Determination Of Volatile Nitrosamines Research Articles

Determination of volatile nitrosamines in urine through gas chromatography-mass spectrometry

To establish a detection method based on gas chromatography-mass spectrometry (GC-MS) for concentrations of volatile nitrosamine compounds in urine, and apply it to the test of real samples. Target compounds dichloromethane in urine samples was extracted with dichloromethane through liquid-liquid extraction, then the dichloromethane extract was filtrated, evaporated with nitrogen at 40°C to dryness, and the volume was set with 0.2 ml dichloromethane. Analysis of nine volatile nitroso-compounds were performed with GC-MS under selected ion monitoring mode, external reference method was used for quantification, and the detection limit, repeatability and sensitivity were evaluated. In addition, nine volatile nitroso-compounds of 92 urine samples in a town of Anhui province were measured. A good linear range of 2 - 200 ng/ml (with correlation coefficient 0.9985 - 0.9999) were obtained for the above mentioned nine kinds of analyte, and the lowest examination concentration was 0.05 - 0.50 ng/ml. The addition standard recoveries were 68%-102% with the RSD of 0.4% - 5.5% (n = 3). The detection limits were 0.001 - 0.013 ng/ml urine. The detection rate of N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR), N-nitrosopiperidine (NPIP), N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiphenylamine (NDPhA) were 71% (65), 74% (68), 65% (60), 80% (73), 92% (85), 78% (72), 76% (70), 87% (80), 98% (90), respectively, with the results (0.27 ± 0.12), (0.75 ± 0.29), (0.06 ± 0.02), (0.16 ± 0.07), (23.66 ± 5.18), (1.01 ± 0.35), (0.38 ± 0.11), (2.47 ± 0.52) and (15.13 ± 3.48) nmol/g creatinine. A gas chromatography-mass spectrometry detect method was developed for low level volatile nitrosamines in urine samples.

Determination of volatile nitrosamines in meat products by microwave-assisted extraction and dispersive liquid–liquid microextraction coupled to gas chromatography–mass spectrometry

Microwave-assisted extraction (MAE) and dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–mass spectrometry (GC–MS) were evaluated for use in the extraction and preconcentration of volatile nitrosamines in meat products. Parameters affecting MAE, such as the extraction solvent used, and DLLME, including the nature and volume of the extracting and disperser solvents, extraction time, salt addition and centrifugation time, were optimized. In the MAE method, 0.25 g of sample mass was extracted in 10 mL NaOH (0.05 M) in a closed-vessel system. For DLLME, 1.5 mL of methanol (disperser solvent) containing 20 μL of carbon tetrachloride (extraction solvent) was rapidly injected by syringe into 5 mL of the sample extract solution (previously adjusted to pH 6), thereby forming a cloudy solution. Phase separation was performed by centrifugation, and a volume of 3 μL of the sedimented phase was analyzed by GC–MS. The enrichment factors provided by DLLME varied from 220 to 342 for N-nitrosodiethylamine and N-nitrosopiperidine, respectively. The matrix effect was evaluated for different samples, and it was concluded that sample quantification can be carried out by aqueous calibration. Under the optimized conditions, detection limits ranged from 0.003 to 0.014 ng mL −1 for NPIP and NMEA, respectively (0.12–0.56 ng g −1 in the meat products).

Determination of volatile nitrosamines in various meat products using comprehensive gas chromatography–nitrogen chemiluminescence detection

An optimized method was developed for the extraction, pre-concentration and analysis of nitrosamines (NAs) in various meat products. Values of reproducibility, linearity, limit of detection (LOD) and limit of quantitation (LOQ) for six NA standards ( N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodi- n-propylamine, N-nitrosopyrrolidine, N-nitrosopiperidine, N-nitrosodi- n-butylamine) were determined. The LODs using this method were between 1.66–3.86 and LOQs between 6.96–16.71 μg L −1. The screening of four different types of meat samples (sausage, salami, sucuk and doner kebab) showed that all samples contained levels of various NAs, identified with high confidence using comprehensive gas chromatography (GCxGC) and a fast responding element specific nitrogen chemiluminescence detector (NCD). The sum of the six NAs were highest in the doner kebab samples, being between 0.51–16.63 μg kg −1 and were lowest in the sausage samples at 0.45–2.93 μg kg −1. The described method is simple, rapid, selective and sensitive.

Determination of volatile nitrosamines in cheese and cured meat products. Model study of a temperature- and pH-dependent artefact formation phenomenon in alkaline medium.

The present paper describes how the formation of artefactual nitrosodimethylamine (NDMA) may jeopardize attempts at determining volatile nitrosamines in cheese by the mineral oil technique (MOT) or the glycerol isolation technique (GIT). When such isolation techniques were performed at an initial pH of about 11 and a final temperature of 100 degrees C (compared to 70 degrees C), up to about 10 micrograms NDMA per kg was formed. In a meat product, which was examined for comparison, even more extensive artefact formation (up to 70 micrograms NDMA per kg) was found. The addition of 10 mg/kg morpholine, as a readily nitrosatable substrate, to this meat product resulted (under the most unfavourable conditions) in formation of 250 micrograms/kg artefactual nitrosomorpholine. Alkalization of samples before nitrosamine analysis is a widely practised method to prevent artefact formation and has been emphatically recommended by an international working group, convened by the International Agency for Research on Cancer (Lyon). The mechanism of this peculiar artefact formation, which is strongly temperature- and pH-dependent, is not as yet known. It may however involve transnitrosation by C-, S- or O-nitroso compounds, e.g. nitrosophenols, nitrosothiols, alkyl nitrites, sugar nitrite esters, or lipid-nitrite reaction products. Several parameters of initial pH, final temperature and use of inhibitors under which the phenomenon will or will not occur are discussed. The artefact formation described here occurs mostly at pH values which are common to laboratory situations, but which are rare as for as the preparation of food in the household is concerned. Therefore, the effect does not appear to imply a risk to the consumer's health.

Improved Method for Determination of Volatile Nitrosamines in Baby Bottle Rubber Nipples and Pacifiers

A method is described for determining volatile nitrosamines in baby bottle rubber nipples and pacifiers. The method consists of overnight soaking of the sample with dichloromethane in the presence of propyl gallate, an inhibitor for artifactual formation of nitrosamines; extraction with dichloromethane using an ambient temperature column procedure; distillation from aqueous alkali; extraction of the aqueous distillate with dichloromethane and concentration of the extract using a Kuderna-Danish concentrator; and final analysis by gas chromatography with detection by thermal energy analyzer. Major improvements over other published methods include a simpler extraction, a more efficient distillation and concentration to minimize losses, and incorporation of propyl gallate inhibitor as well as of a test to detect unsuitable dichloromethane solvent that otherwise might lead to artifactual formation. The method is highly accurate (approximately 90% recovery) and precise (av. CV = 4.7% at greater than 9 ppb levels) and is applicable to determination of nitrosamines in both rubber- and plastic-based products.

Some improvements in the determination of volatile nitrosamines by fused silica capillary-GC in combination with a thermal energy analyzer

Fused silica capillary columns of different diameters and polarities are linked to a thermal energy analyzer and a flame ionisation detector for comparison. Extra column effects are discussed. Unsymmetrical homologue nitrosamines are applied in order to assign the volatile nitrosamines most often to be determined by their linear indices rather than by their overall retention times.

Determination of volatile nitrosamines in crops and soils treated with dinitroaniline herbicides.

Determination of volatile nitrosamines in crops and soils treated with dinitroaniline herbicides.