GCTEA of hydroxyalkylnitrosamines

Volatile hydroxyalkylnitrosamines can be determined directly by GC-TEA if the molecular weight is not too large and high temperatures are used for the GC. Thus the author's group used GC-TEA with a column of 10% Carbowax-20M-TPA on Chromosorb GHP heated to 190°C to separate and determine underivatized N-nitroso-2-, 3-, 4- and 5-hydroxymethylpentylamine, which are metabolites of N-nitrosomethylpentylamine, a potent oesophageal carcinogen in the rat [103].

Most studies have determined hydroxyalkylnitrosamines by GC-TEA of their trimethylsilyl (TMS) derivatives. For example, there is evidence that the inductions of lung cancer by cigarette smoke is in part due to the lung

NNAL /so-NNAL

Figure 9 Tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), NNK metabolite 4-(methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) and two internal standards, /so-NNAL and NPPA, used for NNAL analysis.

NNAL /so-NNAL

Figure 9 Tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN), NNK metabolite 4-(methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) and two internal standards, /so-NNAL and NPPA, used for NNAL analysis.

carcinogen NNK [30]. NNK is metabolized to give 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), which is excreted in the urine together with its fi-O-glucuronide (Figure 9). The urinary level of NNAL plus its glucuronide has been determined in many studies. A standard method [65,104] involves hydrolysis of the glucuronide with ^-glucuronidase, adsorption of the NNAL on Celite columns, elution with dichloromethane, transfer to methanol-HCl, passage through cation exchange cartridges with elution by a water-methanol-NH4OH mixture, evaporation to dryness, conversion to TMS derivatives by treatment with N,O-bis-TMS-trifluoroacetamide and capillary GC-TEA. An internal standard, 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL), is added before ^-glucuronidase treatment and a second nitrosamine, N-nitroso-3-picolylamine, is added before the silylation step as an injection standard. A recent method for NNAL in urine involved HPLC on a molecularly imprinted polymer (MIP) specific for NNAL [105,106]. To prepare this maternal, highly cross-linked polymer is synthesized in the presence of a template molecule that mimics the analyte and forms cavities that are sterically and chemically complementary to the analyte. The HPLC eluate is then analysed for NNAL by electrospray ionization MS-MS. This system requires a less elaborate clean-up than previous methods.

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