Donald J. Harvan

High-performance liquid chromatography—mass spectrometry of triazine herbicides

Abstract Five classes of triazine herbicides were studied by combined high-performance liquid chromatography—mass spectrometry (HLPC—MS). Separations were done on a reversed-phase C 8 column, using acetonitrile—water as the mobile phase, followed by in-line UV and mass spectral analysis. Positive and negative ion mass spectra were recorded. For most of the triazines both positive and negative ion spectra obtained with the direct liquid introduction HPLC—MS probe interface give molecular ion information. Most of the triazine studies were more sensitive in the positive ion mode than in the negative ion mode.

Liquid chromatography—chloride-attachment negative chemical ionization mass spectrometry

Abstract Chloride-attachment negative chemical ionization mass spectra can be generated by the addition of chlorinated solvent modifiers to the high-performance liquid chromatographic mobile phase in liquid chromatography—mass spectrometry. The observed mass spectra of several organophosphorus pesticides are similar to those reported for direct probe analysis with methylene chloride as the reagent gas. For certain classes of compounds, this mode of ionization yields more structural information than does conventional negative chemical ionization mass spectrometry. The addition of chlorinated solvent modifiers to the high-performance liquid chromatographic mobile phase in liquid chromatography—mass spectrometry allows for the analysis of mixtures by chloride-attachment negative chemical ionization.

A gas chromatographic method for the mycotoxin penicillic acid

Abstract Penicillic acid was satisfactorily resolved by gas chromatography either as the trimethylsilyl derivative or in the underivatized form using 3% of Dexsil 300, 3% of OV-17 or 3% of OV-25 liquid phase on Gas-Chrom Q. The limit of quantitation was approximately 25 ng. Extraction and detection of penicillic acid together with another important mycotoxin, patulin, was demonstrated in moldy corn. In addition; a preliminary clean-up procedure using thin-layer chromatography is described for crude extracts, which improves resolution and sensitivity in the gas chromatographic analysis of penicillic acid.

Analysis of Explosives by Liquid Chromatography-Negative Ion Chemical Ionization Mass Spectrometry

On-line high performance liquid chromatography (HPLC)-negative ion chemical ionization (NCI) mass spectrometry has been used for the analysis of explosives mixtures. The liquid chromatography-mass spectrometry (LC/MS) interface used was a commercial direct liquid introduction interface allowing about 1% of the solvent/sample effluent into the ion source. The HPLC mobile phases were acetronitrile/water (50:50) and methanol/water (50:50), which served also as NCI reagent gases. Standard mixtures containing 2,4,6-trinitrotoluene (TNT), cyclonite (RDX), tetryl, and pentaerythritol tetranitrate (PETN), and a military explosive, tetrytol, have been analyzed by the LC/MS system. The minimum detectable amount of TNT was 100 ng injected on column, or approximately 1 ng to the ion source.

Isolation and indentification of a new toxin, altenuene, from the fungus Alternaria tenuis

Abstract A previously unknown metabolite was isolated from four week old cultured of the fungus, Alternaria tenuis. The compound shows cytotoxic activity against five bacteria tested by the paper-disc agar-plate method. After purification by column chromatography on silica gel, the metabolite crystallized from acetone: hexane mixtures as colorless neddles neddles that melted at 190–191° (corr.). High resolution mass spectrometry indicated a parent ion with mol. wt. 292.0938, which identified the empirical formula as C15H16O6. Structural assignments based on infrared, proton magnetic resonance, and ultraviolet spectra established the structure of the compound as 2′,3′,4′,5′-tetrahydro-3,3′,4′-trihydroxy-5-methoxy-6′-mehyl-dibenzo-α-pyrone to which we have given the trival name, altenuene. Altenuene is structurally related to two previously characterized A. tenius metabolites, alternariol and alternariol monomethyl ether.

Gas and thin-layer chromatographic methods for analysis of the mycotoxins altenuene, alternariol, and alternariol monomethyl ether

Abstract 1. 1. A method is presented for production and purification of altenuene, alternariol, and alternariol monomethyl ether from cultures of the fungus Alternaria tenuis . 2. 2. A quantitative analytical procedure based on gas-liquid chromatography is given for the simultaneous analysis of the three toxins. Detection limits for quantitative assays are about 0.1 μg for each. 3. 3. Analysis of the toxins by thin-layer chromatography was explored and satisfactory separation and resolution for each compound was demonstrated, with detection limits of 0.1 μg for each toxin.

Adduct formation between the carcinogen N-acetoxy-2-acetylaminofluorene and synthetic polydeoxyribonucleotides

The chemical carcinogen N-acetoxy-2-acetylaminofluorene (NA-AAF) was reacted with poly(dG-dC) - poly(dG-dC); poly dG - poly dC; poly(dA-dT) - poly (dA-dT); and poly dA - poly dT under a variety of conditions. Poly (dG-homo GC polymer and 10--20 more reactive the A + T polymers. Lowering the ionic strength increased the extent of reaction, while pH change (8.9 vs. 5.5) had only a small effect. If ionic strength was adjusted so that the two guanine-containing polymers showed equal thermal stability (as judged by Tm) then the alternating copolymer was 7 times as reactive as the homopolymer. In aggreement with previous investigators, the major product was found to be 8-(N-2-fluorenylacetamido) deoxyguanosine.

X-Ray crystal structure revision for the fungal metabolite (±)-altenuene

The structure of the fungal metabolite (±)-altenuene has been elucidated by direct method X-ray crystal structure analysis.

Effect of mercuric and silver ions on cesium sulfate equilibrium buoyant densities of synthetic polydeoxyribonucleotides

The effect of Hg2+ and Ag+ on the buoyant density (rho) of four synthetic DNA polymers, poly[d(A-T)]; poly(dA) - poly(dT); oikt[d(G-C)]; and poly(dG) - poly(dC), was investigated. The buoyant density of poly[d(A-T)] in Cs2SO4 increased dramatically after complexing with Hg2+, but little change in the buoyant density of other polymers resulted except at very high molar ratios of Hg2+/DNA-P (rf). Hg2+ raised the thermal transition temperature (Tm) of alternating polymers and lowered the Tm of homopolymers. Measurements in the preparative ultracentrifuge indicated that lowered Tm correlated with Hg2+-induced strand separation of one homopolymer [poly(dA) - poly(dT)], but strand separation was not observed with another homopolymer [poly(dG) - poly(dC)] complexed with Hg2+. When Ag+ was mixed with the polymers, the buoyant density of poly(dG) - poly(dC) increased most markedly. A substantial increase in the buoyant density of poly[d(A-T)] and a small increase in the buoyant density of poly[d(G-C)] were also observed. The Tm changes induced by Ag+ were not related in any obvious way to buoyant density changes. These findings indicate that nucleotide sequence as well as overall base composition is of importance in understanding the buoyant density changes induced by metal ions. Although these data do not allow construction of a detailed molecular model of polymer-metal ion interactions, they may be used to explain much of the behavior of naturally occurring DNA sequences, such as heterochromatic satellite sequences and 5 S and rRNA sequences, in Hg2+/Cs2SO4 and Ag+/Cs2SO4 gradients.

Mass-analyzed ion kinetic energy spectra of the [M + 1]+ ions of aliphatic esters produced by chemical ionization

Abstract To test the similarity of chemical ionization (CI) spectra of esters to the collision-induced decomposition mass-analyzed ion kinetic energy (CID-MIKE) spectra of protonated esters, the CID-MIKE spectra of the [M + 1] + ions of nineteen aliphatic esters were studied. The major fragments produced in the two kinds of experiment are similar, but there are significant differences in the ions of high mass, which would reduce the usefulness of library searches of CI spectra to identify MIKE spectra of [M + 1] + ions.