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Biomedical subjects

T L Barry

Publications and source records attributed to T L Barry.

17 recordsLinked to original sources
PubMed1999

Isolation and identification of process impurities in trimethoprim drug substance by high-performance liquid chromatography, atmospheric pressure chemical ionization liquid chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy.

Twenty-two lots of recently synthesized trimethoprim drug substance, from five different manufacturers, in three different countries of origin, China, Israel and the United States, were investigated for the presence of impurities. A liquid chromatographic system, using gradient elution, and a mobile phase consisting of 0.25% TEA/0.1% formic acid (pH 5.8)--acetonitrile, was used to separate and detect two significant, recurring impurities in trimethoprim drug substance. The two impurities were isolated by preparative liquid chromatography and identified, using a combination of liquid chromatography/mass spectroscopy and nuclear magnetic resonance, as 2,4-diamino-5-(4-ethoxy-3,5-dimethoxybenzyl) pyrimidine and 2,4-diamino-5-(3-bromo-4,5-dimethoxybenzyl) pyrimidine. These impurities were not detected by the compendial method and were present at significant levels in 17 of the lots tested. Total impurity concentrations were in the range of 0.1-2.1%.

Atmospheric Pressure↗
PubMed1996

GC/MS comparison of the West Indian aphrodisiac "Love Stone" to the Chinese medication "chan su": bufotenine and related bufadienolides.

The death of a 23-year-old man resulting from digoxin-like toxicity and heart failure was attributed to ingestion of a West Indian aphrodisiac known as "Love Stone." GC/MS analyses identified bufotenine, a controlled substance under both US and New York State statutes. In addition, a series of bufadienolides, namely resibufogenin, bufalin, and cinobufagin, were also identified. Bufadienolides, which are derived from toad venom or secretions, are cardiotonic steroids that cause symptoms similar to digoxin. GC/MS analyses of the Chinese medication "Chan Su," a product derived from toads, produced a highly similar elution profile and contained the same compounds as "Love Stone." The data demonstrate that the aphrodisiac was also derived from toads.

Adult↗
PubMed1990

Potential misidentification of trichlorophenylethanol in imported peppers.

During regulatory analyses for the determination of pesticide residues on agricultural commodities, a frequently encountered trichlorinated compound was misidentified by the NBS library search routine. This case history illustrates the need for more rigorous confirmation criteria when dealing with multi-chlorinated compounds where fragmentation can be dominated by methyl loss followed by loss of CO and HCI.

Benzyl Alcohols↗
PubMed1977

Structure and fragmentation mechanisms of some ions in the mass spectrum of ephedrine.

This paper describes the use of gas chromatography mass spectrometry for the confirmation of ephedrine in adulterated powdered ipecac and ipecac fluid extract. Deuteration studies of ephedrine hydrochloride and some related compounds were also performed in an attempt to postulate structures for some of the fragment ions appearing in the spectrum of ephedrine.

Chemical Phenomena↗
PubMedDate not supplied

Computer support for continuous quality improvement.

Continuous quality improvement (CQI) methodology is predicated on data-based decision making, using both statistical and nonstatistical data tools. The current generation of commercially available quality management computer software does not integrate the basic CQI tools. A variety of off-the-shelf programs can be used to supplement the resource needs of CQI methodology.

Database Management Systems↗
PubMedDate not supplied

Negative ion chemical ionization mass spectrometric method for confirmation of identity of aflatoxin B1: collaborative study.

An interlaboratory study of a negative ion chemical ionization mass spectrometric (MS) confirmation procedure for aflatoxin B1 was conducted in laboratories in the United States, England, and West Germany. Twelve partially purified, dry film extracts from naturally and artificially contaminated roasted peanuts, cottonseed, and ginger root containing varying quantities of aflatoxin B1 were distributed to the participating laboratories. The extracts required additional cleanup before MS analysis, using either an acidic alumina column and preparative thin layer chromatography (TLC) or a 2-dimensional TLC procedure. Recovery of purified aflatoxin B1 was influenced by the degree of recovery of sample from acid alumina and/or the TLC plate and incomplete elution of aflatoxin B1 from silica gel. Factors affecting MS confirmation included the purity and recovery of aflatoxin and MS instrument sensitivity. Aflatoxin B1 identity was confirmed in 19.5, 90.9, and 100% of samples containing less than 5, 5-10, and greater than 10 ng aflatoxin B1/g product, respectively, by solid probe introduction using full mass scans. The MS method has been adopted official first action.

Aflatoxin B1↗
PubMedDate not supplied

Purge-and-trap gas chromatographic-mass spectrometric determination of benzene in denture adhesives.

A purge-and-trap gas chromatographic-mass spectrometric procedure is presented for determination of trace levels of benzene in denture adhesives and their raw materials. The limit of quantitation is 10 ppb, reproducibility is +/- 10%, and recoveries of d6-benzene are 70-85%. Results of a nationwide survey of 109 finished products and their raw materials representing 32 brand name products from 17 manufacturers are reported.

Adhesives↗
PubMedDate not supplied

Gas chromatographic/mass spectrometric analyses of unknown analytical response in imported Fava beans: 4-chloro-6-methoxyindole.

A halogenated unidentified analytical response (UAR) was encountered in a number of imported Fava bean samples during the Food and Drug Administration's routine pesticide-monitoring program. Gas chromatographic/mass spectrometric (GC/MS) analyses identified the halogenated component as 4-chloro-6-methoxyindole, a naturally occurring promutagen in Fava beans that has been linked to incidents of gastric cancer. Data from electron impact, positive and negative chemical ionization, collision-induced dissociation, and deuteration studies of this compound are presented, along with GC retention time data.

Fabaceae↗