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991.
Manuel Lombardo-Agüí Ana M. García-CampañaLaura Gámiz-Gracia Carmen Cruces Blanco 《Journal of chromatography. A》2010,1217(15):2237-2242
A method for the simultaneous determination of four fluoroquinolones of veterinary use (ciprofloxacin, danofloxacin, enrofloxacin and sarafloxacin) in two complex matrixes, such as bovine raw milk and pig kidney, has been established and validated. The method is based on the use of capillary electrophoresis (CE) coupled with a very sensitive detection mode, such as laser induced fluorescence (LIF) detection, due to the fact the all the compounds selected show native fluorescence. In order to achieve high selectivity in the sample treatment procedure, a commercially available molecularly imprinted polymer has been used for the solid phase extraction of the analytes. Once the retention and elution processes were optimized, the final extract was analyzed by CE-LIF using a 325 nm He–Cd laser. Optimum separation was obtained in a 70 cm × 75 μm capillary using a 125 mM phosphoric acid solution at pH 2.8 with 36% methanol as background electrolyte. The method provided very low detection limits, ranging from 0.17 to 0.98 μg/kg for milk and 1.10 to 10.5 μg/kg for kidney, with acceptable precision and satisfactory recoveries. 相似文献
992.
I. Boldizsár Zs. Füzfai F. Tóth É. Sedlák L. Borsodi I. Molnár-Perl 《Journal of chromatography. A》2010,1217(10):1674-1682
The mass fragmentation patterns and the characteristic behavior of the trimethylsilyl (TMS) derivatives of the dibenzylbutyrolactone-type (arctiin, arctigenin, methylarctigenin, matairesinoside, matairesinol) and those of the diphenylperhydrofurotetrahydrofurane-type (phylligenin, pinoresinol) lignans, obtained by gas chromatography–mass spectrometry (GC–MS), were presented. It was shown that upon acidic hydrolysis the dibenzylbutyrolactone-type lignans are stable while the diphenylperhydrofurotetrahydrofurane-type ones decompose. As a novelty to the field we confirmed that the fragment species of the derivatized lignan glycosides, in the presence of excess hexamethyldisilazane, leaded to their in situ derivatization. Quantification of the selective fragment ions of the TMS derivatives by GC–MS, in respect of the ions found one by one, and concerning the selective fragment ions {SFI(s)} in total, provided acceptable reproducibilities, suitable for quantitation purposes: varying between 1.20% and 6.6% relative standard deviation percentages (RSD%). For characterization of the behavior of various type of lignans, analyses were performed with the untreated and with the trifluoroacetic acid hydrolyzed plant extracts, from the same sample, in parallel, both by GC–MS and by high performance liquid chromatography–mass spectrometry, working in the positive electron ionization mode (HPLC–ESPI-MS). The analysis of lignans in fruit and leaf extracts (obtained from the Arctium, Centaurea and Forsythia plants) was confirmed both by GC–MS and by HPLC–ESPI-MS. Our multicomponent system (including the identification and quantification of sugars, sugar alcohols, and several members of various homologous series of acids, anthraquinones and flavonoids) has been extended to the analysis of lignan glycosides and to the free lignans. Reproducibilities in the quantitation of lignans in plant matrices, as averages on GC and HPLC basis, varied between 0.9% and 11% (RSD). The distribution of the lignan constituents was presented for 5 Arctium, for 8 Centaurea and for 4 Forsythia plant extracts: the total of lignan contents varied between 0.42 and 87.9 mg/g, respectively. 相似文献
993.
Hong Heng See Peter C. Hauser M. Marsin Sanagi Wan Aini Wan Ibrahim 《Journal of chromatography. A》2010,1217(37):5832-5838
A dynamic supported liquid membrane tip extraction (SLMTE) procedure for the effective extraction and preconcentration of glyphosate (GLYP) and its metabolite aminomethylphosphonic acid (AMPA) in water has been investigated. The SLMTE procedure was performed in a semi-automated dynamic mode and demonstrated a greater performance against a static extraction. Several important extraction parameters such as donor phase pH, cationic carrier concentration, type of membrane solvent, type of acceptor stripping phase, agitation and extraction time were comprehensively optimized. A solution of Aliquat-336, a cationic carrier, in dihexyl ether was selected as the supported liquid incorporated into the membrane phase. Quantification of GLYP and AMPA was carried out using capillary electrophoresis with contactless conductivity detection. An electrolyte solution consisting of 12 mM histidine (His), 8 mM 2-(N-morpholino)ethanesulfonic acid (MES), 75 μM cetyltrimethylammonium bromide (CTAB), 3% methanol, pH 6.3, was used as running buffer. Under the optimum extraction conditions, the method showed good linearity in the range of 0.01–200 μg/L (GLYP) and 0.1–400 μg/L (AMPA), acceptable reproducibility (RSD 5–7%, n = 5), low limits of detection of 0.005 μg/L for GLYP and 0.06 μg/L for AMPA, and satisfactory relative recoveries (90–94%). Due to the low cost, the SLMTE device was disposed after each run which additionally eliminated the possibility of carry-over between runs. The validated method was tested for the analysis of both analytes in spiked tap water and river water with good success. 相似文献
994.
Kristoffer Laursen Søren Søndergaard Frederiksen Casper Leuenhagen Rasmus Bro 《Journal of chromatography. A》2010,1217(42):6503-6510
It is common practice in chromatographic purity analysis of pharmaceutical manufacturing processes to assess the quality of peak integration combined by visual investigation of the chromatogram. This traditional method of visual chromatographic comparison is simple, but is very subjective, laborious and seldom very quantitative. For high-purity drugs it would be particularly difficult to detect the occurrence of an unknown impurity co-eluting with the target compound, which is present in excess compared to any impurity. We hypothesize that this can be achieved through Multivariate Statistical Process Control (MSPC) based on principal component analysis (PCA) modeling. In order to obtain the lowest detection limit, different chromatographic data preprocessing methods such as time alignment, baseline correction and scaling are applied. Historical high performance liquid chromatography (HPLC) chromatograms from a biopharmaceutical in-process analysis are used to build a normal operation condition (NOC) PCA model. Chromatograms added simulated 0.1% impurities with varied resolutions are exposed to the NOC model and monitored with MSPC charts. This study demonstrates that MSPC based on PCA applied on chromatographic purity analysis is a powerful tool for monitoring subtle changes in the chromatographic pattern, providing clear diagnostics of subtly deviating chromatograms. The procedure described in this study can be implemented and operated as the HPLC analysis runs according to the process analytical technology (PAT) concept aiming for real-time release. 相似文献
995.
Yu-Yen Kao Kung-Tien Liu Ming-Feng Huang Tai-Chia Chiu Huan-Tsung Chang 《Journal of chromatography. A》2010,1217(4):582-587
We describe simultaneous analysis of naphthalene-2,3-dicarboxaldehyde (NDA)-amino acid and NDA-biogenic amine derivatives by CE in conjunction with light-emitting diode-induced fluorescence detection using poly(ethylene oxide) (PEO) solutions containing sodium dodecyl sulfate (SDS). After sample injection, via EOF 0.1% PEO prepared in 100 mM TB solution (pH 9.0) containing 30 mM SDS entered a capillary filled with 0.5 M TB solution (pH 10.2) containing 40 mM SDS. Under this condition, 14 NDA-amino acid and NDA-amine derivatives were separated within 16 min, with high efficiency ((1.0–3.2) × 105 theoretical plates) and sensitivity (LODs at S/N = 3 ranging from 2.06 to 19.17 nM). In the presence of SDS and PEO, analytes adsorption on the capillary wall was suppressed, leading to high efficiency and reproducibility. The intraday analysis RSD values (n = 3) of the mobilities for the analytes are less than 0.52%. We have validated the practicality of this approach by quantitative determination of 9 amino acids in breast cancer cells (MCF-7) and 10 amino acids in normal epithelial cells (H184B5F5/M10). The concentrations of Tau and Gln in the MCF-7 cells were different than those in the H184B5F5/M10 cells, respectively. Our results show the potential of this approach for cancer study. 相似文献
996.
Novel chromogenic thiourea based sensors 4,4′-bis-[3-(4-nitrophenyl) thiourea] diphenyl ether 1 and 4,4′-bis-[3-(4-nitrophenyl) thiourea] diphenyl methane 2 having nitrophenyl group as signaling unit have been synthesized and characterized by spectroscopic techniques and X-ray crystallography. The both sensors show visual detection, UV-vis and NMR spectral changes in presence of fluoride and cyanide anions in organic solvent as well as in aqueous medium. The absorption spectra indicated the formation of complex between host and guest is in 1:2 stoichiometric ratios. 相似文献
997.
Stella Rovio Anna Kalliola Heli Sirén Tarja Tamminen 《Journal of chromatography. A》2010,1217(8):1407-1413
Capillary zone electrophoresis (CZE) with indirect UV detection was used in developing a method for the simultaneous determination of inorganic anions, aliphatic and heterocyclic organic acids in various processed samples. The analytes were determined simultaneously in 10 min using an electrolyte containing 20 mM 2,3-pyrazine dicarboxylic acid, 65 mM tricine, 2 mM BaCl2, 0.5 mM cetyltrimethylammonium bromide, and 2 M urea at pH 8.06. Linear plots for the analytes were obtained in the concentration range of 2–150 mg L−1. Relative standard deviations (RSDs) of peak areas during a 3-day analysis period varied from 5.5% for glycolate to 9.5% for oxalate. RSDs of migration times varied between 0.4% and 1.1%. The detection limit (at S/N 3) was 1 mg L−1 for all the analytes studied. The proposed method was successfully demonstrated for the determination of carboxylic acids in eight oxygen treated samples of commercial softwood and hardwood kraft lignin and two red wine samples of Pinot Noir grapes. In the kraft lignin samples the concentrations of carboxylic acids correspond to the oxidation time. The acid concentrations of wine varied considerable. 相似文献
998.
考察了采用固相萃取技术时毛发中海洛因毒品及其代谢物的原形释放方法。通过对海洛因吸食者毛发和空白添加标准品毛发的碱消解、酸消解、甲醇超声提取、甲醇-5 mol/L HCI超声提取、甲醇-TFA超声提取5种毛发中毒品及其代谢物的释放方法考察,确立了甲醇超声提取-固相萃取-气相色谱/质谱-选择离子检测的方法为稳定、有效的海洛因滥用者毛发中毒品及其代谢物的释放与检测方法。利用该方法对添加6-单乙酰吗啡的毛发进行萃取和测试,6-单乙酰吗啡的回收率为78.7%,相对标准偏差RSD为2.4%,该方法可有效地检出海洛因滥用者毛发中的6-单乙酰吗啡。 相似文献
999.
1000.