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F L Vandemark

Publications and source records attributed to F L Vandemark.

10 recordsLinked to original sources
PubMed1978

Determination of polyamines by liquid chromatography and precolumn labelling for fluorescence detection.

Procedures are described for the separation and detection of picomole quantities of putrescine, spermidine, and spermine by liquid chromatography. The polyamines are labelled by precolumn derivatization with dansyl chloride followed by reversed-phase chromatography with a methanol and water mobile phase. The derivatized polyamines are measured with a fluorescence detector using an excitation wavelength of 340 nm and emission wavelength of 515 nm. The polyamines are eluted within 12 min and 0.5 ng of each could be detected. Some preliminary data on urine samples is presented.

Chromatography, Liquid↗
PubMed1978

A micro liquid column chromatography procedure for twelve anticonvulsants and some of their metabolites.

Solvent extracts of 50 microliter volumes of serum were sufficient for the determination of twelve anticonvulsant drugs. The liquid chromatography procedure utilized a C-18 reversed-phase column and isocratic elution with 15% acetonitrile in water. No derivatization was required. Eluted anticonvulsants were detected by UV absorption at 195 nm and quantitated by drug--internal standard peak area ratios. The procedure provided linear working curves over the concentration range from 1 to 100 mg/l of drug in the serum. The procedure for serum provided recoveries of the drugs from 92 to 101%. Within-day precision was about 4% and day-to-day precision was about 6.5%. The procedures has been applied to urine samples to facilitate bioavailability studies. Data are also given for several metabolites. There is a discussion of many practical aspects of the procedure to improve the reliability of the results.

Anticonvulsants↗
PubMed1978

Estrogen determination using liquid chromatography with precolumn fluorescence labeling.

A liquid chromatography procedure is described for the determination of some estrogens using fluorescence detection. The estrogens are labeled by precolumn derivatization with 5-dimethylaminonaphthalene-1-sulfonylchloride (dansyl chloride) and chromatographed on a reversed-phase, C-18 column with a mobile phase consisting of methanol, water, and acetic acid. The eluted analytes are measured with a fluorescence detector using excitation and emission wavelengths of 350 and 540 nm, respectively. The chief advantage of this new procedure is its sensitivity, requiring smaller amounts of sample to detect and quantitate estrogens in biological materials. We could detect less than 400 pg of estriol. With our procedure, this corresponded to about 25 ng in the final reaction mixture, before derivatization. The use of smaller sample volumes could improve this limit. Linearity for dansylated estriol, estrone, and estradiol was excellent over the estrogen range below 100 micrograms in the sample. This corresponds to approximately 1.7 micrograms on the column. Within-run precision was better than 5% for the full extraction and derivatization procedure for estriol from pregnancy urine samples. Chromatography is complete within 10 min for dansylated estriol, estrone, and estradiol.

Chromatography, Liquid↗
PubMed1978

Liquid-chromatographic procedure for tricyclic drugs and their metabolites in plasma.

We describe a procedure for determining amitriptyline and imipramine and their active metabolites nortriptyline and desipramine, respectively, at therapeutic concentrations in human plasma by use of liquid chromatography. The drugs are extracted at pH 10.5 into hexane/isoamyl alcohol, which is evaporated and the residue chromatographed. Protriptyline is used as the internal standard. As little as 10 microgram of each drug per liter could be detected in plasma, the limit being established by variability in drug-free plasmas. The day-to-day coefficient of variation for each drug at a concentration of about 100 microgram/liter was about 7%. Doxepin and diphenhydramine interfere with the analysis of amitriptyline. Total analysis time for a single sample is 20 min.

Amitriptyline↗
PubMed1977

Ultramicro GC determination of amino acids using glass open tubular columns and a nitrogen-selective detector.

A glass open tubular (capillary) column together with a nitrogen-selective detector were evaluated for the analysis of amino acids by gas chromatography. Test samples included normal and abnormal human sera and urine and several hydrolysates of pure proteins. Amino acids in the biological samples were isolated by ion exchange pretreatment and derivatized to the n-propyl, N-acetyl derivatives. Protein hydrolysates were derivatized without pretreatment. Compared with a flame ionization detector, the nitrogen-selective detector gave a sensitivity enhancement of 80x-180x for the amino acid derivatives, depending on the particular amino acid. Long-term stability of the detector was excellent. Reproducibility studies gave a long-term precision of about 6% for serum or urine samples while a precision of 5% was obtainable on a day-to-day basis when analyzing protein hydrolyzates. The experiments showed that amino acids at the picomole level could be reliably analyzed with the system. The open tubular column coated with a mixture of Carbowax 20M and Silar 5 CP and having a very thin liquid phase film gave greatly improved thermal stability compared with a previously used packed column.

Amino Acids↗
PubMed1976

The simultaneous determination of lidocaine and procainamide in serum by use of high pressure liquid chromatography.

This report describes an accurate, sensitive rapid procedure for the determination of lidocaine and procainamide at therapeutic concentrations in serum. The drugs and an added internal standard (procaine) are extracted from serum using charcoal adsorption. The analysis is carried out by high pressure liquid chromatography on a reverse-phase column using buffered aqueous acetonitrile as the mobile phase. Chromatography is complete in 10 min. C.V. values of 10% and 6% for concentrations of 1 mg/l and 20 mg/l, respectively, are attainable routinely. Total analysis time is 15 min.

Chromatography, High Pressure Liquid↗
PubMed1976

Ultramicro gas-chromatographic analysis for anticonvulsants, with use of a nitrogen-selective detector.

We describe a procedure for determining phenobarbital, primidone, and diphenylhydantoin simultaneously in 50-mul volumes of serum by use of gas chromatography and a detector with heightened sensitivity and selectivity for nitrogenous compounds. The drugs, together with an internal standard, 5-allyl-5-phenyl barbituric acid, are extracted from serum by the procedure of MacGee [Anal. Chem. 42, 421 (1970)]. The drugs are converted to their methyl derivatives by a modification of the procedure of Greeley [Clin. Chem. 20, 192 (1974)] and then analyzed on a column containing 3% OV-1, with a temperature program, and detected by a nitrogen-selective detector. The method is reproducible to about 7%. Sensitivities of 0.5 mg/liter for 50-mul serum samples are attained routinely. Mephobarbital interferes with the analysis because methylation yields the same product as methylated phenobarbital. Total analysis time for a single sample is 15 min.

Chromatography, Gas↗
PubMed1976

Simultaneous high-pressure liquid-chromatographic determination of some anticonvulsants in serum.

We describe procedures for simultaneously determining some anticonvulsants (phenobarbital, diphenylhydantoin, primidone, ethosuximide, methsuximide, carbamazepine) in serum by high-pressure liquid chromatography. The drugs, together with an internal standard, phenacetin, are adsorbed from serum onto charcoal and eluted from it with organic solvent. The eluate is analyzed isocratically on a reverse-phase column with a mobile phase consisting of acetonitrile/water (17/83 by volume). The eluted drugs are detected by their absorption at 195 nm, and quantities estimated from their peak areas as compared with those of extracted standards. Results are reproducible to about 6%. Sensitivities, for 0.5-ml serum samples, of 0.1 mg/liter for all the drugs analyzed except ethosuximide (0.5 mg/liter) are attained routinely. Correlation of results with gas chromatography was 0.912 for phenobarbital, 0.982 for diphenylhydantoin, 0.886 for primidone, and 0.966 for ethosuximide. Amobarbital and secobarbital interfere with the analysis; chlordiazepoxide, methaqualone, salicylate, diazepam, and oxazepam do not. Including extraction, analysis time for a single sample is 20 min.

Anticonvulsants↗
PubMed1976

More sensitive high-pressure liquid-chromatographic determiantion of theophylline in serum.

We present procedures for determining theophylline in 50 mul of serum. The drug is extracted into a small volume of solvent that contains an internal standard, 8-chlorotheophylline. The extract is Analyzed by isocratic reversedphase chromatography, with measurement of eluted theophylline at 273 nm. Day-to-day reproducibility within 5% is attainable for the concentration range 5--20 mg/liter. Other xanthines and related metabolites do not interfere. Sensitivity is 1 mg/liter. The correlation coefficient, when results by a spectrophotometric procedure were compared, was 0.989. Amobarbital, secobarbital, phenobarbital, and diphenylhydantoin do not interfere. Total analysis time for a single sample is 15 min.

Chromatography, High Pressure Liquid↗