A conductivity detector for liquid chromatography with a cell volume of 0.1 μl

1983 ◽  
Vol 48 (4) ◽  
pp. 1129-1136 ◽  
Author(s):  
Danuše Kouřilová ◽  
Karel Šlais ◽  
Miloš Krejčí
Keyword(s):  
Liquid Chromatography ◽  
Organic Acids ◽  
Cell Volume ◽  
Mobile Phase ◽  
Linear Range ◽  
Phase System ◽  
Reverse Phase ◽  
Micropacked Columns ◽  
A Cell ◽  
Inner Diameter

A conductivity detector with a cell volume of 0.1 μl has been devised to fit glass micropacked columns with an inner diameter of 0.5 mm. D.c. current was used in the measurements, the voltage applied to the electrodes was 30 V. Organic acids separated in a reverse-phase system were detected; the minimum detectable concentrations were 6 . 10-7 - 1 . 10-5 mol l-1 according to the acid concerned and the composition of the mobile phase. The linear range of the detector is 400.

Screening Method for Vitamins A and D in Fortified Skim Milk, Chocolate Milk, and Vitamin D Liquid Concentrates

1979 ◽  
Vol 62 (6) ◽  
pp. 1358-1360
Author(s):  
Susan K Henderson ◽  
Lucia A Mclean
Keyword(s):  
Vitamin D ◽  
High Pressure ◽  
Liquid Chromatography ◽  
Vitamin A ◽  
Mobile Phase ◽  
Screening Method ◽  
Skim Milk ◽  
Chocolate Milk ◽  
Reverse Phase ◽  
Milk Chocolate

Abstract Vitamin A was determined in fortified chocolate milk and skim milk; vitamin D was determined in fortified chocolate milk, skim milk, and vitamin D concentrates, using reverse phase high pressure liquid chromatography (HPLC). The sample is saponified, extracted with hexane, and chromatographed in an HPLC system on a 10 μm Vydac TP reverse phase C18 column, using acetonitrile-methanol (9+1) as the mobile phase. For 6 replicates, the recoveries of vitamins A and D, using this procedure, were 99 and 98%, respectively.

Liquid Chromatography with Amperometric Detection for Determining Phenolic Preservatives

1980 ◽  
Vol 63 (1) ◽  
pp. 137-142 ◽  
Author(s):  
William P King ◽  
Kuriakose T Joseph ◽  
Peter T Kissinger
Keyword(s):  
Liquid Chromatography ◽  
Propyl Gallate ◽  
Amperometric Detection ◽  
Nordihydroguaiaretic Acid ◽  
Phenolic Antioxidants ◽  
Phase System ◽  
Reverse Phase ◽  
Tert Butyl ◽  
Sensitive Method

Abstract Liquid chromatography with amperometric detection is a rapid and sensitive method for determining commonly encountered phenolic antioxidants including 3(2)-tert-butyl-4-hydroxyanisole, tert-butylhydroquinone, n-propyl gallate, nordihydroguaiaretic acid, and 2,6-di-tert-butyl-4-hydroxymethylphenol (Ionox-100), and the antimicrobial parabens, in a variety of commercial products. Sample extracts are chromatographed directly with few interferences on the reverse phase system. The typical linear range extends from 10−11 to 10−6 mole of injected analyte. Pertinent experimental factors are discussed with regard to the requirements of the detector and optimizing the determination of this class of compounds

scholarly journals DEVELOPMENT AND VALIDATION OF STABILITY-INDICATING REVERSE-PHASE HIGHPERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR THE SIMULTANEOUS QUANTIFICATION OF POTENTIAL DEGRADATION PRODUCTS OF REGADENOSON FROM ITS PARENTERAL DOSAGE FORM

2018 ◽  
Vol 11 (8) ◽  
pp. 277
Author(s):  
Murlidhar V Zope ◽  
Rahul M Patel ◽  
Ashwinikumari Patel ◽  
Samir G Patel
Keyword(s):  
Liquid Chromatography ◽  
Degradation Product ◽  
Mobile Phase ◽  
Dosage Form ◽  
Degradation Products ◽  
Reverse Phase ◽  
Chromatography Method ◽  
Stability Indicating ◽  
Liquid Chromatography Method ◽  
Injectable Dosage

Objective: The objective was to develop and validate the stability indicating reverse-phase high-performance liquid chromatography method for the quantification of potential degradation products of regadenoson (REGA) from its injectable dosage form.Methods: YMC-PAK ODS AQ, 150 mm × 4.6 mm, 3 μm composed with hydrophobic high carbon loading and a relatively hydrophilic surface chemically bonded to porous silica particles column was used with the temperature maintained at 40°C. Mobile phase A composed of 0.1% triethylamine buffer having pH 4.5 while mobile phase B is 100 % acetonitrile was used for gradient elution with 1.5 ml/min as a flow rate. The wavelength used for quantification was 245 nm and 20 μl as an injection volume. The suitability of the method has been checked and validated according to the International Council for Harmonization (ICH) guidelines for different parameters, namely, specificity, linearity, accuracy, precision, limit of quantification (LOQ), Limit of detection (LOQ), and robustness studies.Results: The resolution between REGA and its two-degradation product is >8.0 for all pairs of components. The high correlation coefficient (r2>0.990) values are for drug and all potential degradation products from LOQ to 150% of specification limits for impurities calculated based on the maximum daily dose of REGA. LOQ for the drug as well as each degradation product is <0.02% w/w. The % relative standard deviation (RSD) for precision and intermediate precision is in the range of 0.17–0.89, and % RSD for precision at LOQ is 0.86–2.35. The % RSD for robustness study is maximum 2.59.Conclusion: The developed method can quantify the specified and unknown degradation products from 0.1% in the injectable dosage form which indicates that method is sensitive. Method fulfills the ICH criteria for its different validation parameters and demonstrates that the developed analytical method is highly specific, precise, and robust and would have a great value when applied in quality control and stability studies for REGA injection.

Determination of Seven Artificial Sweeteners in Diet Food Preparations by Reverse-Phase Liquid Chromatography with Absorbance Detection

1988 ◽  
Vol 71 (5) ◽  
pp. 934-937 ◽  
Author(s):  
James F Lawrence ◽  
Claudette F Charbonneau
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Sorbic Acid ◽  
Artificial Sweeteners ◽  
Reverse Phase ◽  
Phase Gradient ◽  
Reverse Phase Liquid Chromatography ◽  
Absorbance Detection ◽  
Phase Liquid

Abstract The artificial sweeteners aspartame, saccharin, cyclamate, alitame, acesulfam-K, sucralose, and dulcin are determined in diet soft drinks and tabletop sweetener preparations. Samples are diluted, filtered, and analyzed directly by liquid chromatography on a C-18 reversephase column with a mobile phase gradient ranging from 3% acetonitrile in 0.02M KH2P04 (pH 5) to 20% acetonitrile in 0.02M KH2P04 (pH 3.5). Diet puddings and dessert toppings are extracted with ethanol, filtered, and diluted with mobile phase for analysis. The sweeteners, except sucralose and cyclamate, were detected by UV absorbance at either 200 or 210 nm. Sucralose was determined at 200 nm or by refractive index. Cyclamate was determined after post-column ion-pair extraction. The sweeteners stevioside and talin were not detected. Additives such as caffeine, sorbic acid, and benzoic acid did not interfere.

A Simple Procedure for the Determination of Carbamazepine in Plasma by High Pressure-Liquid Chromatography

1979 ◽  
Vol 16 (1-6) ◽  
pp. 213-216 ◽  
Author(s):  
C. K. Johnston ◽  
G. H. Lester
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Mobile Phase ◽  
Simple Procedure ◽  
Internal Standard ◽  
Reverse Phase ◽  
Coefficients Of Variation ◽  
Initial Results

We describe a simple, rapid procedure for the estimation of carbamazepine in plasma. Protein is precipitated, and extraction is achieved by the addition of acetonitrile containing the internal standard N-acetyltryptophan ethyl ester. Separation is by reverse-phase high-pressure liquid chromatography with an acetonitrile: water mobile phase, and detection is by UV absorption at 280 nm. Total retention time is less than 7 minutes. Initial results gave within-batch and between-batch coefficients of variation of less than 2 %, and mean recovery of 97 %. The method is free from interference by other common anticonvulsant drugs.

Preparation of short glass microbore columns for liquid chromatography and their properties

1984 ◽  
Vol 49 (4) ◽  
pp. 764-771 ◽  
Author(s):  
Danuše Kouřilová ◽  
Karel Šlais ◽  
Miloš Krejčí
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Linear Part ◽  
Theoretical Plate ◽  
Outer Diameter ◽  
Column Length ◽  
Microbore Columns ◽  
Inner Diameter ◽  
Glass Columns ◽  
Short Glass

The preparation is described of thick-walled glass columns, inner diameter 0.5 mm and outer diameter 4.5 mm, packed with Separon SI C 18 (dp = 6 and 10 μm) from suspension under pressures of 20-35 MPa in the presence of an ionogenic detergent; the column length ranged from 5 to 30 cm. The minimum value of the height equivalent to a theoretical plate was Hmin = 2.8 - 3.3dp. The effect of the extra-column contributions to the dispersion on the slope of the linear part of the dependence of the height equivalent to a theoretical plate on the mobile phase velocity was examined and found to become significant at higher velocities, thereby imposing limitations on the shortening of the time of analysis.

Sulfated Polyborate, a novel buffer for low pH mobile phase on a non-end capped stationary phase in reverse phase liquid chromatography

2021 ◽  
Vol 08 ◽  
Author(s):  
Purushottam Sutar ◽  
Pravin Khedkar ◽  
Ganesh Chaturbhuj
Keyword(s):  
Liquid Chromatography ◽  
Stationary Phase ◽  
Mobile Phase ◽  
Basic Drugs ◽  
Buffer Concentration ◽  
Organic Modifier ◽  
Reverse Phase ◽  
Sulfated Polyborate ◽  
Reverse Phase Liquid Chromatography ◽  
Phase Liquid

Background: Sulfated Polyborate, a novel inorganic material primarily designed as a catalyst, has shown properties such as high solubility in organic solvents, low U.V. cut-off, and pKa ≈2.0, which suggests its potential as a mobile phase buffer for reverse-phase liquid chromatography. Objective: This study aims to substantiate the role of Sulfated Polyborate as mobile phase buffer for reverse-phase liquid chromatographic analysis of basic drugs with high pKa values viz. Bisoprolol fumarate, Timolol maleate, Verapamil hydrochloride, and Carvedilol. Methods: Solubilities, U.V. cut-offs, and pKa of Sulfated Polyborate was first experimentally confirmed. The behaviour of Sulfated Polyborate as mobile phase buffer at pH 3.0 was ascertained by varying the buffer concentration, flow rates, and percent organic modifier for elution of the four basic drugs on a non-end capped octyl silyl (C8) column. Similarly, the study was performed with KH2PO4 as a reference buffer. The column performance and conductometric measurements ascertained the impact of Sulfated Polyborate on the stationary phase. Results: Sulfated Polyborate and KH2PO4 buffers showed correlation coefficients of 0.99 and 1.00 for analyte retention factors for variation of buffer concentration and organic modifier composition, respectively. Peak symmetries and the number of theoretical plates were improved from > 2.0 to < 2.0 and ≈1000 to ≈3000, respectively, for Variation in buffer concentrations. Similar Van Deemter plots indicated equivalency of Sulfated Polyborate and KH2PO4 buffers. The column performance and conductometric measurements depicted no adsorption on the stationary phase. Conclusion: The present study demonstrates Sulfated Polyborate as a novel buffer for analytes with higher pKa on reverse-phase liquid chromatography.

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