Thomas G. Hartman

Determination of Alkylphenol Ethoxylates and Their Acetic Acid Derivatives in Drinking Water by Particle Beam Liquid Chromatography/Mass Spectrometry

Abstract Particle beam liquid chromatography/mass spectrometry (PB/LC/MS) was used to analyze finished drinking water for non-volatile organic compounds. 500 liters of finished water were extracted with an on-line continuous liquid/liquid extractor with dichloromethane at pH 7.4. PB/LC/MS was an excellent tool to detect and identify ng/L concentrations of alkylphenol polyethoxylates (n = 3−8), materials which went undetected by on-column gas chromatography/mass spectrometry. In addition, alkylphenol polyethoxylate carboxylates with 2–7 degrees of ethoxylation could be detected without chemical derivatization.

Characterization of powdered turmeric by liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry

Five commercial powdered turmeric samples were analyzed to identify major and minor components. The developed HPLC method allows the separation of curcumin, demethoxycurcumin and bisdemethoxycurcumin, as well as three other major components and numerous minor components. The separation was accomplished on an octadecyl stationary phase using a mobile phase consisting of 50 mM ammonium acetate with 5% acetic acid and acetonitrile as the organic modifier. Thermospray mass spectra were obtained for all of the components. Particle beam EI-mass spectra were obtained for the curcuminoids, but could not be obtained for the other components due to the limitations of the particle beam interface when analyzing volatile and semi-volatile compounds. EI mass spectra for the volatile components were obtained by direct thermal desorption-gas chromatography-mass spectrometry (DTD-GC-MS).

Formation of Pyrazines from the Maillard Reaction of Glucose and Lysine-.alpha.-amine-15N

The contribution of amino and amide nitrogen atoms to pyrazine formation in both dry and aqueous systems was investigated. The 15N isotope labeled at the amide side chain of glutamine was chosen to react with glucose at 180 degrees C in the studies. Pyrazine, methylpyrazine, ethylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2,3-dimethylpyrazine, vinylpyrazine, and 2-ethyl-5-methylpyrazine were identified from heating the isotope-labeled glutamine with glucose in a dry system. Similar types of pyrazines were also found in an aqueous system. The exception was 2-vinyl-5-methylpyrazine, which was produced instead of 2-ethyl-5-methylpyrazine. These results demonstrated that deamidation did participate in pyrazine production and more than half of the nitrogen sources of pyrazines came from the amide side chains of glutamine. The yields of pyrazines from the dry system were higher than that from the aqueous system.

Determination of diquat and paraquat in water using high-performance liquid chromatography with confirmation by liquid chromatography-particle beam mass spectrometry

Abstract A method was developed for the extraction of diquat and paraquat from environmental water samples by ion-exchange column chromatography. Determinations were performed using high-performance liquid chromatography with diode array detection. The HPLC method was developed to be compatible with LC-MS techniques. Results were confirmed with LC-particle beam (electron ionization) MS, where a unique ionization process was observed. Recoveries in drinking water were over 75% for both diquat and paraquat spiked at concentrations of 5–10 μg l . The method presented is uniquely specific since a diode array UV spectrum is obtained as well as an particle beam mass spectrum, insuring correct identification and quantitation of diquat and paraquat.

Application of Particle Beam LC/MS for the Analysis of Water from Publicly Owned Treatment Works

Abstract Effluents from three New Jersey Publicly Owned Treatment Works (POTWs) were analysed for nonvolatile organic compounds using particle beam-liquid chromatography/mass spectrometry (PB-LC/MS). The wastewater samples were extracted by XAD-2 resin adsorption methodology. A comparison between the PB-LC/MS analysis and an on-column gas chromatography/mass spectrometry (GC/MS) analysis showed that 46 additional compounds could be detected by PB-LC/MS. Identifications were made either by mass spectral interpretation or by matches with a mass spectral library data base for 19 of the 46 compounds detected only by PB-LC/MS. The majority of contaminants identified were non-ionic surfactants, plasticizers, plastic additives and other various synthetic organic compounds. PB-LC/MS has proven its ability to detect and identify a number of environmental contaminants which on-column GC/MS failed to detect.

Evolution of novel O-methyltransferases from the Vanilla planifolia caffeic acid O-methyltransferase.

The biosynthesis of many plant secondary compounds involves the methylation of one or more hydroxyl groups, catalyzed by O-methyltransferases (OMTs). Here, we report the characterization of two OMTs, Van OMT-2 and Van OMT-3, from the orchid Vanilla planifolia Andrews. These enzymes catalyze the methylation of a single outer hydroxyl group in substrates possessing a 1,2,3-trihydroxybenzene moiety, such as methyl gallate and myricetin. This is a substrate requirement not previously reported for any OMTs. Based on sequence analysis these enzymes are most similar to caffeic acid O-methyltransferases (COMTs), but they have negligible activity with typical COMT substrates. Seven of 12 conserved substrate-binding residues in COMTs are altered in Van OMT-2 and Van OMT-3. Phylogenetic analysis of the sequences suggests that Van OMT-2 and Van OMT-3 evolved from the V. planifolia COMT. These V. planifolia OMTs are new instances of COMT-like enzymes with novel substrate preferences.

Capillary gas chromatography-mass spectrometry of several macrocyclic trichothecenes

The mass spectra of verrucarin J and the trimethylsilyl derivatives of verrucarin A, roridins A and E, satratoxins G and H, and baccharin B5 have, for the first time, been obtained after sample introduction by gas chromatography (GC). This has been accomplished by the use of a short-length fused-silica capillary column with on-column injection. The macrocyclic trichothecenes studied are separable by GC except for verrucarin J, derivatized verrucarin A and derivatized roridin E. However, these materials are distinguishable by selected ion monitoring. The fragmentation pathways for each of the compounds studied have been partially elucidated. Except for roridin E and satratoxin G, the macrocyclic trichothecenes give usably intense electron impact ions at high mass range for selected ion monitoring at 1–10 ng.

Functional characterization of two new members of the caffeoyl CoA O-methyltransferase-like gene family from Vanilla planifolia reveals a new class of plastid-localized O-methyltransferases.

Caffeoyl CoA O-methyltransferases (OMTs) have been characterized from numerous plant species and have been demonstrated to be involved in lignin biosynthesis. Higher plant species are known to have additional caffeoyl CoA OMT-like genes, which have not been well characterized. Here, we identified two new caffeoyl CoA OMT-like genes by screening a cDNA library from specialized hair cells of pods of the orchid Vanilla planifolia. Characterization of the corresponding two enzymes, designated Vp-OMT4 and Vp-OMT5, revealed that in vitro both enzymes preferred as a substrate the flavone tricetin, yet their sequences and phylogenetic relationships to other enzymes are distinct from each other. Quantitative analysis of gene expression indicated a dramatic tissue-specific expression pattern for Vp-OMT4, which was highly expressed in the hair cells of the developing pod, the likely location of vanillin biosynthesis. Although Vp-OMT4 had a lower activity with the proposed vanillin precursor, 3,4-dihydroxybenzaldehyde, than with tricetin, the tissue specificity of expression suggests it may be a candidate for an enzyme involved in vanillin biosynthesis. In contrast, the Vp-OMT5 gene was mainly expressed in leaf tissue and only marginally expressed in pod hair cells. Phylogenetic analysis suggests Vp-OMT5 evolved from a cyanobacterial enzyme and it clustered within a clade in which the sequences from eukaryotic species had predicted chloroplast transit peptides. Transient expression of a GFP-fusion in tobacco demonstrated that Vp-OMT5 was localized in the plastids. This is the first flavonoid OMT demonstrated to be targeted to the plastids.

Bioassay-directed fractionation of organic compounds associated with airborne particulate matter; An interseasonal study

Abstract Bioassay-directed fractionation based upon a modification of a published technique is applied to the study of three seasonal composites of dichloromethane extracts of inhalable particulate matter collected in Newarks, New Jersey The “profiles” of mass distribution and Salmonella TA98 mutagenic activity vs polarity are similar for the three seasons. Only at the second and especially the third fractionation levels are significant differents seen with a slight shift toward more polar compounds during summer. In all three seasons, polar neutral compounds make the greatest contribution toward mutagenic activity. Hydroxynitropolyciclic aromatic hydrocarbons are difficult to analyse by GC/MS) (El and negative chemical ionization), but HPLC/UV appears to be useful. A number of techniques are emplited in the analysis of specific compounds and classes of compounds. Subsequent acetone extraction of filters yields highly polar mutagens where the acidic fractions account for most of the mutagenic activity. These compounds show significantly enhanced mutagenic activity with TA100 relative to TA98 suggesting the presence of highly polar, acidic substances that are strong alkylating agents. The compound 2-acetoxyl-1-nitronaphthalene, found in fresh diesel particalates, is shown to hydrolyse during fractionation, thus introducing a note of caution into the use of such procedures.

The floral odour of Peltandra virginica contains novel trimethyl-2,5-dioxabicyclo[3.2.1]nonanes

Abstract The qualitative and quantitative composition of the floral odour of Peltandra virginica was determined by trapping odour components from freshly cut inflorescences on Tenax and Carbotrap adsorbents using a purge and trap apparatus. Analysis showed that a single novel compound, 1,3,6-trimethyl-2,5-dioxabicyclo[3.2.1.]nonane, comprised nearly 70% of the odour. Four isomers of this compound were found in much smaller amounts (1.0–7.6%) while an analogue with m, 142 comprised 13% of the odour. Small amounts (ca 0.3-2.5%) of two isomers of methylundecene and three isomers of dimethyldodecenone were also detected. This is the first case of trimethyldioxabicyclo[3.2.1]nonanes reported in floral odours.