RESUMO
A newly developed, ion exchange-based inline pretreatment system was used to mitigate the effect of background constituents in natural water and treated wastewater to achieve rapid, reliable, and sensitive analysis of N-nitrosamines. The pretreatment system (anion exchange module, AEM) was incorporated into a high-performance liquid chromatograph (HPLC) coupled with a photochemical reactor (PR) and chemiluminescence (CL) detector (HPLC-PR-CL), which can analyze four hydrophilic N-nitrosamines at ng/L levels. This system requires no pre-concentration of the water sample nor the use of deuterated surrogates, unlike other conventional N-nitrosamine analytical techniques. The AEM converted anions in the eluent to hydroxide ions after HPLC separation and increased eluent pH, allowing for the subsequent photochemical reactions, which are otherwise achieved by pH conditioning with an additional dosing pump of basic chemical. The AEM also removed anionic interfering compounds (e.g. nitrate) from the samples, allowing for improved N-nitrosamine analysis in treated wastewater. The operating conditions of the AEM and PR were optimized to obtain sensitive and stable analytical performance. As a result, the lowest-concentration minimum reporting levels of N-nitrosodimethylamine, N-nitrosomorpholine, N-nitrosomethylethylamine, and N- nitrosopyrrolidine using the optimized system were 0.42, 0.54, 0.58, and 1.4â¯ng/L, respectively. The improved analytical method was validated by comparing the results with a conventional method based on gas chromatography coupled with a mass spectrometric ion trap detector. These results indicated that HPLC-PR-CL equipped with an inline AEM can be competitively applied as a rapid analytical technique for the determination of N-nitrosamines in various water matrices.
Assuntos
Cromatografia Líquida de Alta Pressão , Nitrosaminas/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Dimetilnitrosamina/análogos & derivados , Dimetilnitrosamina/análise , Cromatografia Gasosa-Espectrometria de Massas , Troca Iônica , Luminescência , N-Nitrosopirrolidina/análiseRESUMO
A sensitive and selective method was developed and validated to detect six volatile nitrosamines (N-nitrosodimethylamine, N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosopiperidine, N-nitrosopyrrolidine and N-nitrosomorpholine) in human urine. This method uses a liquid-liquid extraction cartridge followed by analysis with gas chromatography-tandem mass spectrometry (GC-MS-MS) and quantification based on isotopic dilution. This is the first GC-MS-MS method reported for measuring volatile nitrosamines in human urine. This method reduces the sample volume required in other methods from 5-25 to 2 mL. The limits of detection (2.62, 1.99, 2.73, 0.65, 0.25, 3.66 pg/mL, respectively) were better than existing methods, largely because of improved positive chemical ionization achieved by using ammonia gas and reducing background noise. Using nitrogen as the collision gas allowed the confirmation transition in the low mass region to be monitored. The analysis of human urine using this validated method is accurate (relative bias of 0-19%) and precise (relative standard deviation of 0.2-18% over two months of analyses). The validated method was applied to 100 urine samples and the levels of all six volatile nitrosamines were reported for the first time in urine specimens collected from smokers and nonsmokers, with smoking status determined by urinary cotinine measurement. Among 100 smokers and nonsmokers, the levels of three analytes (N-nitrosodimethylamine, N-nitrosomethylethylamine and N-nitrosopiperidine) were significantly higher in smokers than nonsmokers (p < 0.05).
Assuntos
Dietilnitrosamina/urina , Dimetilnitrosamina/urina , N-Nitrosopirrolidina/análise , Nitrosaminas/urina , Fumar/urina , Cotinina/urina , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Extração Líquido-Líquido , Reprodutibilidade dos Testes , Nicotiana , Compostos Orgânicos Voláteis/urinaRESUMO
N-nitrosamines, biogenic amines, and residual nitrites are harmful substances and are often present in cured meats. The effects of different cooking methods (boiling, pan-frying, deep-frying, and microwave) were investigated on their contents in dry-cured sausage. The various N-nitrosamines were isolated by a steam distillation method and analyzed by gas chromatography mass spectrometry (GC-MS). The biogenic amines were determined after extraction with perchloric acid as dansyl derivatives by high-performance liquid chromatography (HPLC) method. The results showed that initial dry-cured raw sausage contained 5.31 µg/kg of total N-nitrosamines. Cooking by deep-frying or pan-frying resulted in products having the highest (P < 0.05) contents, compared with boiling or microwave treatments, which were not different from the raw. Although frying increased the content of N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and N-nitrosopyrrolidine (NPYR), it decreased the contents of histamine and cadaverine. Boiling and microwave treatments decreased the total biogenic amines significantly (P < 0.05). Residual nitrite was significantly reduced by cooking treatments. The results suggest that boiling and microwave treatments were more suitable methods for cured meat.
Assuntos
Aminas Biogênicas/análise , Culinária/métodos , Dietilnitrosamina/análise , Dimetilnitrosamina/análise , Produtos da Carne/análise , N-Nitrosopirrolidina/análise , Animais , Fenômenos Químicos , Cromatografia Líquida de Alta Pressão , Micro-Ondas , Suínos , Compostos Orgânicos VoláteisRESUMO
N-nitrosamines are meant to be probable or possible carcinogenic components, possibly formed out of a reaction between nitrite and N-containing substances such as amino acids and secondary amines. Nitrite is often used for processing meat products because of its colouring and antimicrobial properties. During this experimental setup, the influence of proline, hydroxyproline or pyrrolidine on N-nitrosamine formation in meat samples was evaluated. The N-nitrosamines concentrations were measured with gas chromatography-thermal energy analyzer. Only the concentrations of N-nitrosodimethylamine and N-nitrosopyrrolidine were found above the limit of detection in a number of tested experimental conditions. The concentration of these two N-nitrosamines was modelled as a function of temperature and nitrite concentration for different situations (presence or absence of added natural N-containing meat components). It could be concluded that proline and pyrrolidine promoted the formation of N-nitrosopyrrolidine. It could also be confirmed that the higher the temperature of the meat processing procedure and the higher the sodium nitrite amounts added, the higher were the yields of the respective N-nitrosamines.
Assuntos
Carcinógenos/análise , Hidroxiprolina/química , Carne/análise , Nitrosaminas/análise , Prolina/química , Pirrolidinas/química , Nitrito de Sódio/química , Carcinógenos/química , Cromatografia Gasosa , Dimetilnitrosamina/análise , Limite de Detecção , N-Nitrosopirrolidina/análise , Nitrosaminas/química , TemperaturaRESUMO
N-Nitrosopyrrolidine (NPYR) and N-nitrosodimethylamine (NDMA), known animal carcinogens, are consistently formed in bacon during frying. As a result, commercial bacon has been subject to regulatory monitoring and compliance for the past 20 years to ensure that N-nitrosamines do not exceed the 10 ppb volatile level. Currently, time-consuming distillation-solvent extraction and solid-phase extraction (SPE) methods are used for this purpose. With an emphasis on reducing solvent use, we investigated supercritical fluid extraction (SFE) using supercritical carbon dioxide (SC-CO2) for isolation of volatile nitrosamines common to fried bacon. Eighteen fried bacon samples were analyzed for NPYR and NDMA by SFE, SPE, mineral oil distillation (MOD), and low-temperature vacuum distillation (LTVD) methods, using the same gas chromatographic-chemiluminescence detection (thermal energy analyzer) conditions. The range of values for SFE was 0.7 to 20.2 ppb for NPYR and none detected (ND) to 2.4 ppb for NDMA. Analysis of variance of the NPYR data showed a significant difference (p < 0.05) between SFE and SPE results and significant differences between these and those obtained by MOD and LTVD. Overall, SFE was superior to the other methods with the highest recoveries, best repeatability, rapidity of analysis, and solvent-sparing characteristics. Similar results were obtained for SFE after comparison with distillation and SPE methods for determining the same nitrosamines in fried bacon drippings.
Assuntos
Carcinógenos/análise , Análise de Alimentos/métodos , Produtos da Carne/análise , N-Nitrosopirrolidina/análise , Compostos Nitrosos/análise , Análise de Variância , Animais , Dióxido de Carbono/química , Carcinógenos/metabolismo , Cromatografia Gasosa , Interpretação Estatística de Dados , Análise de Alimentos/normas , Contaminação de Alimentos , Manipulação de Alimentos , Medições Luminescentes , N-Nitrosopirrolidina/metabolismo , Compostos Nitrosos/metabolismo , Padrões de Referência , Reprodutibilidade dos Testes , Solventes/químicaRESUMO
A total of 391 gastric juice samples was collected from Ji Yuan and An Shi counties, high and medium risk areas of esophageal carcinoma in Henan province. NDMA, NDEA, NMBzA, NPip and unknown compounds were assayed in the fasting gastric juice. Among these nitrosamines, NMBzA, NPyr and NPip were specific in inducing esophageal cancer in animals. The amount of nitrosamines in the gastric juice collected from Ji Yuan county was higher than that from An Shi county. The exposure level of nitrosamines of subjects from these two localities were significantly different (P < 0.001). There was a positive relationship between the nitrosamines exposure level and esophageal cancer mortality rate. The amount of gastric N-nitrosamines from An Shi subjects as treated with vitamin C was reduced. It is evident that vitamin C can inhibit N-nitrosamine formation in the stomach, thereby, reducing the N-nitrosamines exposure level.
Assuntos
Ácido Ascórbico/farmacologia , Neoplasias Esofágicas/química , Suco Gástrico/química , Nitrosaminas/análise , Adulto , Idoso , Dimetilnitrosamina/análogos & derivados , Dimetilnitrosamina/análise , Esôfago/patologia , Feminino , Humanos , Hiperplasia , Masculino , Pessoa de Meia-Idade , N-Nitrosopirrolidina/análise , Nitrosaminas/antagonistas & inibidores , Lesões Pré-Cancerosas/químicaRESUMO
The second check sample survey for the determination of N-nitrosamines in beer and malt has been initiated. Each laboratory received four samples: two beer, from the same batch, spiked respectively with 0.5 microgram/l N-nitrosodimethylamine (NDMA) and 4 micrograms/l NDMA plus 30 micrograms/l N-nitrosoproline (NPRO) and two naturally contaminated malts. Sixteen laboratories sent their results and two apologized in view of analytical problems. Results from this have been statistically evaluated. Comparison to those from the previous study demonstrated a distinct improvement in the results from the analysis of NDMA in beer and malt. Little has been achieved for the other two common contaminants of beer and malt, N-nitrosopyrrolidine (NPYR) and NPRO. For this latter compound in beer, however, some hope came from the data produced by the method of Sen et al. (1983), but the number of results is insufficient to allow firm conclusions to be drawn.
Assuntos
Cerveja/análise , Contaminação de Alimentos/análise , Compostos Nitrosos/análise , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Dimetilnitrosamina/análise , Cromatografia Gasosa-Espectrometria de Massas , N-Nitrosopirrolidina/análise , Nitrosaminas/análiseRESUMO
The metabolism of N-mononitrosopiperazine (NPz) and N,N'-dinitrosopiperazine (DNPz) was investigated in Sprague-Dawley rats. When an oral dose of 50 micrograms/rat NPz was administered, 10.5% of the dose was recovered unchanged in urine together with N-nitroso-3-hydroxypyrrolidine (NHPYR, 1.3% of administered NPz dose) and N-nitrosodiethanolamine (NDELA, 0.3%). For DNPz, 7.7% of the administered dose together with NPz (0.04%), NHPYR (2.9%), NDELA (6.7%) and N-nitroso(2-hydroxyethyl)glycine (NHEG, 20.2%) was recovered in urine after 24 h. These results show extensive metabolism of both NPz and DNPz and suggest that both NPz and NHPYR could be analysed in urine as markers for the endogenous nitrosation of piperazine in patients receiving antihelminthic treatment with piperazine.
Assuntos
Carcinógenos/metabolismo , Nitrosaminas/metabolismo , Animais , Cromatografia Gasosa , Dietilnitrosamina/análise , Masculino , N-Nitrosopirrolidina/análogos & derivados , N-Nitrosopirrolidina/análise , Nitrosaminas/urina , Ratos , Ratos EndogâmicosRESUMO
Traces of N-nitrosopyrrolidine (NPYR) may occur in some samples of both instant coffee and fine-ground roasted coffee. The identity of NPYR in 2 samples of instant coffee was confirmed by mass spectrometry as well as by liquid chromatography-thermal energy analysis. A 2-step cleanup procedure, involving fractionation on basic alumina followed by gradient elution on reverse-phase C18 cartridge, is described that allows full-scan mass spectrometric confirmation of NPYR in tested samples.
Assuntos
Café/análise , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Cromatografia Gasosa , Cromatografia Líquida , Indicadores e Reagentes , Espectrometria de Massas , SolventesRESUMO
Dry-cured or "country-style" bacon is a low volume specialty product typically made by small producers whose production practices vary widely. These practices include the direct application of dry-cure formulations containing varying concentrations of salt, sugar, flavoring agents, sodium nitrite, and sometimes sodium nitrate, and the use of lengthy curing and processing times. Because of the possibility of generating higher levels of N-nitrosopyrrolidine (NPYR) after frying in this product type compared with pump-cured bacon, an investigation was carried out on dry-cured bacon obtained from cooperating state or federally inspected establishments. Three different samples from each of the 16 plants were analyzed. Only one sample from each of 2 different producers exceeded the Food Safety and Inspection Service (FSIS) action level of 17 ppb NPYR, indicating that the majority of samples tested were in compliance. A significant correlation (P less than 0.01) was found between residual NaNO2 prior to frying and NPYR after frying. The elimination of added nitrate in the dry-cure formulations is recommended.
Assuntos
Contaminação de Alimentos/análise , Carne/análise , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Animais , Cromatografia Gasosa , Culinária , Gorduras na Dieta/análise , Proteínas Alimentares/análise , Indicadores e Reagentes , Nitratos/análise , Peróxidos/análise , Cloreto de Sódio/análise , Nitrito de Sódio/análise , Suínos , Água/análiseRESUMO
Foods on the Swedish market in 1980-1986 were analysed for volatile N-nitrosamines using gas chromatography-thermal energy analysis. Detectable levels were found in 474 of the 764 samples analysed. The average daily intake of volatile N-nitrosamines was estimated to be 0.29 microgram per person. Over 93% of the intake comes from meat and malt products.
Assuntos
Análise de Alimentos , Alimentos , Nitrosaminas/análise , Animais , Cromatografia Gasosa , Dimetilnitrosamina/análise , Ingestão de Alimentos , Carne/análise , N-Nitrosopirrolidina/análise , Suécia , Suínos , VolatilizaçãoRESUMO
A total of 353 samples of gastric juice was collected from Lin-xian subjects who were examined by endoscopy. NDMA, NDEA, NMBzA, Npyr, Npip, NSAR and other unknown compounds were detected in the fasting gastric juice. NMBzA, Npyr, Npip and NSAR can induce esophageal cancer in animals. Among the concentrations of N-Nitrosamines in gastric juice, the level of NDMA was the highest, its mean value 17.09 ppb; the level of NDEA stood next with a mean value of 6.95 ppb; the amounts of NMBzA, Npyr and Npip were 4.77, 2.45 and 1.30 ppb, respectively. A positive correlation was found between the amount of N-Nitrosamines in gastric juice and the various lesions in the esophageal epithelium of the subjects, the amount of N-Nitrosamines in gastric juice from subjects with normal esophageal epithelium was lower than that from subjects with marked dysplasia or carcinoma of esophagus. This finding lends further support to their possible involvement in esophageal cancer development.
Assuntos
Neoplasias Esofágicas/análise , Esôfago/patologia , Suco Gástrico/análise , Nitrosaminas/análise , Carcinógenos/análise , Dimetilnitrosamina/análogos & derivados , Dimetilnitrosamina/análise , Epitélio/patologia , Humanos , Hiperplasia , N-Nitrosopirrolidina/análiseRESUMO
Three methods, the mineral oil distillation (MOD), the dry column (DC), and a low temperature vacuum distillation (LTVD), for the determination of N-nitrosopyrrolidine in dry-cured and pump-cured bacon were compared. Each method uses the thermal energy analyzer for the determinative step. The coefficients of variation for repeatability were 10.3% (MOD), 7.2% (DC), and 9.1% (LTVD) for the dry-cured bacon study and 8.7% (MOD), 8.5% (DC), and 7.1% (LTVD) for the pump-cured bacon study. The pooled coefficients of variation for between-method reproducibility were 11.8% for the dry-cured bacon and 10.8% for the pump-cured bacon. The pooled coefficients of variation for repeatability were 9.0% for the dry-cured bacon and 8.2% for the pump-cured bacon. These values compare favorably with the values from previous collaborative or validation studies of the individual methods, and the methods can be considered to be equivalent.
Assuntos
Culinária , Carne/análise , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Animais , Fenômenos Químicos , Química , Estudos de Avaliação como Assunto , Conservação de Alimentos , Óleo Mineral , SuínosRESUMO
Bacon was soaked in water before frying and the effect on the formation of N-nitrosodimethylamine and N-nitrosopyrrolidine was studied. Soaking for 5 minutes reduced N-nitrosopyrrolidine levels by as much as 52%, but had little effect on N-nitrosodimethylamine levels. Longer soaking periods, up to 17 hours, gave the same results.
Assuntos
Carne/análise , Nitrosaminas/análise , Água , Animais , Culinária , Dimetilnitrosamina/análise , Contaminação de Alimentos/análise , Manipulação de Alimentos , N-Nitrosopirrolidina/análise , Nitrito de Sódio/análise , Suínos , Água/análiseRESUMO
Evidence is presented that the likely major amine precursors to N-nitrosopyrrolidine in cooked bacon are free proline in the adipose tissue and to a lesser extent, collagenous connective tissues. A model system in which animal lipid is replaced with hydrogenated vegetable oil is described and used in investigating the potential role of prolyl derivatives as precursors to N-nitrosopyrrolidine.
Assuntos
Carne/análise , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Tecido Adiposo/análise , Animais , Fenômenos Químicos , Química , Culinária , Gorduras na Dieta/análise , Indicadores e Reagentes , Prolina/análise , SuínosRESUMO
A method is presented, wherein concentrated dichloromethane extracts from malt, beer, and nonfat dried milk powder containing N-nitrosodimethylamine (NDMA), and fried dry-cured and pump-cured bacon containing NDMA and N-nitrosopyrrolidine (NPYR) undergo 3N HClO4-Celite microcolumn cleanup followed by peroxidation with pentafluoroperoxybenzoic acid, a stable solid peroxyacid, to N-nitrodimethylamine and N-nitropyrrolidine, as an aid to nitrosamine confirmation. The nitramine-containing solution underwent further cleanup with 6N HClO4-Celite and acid alumina-6% H2O microcolumns for subsequent analysis by gas chromatography interfaced with thermal energy analyzer and 63Ni electron capture detectors. With a 20 g sample, 1 ppb NDMA and 2.5 ppb NPYR could be confirmed by this method. The extract can be concentrated further before analysis, so the detection level can be reduced to less than 1 ppb NDMA and 1 ppb NPYR.
Assuntos
Dimetilnitrosamina/análise , Contaminação de Alimentos/análise , Hidroxilaminas , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Fenômenos Químicos , Química , Peróxido de Hidrogênio/análise , Peróxidos/análiseRESUMO
A dry column method for isolating N-nitrosopyrrolidine (NPYR) from fried, cure-pumped bacon and detection by gas chromatography-thermal energy analyzer (TEA) was studied collaboratively. Testing the results obtained from 11 collaborators for homogeneous variances among samples resulted in splitting the nonzero samples into 2 groups of sample levels, each with similar variances. Outlying results were identified by AOAC-recommended procedures, and laboratories having outliers within a group were excluded. Results from the 9 collaborators remaining in the low group yielded coefficients of variation (CV) of 6.00% and 7.47% for repeatability and reproducibility, respectively, and the 8 collaborators remaining in the high group yielded CV values of 5.64% and 13.72%, respectively. An 85.2% overall average recovery of the N-nitrosoazetidine internal standard was obtained with an average laboratory CV of 10.5%. The method has been adopted official first action as an alternative to the mineral oil distillation-TEA screening procedure.
Assuntos
Carne/análise , N-Nitrosopirrolidina/análise , Nitrosaminas/análise , Animais , Cromatografia Gasosa/métodos , Culinária , Conservantes de Alimentos/análise , SuínosRESUMO
A rapid and sensitive procedure is described for determining 4 N-nitrosodialkylamines (dimethyl, diethyl, dipropyl, and dibutyl) and the N-nitroso analogs of piperidine, pyrrolidine, and morpholine in animal feed. The volatile N-nitrosamines were isolated by using a modified high temperature purge and trap apparatus designed for multiple sample cleanup. The feed sample was mixed with mineral oil and a nitrosation inhibitor, and the N-nitrosamines were purged onto a ThermoSorb/N cartridge, eluted with acetone-dichloromethane (1 + 1), and determined by gas chromatography, using a thermal energy analyzer. The effects of purge rate, purge time, and temperature on recovery are discussed. Feed samples spiked with 10, 50, and 200 ppb of the 7 N-nitroso compounds yielded recoveries ranging from 70 to 97%, with precision ranging from 1.3 to 5.4% and minimum detectable levels in the low parts-per-billion range.
Assuntos
Ração Animal/análise , Nitrosaminas/análise , Cromatografia Gasosa/instrumentação , Cromatografia Gasosa/métodos , Dietilnitrosamina/análise , Dimetilnitrosamina/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Temperatura Alta , N-Nitrosopirrolidina/análiseRESUMO
The recently developed Eastern Regional Research Center ( ERRC ) dry column chromatographic procedure for determining N-nitrosopyrrolidine (NPYR) in fried cure-pumped bacon was evaluated for its applicability to fried dry-cured bacon. The method was then compared with 2 established procedures for volatile nitrosamine analysis in cured meat products: the multidetection thermal energy analyzer (MD) method and the mineral oil distillation (MOD) screening procedure. No significant difference (P less than 0.05) in NPYR values was found between the ERRC and MD procedures, but significant differences were found between the ERRC and MOD procedures and between the MOD and MD procedures. No artifactual nitrosamine formation was found in the ERRC procedure, but significant amounts were found in samples analyzed by the MOD procedure. The ERRC method was demonstrated to be rugged and very rapid. It is proposed that the ERRC method replace the MOD method as the official screening procedure for NPYR in fried bacon.