The collision-induced dissociations of the even-electron [M + H](+) and/or [M - H](-) ions of 121 model compounds (mainly small aromatic compounds with one to three functional groups) ionized by electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI) have been studied using an ion trap instrument, and the results are compared with the literature data. While some functional groups (such as COOH, COOCH(3), SO(3)H in the negative ion mode, or NO(2) in both the positive and negative ion modes) generally promote the loss of neutrals that are characteristic as well as specific, other functional groups (such as COOH in the positive ion mode) give rise to the loss of neutrals that are characteristic, but not specific. Finally, functional groups such as OH and NH(2) in aromatic compounds do not lead to the loss of a neutral that reflects the presence of these substituents. In general, the dissociation of [M + H](+) and [M - H](-) ions generated from aliphatic compounds or compounds containing an aliphatic moiety obeys the even-electron rule (loss of a molecule), but deviations from this rule (loss of a radical) are sometimes observed for aromatic compounds, in particular for nitroaromatic compounds. Thermochemical data and ab initio calculations at the CBS-QB3 level of theory provide an explanation for these exceptions. When comparing the dissociation behaviour of the even-electron [M + H](+) and/or [M - H](-) ions (generated by ESI or APCI) with that of the corresponding odd-electron [M](+) ions (generated by electron ionization, EI), three cases may be distinguished: (1) the dissociation of the two ionic species differs completely; (2) the dissociation involves the loss of a common neutral, yielding product ions differing in mass by one Da, or (3) the dissociations lead to a common product ion.

Recently, it was reported that Bisphenol-A (BPA) was released from one fissure sealant (Delton) into saliva causing estrogenic activity in vitro. The aim of this study was to chemically analyze the BPA content of different fissure sealant resin monomers and their release of BPA under hydrolytic conditions. BPA content was first measured in commercially available monomers of bisphenol-A glycidyldimethacrylate (Bis-GMA), bisphenol-A dimethacrylate (Bis-DMA) and bisphenol-A diglycidylether (BADGE). Then, Bis-GMA-monomer and Bis-DMA-monomer in methanol were subjected to pH values of 0 to 11 for 30 minutes at 50 degrees C, to porcine liver esterase, and to pooled saliva for up to 24 hours. The BPA-content was determined by high-performance liquid chromatography (HPLC). Bis-GMA-monomer and BADGE-monomer from one manufacturer did not contain any detectable amounts of BPA (< or = 2 ppm); Bis-DMA and BADGE-monomer from a second manufacturer contained BPA quantities of 4-155 ppm. For Bis-GMA-monomer, no BPA could be detected under any hydrolytic conditions chosen (detection limit: < or = 1%). For Bis-DMA-monomer an increase of BPA was observed at pH 11, resulting in a conversion of approx. 100% Bis-DMA to BPA. When Bis-DMA was subjected to esterase, a conversion of 82.5% resulted after 24 h; saliva led to an 81.4% conversion of Bis-DMA after 24 h. Hence, we conclude that the results reported in the literature may be attributed to the Bis-DMA-content of the fissure sealant tested (Delton). No BPA-release is expected under physiologic conditions from fissure sealants based on Bis-GMA if pure base monomers are used.

It was recently reported that estrogenic activity was detected in saliva samples collected during 1 h after placement of one fissure sealant (Delton) and this related to Bisphenol-A (BPA) content. The aim of the present study was to determine the time-related BPA content and estrogenic activity in saliva samples collected before and after placement of two fissure sealants each with a different monomer composition. Eight healthy male volunteers with no history of prior placement of fissure sealants or composite resin fillings had four molars sealed with either Delton LC (four people) or Visio-Seal (four people). Base-line saliva samples were collected preexperimentally, in the morning when fasting. Fissure sealants were placed and saliva samples collected immediately, 1 h and 24 hs after placement of the fissure sealant. BPA was found in saliva samples collected immediately after placement of Delton LC (range 0.3-2.8 ppm). No detectable amounts of BPA were determined 1 h and 24 h after Delton treatment (detection limit < or = 0.1 ppm). In base-line samples and in all samples collected from Visio-Seal treated individuals, no BPA was detected. In a recombinant yeast cell assay, significantly increased estrogenic activity was found in saliva samples collected immediately after placement of Delton LC sealant (P < 0.05; ANOVA) whereas no statistically significant estrogenic activity was observed in the remaining groups. In conclusion, minute amounts of BPA, however considerably lower than previously reported, were detected in saliva samples collected immediately after but not 1 and 24 h(s) after placement of Delton LC fissure sealant. BPA was not detected after placement of Visio-Seal fissure sealant.

(-)-Jasmonic acid was identified as a plant growth inhibitor of the pericarp of Vicia faba by means of gas-liquid chromatography, high resolution mass spectrometry, (1)H-nuclear magnetic resonance ((1)H-NMR), and (13)C-NMR. Additionally, the pericarp contains very small amounts of abscisic acid (ABA) and 4'-dihydrophaseic acid. The highest level of jasmonic acid was reached prior to full pericarp length. This amount (3 μg g(-1) fresh weight) is similar to the maximal ABA content in the developing seed. Jasmonic acid is a plant growth inhibitor possessing a relative activity in the wheat seedling bioassay of 1-2.5%, compared to ABA. Contrary to ABA, jasmonic acid does not cause retardation of leaf emergence. The possible physiological role of jasmonic acid in the pericarp is discussed and compared with the assumed function of ABA in developing seeds.

Coupling of HPLC to NMR was applied for the first time to the analysis of environmental samples, i.e., water samples from an ammunition hazardous waste site. Using the continuous flow mode at very low flow rates (< or = 0.017 mL/min) and large volume injection (400 microL), the confirmation of many nitroaromatic compounds could be achieved down to the microgram-per-liter level after solid phase extraction of a groundwater sample from a former ammunition production site. At a flow rate of 0.006 mL/min, it is possible to detect less than 29 nmol (5 micrograms) of 1,3-dinitrobenzene injected on a 75 mm x 4 mm reversed phase C-18 column (particle size, 5 microns). The results obtained by HPLC-NMR are compared to those obtained by HPLC-PDA (photodiode array) of the same sample, demonstrating that many more compounds can be identified by the former compared to the latter method as a result of coelution of major and minor components in the HPLC chromatogram.