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.

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.

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).

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.

Liquid-chromatographic determination of 4-aminopyridine in serum, saliva, and urine.

1981 ◽  
Vol 27 (3) ◽  
pp. 437-440 ◽  
Author(s):  
D R Uges ◽  
P Bouma
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Drug Concentrations ◽  
Liquid Chromatographic Determination ◽  
High Concentrations ◽  
Liquid Chromatographic

Abstract We have developed "high-performance" liquid-chromatographic methods for determining 4-aminopyridine, an acetylcholine-releasing drug, in serum, saliva, and urine. As little as 1 microgram/L can be detected by extracting the alkalinized sample plus the internal standard (3,4-diaminopyridine) into dichloromethane, mixing the organic phase with 1-pentanol, evaporating the dichloromethane, and injecting the residue onto a reversed-phase column, where it is eluted with acetonitrile/methanol/aqueous ammonium carbonate, with detection at 245 nm. Analytical recoveries from serum averaged 86.7%. The CV at 50 micrograms/L was 2.9% (n = 8). For urine samples containing very high concentrations of 4-aminopyridine, we mixed urine and potassium carbonate in an automatic injector vial, extracted the drug into dichloromethane, centrifuged, and injected an aliquot of the extract into the chromatograph. Analytical recoveries averaged 92%, and the CV was about 2% for drug concentrations of 0.1-8 mg/L of urine.

Liquid-chromatographic determination of pentobarbital in plasma with use of a resin column and an alkaline mobile phase.

1982 ◽  
Vol 28 (8) ◽  
pp. 1772-1774 ◽  
Author(s):  
R N Gupta ◽  
P T Smith ◽  
F Eng
Keyword(s):  
Mobile Phase ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Enhanced Sensitivity ◽  
Acidic Drugs ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a liquid-chromatographic method involving a new, nonsilica column (XAD-2, Hamilton Co.) for pentobarbital in plasma. Plasma is extracted with chloroform after addition of the internal standard, 5-ethyl-5-p-tolyl-barbituric acid. Acidic drugs are back-extracted into alkali, then chromatographed on the resin-base reversed-phase column. The use of alkaline mobile phase allows enhanced sensitivity and detection of barbiturates at 240 nm. The within-run CV for 10 samples was 1.9%, the between-run CV 1.8%. Ten commonly used barbiturates are separated isocratically in less than 15 min. Other commonly prescribed acidic drugs do not interfere with determination of pentobarbital.

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.

Simultaneous liquid-chromatographic determination of some bronchodilators, anticonvulsants, chloramphenicol, and hypnotic agents, with Chromosorb P columns used for sample preparation.

1989 ◽  
Vol 35 (8) ◽  
pp. 1615-1618 ◽  
Author(s):  
D A Svinarov ◽  
D C Dotchev
Keyword(s):  
Internal Standard ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Bioactive Metabolites ◽  
Therapeutic Drug ◽  
Simple Liquid ◽  
Analytical Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract We describe a simple liquid-chromatographic system for simultaneously measuring bronchodilators, anticonvulsants, hypnotics, and chloramphenicol. Use in therapeutic drug monitoring includes determination of theophylline, caffeine, chloramphenicol, ethosuximide, primidone, phenobarbital, phenacemide, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites within 13 min. In the "toxicology mode" theophylline, caffeine, barbital, butabarbital, pentobarbital, amobarbital, secobarbital, primidone, phenobarbital, methylprylon, glutethimide, methaqualone, phenytoin, mephenytoin, nirvanol, and carbamazepine and its bioactive metabolites are resolved within 17 min. A reversed-phase C8 column (5-microns particles) is used, with acetonitrile/water (20/80 by vol) as mobile phase. The drugs are extracted from 50 microL of serum with use of a Chromosorb P microcolumn and chloroform/isopropanol (6/1 by vol). The drugs are quantified by absorbance at 208 nm, with tolylphenobarbital as internal standard. Lower limits of detection varied from 0.05 to 0.1 mg/L, analytical recovery from 94% to 106%; CVs were less than 5.6% within run, less than 6.9% between runs.

Simultaneous liquid-chromatographic determination of prednisone and prednisolone in plasma.

1988 ◽  
Vol 34 (9) ◽  
pp. 1897-1899 ◽  
Author(s):  
M H Cheng ◽  
W Y Huang ◽  
A I Lipsey
Keyword(s):  
High Performance ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Hplc Method ◽  
Liquid Chromatographic Determination ◽  
Standard Solution ◽  
Liquid Chromatographic

Abstract This high-performance liquid-chromatographic (HPLC) method for simultaneous determination of prednisone and its metabolite, prednisolone, in plasma is a modification of the method of Frey et al. (Clin Chem 1979;25:1944-7). Heparinized plasma (1.0 mL) with 0.1 mL of internal standard solution (11-deoxy-17-hydroxycorticosterone, 2 mg/L) is extracted with 7.0 mL of dichloromethane, then washed sequentially with 0.1 mol/L HCl, 0.1 mol/L NaOH, and deionized water, 2.0 mL each. The extract is evaporated and the residue reconstituted with 75 microL of mobile phase, methanol/H2O (40/60 by vol). Thirty microliters of this is injected onto a reversed-phase C6 column, which is eluted at 1.4 mL/min. Analytical recoveries of prednisone and prednisolone were 94-98% and 102-106%, respectively. Day-to-day precision (CV) was 3.8% for prednisone, 6.1% for prednisolone. We encountered no interference from the 21 other steroids and 25 drugs tested. This method is simple, accurate, and precise.

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