Joseph D. Rosen

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.

The photochemical isomerization of dieldrin and endrin and effects on toxicity

The commonly-used insecticides dieldrin (I) and endrin (II) persist in our environment for extended periods (2). Because these insecticides are exposed to sunlight during this time, it is important to determine the identity and toxicity of materials being added to our environment by photochemical pathways. Previous studies have shown that both dieldrin and endrin are readily decomposed by ultraviolet light (3,4). In addition, it was found that one of the ultraviolet decomposition products of dieldrin was the same (by paper and gas chromatography) as the material that was obtained by exposing dieldrin-treated grass to sunlight under natural conditions for several months (4).

Sequential degradation of chlorophenols by photolytic and microbial treatment

Using the radiolabeled model pollutants 2,4-dichlorophenol (DCP) and 2,4,5-trichlorophenol (TCP) the authors demonstrated that the brief UV (300-nm) photolysis greatly facilitates the removal of the two chlorophenols from sewage through accelerated mineralization and binding of polar products. The addition of 0.1 M H/sub 2/O/sub 2/ strongly accelerated the photolysis process resulting in the half-lives of 1.68 and 0.87 min for DCP and TCP, respectively. In natural sunlight, half-lives of the chlorophenols were less than 1 day when H/sub 2/O/sub 2/ was present. During 4 days of incubation in activated sewage sludge, only 3% of unphotolyzed DCP and 1% of unphotolyzed TCP were mineralized. Mineralization rose to 79 and 59%, respectively, after photolysis in the presence of H/sub 2/O/sub 2/. Photolysis without H/sub 2/O/sub 2/ resulted in removal of chlorophenols from solution chiefly by binding. Increased mineralization and binding were observed also upon incubation of photolyzed chlorophenols in soil. Disruption of carbon-halogen bonds by brief photolysis followed by traditional biological effluent treatment offers an alternative to activated charcoal treatment for removal of xenobiotics from industrial effluents.

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.

Quantification and confirmation of four fusarium mycotoxins in corn by gas chromatography-mass spectrometry-selected ion monitoring

A rapid method for the simultaneous determination of T-2 toxin, HT-2 toxin, diacetoxyscirpenol and zearalenone has been developed. Corn samples (10 g) are extracted with methanol, defatted with hexane and subsequently cleaned-up using both reversed-phase (C18) and normal-phase (silica gel) Sep-Pak cartridges. Confirmation of identity is made by gas chromatography-mass spectrometry-selected ion monitoring of three ions characteristic of the trimethylsilyl derivatives of the mycotoxins. Use of deuterated internal standards makes the method quantitatively reliable and increases sensitivity. Confirmation of identity as well as quantitation can be achieved at levels of ca. 20-50 ppb, depending on the mycotoxin. Detection limits (without confirmation of identity) are estimated at 1-20 ppb. Recoveries at the 46-111 ppb level ranged from 80 to 103% with coefficients of variation ranging from 1.6 to 14.2%.

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.

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.

Ammonium bicarbonate inhibition of mycotoxigenic fungi and spoilage yeasts

Sodium bicarbonate inhibits growth and aflatoxin production by Aspergillus parasiticus . This survey determined that other mycotoxigenic fungi were also sensitive to bicarbonates. Sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, ammonium sulfate, and sodium chloride were added to buffered or unbuffered potato-dextrose agar to determine the bicarbonate effect on growth and morphology of six mycotoxigenic fungi. Three nonmycotoxigenic fungi and four yeast species were also examined. Ammonium bicarbonate at 0.11M completely inhibited the growth of Fusarium tricinctum NRRL 13442, F. tricinctum NRRL 13426, F. graminearum NRRL 5883, F. sporotrichioides NRRL 3249, Penicillium griseofulvum NRRL 989, Aspergillus ochraceus NRRL 3174, A. flavus NRRL 1957, A. niger , and P. notatum . Sodium chloride and pH elevated through the use of ampso-NaOH, capso-NaOH, or glycine-NaOH buffer did not display an inhibitory effect on the filamentous fungi examined. Buffered ammonium sulfate treatments (pH approximately 9.0) completely inhibited all of the mycotoxigenic fungi, but at pH 5.6, ammonium sulfate treatments were not inhibitory. Sodium bicarbonate (0.11M) was effective only against P. griseofulvum , A. flavus NRRL 1957, A. niger , and P. notatum , causing viability reductions of 5.6, 3.7, 4.9, and 2.9 log cycles, respectively. Potassium bicarbonate was generally as inhibitory as the sodium salt. In contrast, elevated pH, alone, appeared to account for the >6 log reduction observed for the yeasts Lipomyces starkeyi , Geotrichum candidum , Kluyveromyces marxianus , and Debaryomyces hansenii .

Convenient Synthesis of the Food Mutagen 2-Amino-3-Methylimidazo[4,5-f]Quinoline (IQ), and IQ-D3

Abstract The title compounds (5 and 10) were each prepared in four steps from commercially available 5-amino-6-nitroquinoline (1) in 41% overall yield. The key step was the displacement of the methylsulfonyl group of 4 by sodamide.

Synthesis of the food mutagens MelQx and 4,8-DiMelQx by copper(I) promoted quinoxaline formation

Abstract The regiocontrolled syntheses of the title compounds ( 1 and 2 ) is described. The key step is a new intramolecular alkyne amination and aromatization process ( 5 → 6 ; 8 → 9 ) effected by tetrakis(acetonitrile)copper(I) tetrafluoroborate.