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11.
F. A. L. van der Horst M. H. Post J. J. M. Holthuis U. A. Th. Brinkman 《Chromatographia》1989,28(5-6):267-273
Summary Micellar phase-transfer catalysis (MPTC) offers the opportunity to derivatize carboxylic acids directly in an aqueous matrix without prior extraction of the acids into a suitable aprotic solvent. The currently developed MPTC system consists of a non-ionic surfactant, Arkopal N-130, an ion-pair agent, tetrakis-(decyl)-ammonium bromide, and a novel fluorescence reagent, 9-bromomethylacridine. The MPTC system can be applied to the derivatization of many types of carboxylic acids. The reaction rate is affected by the lipophilicity of the acid and by the presence of other functional groups. For lipophilic carboxylic acids the reaction is complete within 5 min at 60°C and pH 7.0. 相似文献
12.
建立了一种可同时对醛、酮糖进行精确定性和定量分析的方法。以肌醇作为内标,用80%乙醇超声提取,利用醋酸酐和HMDS+TMCS(1:3)进行差异衍生,在EI源下用SIM模式进行GC/MS分析。结果表明:11种标准单糖在1—4mg/L范围内线性良好;仪器检出限:醛糖在8.15—22.4μg/L之间;酮糖为2.32μg/L和3.47μg/L;高、中、低3个量的平均回收率在73.0%-95.7%,相对标准偏差在3.1%-10.0%。对枸杞游离单糖进行测定,各单糖含量分别在0.26—368.6mg/g。该方法弥补了以前单糖分析中的缺陷,对既含有醛糖又含有酮糖的样品可同时进行精确的定性定量分析。 相似文献
13.
A pre-column derivatization liquid chromatographic method has been developed for the analysis of aminoglycoside antibiotics using phenylisocyanate as a derivatization reagent. Derivatives including kanamycin, neomycin and gentamicin were formed by reaction of the analytes with phenylisocyanate in the presence of triethylamine. Phenylisocyanato groups were attached to corresponding amino groups of aminoglycoside and their molecular mass was confirmed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). The experimental conditions for derivatization and separation of aminoglycoside derivatives were optimized and validated. A simple liquid chromatographic method for the determination of aminoglycoside antibiotics was demonstrated. 相似文献
14.
A simple high-performance liquid chromatographic method, using photodiode array detection was developed for the determination
of propylene glycol in human plasma and in the fluid retreived after continuous veno-venous hemofiltration. The method entailed
alkaline derivatization with benzoyl chloride and ethylene glycol as internal standard. The separation of the compounds, after
extraction with pentane, was carried out on a Pursuit C8 column with UV-detection at 230 nm. Validation samples were analyzed
with an accuracy between 95 and 105%, and intra- and inter-day coefficients of variation of less than 8%. The calibration
curve was linear over a concentration range of 5–100 mg L−1 with a detection limit of 1 mg L−1. Blood plasma samples of several patients were analysed by using the prescribed method with propylene glycol concentrations
varying from 5 to 98 mg L−1. Compared to previously described LC methods, this method is ten times more sensitive and thus suitable for use in pharmacokinetic
studies of propylene glycol. 相似文献
15.
Summary Clenbuterol has been determined in urine by solidphase extraction on a C18 cartridge, diazotization of the eluate with nitrite, coupling of the diazonium ion with 1-(naphthyl)ethylenediamine, and
separation of the azo dye formed by HPLC with a C18 column and a micellar mobile phase containing 0.1 M sodium dodecyl sulphate, 12%n-butanol and 0.05 M citrate buffer, pH 3. Recoveries higher than 90% were obtained by mixing the samples with a 20% 0.2 M
NaOH before extraction. Limits of detection of 51 and 6.7 ng L−1 were obtained with spectrophotometric and thermal lens spectrometric detection, respectively; respective repeatabilities
were 3.1% (5 μg mL−1) and 5.6% (0.16 μg mL−1). 相似文献
16.
17.
Summary The enantiomers of chiral carboxylic acids were separated as their diastereomeric amides with (1R,2R)-(−)-1-(4-nitrophenyl)-2-amino-1,3-propanediol
(“levobase”) and with “dextrobase” (the enantiomer of levobase) by high-performance liquid chromatography using a conventional
C-18 column and various solvent systems containing acetonitrile, methanol, water, and phosphoric acid. 相似文献
18.
We report on the effect on performance of varying the length of the capillary during throughout in-capillary derivatization (TICD) capillary electrophoresis (CE). Performance was evaluated by on-line coupling with a sample and CE runbuffer loading device that was newly introduced for this study. The device was assembled with a low cost using two 5 mm inner diameter (ID) disposable polyethylene syringes. First, a sequence was manually formed consisting of a 200 microL run buffer solution plug, a 100 microL sample plug and another 200 microL run buffer solution plug. Each plug was separated from its neighbor by a 100 microL air plug. When each plug reached the injection point where both a platinum-wire anode and the end of the separation capillary tube were located, 340 V/cm separation voltage (electrophoresis voltage) and 34 V/cm injection voltage were applied to the capillary for 3 s. Then the analytes were derivatized during migration in 50 microm ID capillaries filled with 2 mM o-phthalaldehyde (OPA)/N-acetylcysteine (NAC) in a 20 mM phosphate-borate buffer (pH 10), followed by separating and detecting of OPA derivatives by absorbance of 340 nm. Derivatization, separation, and detection were performed systematically using capillaries which varied in length from 5 to 80 cm. In the case of TICD-CE of a mixture containing 1 mM aspartic acid (Asp) and 20 mM m-nitorophenol (MNP) as a test solution, it was determined that peak area and peak width ratios of Asp to MNP did not depend on capillary length. Enantiomeric separations of DL-alanine (Ala) and Asp were examined using a run buffer consisting of a 45 microM beta-cyclodextrin (CD)-2 mM OPA/NAC-20 mM phosphate-borate buffer (pH 10). Even though the resolution of these enantiomeric pairs decreased with decreasing capillary length, as expected, the peaks corresponding to both enantiomeric amino acids were identified even when a 5 cm capillary was used. An 8-component amino acid mixture was also tested with 5 cm and 10 cm capillaries. 相似文献
19.
Kenichiro Todoroki 《Analytica chimica acta》2006,555(1):14-19
A fluorimetric liquid chromatographic method for the determination of 5-hydroxyindoles based on the benzylamine derivatization process mediated through an online photocatalytic oxidation has been developed. In this study, we used a photocatalytic column comprising tefzel tubing packed with TiO2-coated glass beads, as a pre-column derivatization reactor. The fluorescence derivatization of 5-hydroxyindoles using benzylamine proceeded during their passage through the reaction column under near-UV irradiation. The 5-hydroxyindole derivatives were separated continuously on a reversed-phase liquid chromatography within 50 min, using 100 mM acetate buffer (pH 4.6)-acetonitrile (72:28, v/v; isocratic elution) containing 3 mM sodium octanesulfonate; the samples were detected fluorimetrically at 465 nm upon excitation at 350 nm. The detection limits (signal-to-noise ratio = 3) of the 5-hydroxyindoles were in the range from 160 to 360 fmol per 5 μL injection. We have applied this method, which requires minimal sample pre-treatment, to the determination of 5-hydroxyindole-3-acetic acid in human urine. 相似文献
20.
微波衍生-离子对高效液相-磺化四苯基卟啉光度法同时测定痕量镍、铜、锰和锌 总被引:2,自引:0,他引:2
用磺化四苯基卟啉 (TPPS4 )作柱前衍生试剂 ,在微波作用下进行衍生反应 ,研究了衍生和分离Ni2 + ,Mn2 + ,Zn2 + 和Cu2 + 的最佳条件。在 75 0W的微波作用下衍生反应 3min ,在C18柱上采用乙腈 水 (体积比为 2 2 5∶77 5 )体系作流动相 ,四乙基溴化铵 (TEABr)作离子对试剂 ,在 415nm处检测 ,建立了微波衍生 离子对高效液相快速分离、光度检测Ni2 + ,Mn2 + ,Zn2 + 和Cu2 + 的新方法。络合物和反应试剂在 15min内出峰完毕。Zn2 + ,Cu2 + ,Ni2 + 和Mn2 + 的检测限分别为 0 0 5 μg/L ,0 0 1μg/L ,0 10 μg/L和 0 40 μg/L。 相似文献