Improved liquid-chromatographic determination of caffeine in plasma.

1980 ◽  
Vol 26 (9) ◽  
pp. 1351-1354 ◽  
Author(s):  
J Blanchard ◽  
J D Mohammadi ◽  
K A Conrad
Keyword(s):  
Plasma Sample ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Small Sample ◽  
Small Animals ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Reversed Phase Column

Abstract We describe a rapid, specific, and sensitive liquid-chromatographic micro-method for caffeine in plasma. Each plasma sample can be assayed within about 15 min of its receipt. Samples are denatured with acetonitrile, centrifuged, and the supernate is chromatographed on a reversed-phase column. Only 100 microL of plasma is required, and concentrations as low as 0.3 mg/L can be measured accurately. Other xanthines and their metabolites do not interfere. The small sample required makes the procedure ideally suited for measuring caffeine in the plasma of infants and small animals as well as adults.

Improved liquid-chromatographic determination of 3-methoxy-4-hydroxyphenylethyleneglycol in urine with electrochemical detection.

1984 ◽  
Vol 30 (1) ◽  
pp. 140-143 ◽  
Author(s):  
J R Shipe ◽  
J Savory ◽  
M R Wills
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Improved Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Mean Concentration ◽  
Phase Column

Abstract In this improved method for quantifying 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in urine, after a multistep extraction of MHPG and internal standard (iso-MHPG) from 3.0 mL of urine, the compounds are separated on a C18 reversed-phase column and quantified by use of an electro-chemical detector. The isocratic chromatographic separation takes about 16 min. The mobile phase is phosphate buffer/acetonitrile (88/12 by vol), the flow rate 0.7 mL/min. Recycling the mobile phase and automating the sample injection make possible the unattended assay of more than 70 samples per day. The within-run precision of the method is excellent (CV 1.8%) at a mean concentration of 1.1 mg/L.

scholarly journals Liquid Chromatographic Determination of Patulin in French Apple Ciders

1996 ◽  
Vol 79 (5) ◽  
pp. 1107-1110 ◽  
Author(s):  
Marie P Herry ◽  
Nicole Lemétayer
Keyword(s):  
Chromatographic Determination ◽  
Reversed Phase ◽  
Calibration Graph ◽  
Apple Cider ◽  
Quantitation Limit ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Elution Gradient ◽  
Phase Column

Abstract A liquid chromatographic (LC) method was developed for detection and quantitation of patulin in French apple ciders. Cider was applied to an Extrelut column; patulin was extracted with ethyl acetate- toluene, and the extract was cleaned up on a Sep-Pak Florisil cartridge. Patulin was detected with a UV photometer at 275 nm. A reversed-phase column and an elution gradient were used for LC separation. Patulin recoveries at 3 levels ranged from 90.4 to 91.7%. Repeatability at 50 and 100 ppb levels did not exceed 15%. The calibration graph was rectilinear from 0.2 to 1 μg/mL patulin working solutions corresponding to 20-100 ppb patulin in sample. The quantitation limit was 10 ppb. The method represents an improvement in selectivity for determination of patulin in a specific matrix such as French apple cider.

Liquid-chromatographic determination of nadolol in plasma.

1983 ◽  
Vol 29 (6) ◽  
pp. 1085-1087 ◽  
Author(s):  
R N Gupta ◽  
R B Haynes ◽  
A G Logan ◽  
L A Macdonald ◽  
R Pickersgill ◽  
...  
Keyword(s):  
Plasma Sample ◽  
Antihypertensive Drugs ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Standard Curve ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a liquid-chromatographic procedure for determining nadolol in plasma. After an analog of nadolol is added as internal standard, the plasma sample is passed through a disposable BondElut C18 column. After several column washes, nadolol and the internal standard are eluted with methanol, and the eluate is evaporated and reconstituted with the mobile phase (acetonitrile/water, perchloric acid, and tetramethylammonium hydroxide). An aliquot of the extract is chromatographed on a non-silica resin-base reversed-phase column. The peaks are detected by fluorescence (lambda ex = 265 nm and lambda em = 305). Drug and internal standard are well resolved, and only a few extraneous peaks appear. The standard curve ranges from 10 to 400 micrograms/L. We are using this procedure to determine steady-state concentrations of nadolol in patients receiving various dosages of nadolol along with other types of antihypertensive drugs.

Liquid-chromatographic determination of penbutolol and its principal metabolites in plasma and urine.

1984 ◽  
Vol 30 (5) ◽  
pp. 717-723 ◽  
Author(s):  
D J Miner ◽  
D A Binkley ◽  
L D Bechtol
Keyword(s):  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Enzymic Hydrolysis ◽  
Organic Extraction ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Phase Column ◽  
Hydroxy Metabolite

Abstract We describe a sensitive, specific liquid-chromatographic determination of penbutolol and its 4-hydroxy metabolite in plasma and urine. The method involves a simple organic extraction, evaporation of the solvent, reconstitution in methanol/water, and injection into the chromatograph. Penbutolol, its metabolites, and the internal standard, propranolol, are resolved on a CN reversed-phase column and detected fluorometrically. Conjugates of penbutolol and its 4-hydroxy metabolite may be determined after a 2-h enzymic hydrolysis. Detection limits are in the range of 3 to 12 micrograms/L of plasma. The assay is reproducible and nearly free of interferences. Representative concentrations in blood and urine of normal volunteers are reported.

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