Abstract A rapid and sensitive high-performance liquid chromatography procedure is reported for the analysis of uric acid in serum. The method employs a single treatment of serum with cyclohexane and an excess of ammonium sulfate to eliminate endogenous serum components which easily contaminate the chromatographic system. Reversed-phase chromatography is performed at room temperature using a binary-solvent gradient, monitoring the effluent at 290 nm. Quantitation is based on peak-height ratio of uric acid to internal standard (β-hydroxyethyltheophylline). A linear response is obtained to 160 mg/1. Within-day and between-day precisions for the mean of this range varied from 0.59 to 1.1% and from 0.71 to 1.2%, respectively. Numerous potential interfering substances tested do not interfere. 相似文献
Lipooligosaccharides (LOS) are major microbial virulence factors displayed on the outer membrane of rough-type Gram-negative bacteria. These amphipathic glycolipids are comprised of two domains, a core oligosaccharide linked to a lipid A moiety. Isolated LOS samples are generally heterogeneous mixtures of glycoforms, with structural variability in both domains. Traditionally, the oligosaccharide and lipid A components of LOS have been analyzed separately following mild acid hydrolysis, although important acid-labile moieties can be cleaved. Recently, an improved method was introduced for analysis of intact LOS by MALDI-TOF MS using a thin layer matrix composed of 2,4,6-trihydroxyacetophenone (THAP) and nitrocellulose. In addition to molecular ions, the spectra show in-source “prompt” fragments arising from regiospecific cleavage between the lipid A and oligosaccharide domains. Here, we demonstrate the use of traveling wave ion mobility spectrometry (TWIMS) for IMS-MS and IMS-MS/MS analyses of intact LOS from Neisseria spp. ionized by MALDI. Using IMS, the singly charged prompt fragments for the oligosaccharide and lipid A domains of LOS were readily separated into resolved ion plumes, permitting the extraction of specific subspectra, which led to increased confidence in assigning compositions and improved detection of less abundant ions. Moreover, IMS separation of precursor ions prior to collision-induced dissociation (CID) generated time-aligned, clean MS/MS spectra devoid of fragments from interfering species. Incorporating IMS into the profiling of intact LOS by MALDI-TOF MS exploits the unique domain structure of the molecule and offers a new means of extracting more detailed information from the analysis.
Abstract It has been demonstrated, by operation on a series of thermosetting phenolic-asbestos composites, that pyrolysis gas chromatography may be applied as a general method for estimating polymer content in cured composite materials. A platinum filament is employed for flash pyrolysis and quantitative estimation is based on the internal standard method. 相似文献
Essential components of N-glycoproteins were synthesized in octyl glycoside form starting from 3-O-allyl-D-glucose derivative. The β-mannosidic linkage was formed by the oxidation reduction method. MALDI-TOF mass spectrometry and its post-source decay (PSD) mode were used for identification and structural elucidation of protected synthetic oligosaccharides related to N-glycoproteins. Most fragments, identified in the PSD spectra, were products of the cleavage of glycosidic bonds. 相似文献
ABSTRACT An internal standard quantitative method of tetrodotoxin by capillary electrophoresis was developed, ephedrine hydrochloride being chosen as the internal standard of tetrodotoxin. The calibration curve was built with the correlation coefficient of 0.9997, and the linear range was from 0.01 mg.ml?1 to 10.0 mg-ml?1 with the detection limit of 1.0 x 10?3 mg.m1?1. RSD of the migration time of ephedrine hydrochloride and tetrodotoxin were all less than 1.0 %. The method was applied to determine tetrodotoxin in the poisonous frilled fish samples. 相似文献
Protein analysis is vital for biological and clinical research, but the measurement of unseparated, intact and high-mass proteins is also a challenging task by mass spectrometry-based methods. Here, we present a protocol for rapid and high-throughput analysis of intact proteins in tissue samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDITOF MS) combined with a high-mass detector platform. The method involves tissue specimens that undergo a simple protein extraction before MALDI-MS analysis. Using this method, the high abundance proteins in human thyroid carcinoma and paracarcinoma tissues were successfully investigated, and the mass spectra of the tissues of the 30 illustrated thyroid cancers showed remarkable differences. The peak intensity revealed a significant increase in human albumin in thyroid carcinoma tissues(p0.05). To validate the feasibility and credibility of this method, label-free proteomics quantitative analysis and Western blotting were used to relatively quantify the proteins in these tissues. Those results demonstrated a nearly 3-fold difference in human albumin levels between thyroid carcinoma and para-carcinoma tissues, which were consistent with the results of our method. The advantages of our method are easy sample handling, remarkable reproducibility and the ability to analyze high-mass proteins without digestion, which make them have the potential to be used in biological research and in clinical practice. 相似文献
Malondialdehyde (MDA) is a widely accepted biomarker of lipid peroxidation. Thus, the measurement of MDA in clinical samples is useful in the evaluation of oxidative stress. In this study, a micro-extraction-spectrophotometric assay was developed, based on the formation of MDA–thiobarbituric acid (TBA) adduct. To enhance the analytical performance, Erioglaucine A was used as an internal standard (IS), and the first derivative spectra were obtained. The volume of serum sample was 20µL and the total volume of aqueous phase 420µL (200µL of 0.6% TBA in acetic acid, pH 2.5 and 200µL of 6.25·10–4% IS). The extraction of adduct and IS was carried out with 300µL of aliquat 336 (0.06%) in ethyl acetate. The analytical signal S was defined as the ratio between the first derivative absorbances measured at 543.1nm (adduct) and 644.4nm (IS). In the calibration range up to 10µmolL–1 MDA, the linear regression coefficient was 0.9998. The quantification limit was 0.19µmolL–1 and the CV values for 2µmolL–1 and 5µmolL–1 MDA, respectively, were 0.8% and 0.7%. The procedure was applied to the analysis of diabetic sera and the results compared with those obtained by HPLC (derivatization with 2,4-dinitrophenylhydrazine). Lower HPLC results (about 15%) indicated that interferences from other TBA reactive substances had not been completely eliminated by the extraction procedure and derivatization of spectral data. On the other hand, the micro-procedure presents important advantages: it is simple, precise and environmentally friendly (small amounts of reagents), which makes it readily adaptable to the analysis of large sample series. The feasibility of micro-assay in the evaluation of lipid peroxidation status was demonstrated in the analysis of 156 serum samples from diabetic patients divided into three groups according to the stage of development of typical complications. 相似文献
Oxidized carbon nanotubes are tested as a matrix for analysis of small molecules by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Compared with nonoxidized carbon nanotubes, oxidized carbon nanotubes facilitate sample preparation because of their higher solubility in water. The matrix layer of oxidized carbon nanotubes is much more homogeneous and compact than that of nonoxidized carbon nanotubes. The efficiency of desorption/ionization for analytes and the reproducibility of peak intensities within and between sample spots are greatly enhanced on the surface of oxidized carbon nanotubes. The advantage of the oxidized carbon nanotubes in comparison with alpha-cyano-4-hydroxycinnamic acid (CCA) and carbon nanotubes is demonstrated by MALDI-TOF-MS analysis of an amino acid mixture. The matrix is successfully used for analysis of synthetic hydroxypropyl beta-cyclodextrin, suggesting a great potential for monitoring reactions and for product quality control. Reliable quantitative analysis of jatrorrhizine and palmatine with a wide linear range (1-100 ng/mL) and good reproducibility of relative peak areas (RSD less than 10%) is achieved using this matrix. Concentrations of jatrorrhizine (8.65 mg/mL) and palmatine (10.4 mg/mL) in an extract of Coptis chinensis Franch are determined simultaneously using the matrix and a standard addition method. 相似文献