Concurrent liquid-chromatographic assay of retinol, alpha-tocopherol, beta-carotene, alpha-carotene, lycopene, and beta-cryptoxanthin in plasma, with tocopherol acetate as internal standard.

1988 ◽  
Vol 34 (2) ◽  
pp. 377-381 ◽  
Author(s):  
D I Thurnham ◽  
E Smith ◽  
P S Flora
Keyword(s):  
Quality Control ◽  
Mobile Phase ◽  
Sodium Dodecyl ◽  
Internal Standard ◽  
Beta Carotene ◽  
Alpha Tocopherol ◽  
Organic Layer ◽  
Tocopherol Acetate ◽  
Liquid Chromatographic ◽  
Control Samples

Abstract A method is described for simultaneously determining retinol, alpha-tocopherol, beta-carotene, alpha-carotene, lycopene, and beta-cryptoxanthin in 0.25 mL of plasma. Plasma mixed with sodium dodecyl sulfate is deproteinized with ethanol containing tocopherol acetate, then extracted with heptane. The evaporated organic layer is reconstituted with mobile phase (methanol/acetonitrile/chloroform, 47/47/6 by vol) and injected onto a 100 x 4.6 mm 3-micron column of Spherisorb ODS-2 (LKB) at 1.5 mL/min. The alpha- and beta-carotenes are well resolved during the 6.5-min run. Retinol is monitored at 325 nm, the tocopherols at 292 nm, and the carotenoids at 450 nm. Extraction of concentrations as great as 135 mumol/L is complete. Intrabatch CVs were 1.7%, 2.3%, 4.1%, 10.4%, 6.4%, and 3.6% for retinol, alpha-tocopherol, beta-carotene, alpha-carotene, lycopene, and beta-cryptoxanthin, respectively. Interbatch CVs for measurements on 30 occasions over 11 weeks were about 10% for all components except alpha-tocopherol (5.3%). Results agree well with those for retinol, alpha-tocopherol, and beta-carotene in quality-control samples.

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.

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).

scholarly journals Determination of Fleroxacin in Pure and Tablet Forms by Liquid Chromatography and Derivative UV-Spectrophotometry

2003 ◽  
Vol 86 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Dorota Kowalczuk ◽  
Hanna Hopkała
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Spectrophotometric Assay ◽  
Uv Spectrophotometry ◽  
Aminobenzoic Acid ◽  
Tetrabutylammonium Hydroxide ◽  
Relative Standard ◽  
Liquid Chromatographic ◽  
Derivative Uv Spectrophotometry

Abstract Derivative UV-spectrophotometric and liquid chromatographic (LC) methods for fleroxacin determination were validated. In the spectrophotometric assay, first-, second-, third-, and fourth-order measurements were applied with the use of peak–zero and peak–peak techniques. The linear correlation between amplitude of the peak and concentration of the examined drug ranged from 2.0 to 12.0 μg/mL. An isocratic LC analysis was performed on a Purospher ODS column with an acidic mobile phase containing tetrabutylammonium hydroxide. Measurements were made at a wavelength of 285 nm with 4-aminobenzoic acid (PABA) as internal standard. The calibration curve was linear (r = 0.9999) in the studied range of concentration (1.0–10.0 μg/mL). The accuracy (mean recovery, about 100%), precision (relative standard deviation <1%), selectivity, and sensitivity of the elaborated methods were satisfactory.

Liquid Chromatographic Determination of Carbofuran in Technical and Formulated Products: Collaborative Study

1986 ◽  
Vol 69 (5) ◽  
pp. 915-918
Author(s):  
Edward J Kikta ◽  
◽  
E Bane ◽  
A Burns ◽  
A Christensen ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Collaborative Study ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Data Sets ◽  
Matched Pairs ◽  
Reverse Phase ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method for the analysis of technical and formulated carbofuran samples was evaluated in a collaborative study. Carbofuran is determined by reverse phase LC, using a water-methanol mobile phase and acetophenone as internal standard, and detected at 280 nm. Twelve samples, 5 formulations and technical matched pairs, were analyzed by 17 collaborating laboratories. Accuracy and variability of results are typical of large LC data sets. The method has been adopted official first action.

Determination of Cymiazole Residues in Honey by Liquid Chromatography

1993 ◽  
Vol 76 (1) ◽  
pp. 92-94 ◽  
Author(s):  
Paolo Cabras ◽  
Marinella Melis ◽  
Lorenzo Spanedda
Keyword(s):  
Liquid Chromatography ◽  
Chromatographic Analysis ◽  
Mobile Phase ◽  
Chromatographic Method ◽  
Reversed Phase ◽  
Limit Of Determination ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic ◽  
Control Samples

Abstract A liquid chromatographic method is described for the determination of cymiazole residues in honey. This acaricide is determined on a reversed-phase (C18) column, with a CH3CN-O.OOIN HCI-NaCI mixture (950 mL + 50 mL + 0.3 g/L) as the mobile phase, and UV detection at 265 nm. Cymiazole is extracted with n-hexane from aqueous alkalinized (pH 9) honey solutions. No further cleanup of the honey extract was required before chromatographic analysis. Recoveries on control samples fortified with 0.01,0.10, and 1.00 ppm cymiazole ranged from 92 to 102%. The limit of determination was 0.01 ppm.

Improved liquid-chromatographic assay of labetalol in plasma.

1987 ◽  
Vol 33 (8) ◽  
pp. 1450-1452 ◽  
Author(s):  
D R Luke ◽  
G R Matzke ◽  
J T Clarkson ◽  
W M Awni
Keyword(s):  
High Performance Liquid Chromatography ◽  
Mobile Phase ◽  
High Performance ◽  
Internal Standard ◽  
Excitation Wavelength ◽  
Plasma Samples ◽  
Standard Curve ◽  
Low Concentrations ◽  
Styrene Divinylbenzene ◽  
Liquid Chromatographic

Abstract This is an assay for labetalol in plasma by "high-performance" liquid chromatography, with 5-(2-[4-(4-chlorophenyl)ethyl]) salicylamide hemihydrate as the internal standard. Plasma samples (500 microL) are extracted with acetonitrile, evaporated under nitrogen, reconstituted in the mobile phase, and injected onto a PRP-1 (Hamilton) column packed with particles of poly(styrene-divinylbenzene) copolymer. Fluorescence, enhanced by post-column introduction of NH4OH, was measured in the effluent (excitation wavelength 340 nm, emission wavelength 418 nm). Retention times for labetalol and the internal standard were 1.99 and 3.32 min, respectively. Inter- and intraday CVs for high and low concentrations of the drug were less than 7.5%. The assay standard curve is linear from 1 to 250 micrograms/L. Some commonly co-administered drugs were tested and did not interfere.

scholarly journals Micellar Liquid Chromatographic Determination of Carbaryl and 1-Naphthol in Water, Soil, and Vegetables

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Mei-Liang Chin-Chen ◽  
Maria Rambla-Alegre ◽  
Abhilasha Durgbanshi ◽  
Devasish Bose ◽  
Sandeep K. Mourya ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Limit Of Detection ◽  
Cetylpyridinium Chloride ◽  
Sodium Dodecyl ◽  
Chromatographic Determination ◽  
Limit Of Quantification ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250’mm’ × ’4.6’mm) with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333’nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS), Brij-35 andN-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15’M SDS-6% (v/v)-pentanol-0.01’M NaH2PO4buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r>0.999), limit of detection (5 and 18’ng mL-1, for carbaryl and 1-naphthol, resp.), and limit of quantification (15 and 50’ng mL-1, for carbaryl and 1-naphthol, resp.), with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples.

Simultaneous liquid-chromatographic determination of three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine.

1980 ◽  
Vol 26 (2) ◽  
pp. 197-200
Author(s):  
J G Flood ◽  
G N Bowers ◽  
R B McComb
Keyword(s):  
Mobile Phase ◽  
Antiarrhythmic Drugs ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Peak Height ◽  
Reversed Phase ◽  
Multiple Drug ◽  
Evaporation Technique ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We report a common methodology for determining three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine. Alkalinized serum and internal standard (p-chlorodisopyramide) are extracted into dichloromethane, the organic phase is evaporated, and the redissolved residue is injected onto a reversed-phase column (micron Bondapack C18). Quantitation is via peak-height ratios of analyte vs internal standard (as detected at 205 nm) referenced to a serum-based multiple-drug standard. A mobile phase of 30 mmol/L phosphate buffer and acetonitrile (72/28 by vol) is used. These conditions yiel; optimum separation and band symmetry for the analytes and some of their metabolites. Crucial factors in this simultaneous assay include pH of the mobile phase and injected solution, extraction time, and evaporation technique. Day-to-day precision (CV) for all drugs was less than 5%, and correlation with other assay techniques for each drug is reported. The method enables more efficient use of personnel and instrumentation without sacrificing analytical quality.

scholarly journals Simultaneous liquid-chromatographic determination of three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine.

1980 ◽  
Vol 26 (2) ◽  
pp. 197-200 ◽  
Author(s):  
J G Flood ◽  
G N Bowers ◽  
R B McComb
Keyword(s):  
Mobile Phase ◽  
Antiarrhythmic Drugs ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Peak Height ◽  
Reversed Phase ◽  
Multiple Drug ◽  
Evaporation Technique ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We report a common methodology for determining three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine. Alkalinized serum and internal standard (p-chlorodisopyramide) are extracted into dichloromethane, the organic phase is evaporated, and the redissolved residue is injected onto a reversed-phase column (micron Bondapack C18). Quantitation is via peak-height ratios of analyte vs internal standard (as detected at 205 nm) referenced to a serum-based multiple-drug standard. A mobile phase of 30 mmol/L phosphate buffer and acetonitrile (72/28 by vol) is used. These conditions yiel; optimum separation and band symmetry for the analytes and some of their metabolites. Crucial factors in this simultaneous assay include pH of the mobile phase and injected solution, extraction time, and evaporation technique. Day-to-day precision (CV) for all drugs was less than 5%, and correlation with other assay techniques for each drug is reported. The method enables more efficient use of personnel and instrumentation without sacrificing analytical quality.

Impurity Problems in Chromatographic Method Studies for Fenthion Formulations

1985 ◽  
Vol 68 (5) ◽  
pp. 925-929
Author(s):  
Willard G Boyd
Keyword(s):  
Mobile Phase ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Internal Standard ◽  
Flame Ionization Detection ◽  
Private Communication ◽  
Flame Ionization ◽  
Glass Column ◽  
Liquid Chromatographic ◽  
Chromatographic Mass

Abstract Several gas chromatographic (GC) methods for analyzing fenthion were studied, and flame ionization detection, a glass column packed with SE-52 on Chromosorb GHP, and on-column injection were selected as parameters. No suitable internal standard was found because of coeluting, bias-producing impurities in fenthion. Several liquid chromatographic (LC) methods were also studied, and UV detection, a Zorbax ODS column, and a methanol-water-H3P04 mobile phase were finally selected as parameters. Dipentyl phthalate was selected as internal standard. After testing, this LC method was submitted for collaborative study. During the collaborative study, the manufacturer found an impurity, 3-methyl-4-(methylthio)anisole, co-eluting with fenthion in the collaborative method. The manufacturer's method was then evaluated as an alternative for collaborative study, but a significant unidentified impurity from the formulation blank, used for formulating emulsifiable concentrates, was also found co-eluting with fenthion. The anisole impurity was verified by LC, and the presence of the S-isomer and bis-methylthio-fenthion impurities was found by gas chromatographic- mass spectrometric (GC-MS) analyses. An anisole material obtained from Mobay was also verified by GC-MS analysis. Several other impurities were identified from literature references and from private communication with the manufacturer.

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