Improved sample preparation in determination of urinary metanephrines by liquid chromatography with electrochemical detection

1990 ◽  
Vol 36 (3) ◽  
pp. 538-540 ◽  
Author(s):  
R N Gupta
Keyword(s):  
Liquid Chromatography ◽  
Sample Preparation ◽  
Mobile Phase ◽  
Sodium Acetate ◽  
Simple Procedure ◽  
Internal Standard ◽  
Boiling Water Bath ◽  
Reduced Pressure ◽  
Urinary Metanephrines

Abstract In this relatively simple procedure for extracting metanephrines from urine, after an internal standard (4-hydroxy-3-methoxybenzylamine in 1 mmol/L HCl) is added, the sample is hydrolyzed in a boiling water bath, then treated with ammonia and alumina. Excess ammonia is removed under reduced pressure and the sample is applied to a 1-mL Bond Elut SCX column, which is washed, and metanephrines and internal standard are eluted with 0.5 mmol/L sodium acetate/acetonitrile (3/1 by vol). Of this elute, 5 microL is injected into a 15 cm x 4.6 mm (i.d.) column packed with 5-microns octadecylsilyl silica particles, which is eluted with a mobile phase containing tetramethylammonium perchlorate. Peaks are detected coulometrically at +0.28 V. In the resulting chromatogram, metanephrines give sharp peaks, well resolved from peaks for solvent and internal standard. There are no extraneous peaks for catechols or mono-oxygenated phenylethylamines. Results correlated well (r = 0.999, n = 13) with those by earlier described liquid-chromatography.

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.

scholarly journals Simultaneous Determination of Levocetirizine and Pseudoephedrine in Dog Plasma by Liquid Chromatography-Mass Spectrometry in the Presence of Dextrocetirizine

2012 ◽  
Vol 15 (4) ◽  
pp. 519 ◽  
Author(s):  
Jae Kuk Ryu ◽  
Sun Dong Yoo
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Oral Administration ◽  
Mobile Phase ◽  
Internal Standard ◽  
Liquid Chromatography Mass Spectrometry ◽  
Chiral Column ◽  
Accuracy And Precision ◽  
Dog Plasma

Purpose. This study describes the development of a rapid and sensitive LC-ESI-MS assay for simultaneous enantioselective determination of levocetirizine and pseudoephedrine in dog plasma in the presence of dextrocetirizine. Methods. Separations were achieved on an Ultron ES-OVM chiral column using the mobile phase consisting of 10 mM aqueous NH4OAc (pH 6.6) and acetonitrile (9:1 v/v). Results. The retention times of pseudoephedrine, dextrocetirizine, levocetirizine and diazepam (internal standard) were 5.2, 8.3, 9.6 and 11.6 min, respectively, and the total run time was less than 15 min. The assay was validated to demonstrate the linearity, accuracy and precision, recovery and stability. The calibration curves were linear over the concentration range from 1 – 200 ng/mL for levocetirizine and from 5 – 1000 ng/mL for pseudoephedrine. Conclusions. The developed assay was successfully applied to a pharmacokinetic study after oral administration of the racemic cetirizine (0.5 mg/kg, or 0.25 mg/kg as levocetirizine) and pseudoephedrine (12 mg/kg) in the dog. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Capillary Gas Chromatographic Determination of Thiabendazole in Citrus and Apple Juices

1994 ◽  
Vol 77 (5) ◽  
pp. 1293-1296 ◽  
Author(s):  
Mitsuo Oishi ◽  
Kazuo Onishi ◽  
Itsu Kano ◽  
Hiroyuki Nakazawa ◽  
Shinzo Tanabe
Keyword(s):  
Limit Of Detection ◽  
Simple Procedure ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Fruit Juices ◽  
Reduced Pressure ◽  
Standard Solution ◽  
Juice Sample ◽  
Nitrogen Phosphorus

Abstract A rapid and simple procedure for the determination of thiabendazole (TBZ) residue in citrus and apple juices is described. A juice sample is made basic with 2M NaOH and applied to a disposable Extrelut prepacked column. TBZ is eluted with hexane–ethyl acetate (3 + 1) from the column. The eluate is evaporated to dryness under reduced pressure and then dissolved in an internal standard solution. TBZ is monitored without derivatization by capillary gas chromatography with nitrogen-phosphorus detection. The recoveries of TBZ added to fruit juices at 0.05-1.0 μg/g were 90-96%. The limit of detection of the method for TBZ was 0.01 μg/g. The proposed method is rapid, simple, and sensitive and is applicable to the determination of TBZ in commercial fruit juices.

A NOVEL VALIDATED ANALYTICAL METHOD FOR THE ESTIMATION OF MIDODRINE HYDROCHLORIDE IN PHARMACEUTICAL FORMULATION BY LC-MS/MS

INDIAN DRUGS ◽  
2020 ◽  
Vol 57 (02) ◽  
pp. 41-44
Author(s):  
Narenderan S.T. ◽  
◽  
Meyyanathan S.N. ◽  
Babu B. ◽  
Karthik Y.
Keyword(s):  
Regression Analysis ◽  
Liquid Chromatography ◽  
Present Method ◽  
Mobile Phase ◽  
Internal Standard ◽  
Tandem Mass ◽  
Ich Guidelines ◽  
Liquid Chromatography Tandem Mass ◽  
Tandem Mass Spectroscopy

A novel simple, precise, accurate and validated, liquid chromatography-tandem mass spectroscopy method has been developed for the quantitative determination of midodrine hydrochloride from a commercially available formulation. Caffeine was used as the internal standard. Isocratic separation was achieved using jones C18 column (4.6 x 150mm, 3μm) as a stationary phase and the mobile phase consistsed of 10mM ammonium formate (pH 4.0): methanol (30:70 v/v) with a flow of 0.5 ml/min. Detection was carried out in positive ionization with a mass transitions of 255→237.1 and 195→138.1 to monitor Midodrine hydrochloride and caffeine. The method was found to be linear over a concentration range of 0.30 – 110 ng/ml with a regression analysis of 0.9991. The percentage recovery in the present method was found to be 99.5 ± 1.20. The LC-MS/MS method was validated as per ICH guidelines.

A Novel LC-MS Method for the Determination of Abiraterone in Rat Plasma and its Application to Pharmacokinetic Studies

2021 ◽  
Vol 17 ◽  
Author(s):  
Linzhi Dai ◽  
Pei Lv ◽  
Yun He ◽  
Xiaoli Wang ◽  
Lili Chen ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
High Performance ◽  
Analytical Procedure ◽  
Internal Standard ◽  
Rat Plasma ◽  
Pharmacokinetic Studies ◽  
Quadrupole Mass ◽  
Limit Of Quantitation

Background: High–performance liquid chromatography (HPLC)–ultraviolet (UV) and liquid chromatography (LC)–mass spectrometry (MS)/MS methods have been used to analyse abiraterone (ART); however, a single-quadrupole mass spectrometer with LC-MS systems has never been used to analyse ART. Objective: The study aimed to establish a novel, simple assay of quantitating ART in rat plasma through LC–MS. Method: The analytical procedure involved the extraction of ART and D4-ART (internal standard, IS) from rat plasma through simple protein precipitation. Chromatographic separation was achieved using an isocratic mobile phase (acetonitrile: 5 mM ammonium formate with 0.1% formic acid, 50:50 v/v) at a flow rate of 0.30 mL/min on a Waters XBridge® C18 column with a total run time of 5 min. LC–MS ion transitions monitored were 350.1 and 354.1 for ART and IS, respectively. The method was validated, and the results met acceptance criteria. Results: The lower limit of quantitation achieved was 1 ng/mL, and linearity was 1–8000 ng/mL. The intra- and inter-day precisions were 1.26%–14.20% and 5.49%–13.08%, respectively, in rat plasma.

Simultaneous Determination of Xylazine and Its Major Metabolite, 2,6-Dimethylaniline, in Bovine and Swine Kidney by Liquid Chromatography

1993 ◽  
Vol 76 (4) ◽  
pp. 720-724 ◽  
Author(s):  
David C Holland ◽  
Robert K Munns ◽  
José E Roybal ◽  
Jeffrey A Hurlbut ◽  
Austin R Long
Keyword(s):  
Acetic Acid ◽  
Liquid Chromatography ◽  
Simultaneous Determination ◽  
Mobile Phase ◽  
Sodium Acetate ◽  
Major Metabolite ◽  
Bovine Kidney ◽  
Liquid Chromatographic ◽  
Swine Kidney

Abstract A liquid chromatographic (LC) method is described for the simultaneous determination of xylazine (XY) and its major metabolite, 2,6-dimethylaniline (2,6- DMA), in bovine and swine kidney in the 25– 100 ppb range. XY and 2,6-DMA are extracted from kidney with chloroform, followed by cleanup on an acidic Celite 545 column. A μBondapak phenyl column is used for LC separation with UV determination at 225 nm. The mobile phase is a mixture of acetonitrile, water, sodium acetate, and acetic acid. Mean recoveries from bovine kidney were 78.3% for XY, with a standard deviation (SD) of 7.45 and a coefficient of variation (CV) of 9.51 %, and 87.2% for 2,6-DMA, with an SD of 8.38 and a CV of 9.61 %. Mean recoveries from swine kidney were 80.8% for XY, with an SD of 5.92 and a CV of 7.33%, and 86.7% for 2,6-DMA, with an SD of 6.16 and a CV of 7.10%.

scholarly journals Determination of Methomyl in Insecticidal Formulations by Reversed-Phase Liquid Chromatography: Collaborative Study

1996 ◽  
Vol 79 (4) ◽  
pp. 941-948
Author(s):  
James E Conaway ◽  
J B Audino ◽  
E Bane ◽  
S K Carrigan ◽  
R Glinsky ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Coefficient Of Variation ◽  
Mobile Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Reversed Phase ◽  
Reversed Phase Liquid Chromatography ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A reversed-phase liquid chromatographic (LC) method for methomyl was studied. Twelve collaborators analyzed 3 solid and 4 liquid formulations on both a Zorbax octadecylsilane (ODS) column and a similar column of their choice. Methomyl and the internal standard were separated by using a mobile phase consisting of approximately 8% acetonitrile in water, which was monitored at 254 nm. The coefficient of variation on the Zorbax column ranged from 0.70 to 5.23%, while the range on the collaborators' house columns was 1.08 to 6.01%. Results with the Zorbax ODS column fell within the 5% 2-tail limits, and 10 of 11 collaborators' results fell within these limits on house columns. The LC method for determination of methomyl in insecticidal formulations has been adopted first action by AOAC INTERNATIONAL.

Simultaneous Assay for Six Alkaloids in Opium, Using High-Performance Liquid Chromatography

1975 ◽  
Vol 58 (5) ◽  
pp. 888-897
Author(s):  
Howard W Ziegler ◽  
Thomas H Beasley ◽  
David W Smith
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Internal Standard ◽  
Dilute Acid ◽  
Reduced Pressure ◽  
Double Beam ◽  
Flow Through ◽  
Chloroform Methanol

Abstract A method is described for the quantitative determination of morphine, codeine, cryptopine, thebaine, papaverine, and narcotine in opium by high-performance liquid chromatography. The alkaloids are isolated from a dilute acid extract by adsorption on an Amberlite XAD-2 resin column and eluted first with methanol and then with chloroform-methanol ( 3+1 ) . After solvent removal by reduced pressure evaporation, the alkaloids are redissolved in chloroformmethanol ( 3+1 ) . The sample solution, plus brucine as an internal standard, is injected onto a Corasil II column and eluted with hexane that is gradient programmed with a solution of chloroform-methanol-diethylamine ( 100+300+1). The absorbances of the separated alkaloids are continuously monitored at 254 nm, using a flow-through ultraviolet double-beam photometer.

scholarly journals Determination of Ceftriaxone in Cerebrospinal Fluid by Ion-Pair Liquid Chromatography

2005 ◽  
Vol 88 (2) ◽  
pp. 436-439 ◽  
Author(s):  
Marta de Diego Glaría ◽  
Gloria Godoy Moscciati ◽  
Ricardo Godoy Ramos
Keyword(s):  
Cerebrospinal Fluid ◽  
Liquid Chromatography ◽  
Mobile Phase ◽  
Tetrabutylammonium Bromide ◽  
Internal Standard ◽  
Ion Pair ◽  
Deionized Water ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic

Abstract An ion-pair liquid chromatographic assay was developed and validated for the determination of ceftriaxone in cerebrospinal fluid. Chromatographic separation was achieved on a C18 column (125 × 4 mm, 5 μm) with detection at 270 nm, a 1 mL/min flow rate and a 50 μL loop. The mobile phase consisted of 300 mL acetonitrile, 50 mL 0.1M phosphate buffer (pH 7.4), 3.2 g tetrabutylammonium bromide as the ion-pairing agent, and dilution with distilled deionized water to 1 L. Cephradine was used as the internal standard. The assay was linear for ceftriaxone concentrations of 0.5–50 μg/mL. The coefficients of variation for precision were <4.61%. The accuracy ranged from 96.07 to 102.42%. The detection and quantitation limits were 0.019 and 0.065 μg/mL, respectively. This method was used to quantify ceftriaxone in the cerebrospinal fluid of children with meningitis. The results showed that the method described here is useful for the determination of ceftriaxone in cerebrospinal fluid.

Determination of bethanidine in plasma by liquid-chromatography with a microbore reversed-phase column.

1983 ◽  
Vol 29 (10) ◽  
pp. 1793-1795 ◽  
Author(s):  
J R Shipe ◽  
A F Arlinghaus ◽  
J Savory ◽  
M R Wills ◽  
J P DiMarco
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Ultraviolet Absorbance ◽  
Standard Curve ◽  
Novel Method ◽  
Phase Column ◽  
Reversed Phase Column

Abstract In this novel method for quantifying bethanidine in plasma, after a multi-step extraction of bethanidine and internal standard from 2.0 mL of plasma, the drugs are separated on a "microbore" C18 reversed-phase column and quantified by their ultraviolet absorbance at 210 nm. The isocratic chromatographic separation takes about 15 min with use of an ion-pairing regent in the mobile phase (acetate buffer/acetonitrile, 9/1 by vol) and a flow rate of 0.25 mL/min. Sensitivity is increased relative to conventional columns, and solvent consumption is reduced by 90%. The standard curve is linear to at least 5 mg/L, and the detection limit is 0.02 mg/L. The within-run precision of the method is excellent (CV 4%) at a midrange concentration of 1.25 mg/L.

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