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81.
82.
Simple and rapid micellar electrokinetic capillary chromatographic method for simultaneous determination of four antiepileptics in human serum 总被引:1,自引:0,他引:1
A very rapid and simple MEKC method was developed for the simultaneous determination of four antiepileptic drugs, ethosuximide (Etho), primidone (Pri), phenytoin (Pht) and carbamazepine (Cbz) in human serum. Sample analysis required only 100 microL of human serum which only needed to be centrifuged, decanted and combined with the running buffer [5.3 mM Na(2)HPO(4)/3.2 mM borax buffer (pH 9.5) containing 55 mM SDS and 3.5% (v/v) acetone]. The analysis was performed in only 10 min into fused-silica capillaries (57 cm total length with 50 microm i.d. and 50 cm to the detector) using the MEKC methodology with diode-array detection at 220 nm. The calibration graphs were established for ethoximide, primidone, phenytoin and carbamazepine between 0 and 20 mg/L. Recoveries were between 85 and 87%. The simplicity of the proposed methodology makes it suitable for routine clinical use, especially for epileptic patients on polytherapy. 相似文献
83.
工业废水中微量铜(Ⅱ)和氰化物的流动注射光度分析 总被引:2,自引:0,他引:2
采用FIA技术,以光度比色法为基础,建立了工业废水中微量Cu^2+和CN^-的顺序自动分析方法和装置。其对二种离子的测定频率为60样/h,相对标准偏差<1.0%,工作曲线的r值≥0.999,各项分析技术指标均优于手工法操作。 相似文献
84.
Weil Joseph Brewer Mark Hendrickson Richard Sarikaya Ayda Ladisch Michael R. 《Applied biochemistry and biotechnology》1998,(1):99-111
Yellow poplar wood sawdust consists of 41% cellulose and 19% hemicellulose. The goal of pressure cooking this material in
water is to hydrate the more chemically resistive regions of cellulose in order to enhance enzymatic conversion to glucose.
Pretreatment can generate organic acids through acid-catalyzed degradation of monosaccharides formed because of acids released
from the biomass material or the inherent acidity of the water at temperatures above 160°C. The resulting acids will further
promote the acid-catalyzed degradation of monomers that cause both a reduction in the yield and the formation of fermentation
inhibitors such as hydroxymethyl furfural and furfural. A continuous pH-monitoring system was developed to help characterize
the trends in pH during pretreatment and to assist in the development of a base (2.0 M KOH) addition profile to help keep
the pH within a specified range in order to reduce any catalytic degradation and the formation of any monosac-charide degradation
products during pretreatment. The results of this work are discussed. 相似文献
85.
Linsinger TP Gawlik BM Trapmann S Lamberty A Emons H 《Analytical and bioanalytical chemistry》2004,378(5):1168-1174
Over the years, the nature of CRMs has changed considerably. Recently, more and more CRMs have been certified in their "natural" form, that is processed as little as possible, with analytes at their natural concentration level. This and the trend towards certified properties other than the concentrations of clearly defined molecules/elements have made guaranteeing stability of CRMs and estimating a shelf life an even more important issue for reference material producers than it has been before. One way to meet this challenge is to take more care in processing, storage and dispatch of CRMs. At IRMM, approximately 20 % of the RMs are stored at –20 °C or below and about 10% require cooled transportation. In addition, increased efforts for assessing stability are needed. Shelf lives are estimated using addition of an uncertainty component based on real-temperature stability studies rather than by accelerated stability studies. These pre-certification efforts are complemented by a stability-monitoring program, which at IRMM includes 80 % of the non-nuclear and non-isotopic materials. Although the costs for these efforts are high in absolute terms, they are only a minor and indispensable contribution to the total costs of CRM production. 相似文献
86.
Using column-switching liquid chromatography/tandem mass spectrometry (LC-MS/MS), we developed an improved analytical method of urinary estriol glucuronides. This new method is derived predominantly from maternal and fetal precursors in pregnancy. We used in the following procedure: first, we filtered urine samples with a membrane filter. Next, we directly injected the 50 microL aliquot of urine samples onto a pre-column. Then, after activating the column-switching valve, we backflushed the loaded samples onto the C(18) analytical column. Urine samples can be assayed within 20 min without any sample preparation steps. We monitored separated estriol glucuronides by negative electrospray ionization (ESI) and selected-reaction monitoring (SRM). The calibration range of estriol-3-glucuronide (E3-3G) and estriol-16-glucuronide (E3-16G) was 0.1-20 microg/mL and the linearity of the method was 0.9984 for E3-3G and 0.9987 for E3-16G. The limits of detection at a signal-to-noise (S/N) ratio of 3 were 10 ng/mL (E3-3G) and 5 ng/mL (E3-16G). The analytical recovery was over 85% and, in general, inter-day and intra-day variability for precision and accuracy were less than 10%. When applied to a pregnancy urine sample to biomedical monitoring of the function of the maternal/fetal unit, the proposed method allowed rapid and sensitive screening for the detection of E3-3G and E3-16G. 相似文献
87.
Anna Worobiec Lucyna Samek Zoya Spolnik Velichka Kontozova Elzbieta Stefaniak René Van Grieken 《Mikrochimica acta》2006,156(3-4):253-261
The St. Michael Archangel’s Church in Szalowa, Poland, was selected for closer investigation with respect to the indoor/outdoor
air exchange and its influence on the air quality and work arts preservation. Chemical composition, size and abundance of
particulate matter and concentration of gases NO2, SO2, O3 inside and outside the church were determined. To study seasonal variation of the weather condition (temperature, inversion
level, wind direction) and the influence of seasonal sources of the air pollution (like heating of the nearby houses), samples
were collected in winter and summer time. It was stated that suspended particulate matter inside the wooden church has in
general an outdoor source. Several groups of particles were distinguished such as the organic ones, soil dust, nitrates and
sulphates. In case of organic and soil dust particles, the concentration inside was higher than outside. From the results,
in comparison to literature data, one can conclude that accumulation of particulate suspended matter in the church is more
intense than in other types of buildings. Gaseous pollutants were detected but their concentration was negligible. 相似文献
88.
The reaction of styrene oxide, a potential carcinogen in humans, with DNA constituents has been used to develop an improved method for quantification of DNA adducts. To enable monitoring of DNA adducts caused by xenobiotics at physiological relevant levels, a robust, reliable and powerful method based on monitoring of phosphorus in nucleotides is described. An efficient enzymatic digestion step and a sample-preconcentration procedure are essential, and enable separation of alkylated nucleotides from the large excess of native nucleotides. The adducts are detected by means of the phosphorus signal measured at mass m/z=31 with an inductively-coupled-plasma mass spectrometer. Bis(4-nitrophenyl)phosphate (BNPP) serves as internal standard for quantification of the adducts. The absolute limit of detection, 45 fmol, corresponds to detection of three modified nucleotides among 107 native nucleotides (the calculation is based on use of 50 g calf thymus DNA). An adduct formation ratio at the DNA of 3.6 adducts per 1000 nucleotides was measured, which is 75% lower than for reaction with monomeric 2-deoxy-nucleotides. In addition, a substantial amount of phosphate adducts were detected, but in DNA the rate of phosphate formation was lower than with monomeric nucleotides. Most probably these adducts escaped unnoticed when 31P-post-labelling was employed. 相似文献
89.
90.
Interfacial layers have been widely applied to study the formation and stability of emulsion-based systems. However, the application of isolated interfaces to address digestibility of emulsions is often limited because of the complexity of experimental methods and results. This review summarizes the latest developments in analytical methods and literature data on effects of digestion on interfacial layers. Particular emphasis is given to understand the changes on interfacial magnitudes during oral, gastric, and duodenal digestion, either applied separately or sequentially. Limitations of interfacial aspects and key factors that influence emulsion microstructure in bulk and lipid digestion are identified. Understanding the behavior of interfacial layers upon gastrointestinal digestion promotes an accurate tracking of the physiological fate of emulsions. 相似文献