scholarly journals A Rapid HPLC Method for Monitoring Plasma Levels of Caffeine and Theophylline Using Solid Phase Extraction Columns

1986 ◽  
Vol 23 (4) ◽  
pp. 440-446 ◽  
Author(s):  
Clare E Pickard ◽  
A D Stewart ◽  
R Hartley ◽  
M D Lucock
Keyword(s):  
Acetic Acid ◽  
Sample Preparation ◽  
Solid Phase Extraction ◽  
Mobile Phase ◽  
Solid Phase ◽  
Hplc Method ◽  
Phase Extraction ◽  
The Cost ◽  
Good Agreement

A simple HPLC method for the determination of caffeine and theophylline in plasma is described. Separation of theobromine, paraxanthine, theophylline, β-hydroxyethyltheophylline and caffeine is obtained using a mobile phase of 1% acetic acid/methanol (83:17, v/v) and a Waters Associates NOVA-PAK C18 column protected by a Guard-PAK precolumn module containing a Guard-PAK CN cartridge. Rapid sample preparation is achieved by solid-phase extraction columns (Bond-Elut C18, 1 mL capacity) which provide excellent recovery values for both drugs. The cost per sample using this approach can be minimised by column regeneration and re-use. Results obtained for theophylline are in good agreement with values determined by other techniques.

scholarly journals HPLC determination of hydrochlorothiazide in urine after solid-phase extraction

2005 ◽  
Vol 51 ◽  
pp. 23-28 ◽  
Author(s):  
Violeta Ivanova ◽  
Dragica Zendelovska ◽  
Marina Stefova
Keyword(s):  
Particle Size ◽  
Solid Phase Extraction ◽  
Mobile Phase ◽  
Solid Phase ◽  
Hplc Method ◽  
Phase Extraction ◽  
Hplc Separation ◽  
Isocratic Elution ◽  
Extraction Recovery

A simple, rapid and precise HPLC method has been developed for the assay of hydrochlorothiazide in urine. The clean-up of the urine samples was carried out by solid-phase extraction using HLB cartridges. Extraction recovery was 94.00-100.28 %. HPLC separation was performed with isocratic elution on Hypersil BDS C18 column (100 x 4.0 mm I.D., 3 µm particle size) protected with appropriate guard column. The mobile phase was 18 % acetonitrile and 0.025 mol/L solution of KH2PO4, pH 4 at flow rate of 0.3 mL/min. Detection of the substances was performed at 220 nm. The calibration curves were linear in the range of 2-50 µg/mL. The developed method is validated by checking its accuracy, precision and stability. The detection limit is 2 µg/mL hydrochlorothiazide. The method is proved to be convenient for routine analysis of hydrochlorothiazide in urine.

scholarly journals Determination of urinary free cortisol by HPLC

1997 ◽  
Vol 43 (8) ◽  
pp. 1386-1391 ◽  
Author(s):  
Ursula Turpeinen ◽  
Helene Markkanen ◽  
Matti Välimäki ◽  
Ulf-Håkan Stenman
Keyword(s):  
Solid Phase Extraction ◽  
Mobile Phase ◽  
Solid Phase ◽  
Internal Standard ◽  
Reversed Phase ◽  
Hplc Method ◽  
Extraction Column ◽  
Phase Extraction ◽  
Free Cortisol

Abstract We here report a reversed-phase HPLC method for the determination of free cortisol in human urine, using methylprednisolone as the internal standard. Before chromatography, samples were extracted with a C18 solid-phase extraction column and the steroids were separated on a LiChrospher 100 C18 column with a mobile phase of methanol/acetonitrile/water (43/3/54 by vol). Linearity, precision, and accuracy of the method were established. The detection limit was 10 pmol of cortisol, and total CVs were <8%. With various solid-phase extraction columns the recovery of cortisol was 36–97%; recovery of the internal standard was 43–85%. Study of interference by 6 other steroids and metabolites and 24 drugs showed that carbamazepine and digoxin partly overlapped with cortisol, but this interference could be reduced by modification of the mobile phase. The HPLC method was compared with an RIA and an automated immunoassay method. The results obtained by HPLC averaged 40% of the RIA values.

Recent Trends in the Development of Green Microextraction Techniques for the Determination of Hazardous Organic Compounds in Wine

2019 ◽  
Vol 15 (7) ◽  
pp. 788-800 ◽  
Author(s):  
Natasa P. Kalogiouri ◽  
Victoria F. Samanidou
Keyword(s):  
Sample Preparation ◽  
Solid Phase Extraction ◽  
Organic Compounds ◽  
Method Development ◽  
Solid Phase ◽  
Stir Bar Sorptive Extraction ◽  
Phase Extraction ◽  
Microextraction Techniques ◽  
Hazardous Organic Compounds

Background:The sample preparation is the most crucial step in the analytical method development. Taking this into account, it is easily understood why the domain of sample preparation prior to detection is rapidly developing. Following the modern trends towards the automation, miniaturization, simplification and minimization of organic solvents and sample volumes, green microextraction techniques witness rapid growth in the field of food quality and safety. In a globalized market, it is essential to face the consumers need and develop analytical methods that guarantee the quality of food products and beverages. The strive for the accurate determination of organic hazards in a famous and appreciated alcoholic beverage like wine has necessitated the development of microextraction techniques.Objective:The objective of this review is to summarize all the recent microextraction methodologies, including solid phase extraction (SPE), solid phase microextraction (SPME), liquid-phase microextraction (LPME), dispersive liquid-liquid microextraction (DLLME), stir bar sorptive extraction (SBSE), matrix solid-phase dispersion (MSPD), single-drop microextraction (SDME) and dispersive solid phase extraction (DSPE) that were developed for the determination of hazardous organic compounds (pesticides, mycotoxins, colorants, biogenic amines, off-flavors) in wine. The analytical performance of the techniques is evaluated and their advantages and limitations are discussed.Conclusion:An extensive investigation of these techniques remains vital through the development of novel strategies and the implication of new materials that could upgrade the selectivity for the extraction of target analytes.

scholarly journals Development and validation of a bioanalytical LC-UV method with solid-phase extraction for determination of valproic acid in saliva

2012 ◽  
Vol 62 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Jasmina Tonic-Ribarska ◽  
Arlinda Haxhiu ◽  
Zoran Sterjev ◽  
Gordana Kiteva ◽  
Ljubica Suturkova ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Human Saliva ◽  
Hplc Method ◽  
Therapeutic Monitoring ◽  
Phase Extraction ◽  
Free Drug Concentration ◽  
Development And Validation

Development and validation of a bioanalytical LC-UV method with solid-phase extraction for determination of valproic acid in saliva A bioanalytical HPLC method with UV detection for the determination of the antiepileptic drug valproic acid in human saliva has been developed and validated. Saliva represents an alternative matrix for therapeutic monitoring of antiepileptic drugs due to the increasing interest in free drug concentration. The proposed method involved solid-phase extraction for sample preparation and yielded very good mean recoveries of 99.4 % and 97.9 % for valproic acid and IS, respectively. The calibration function for valproic acid was linear over the concentration range of 1.0-50.0 μg mL-1 (R2 = 0.9989). Within-run and between-run precision and accuracy were studied at four concentrations and RSDs were less than 7.3 and 2.2 %, while accuracy values were higher than 96.8 and 97.5 %, respectively. The described method provides sensitivity, linearity, precision, accuracy and is suitable for analyses of valproic acid in saliva samples.

scholarly journals Determination of dimethoate, 2,4-dichlorophenoxy acetic acid, mecoprop and linuron pesticides in environmental waters in Republic of Macedonia by high performance liquid chromatography

2008 ◽  
Vol 27 (1) ◽  
pp. 25 ◽  
Author(s):  
Aleksandra Nestorovska-Krsteska ◽  
Meri Mirčeska ◽  
Jean-Jacques Aaron ◽  
Zoran Zdravkovski
Keyword(s):  
Acetic Acid ◽  
Solid Phase Extraction ◽  
High Performance ◽  
Solid Phase ◽  
Sampling Period ◽  
Phase Extraction ◽  
Environmental Waters ◽  
Spe Method ◽  
Dichlorophenoxy Acetic Acid

An HPLC-UVDAD method for determination of dimethoate, 2,4-dichlorophenoxy acetic acid (2,4-D), mecoprop (MCPP) and linuron in environmental waters was developed. The water samples were concentrated and extracted by a solid phase extraction (SPE) method on Bond Elut PPL cartridges. After extraction the investigated compounds were separated on Stability RP Pesticides chromatographic column using mobile phase composed of acetonitrile- water-acetic acid in volume fractions of 39:59:2 and flow rate of 0.7 mL/min. Ultraviolet absorption detection was carried out for dimethoate, 2,4-D and MCPP at 229 nm, and for linuron at 249 nm. Recoveries made from 500 mL of drinking waters using solid phase extraction ranged between 64.3–92.1 %. The method was applied to environmental waters in Macedonia that receive runoffs from agriculture lands. The levels of pesticides under study ranged between 0.31 μg/L and 7.05 μg/L, depending on the compound and sampling period.

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