scholarly journals Rapid quantification of alpha-tocopherol in plasma and low- and high-density lipoproteins

1996 ◽  
Vol 42 (3) ◽  
pp. 430-435 ◽  
Author(s):  
E Teissier ◽  
E Walters-Laporte ◽  
C Duhem ◽  
G Luc ◽  
J C Fruchart ◽  
...  
Keyword(s):  
Internal Standard ◽  
Tocopherol Content ◽  
Reversed Phase ◽  
Small Sample ◽  
Alpha Tocopherol ◽  
High Density Lipoproteins ◽  
Organic Layer ◽  
Ethanol Mixture ◽  
Assay Time

Abstract We have developed two methods for measuring the alpha-tocopherol content in plasma and lipoproteins (LDL and HDL). In procedure 1, plasma or lipoproteins are deproteinized with ethanol containing delta-tocopherol as internal standard and then extracted with hexane or ethyl acetate. The organic layer is removed and evaporated, and the residue is redissolved in methanol and injected into a reversed-phase HPLC. In procedure 2, plasma or lipoproteins are diluted in a methanol and ethanol mixture containing the same internal standard. The solution is vortex-mixed, centrifuged, and directly injected into the column. The tocopherols are eluted with an isocratic methanol mobile phase at a flow rate of 1 mL/min and detected by fluorescence (lambda(exc)= 295 nm, lambda(em)= 330nm). Recoveries are approximately 100% in both cases. Between-run CVs were 8.39% for procedure 1 and 6.55% for procedure 2. Small sample requirement, simplicity of sample preparation, short assay time, and good reproducibility make procedure 2 ideal for clinical or research use. This method was applied to determination of alpha-tocopherol in plasma of patients whose diet was supplemented with alpha-tocopherol and in LDL and HDL.

Retinol, alpha-tocopherol, lycopene, and alpha- and beta-carotene simultaneously determined in plasma by isocratic liquid chromatography.

1986 ◽  
Vol 32 (5) ◽  
pp. 874-876 ◽  
Author(s):  
D B Milne ◽  
J Botnen
Keyword(s):  
Liquid Chromatography ◽  
Internal Standard ◽  
Beta Carotene ◽  
Reversed Phase ◽  
Small Sample ◽  
Alpha Tocopherol ◽  
Organic Layer ◽  
Retinyl Acetate ◽  
Mobile Phase Flow Rate ◽  
Short Run

Abstract Retinol, alpha-tocopherol, lycopene, and alpha- and beta-carotene can be simultaneously determined in human plasma by reversed-phase liquid chromatography. Plasma--0.5 mL plus added internal standard, retinyl acetate--is deproteinized with 0.5 mL of ethanol, then extracted with 1.0 mL of petroleum ether. The organic layer is removed and evaporated, the residue is redissolved in 0.25 mL of ethanol, and 8-microL samples are injected into a 60 X 4.6 mm column of Hypersil ODS 3-microns particles at 35 degrees C. An isocratic methanol mobile phase, flow rate 0.9 mL/min, is used for the 9-min run. Retinol and retinyl acetate are monitored at 305 nm, the tocopherols at 292 nm, and the carotenoids at 460 nm. Between-run CVs were 3.1, 6.9, 6.1, and 6.5% for retinol, alpha-tocopherol, lycopene, and beta-carotene, respectively. Small sample requirement, simplicity of extraction, short run time, and good reproducibility make this procedure ideal for clinical or research use.

Determination of retinol, alpha-tocopherol, and beta-carotene in serum by liquid chromatography with absorbance and electrochemical detection.

1987 ◽  
Vol 33 (9) ◽  
pp. 1585-1592 ◽  
Author(s):  
W A MacCrehan ◽  
E Schönberger
Keyword(s):  
Electrochemical Detection ◽  
Chromatographic Separation ◽  
Protein Denaturation ◽  
Internal Standard ◽  
Beta Carotene ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Alpha Tocopherol ◽  
Phase Gradient

Abstract We describe a method for the determination of retinol, alpha-tocopherol, and beta-carotene in serum, using a liquid-chromatographic separation with wavelength-programmed ultraviolet/visible absorbance and amperometric electrochemical detection with a glassy carbon electrode. After protein denaturation and addition of an internal standard, tocol, 250-microL samples are twice extracted with hexane. The reversed-phase, gradient-elution chromatographic separation provides baseline resolution of: the all-trans isomer of retinol from the cis isomers, alpha- from gamma-tocopherol, and all-trans-beta-carotene from alpha-carotene and from cis-beta-carotene isomers. The linearity of response and the detection limits for the two detectors for the three analytes are measured. A comparison of the values obtained for serum extracts shows good agreement between the absorbance and electrochemical detectors.

Determination of vitamin E in microsamples of serum by liquid chromatography with electrochemical detection.

1985 ◽  
Vol 31 (6) ◽  
pp. 880-882 ◽  
Author(s):  
P P Chou ◽  
P K Jaynes ◽  
J L Bailey
Keyword(s):  
Liquid Chromatography ◽  
Vitamin E ◽  
Electrochemical Detection ◽  
High Performance ◽  
Internal Standard ◽  
Small Sample ◽  
Alpha Tocopherol ◽  
Tocopherol Concentration ◽  
Minimum Concentration

Abstract In this procedure for determination of vitamin E by "high-performance" liquid chromatography with electrochemical detection, 25-microL serum specimens are deproteinized with ethanol. Vitamin E (alpha-tocopherol), its derivatives (beta- and gamma-tocopherols), and the internal standard (delta-tocopherol) are extracted into heptane and the extract is evaporated and the residue reconstituted with methanol before injection into the chromatograph. Within- and between-run CVs for an alpha-tocopherol concentration of 13.6 mg/L were 5.1% (n = 28) and 6.0% (n = 5), respectively. The standard curve is linear to 100 mg/L; the minimum concentration detectable is 0.1 mg/L. Analytical recovery ranged from 99.8% to 104.8%. In 36 specimens collected from apparently healthy subjects who were not taking vitamin supplements, alpha-tocopherol as determined by this method ranged from 4.3 to 9.7 mg/L, from 1.8 to 3.9 mg/L for beta- and gamma-tocopherols. Results by this method (y) and an HPLC-ultraviolet method (x) correlate reasonably (r = 0.81): y = 0.88x - 0.55 mg/L (n = 45). This procedure is adaptable to automated analysis, and the small sample requirement facilitates its applicability to neonates.

scholarly journals Determination of Finasteride in Tablets by High Performance Liquid Chromatography

2007 ◽  
Vol 4 (1) ◽  
pp. 109-116 ◽  
Author(s):  
K. Basavaiah ◽  
B. C. Somashekar
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Calibration Graph ◽  
Official Method ◽  
Pharmaceutical Dosage Forms ◽  
Bulk Drug ◽  
Liquid Chromatographic

A rapid, highly sensitive high performance liquid chromatographic method has been developed for the determination of finasteride(FNS) in bulk drug and in tablets. FNS was eluted from a ODS C18reversed phase column at laboratory temperature (30 ± 2°C) with a mobile phase consisting of methanol and water (80+20) at a flow rate of 1 mL min-1with UV detection at 225 nm. The retention time was ∼ 6.1 min and each analysis took not more than 10 min. Quantitation was achieved by measurement of peak area without using any internal standard. Calibration graph was linear from 2.0 to 30 μg mL-1with limits of detection (LOD) and quantification (LOQ) being 0.2 and 0.6 μg mL-1, respectively. The method was validated according to the current ICH guidelines. Within-day co efficients of variation (CV) ranged from 0.31 to 0.69% and between-day CV were in the range 1.2-3.2%. Recovery of FNS from the pharmaceutical dosage forms ranged from 97.89 – 102.9 with CV of 1.41-4.13%. The developed method was compared with the official method for FNS determination in its tablet forms.

Determination of tigecycline in turkey plasma by LC-MS/MS: validation and application in a pharmacokinetic study

2017 ◽  
Vol 20 (2) ◽  
pp. 241-249 ◽  
Author(s):  
A. Jasiecka-Mikołajczyk ◽  
J.J. Jaroszewski
Keyword(s):  
Pharmacokinetic Study ◽  
High Performance ◽  
Limit Of Detection ◽  
Internal Standard ◽  
Reversed Phase ◽  
Selected Reaction Monitoring ◽  
Limit Of Quantification ◽  
Complicated Skin ◽  
Intravenous And Oral Administration

Abstract Tigecycline (TIG), a novel glycylcycline antibiotic, plays an important role in the management of complicated skin and intra-abdominal infections. The available data lack any description of a method for determination of TIG in avian plasma. In our study, a selective, accurate and reversed-phase high performance liquid chromatography-tandem mass spectrometry method was developed for the determination of TIG in turkey plasma. Sample preparation was based on protein precipitation and liquid-liquid extraction using 1,2-dichloroethane. Chromatographic separation of TIG and minocycline (internal standard, IS) was achieved on an Atlantis T3 column (150 mm × 3.0 mm, 3.0 μm) using gradient elution. The selected reaction monitoring transitions were performed at 293.60 m/z → 257.10 m/z for TIG and 458.00 m/z → 441.20 m/z for IS. The developed method was validated in terms of specificity, selectivity, linearity, lowest limit of quantification, limit of detection, precision, accuracy, matrix effect, carry-over effect, extraction recovery and stability. All parameters of the method submitted to validation met the acceptance criteria. The assay was linear over the concentration range of 0.01-100 μg/ml. This validated method was successfully applied to a TIG pharmacokinetic study in turkey after intravenous and oral administration at a dose of 10 mg/kg at various time-points.

scholarly journals The Determination of Six Ionophore Coccidiostats in Feed by Liquid Chromatography with Postcolumn Derivatisation and Spectrofotometric/Fluorescence Detection

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Małgorzata Olejnik ◽  
Piotr Jedziniak ◽  
Teresa Szprengier-Juszkiewicz
Keyword(s):  
Drug Resistance ◽  
Liquid Chromatography ◽  
Fluorescence Detection ◽  
Internal Standard ◽  
Reversed Phase ◽  
Feed Additives ◽  
Core Shell ◽  
Proficiency Tests ◽  
Reversed Phase Hplc

The control of levels of anticoccidial feed additives in targeted feeds plays an important role in the assurance of efficiency of animal treatment, prevention of drug resistance, and food safety. The robust and labour-efficient method for the simultaneous determination of six ionophore coccidiostats (lasalocid, maduramicin, monensin, narasin, salinomycin, and semduramicin) in targeted feed has been developed. Properly grinded and homogenized feed sample was spiked with internal standard (monesin methyl ester) and extracted with methanol. The extract was analysed with reversed phase HPLC without any further purification. The separation of the analytes with conventional C18 and core-shell columns was compared. Lasalocid was analysed with fluorescence detection, whereas other ionophores were detected with UV-Vis detector after derivatisation with vanillin in the presence of sulfuric acid. Fortified samples and targeted feeds at authorized levels were used for method validation. Recovery was in the range of 85–110%, depending on the analyte. The within-laboratory reproducibility did not exceed the target value from Horwitz equation. The results of the proficiency tests (z-scores in the range of −1.0 to 1.9) confirmed the reliability of the developed protocol.

Improved liquid-chromatographic determination of haloperidol in plasma.

1984 ◽  
Vol 30 (7) ◽  
pp. 1228-1230 ◽  
Author(s):  
A K Dhar ◽  
H Kutt
Keyword(s):  
Mobile Phase ◽  
High Performance ◽  
Room Temperature ◽  
Internal Standard ◽  
Isoamyl Alcohol ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract This method for determination of haloperidol in plasma is based on "high-performance" isocratic liquid chromatography with the use of a C8 bonded reversed-phase column at room temperature. Haloperidol and the internal standard (chloro-substituted analog) are extracted from alkalinized plasma into isoamyl alcohol/heptane (1.5/98.5 by vol) and back-extracted into dilute H2SO4. The aqueous phase is directly injected onto the column. The mobile phase is a 30/45/25 (by vol) mixture of phosphate buffer (16.5 mmol/L, pH 7.0), acetonitrile, and methanol. Unlike other liquid-chromatographic procedures for haloperidol, commonly used psychotropic drugs do not interfere. Analysis can be completed within an hour. The procedure is extremely sensitive (1.0 microgram/L) and is well reproducible (CV 5.6% for a 2.5 micrograms/L concentration in plasma).

Determination of 8-methoxypsoralen in suction-blister fluid and serum by liquid chromatography.

1980 ◽  
Vol 26 (13) ◽  
pp. 1825-1828 ◽  
Author(s):  
M J Herfst ◽  
P M Edelbroek ◽  
F A de Wolff
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Reversed Phase ◽  
Pharmacokinetic Studies ◽  
Blister Fluid ◽  
Liquid Chromatograph ◽  
Suction Blister ◽  
Drug Concentrations ◽  
Suction Blister Fluid

Abstract A method is described for determination of 8-methoxypsoralen to 0.2 mL of suction-blister fluid or 1 mL of serum from psoriatic patients being treated with this drug. The drug is extracted from the biological matrix at pH 9.0 with a mixture of dichloromethane and light petroleum ether. 5-Methoxypsoralen is used as internal standard. Separation and quantitation are performed on a “high-performance” liquid chromatograph with use of an RP 18 reversed-phase column and detection at 245 nm. Accuracy and precision are good. Some benzodiazepines and their metabolites interfere. The lowest detectable concentration is 10 microgram/L, which means that the method is sufficiently sensitive to measure the drug concentrations in serum and suction-blister fluid for pharmacokinetic studies in patients being treated with a therapeutic dosage.

Determination of urinary normetanephrine and metanephrine by radial-compression liquid chromatography and electrochemical detection.

1983 ◽  
Vol 29 (2) ◽  
pp. 305-309 ◽  
Author(s):  
P J Orsulak ◽  
P Kizuka ◽  
E Grab ◽  
J J Schildkraut
Keyword(s):  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
Depressive Disorders ◽  
Internal Standard ◽  
Normal Subjects ◽  
Reversed Phase ◽  
Radial Compression ◽  
Ion Pair Chromatography ◽  
Catecholamine Metabolites

Abstract A procedure has been developed for determining the O-methylated catecholamine metabolites, normetanephrine and metanephrine, in urine by use of radial-compression liquid chromatography followed by electrochemical detection. Normetanephrine and metanephrine are isolated from hydrolyzed urine by ion-exchange on small, commercially available, disposable columns and preconcentrated by solvent extraction. They are then separated by reversed-phase ion-pair chromatography, with use of a radial compression cartridge and radial compression module, and quantified with 3-methoxy-4-hydroxybenzylamine as internal standard. Normetanephrine, metanephrine, and the internal standard are separated from interfering peaks in about 15 min. The method is applicable to the relatively low amounts of normetanephrine (100-600 micrograms/24 h) and metanephrine (50-400 micrograms/24 h) found in normal subjects and patients with depressive disorders or hypertension. Within-day CVs ranged from 1.1 to 2.2% for normetanephrine and 1.2 to 6.9% for metanephrine; the corresponding between-day CVs were 4.9 and 5.7% over these ranges.

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