Determination of cefcanel in plasma and urine by high-performance liquid chromatography using coupled columns, after administration of the new cephalosporin prodrug cefcanel daloxate hydrochloride.

A rapid and sensitive high-performance liquid chromatographic method has been developed for the determination in plasma and urine of the new cephalosporin cefcanel. The method involves a simple deproteinizing step followed by separation on a coupled-column chromatographic system with ultraviolet detection. Limits of quantification were 0.2 microM for plasma samples and 2 microM for urine samples. The method has been used for the determination of cefcanel in various clinical studies.     

Determination of ampicillin in biological fluids by coupled-column liquid chromatography and post-column derivatization

A rapid and sensitive high-performance liquid chromatographic method has been developed for the determination of ampicillin in plasma and urine. The method involves a simple deproteinization step and separation on a coupled-column chromatographic system followed by post-column derivatization and fluorescence detection. The method has been used for the determination of ampicillin in various clinical studies. The high sensitivity makes it especially useful for small sample volumes, e.g. samples from pediatric patients.     

Determination of alpidem and its metabolites in human plasma by high-performance liquid chromatography and fluorimetric detection

A high-performance liquid chromatographic method has been developed for the simultaneous determination of alpidem and its metabolites in human plasma. The method involved a single extraction of the parent drug and metabolites into diethyl ether from alkalinized plasma, evaporation of the organic solution and chromatography of the extracts on a C18 column coupled to a fluorimetric detector. An internal standard was used for the quantitative determination of the compounds. The method was selective for alpidem and three of its metabolites and has a limit of detection of less than 1 ng ml-1 for all the compounds. Since the chromatographic run took more than 20 min, the chromatographic process was fully automated and performed overnight.     

离子色谱法测定青霉素残渣中砷的研究

对离子色谱法测定砷及其淋洗条件进行了考察，排除了大量无机阴离子对砷测定的干扰，并应用该法于青霉素残渣中Ａｓ（Ⅴ）的测定。结果表明该法的分离度、重现性、线性响应方面均满足定量分析要求，结果令人满意。     

Quality Control of Industrial Fluorinated Inorganic Acids by Ion Chromatography

A simple ion chromatographic method has been applied to the determination of anionic impurities chloride, bromide, nitrate, and sulfate in hexafluorotitanic acid and hexafluorozirconic acid samples. Industrial samples analyzed may contain high levels of fluorinated species at pH values lower than 1.0, which represents a handicap for the instrumental analysis of these matrixes. Up to now, these samples have been analyzed by chemical methods, which have interferences, involving detection of the final point in chloride determination by volumetry and coprecipitation in sulfate determination by gravimetry. The optimization of the method was carried out using industrial samples. In order to obtain the best chromatographic resolution, the dilution factor of the samples, flow rate, and eluent concentration were studied using isocratic elution. The ion chromatographic method was suitable for the determination of anionic impurities in acidic matrixes, except for chloride in hexafluorozirconic acid. The analytes were separated in hexafluorotitanic acid and hexafluorozirconic acid, without using any sample treatment apart from dilution, with good linearity with correlation coefficients higher than 0.99 and inter- and intra-day repeatability lower than 15 percent, expressed in terms of the relative standard deviation.     

Determination of procaine and tetracaine in plasma samples by micellar liquid chromatography and direct injection of sample

Summary A liquid chromatographic procedure is proposed for the determination of procaine and tetracaine in plasma samples with direct injection. The method uses a Spherisorb octadecylsilane ODS-2 C₁₈ analytical column and a micellar mobile phase containing 0.15 M sodium dodecyl sulphate, 0.5% triethylamine at pH 2.5 and 10% propanol. The UV detection was carried out at 300 nm. Plasma sample preparation required only adequate dilution with the mobile phase before injection into the chromatographic system. The proposed method allows the determination of procaine and tetracaine in plasma at therapeutic levels.     

Monitoring and control of industrial downstream processing of sugar beet molasses

In present work the determination of several amino acids during the industrial chromatographic desugarisation of molasses is presented. The use of innovative biosensor systems for highly specific detection of serine is described. Using two-dimensional fluorescence spectrometry, a non-invasive method for the determination of several product fractions could be established in an industrial chromatographic procedure.     

三元重叠色谱峰面积的定量方法

本从色谱峰的ＥＭＧ模型出发，通过对重叠色谱峰的模拟和回归分析，提出了一种三元重叠色谱峰的面积的定量方法，三元重叠色谱峰的每一个峰面积可以由峰面积比和总面积求得，此法所需的数据都由实验色谱图上测得，峰面积计算结果的相对误差小于±５％，适用于相对峰谷为５０％－９５％的三元重叠色谱峰面积的定量。     

How to count strong adsorption sites by gas chromatography?

Summary A simple gas chromatographic method is presented for the determination of the quantity of the strongest adsorption sites on an adsorbent's surface. The method consists of the blockage of the sites with quasi-irreversibly adsorbed, known amount of a strongly interacting compound and subsequent measuring of the retention of a hydrocarbon during the presence of the blocking compound in the column. Heterogeneity of chromatographic grade silicas is investigated with this method.     

Automatic determination of urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid by liquid chromatography with electrochemical detection

An automated liquid chromatographic method for the determination of urinary concentrations of 4-hydroxy-3-methoxymandelic acid (VMA) is described. Urine samples are purified by solid-phase extraction on an anion-exchange cartridge and automated on-line chromatographic elution is carried out using a Varian AASP (advanced automated sample processor) system. The column effluent is monitored with an electrochemical detector using a glassy carbon working electrode. The method allows the determination of VMA in 0.05 ml of normal urine with a relative standard deviation of less than 3%. The analysis time can be shortened by use of back-flushing technique, and the correlation with a classical (but non-automated) VMA analysis method is excellent.     

Baclofen impurities: Facile synthesis and novel environmentally benign chromatographic method for their simultaneous determination in baclofen

An efficient, economic and high yielding method was described for the synthesis of baclofen (BAC) pharmacopoeial impurities (impurity A and impurity B) which can be used for gram‐scale synthesis. Furthermore, a novel ecofriendly thin‐layer chromatographic TLC–densitometric method was established and validated for the determination of BAC and its synthesized impurities. The developed TLC–densitometric method is based on the chromatographic separation using TLC plates (60 F₂₅₄) using a green mobile phase of ethyl acetate–methanol–ammonia solution, 33% (8:2:0.1, by volume) with UV scanning at 220 nm. The proposed method was validated with respect to International Conference on Harmonization guidelines. The validated method was successfully applied for determination of BAC in pure form and in its commercial dosage form. Additionally, the greenness profile of the developed method was evaluated and compared with those of the reported chromatographic methods. The developed method was found to be superior to the published methods, being environmentally benign.     

HPLC Determination of Chloramphenicol,Chloramphenicol Monosuccinate and Chloramphenicol Glucuronide in Biological Matrices

Abstract

An isocratic reversed-phase liquid chromatographic method for the determination of chloramphenicol 1- and 3-succinate and chloramphenicol in serum within 5 minutes following precipitation with perchloric acid is described. An ion-pair chromatographic method gives the additional option of co-determination of chloramphenicol 3-glucuronide in urine and serum. An extraction method for the determination of chloramphenicol in biological tissues is presented.     

Simultaneous determination of methylxanthines in different types of tea by a newly developed and validated TLC method

The aim of this paper is to develop a new simple, fast and economical method for simultaneous quantitative determination of methylxanthine compounds based on TLC combined with image analysis. To obtain certain results, both extraction and chromatographic separation were optimized. The optimum extraction conditions were maceration in ethanol-water 8:2, v/v. The chromatographic separations were done on the silica gel F(254) TLC plates developed with chloroform-dichloromethane-isopropanol, 4:2:1 v/v/v. Detection was performed under UV lamp at 254?nm and the evaluation of the chromatographic plate was based on digital processing of chromatographic images. The developed TLC method was validated for parameters such as specificity, linearity and range, LOD and LOQ, precision, robustness and accuracy. This method was then applied for determination of caffeine, theobromine and theophylline in different types of tea, commercially available. Moreover, the content of methylxanthines detected and determined in commercial tea samples can be used as chemical marker in quality control.     

Peak purity determination with principal component analysis of high-performance liquid chromatography-diode array detection data

A method is proposed for the determination of chromatographic peak purity by means of principal component analysis (PCA) of high-performance liquid chromatography with diode array detection (HPLC-DAD) data. The method is exemplified with analysis of binary mixtures of lidocaine and prilocaine with different levels of separation. Lidocaine and prilocaine have very similar spectra and the chromatograms used had substantial peak overlap. The samples analysed contained a constant amount of lidocaine and a minor amount of prilocaine (0.02-2 conc.%) and hence the focus was on determining the purity of the lidocaine peak in the presence of much smaller levels of prilocaine. The peak purity determination was made by examination of relative observation residuals, scores and loadings from the PCA decomposition of DAD data over a chromatographic peak. As a reference method, the functions for peak purity analysis in the chromatographic data system used (Chromeleon) were applied. The PCA method showed good results at the same level as the detection limit of baseline-separated prilocaine, outperforming the methods in Chromeleon by a factor of ten. There is a discussion of the interpretation of the result, with some comparisons with evolving factor analysis (EFA). The main advantage of the PCA method for determination of peak purity over methods like EFA lies in its simplicity, short time of calculation and ease of use.     

A rapid method for direct quantitative analysis on chromatographic layers

Summary A rapid method is described for direct quantitative determination on the chromatographic layer. The method is based on the measurement of the length of the chromatographic band in the direction of flow.     

Separation and determination of pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection

A method for rapid and simultaneous determination of multiple pyrrolidinium ionic liquid cations by ion chromatography with direct conductivity detection was developed.Chromatographic separations were performed on a cation exchange column using ethylenediamine-acetonitrile as the mobile phase.The effects of chromatographic column and the mobile phase,as well as the column temperature on the retention of the cations were investigated.The retention rules of the cations under different chromatographic conditions were formulated.The retention of the cations followed the carbon number rule.The method has been successfully applied to the determination of three ionic liquids synthesized by a chemical laboratory.     

Determination of pesticide residues in red wines with microporous membrane liquid–liquid extraction and gas chromatography

A sample pretreatment method based on microporous membrane liquid-liquid extraction (MMLLE) was developed for the subsequent gas chromatographic determination of pesticides in wine. MMLLE provided efficient and selective extraction with enrichment factors in the range 3-13. The gas chromatographic separation was carried out using on-column injection and flame ionization detection. The method was linear, repeatable and sensitive. The limits of quantification were better than 0.006 mg/L for all the analytes except for iprodione (0.37 mg/L). The method was applied to the determination of pesticides in several red wines of different origin.     

Quantitative determination of acemetacin and its metabolite indometacin in blood and plasma by column liquid chromatography

A column liquid chromatographic (LC) method using UV detection for the determination of acemetacin and its metabolite indometacin in blood is described. The lower detection limit for both compounds is ca. 25 micrograms/l, the precision (coefficient of variation) is 6% for acemetacin and 10% for indometacin. The method is also suited for determination of both compounds in plasma, precisions in this case are even better than for blood, i.e. around 3% for both acemetacin and indometacin. Blood samples of three volunteers who had received 90 mg of acemetacin orally were analysed using the new method and very good agreement with results from a thin-layer chromatographic/fluorescence method was found.     

Quantitative analysis of disulfiram and its metabolites in human blood by gas-liquid chromatography.

A simple method is described that permits the direct quantitative determination of carbon disulphide, free diethyldithiocarbamate and disulphides derived from disulfiram in 1 ml of a patient's blood. It is based on a gas chromatographic determination of carbon disulphide produced from diethyldithiocarbamate and disulfiram using the head-space technique and a flame-photometric detector. The method is compared with a recently described spectrophotometric method.     

The uncertainty in the calculation of the amount of blocked and reactive lysine in milk products,as determined by the furosine method

The measurement uncertainty in the calculation of the amount of blocked and reactive lysine (as determined by the furosine method) was evaluated according to the procedure described in the Eurachem/CITAC guide. The analytical method involves the chromatographic determination of lysine and furosine after acid hydrolysis. The calculation of blocked and reactive lysine in the initial protein is based on known conversion factors. The estimation of the uncertainty was performed in two steps: (1) determination of the uncertainty in the chromatographic determination of lysine and furosine, and (2) determination of the uncertainty in the calculation of blocked and reactive lysine. The individual contributions to the final uncertainty were identified, quantified, and combined in uncertainty budgets. The largest contribution to the calculation of blocked lysine came from estimating the conversion factor of blocked lysine into furosine during acid hydrolysis. For the calculation of reactive lysine, the main contribution came from the chromatographic determination of lysine. The uncertainty estimates were compared to available validation data (in-house and collaborative standard deviations of reproducibility).