Nitropyrenes detection

Nitro polycyclic aromatic hydrocarbons are environmental contaminants which have been detected in airborne particulates, coal fly ash, diesel emission and carbon black photocopier toners. These compounds are metabolized Tn vitro to genotoxic agents through ring oxidation and/or nitroreduction. The details of these metabolic pathways are considered using 4-nitrobiphenyl, 1- and 2-nitronaphthalene, 5-nitro-acenaphthene, 7-nitrobenz[a]anthracene, 6-nitro-chrysene, 1-nitropyrene, 1,3-, 1,6- and 1,8-dinitro-pyrene, and 1-, 3- and 6-nitrobenzo[a] pyrene as examples ... 

Although 1-aminopyrene is a reduced metabolite of 1-nitropyrene, this arylamine will not covalently bind to DNA in vitro (72). In contrast, when incubations were conducted with the intermediate reduction product, N-hydroxy-l-aminopyrene, extensive covalent binding to DNA was detected (72). This observation is consistent with the previous report that several N-hydroxy arylamines formed DNA adducts and induced mutations in S. typhimurium (116), and suggests that, at least for 1-nitropyrene, reduction to N-hydroxy-l-aminopyrene is a critical step in mutation induction. 

Recently, Bryant t al. (70) examined the metabolism of 1,8-dinitropyrene in several S. typhimurium strains and found reduction to l-amino-8-nitropyrene and 1,8-diaminopyrene. In addition, other unidentified metabolites were detected in strains which were sensitive to 1,8-dinitropyrene-induced mutations (TA98 and TA98NR) but not in the resistant strains, TA98/1,8-DNP and TA98NR/1,8-DNP6. 

Other bacteria. Intestinal bacteria may play a critical role in the metabolic activation of certain nitroaromatic compounds in animals (119) and several reports have appeared on the metabolism of nitro PAHs by rat and human intestinal contents and microflora (120-123). Kinouchi et al. (120) found that 1-nitropyrene was reduced to 1-aminopyrene when incubated with human feces or anaerobic bacteria. More recently, Kinouchi and Ohnishi (121) isolated four nitroreductases from one of these anaerobic bacteria (Bacteroides fragilis). Each nitroreductase was capable of converting 1-nitropyrene into 1-aminopyrene, and one form catalyzed the formation of a reactive intermediate capable of binding DNA. Howard ej al. (116) confirmed the reduction of 1-nitropyrene to 1-aminopyrene by both mixed and purified cultures of intestinal bacteria. Two additional metabolites were also detected, one of which appeared to be 1-hydroxypyrene. Recently, similar experiments have demonstrated the rapid reduction of 6-nitro-BaP to 6-amino-BaP (123). 

In the PO-CL system, the compounds showing native fluorescence or that fluoresce after chemical derivatization can be detected. As examples of the PO-CL detection of native fluorescence compounds, dipyridamole and benzydamine in rat plasma [57] and fluphenazine [58] have been reported in the former method, the detection limits of dipyridamole and benzydamine were 345 pM and 147 nM in plasma, respectively. Diamino- and aminopyrenes were sensitively determined using TCPO and their detection limits were in the sub-fmol range [59], Carcinogenic compounds such as 1- nitropyrene and its metabolites, can also be determined by the HPLC-PO-CL system. Nonfluorescent nitropyrenes were converted into the corresponding fluorescent aminopyrenes by online reduction on a Zn column followed by detection 2-50-fmol detection limits were achieved in the determination of ethanol extracts from airborne particulates (Fig. 13) [60],... 

The human cell mutagenicities of several mono- and dinitropyrenes were determined by Busby and coworkers (1994b) in a forward mutation assay using a metabolically competent line of MCL-5 cells. Minimum detectable mutagen concentrations (MMC, in nmol ml-1 the smaller the detectable concentration, the greater the potency) were as follows 1,6-dinitropyrene, 0.8 1,8-dinitropyrene, 1.5 4-nitropyrene, 3.1 1-nitro-pyrene, 9.1. Other PACs tested, 2-nitropyrene, 1,3-dinitropyrene, and pyrene, were nonmutagens in this... 

In the mid-1980s, the discovery of significant amounts of 2-nitropyrene in ambient particulate matter collected in a rural region of Denmark by Nielsen and co-workers (1984) and 2-nitrofluoranthene in southern California by Pitts and colleagues (1985b) provided unique initial evidence for the possible formation of nitroarenes by reactions of precursor PAHs in ambient air. Thus, these compounds are not electrophilic nitration products of their parent PAHs and are generally not observed in combustion sources such as diesel soot see, for example, Table 10.34 and the report of Ciccioli and co-workers on the detection of emissions of 2-nitrofluoranthene and 2-nitropyrene solely from a very minor Italian industrial source (see Ciccioli et al., 1993, 1995, 1996, and references therein). 

Additionally, in two different monitoring campaigns conducted in the center of Milan, Italy, Ciccioli and co-workers (1993) reported 2-nitrofluoranthene, 2-nitropyrene, and 1-nitropyrene were the only ni-troarenes detected. Subsequently, in a comprehensive study of the atmospheric formation and transport of 2-nitrofluoranthene and 2-nitropyrene, they established their presence and levels in ambient particles collected at sites located in urban, suburban, forest, and remote areas in Europe, Asia, America, and Antarctica (Ciccioli et al., 1996, and references therein see also Ciccioli et al., 1995). 

Hayakawa and co-workers have intensively developed HPLC techniques with on-line reduction of NPAC to aminoPAC (APAC) and chemiluminescence detection of APAC for trace analysis of NPAC, particularly of nitropyrenes. In this study, we examined the HPLC method for the analysis of novel NPAC, 3-NBA and 2-NTP in airborne particles including the interference of coexisting NPAC in the sample in separation and the efficiency of the on-line reduction to selective conversion of 3-nitrobenzanthrone, which has one carbonyl group, to detectable 3-aminobenzanthrone in the HPLC system. 

Hayakawa K, Murahashi T, Butoh M, Miyazaki M. Determination of 1,3-, 1,6-and 1,8-dinitropyrenes and 1-nitropyrene in urban air by high-performance liquid chromatography using chemiluminescence detection. Environ Sci Technol 1995 29 928-32. 

In this study, the concentrations of several kinds of nitro-PAH, such as 1-nitropyrene (1-NP), 2-nitropyrene (2-NP), 2-nitrofluoranthene (2-NF), and 2-NTP, in the soluble organic fraction of airborne particles were determined by a column switching HPLC-chemiluminescence detection system in order to clarify the occurrence and behaviour of 2-NTP in the atmosphere. 

Detection of nitrated PAHs (NPAHs) is possible using ECD and can be made more sensitive by preparing the fluorinated derivatives of NPAHs with heptafluorobutyric anhydride (HFBA). The fine fraction (<0.5 /rm) of urban air particulate matter in Saitama, Japan contained about ten times the amount of NPAHs as the course fraction with levels as high as 111 pg m for 1-nitropyrene and 18 pg m for 1-nitronaphthalene. 

For each extract, the percentage of measured mutagenic activity due to 1-nitropyrene was calculated and is given in Table 4. The value of 918 rev/yg was used as the mutagenic activity of 1-nitropyrene for these calculations. In addition, the percentage of measured mutagenic activity due to those nitro-aromatics detected by mass spectrometry was calculated for each extract using the specific activities listed in Table 2. 

A comparison of mutagenic activity using normal and nitroreductase-deficient bacteria provides a method for detection and identification of nitroaromatic mutagens. But this idea is complicated by the existence of several bacterial nitroreductases with differing specificities (11). Three different nitroreductase-deficient derivatives of the normal tester strain TA98 were obtained from Dr H. S. Rosenkranz at Case Western University who has isolated and characterized these strains. Strain TA98NR was selected for its resistance to the nitrocompound niridazole and subsequently found to be resistant to the mutagenicity of niridazole, and also to that of the nitrofurans, nitronaphthalenes, and nitrofluorene (3). It is also resistant to 1-nitropyrene and a number of other nitro-PAH... 

Hayakawa, K. Lu, C. Mizukami, S. Toriba, A. Tang, N. Determination of 1-nitropyrene metabolites by high-performance hquid chromatography with chemiluminescence detection. J. Chromatogr. A, 2006, 1107, 286-289. 

Nitrated polycyclic aromatic hydrocarbons, such as 1-nitropyrene, 1-nitrosopyr-ene and 1,3-dinitropyrene, have been measured in car exhaust deposits by HPLC with chemiluminescence detection after on-line EC reduction (PGEs, —1.6 V vs Pd)." LoDs of fmol on-column were claimed. 

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