilution mass spectrometry has been employed successfully in numerous fields of analytical chemistry enabling the establishment of fast and reliable procedures. In equine sports, xanthine derivatives such as caffeine and theobromine are prohibited, and doping control laboratories analyze horse urine specimens regarding these illicit performance-enhancing drugs. Theobromine has to exceed a threshold level of 2,,g/mL, hence a robust and reliable quantitation is required. Stably deuterated theobromine and caffeine were synthesized by the reaction of xanthine or theobromine with iodomethane-d3 in the presence of N -methyl- N -trimethylsilyltrifluoroacetamide or potassium carbonate in acetonitrile, respectively. Both compounds were characterized by nuclear magnetic resonance spectroscopy and electrospray ionization tandem mass spectrometry, and a robust and fast assay for the qualitative and quantitative analysis of theobromine in equine urine samples was validated. Urine specimens were extracted by means of solid-phase extraction cartridges, and concentrated extracts were analyzed by liquid chromatography interfaced to a triple-quadrupole mass spectrometer. In addition, the dissociation behavior of deuterated analogues to caffeine and theobromine allowed proposals for fragmentation routes of xanthine derivatives after atmospheric pressure ionization and collisionally activated dissociation. Copyright © 2004 John Wiley & Sons, Ltd. [source] Testing extraction and storage parameters for a fecal hormone methodAMERICAN JOURNAL OF PRIMATOLOGY, Issue 11 2010David J. Pappano Abstract Four experiments were conducted to test different aspects of a "field-friendly" fecal hormone extraction method that utilizes methanol extraction in the field followed by storage on C18 solid-phase extraction cartridges. Fecal samples were collected from geladas (Theropithecus gelada) housed at the Bronx Zoo, and the experiments were conducted in a laboratory setting to ensure maximum control. The experiments were designed to either simulate the conditions to which fecal samples are subjected during fieldwork or improve on an existing protocol. The experiments tested the relationship between fecal hormone metabolite preservation/recovery and: (1) the amount of time a sample is stored at ambient temperature; (2) the number of freeze/thaw cycles a sample undergoes; (3) the effectiveness of different extraction solutions; and (4) the effectiveness of different cartridge washes. For each experiment, samples were assayed by radioimmunoassay for fecal glucocorticoid (GC) and testosterone (T) metabolites. Results for each of the experiments were as follows. First, storage at ambient temperature did not affect hormone levels until 4 weeks of storage, with significant increases for both GC and T metabolites at 4 weeks. Second, hormone levels significantly decreased in samples after two freeze/thaw cycles for GCs and six freeze/thaws cycles for T. Third, for both GCs and T, hormone extraction using various methanol solutions was significantly higher than using 100% ethanol. Finally, using a 20% methanol solution to wash cartridges significantly increased GC levels but had no effect on T levels. These results suggest that, when utilizing C18 cartridges for fecal steroid storage, researchers should consider several methodological options to optimize hormone preservation and recovery from fecal samples. Am. J. Primatol. 72:934,941, 2010. © 2010 Wiley-Liss, Inc. [source] Studies on neurosteroids XXIV.BIOMEDICAL CHROMATOGRAPHY, Issue 12 2008-androstane-, -diol, Determination of neuroactive androgens, androsterone, in rat brain, serum using liquid chromatography, tandem mass spectrometry Abstract The development and validation of liquid chromatography,electrospray ionization,tandem mass spectrometric (LC,ESI-MS/MS) methods that enable the quantification of neuroactive androgens, androsterone (5, -androstan-3, -ol-17-one, 3,,5, -A) and 5, -androstane-3,,17, -diol (3,,5, -Adiol), in the rat brain and serum are presented. The androgens were extracted with methanol,acetic acid, purified using solid-phase extraction cartridges, derivatized with an ESI-active reagent, isonicotinoyl azide (INA), and then subjected to LC,ESI-MS/MS. The quantifications were based on selected reaction monitoring mode using the characteristic transitions of the INA derivatives. The methods allowed the reproducible and accurate quantification of the brain and serum neuroactive androgens using a 100 mg or 100 µL sample; the intra- and inter-assay relative standard deviations were below 3.6%, and the percentage accuracy values were 97.1,103.7% for both androgens. The animal study using the methods suggests that most of 3,,5, -Adiol found in the brain is derived from the periphery, while 3,,5, -A is not only transported from the periphery into the brain, but also synthesized in the brain by the oxidation of 3,,5, -Adiol. The androgens in the rats intraperitoneally administered finasteride, a 5, -reductatse inhibitor, were also measured; this treatment significantly reduced the brain 3,,5, -A and 3,,5, -Adiol levels and increased only the brain level of androstenedione, the precursor of 3,,5, -A. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass SpectrometryCHINESE JOURNAL OF CHEMISTRY, Issue 9 2007Yan Liu Abstract A determination method has been optimized and validated for the simultaneous analysis of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) in honey. Tetracyclines (TCs) were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction (SPE), while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile, and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 µg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% (n=18). Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey(2,50 ng/g) was realized by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r>0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey. [source] | |||||||||||||