Non-target environmental analysis by liquid chromatography/high-resolution mass spectrometry with a product ion and neutral loss database.

Despite the increasing detection of emerging substances in the environment, the identity of most are left unknown due to the lack of efficient identification methods. We developed a non-target analysis method for identifying unknown substances in the environment by liquid chromatography/high-resolution mass spectrometry (LC/HRMS) with a product ion and neutral loss database (PNDB). The present analysis describes an elucidation method with elemental compositions of the molecules, product ions, and corresponding neutral losses of the unknown substance: (1) with the molecular formula, possible molecular structures are retrieved from two chemical structure databases (PubChem and ChemSpider); then (2) with the elemental compositions of product ions and neutral losses, possible partial structures are retrieved from the PNDB; and finally, (3) molecular structures that match the possible partial structures are listed in order of number of hits. A molecular structure with a higher number of hits is more similar to the structure of the analyzed substance. The performance of the non-target method was evaluated by simulated analysis of 150 LC/HRMS spectra registered in MassBank. First, all substances of the same mass data (41/41) and 68% (39/57) of the mass data of the same substances not registered in the PNDB were elucidated. It was demonstrated that 14% (7/52) and 31% (16/52) of the substances with no mass spectral data registered in the PNDB were obtained at the first and within the fifth place, respectively. Owing to the fact that 10 of the total hits occurred in product ions and neutral losses, almost 50% of the substances evaluated with this method were placed at the top 4 positions in the similarity ranking. Importantly, the proposed method is effective for analyzing mass spectral data that has not been registered in the PNDB and thus is expected to be used for a variety of non-target analyses.

Discovery of novel halogenated polycyclic aromatic hydrocarbons in urban particulate matters: occurrence, photostability, and AhR activity.

Halogenated aromatic compounds (HACs) in the environment have created great concern because of the associated adverse health implications. In this study we investigated the atmospheric behavior and exposure risk of brominated polycyclic aromatic hydrocarbons (BrPAHs) larger than three rings which were associated with particles in the urban air in Japan, and which were discovered as novel HACs in the air. Furthermore, the ambient levels of chlorinated polycyclic aromatic hydrocarbons (CIPAHs) and PAHs, in addition to BrPAHs, were also simultaneously investigated to emphasize the differences. Seven of 11 target BrPAHs were newly detected from the urban air samples in Japan between 2004 and 2005. Of the BrPAHs detected, 5,7-Br2BaA was most abundant (mean concentration, 8.7 pg m(-3)), followed by 7,12-Br2BaA (6.3 pg m(-3)) and 6-BrBaP (3.3 pg m(-3)). The mean concentrations of total BrPAHs, CIPAHs, and PAHs detected were 8.6 pg m(-3), 15.2 pg m(-3), and 1.2 ng m(-3), respectively, which showed that concentrations of such halogenated PAHs (Br-/Cl-PAHs) tended to be approximately 100-fold lower than PAHs. The BrPAHs had photolysis rates that were relatively faster than the corresponding CIPAHs. Comparing the ambient profiles among the PAH congeners suggested that ambient BrPAHs that came from the specific local emission sources differed from CIPAHs and PAHs, and/or could be driven by various seasonal factors, including photodecay processes. Most of the BrPAHs used showed inherent AhR-mediated activities. Toxic equivalents based on the relative potencies of each AhR activity and the ambient concentrations showed that either BrPAHs or CIPAHs accounted for a smaller proportion (approximately 1%) of the total.

Chlorinated polycyclic aromatic hydrocarbons in the atmosphere: seasonal levels, gas-particle partitioning, and origin.

Ambient concentrations of 26 chlorinated polycyclic aromatic hydrocarbons (CIPAHs) with 2- to 5-rings were investigated in a Japanese urban city from December 2004 to December 2005. All the targeted CIPAHs were detected in either the gaseous or particulate phase. During the study, the ambient (gaseous + particulate) concentration of total CIPAH ranged from 18 to 330 pg m(-3). The concentrations of gaseous CIPAHs tended to be 2 approximately 100 times higher than those of particulate CIPAHs. A seasonal variability of both gaseous and particulate CIPAH concentrations was observed, with higher concentrations in winter than in summer. A compositional analysis also showed a characteristic trend: relatively low molecular weight CIPAHs dominated in warmer seasons, and high molecular weight CIPAHs dominated in colder seasons. For some CIPAHs, temperature dependence of gas-phase concentrations was statistically significant (p < 0.05), and temperature accounted for 27-63% of the variability in their concentrations. The natural logarithm of total concentrations of particulate CIPAHs were significantly correlated (p < 0.05) with the reciprocal mean temperatures, but not for gaseous CIPAHs, suggesting that there are differences of the sources and ambient fates between gaseous and particulate CIPAHs. Back trajectory analyses suggested that air masses, originating from China, were associated with the highest CIPAH concentrations.

Dichlorodiphenyltrichloroethane suppresses neurite outgrowth and induces apoptosis in PC12 pheochromocytoma cells.

It is well known that dichlorodiphenyltrichloroethane (DDT) is used as an insecticide and prevents many people in the tropical zone from devastating malaria. On the other hand, a number of reports have indicated that it may act as an endocrine disruptor and also has possible carcinogenic effects. However, the effects of DDT on the neural cells remain to be investigated. In this study, therefore, we observed the effects of p,p'-DDT, o,p'-DDT and its major metabolite p,p'-DDE on the differentiation and survival of PC12 pheochromocytoma cells. After stimulation with nerve growth factor, PC12 cells exhibited remarkable neurite outgrowth, suggesting that neuronal differentiation was induced by this growth factor. p,p'-DDT and o,p'-DDT suppressed this neurite outgrowth dose dependently, and p,p'-DDE also revealed a similar effect but to a lesser extent. Apoptotic cell death was induced within 3-6 h after treatment with p,p'-DDT and o,p'-DDT. Again p,p'-DDE showed a weaker apoptosis-inducing effect. In the organochlorine-treated PC12 cells phosphorylation of p44/42 mitogen-activated protein kinase (MAPK) was upregulated, whereas phosphorylation bands were not detected in any kinases of other MAPK groups such as p38 MAPK and SAPK/JNK. A kinase assay on p44/42 MAPK revealed that the extent of phosphorylation of Elk-1 substrates well correlated with the suppressive effect on neuronal differentiation and apoptosis-inducing activity. These results suggest that p,p'-DDT and o,p'-DDT exerted their effects on neuronal cells by the stimulation of p44/42 MAPK, and p,p'-DDE had less effects than the other two organochlorines.