Release of N-nitrosamines and N-nitrosatable substances from baby bottle teats and rubber kitchen tools in Korea

A Novel Method for Monitoring N-Nitrosamines Impurities Using NH2-MIL-101(Fe) Mediated Dispersive Micro-Solid Phase Extraction Coupled with LC-MS/MS in Biopharmaceuticals

A highly efficient and convenient method for the simultaneous determination of 12 N-nitrosamines (NAs) has been developed using an amine-functionalized metal-organic framework (NH2-MIL-101(Fe)) as sorbent for dispersive micro-solid phase extraction (D-μSPE) coupled with LC-MS/MS in biopharmaceuticals. The experimental variables involved in the extraction process (i.e., amount of the sorbent, extraction time, desorption time, ionic strength, desorption solvent and volume) were optimized to achieve the best extraction efficiency of the target analytes. Under the optimum conditions, the method was successfully validated, showing good linearity in the range of 0.5-3.0 μg/L with determination coefficients (R2) higher than 0.990, repeatability (RSD ≤ 10.0%, spiked level at 2.0 μg/L) and precision (RSD ≤ 8.2%). The limit of detection (LOD) and limit of quantitation (LOQ) were in the range of 0.005-0.025 μg/L and 0.010-0.250 μg/L, respectively. Satisfactory recoveries ranging from 82.4 to 116.8% were obtained by spiking standards at three different concentrations (0.5 μg/L, 2.0 μg/L and 3.0 μg/L). Other validation parameters, including specificity, stability, and robustness, met the validation criteria. More importantly, the plausible adsorption mechanism on NH2-MIL-101(Fe) was proposed by Fourier-transform infrared (FTIR) spectra technique. Finally, this method was successfully applied to detect trace nitrosamines in biopharmaceuticals.

Analysis of N-nitrosamines and N-nitrosatable substances from baby bottle rubber teats by liquid chromatography tandem mass spectrometry

A simple and sensitive method based on liquid chromatography-atmospheric pressure chemical ionisation-tandem mass spectrometry (LC-APCI-MS/MS) was developed and validated to determine the levels of 13N-nitrosamines and N-nitrosatable substances migrated from rubber teats into artificial saliva. The migration test from rubber teats was conducted at 40 °C and for 24 h in artificial saliva, and the migrated artificial saliva solution was analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) without further extracting steps. The sensitivity of N-nitrosamines was examined by applying atmospheric chemical ionisation and electrospray ionisation to optimise the mass spectrometric conditions, and the atmospheric chemical ionisation (APCI) mode exhibited 1.6-19 times higher sensitivity. Method validation showed acceptable linearity, precision, and accuracy, and the detection and quantification limits were 0.07-0.35 and 0.24-1.1 μg kg^-1, respectively. The developed liquid chromatography-atmospheric chemical ionisation-tandem mass spectrometry method was applied to 39 domestic and imported rubber teats. From 39 samples, N-nitrosamines [N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), and N-nitroso n-methyl N-phenylamine (NMPhA)] were detected in 30 samples, with N-nitrosatable substances in 17 samples give rise to NDMA, NMOR, and N-nitrosodiethylamine. However, the levels were below the specific migration limit of Korean Standards and Specifications for Food Containers, Utensils, and Packages and EC Directive 93/11/EEC.

Metabolomics-based molecular signatures reveal the toxic effect of co-exposure to nitrosamines in drinking water

Nitrosamines, a group of emerging nitrogenous pollutants, are ubiquitously found in the drinking water system. However, less is known about how systemic biological responses resist or tolerate nitrosamines, especially long-term co-exposure at low concentrations. In this study, untargeted metabolomics was used to investigate the metabolic perturbations in human esophageal epithelial Het-1A cells induced by a mixture of nine common nitrosamines in drinking water at environmentally relevant, human-internal-exposure, and genotoxic concentrations. Generally, the disrupted metabolic spectrum became complicated with nitrosamines dose increasing. Notably, two inflammation-associated pathways, namely, cysteine (Cys) and methionine (MET) metabolism, and nicotinate and nicotinamide metabolism, changed significantly under the action of nitrosamines, even at the environmentally relevant level. Furthermore, targeted metabolomics and molecular biology indicators in cells were identified in mice synchronously. For one thing, the up-regulated Cys and MET metabolism provided methyl donors for histone methylation in the context of pro-inflammatory response. For another, the down-regulated NAD⁺/NADH ratio inhibited the deacetylation of NF-кB p65 and eventually activated the NF-кB signaling pathway. Taken collectively, the metabolomics molecular signatures were important indicative markers for nitrosamines-induced inflammation. The potential crosstalk between the inflammatory cascade and metabolic regulation also requires further studies. These findings suggest that more attention should be paid to long-term co-exposure at low concentrations in the control of nitrosamines pollution in drinking water. Additionally, this study also highlights a good prospect of the combined metabolomic-molecular biology approach in environmental toxicology.

Comparison of EI-GC-MS/MS, APCI-LC-MS/MS, and ESI-LC-MS/MS for the Simultaneous Analysis of Nine Nitrosamines Eluted from Synthetic Resins into Artificial Saliva and Health Risk Assessment

Nitrosamines can be produced during the manufacture of rubber-type products such as pacifiers or the nipples of baby bottles. Humans can be exposed to the nitrosamines in these products when they are eluted into saliva. In this study, we compared the efficiency of electron impact ionization (EI), atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI) methods for the analysis of nine nitrosamines eluted into artificial saliva. In addition, nine nitrosamines eluted from 54 rubber-type products (rubber, thermoplastic elastomer, thermoplastic polyurethane, and polyurethane) marketed in Korea were monitored. Finally, non-carcinogenic and carcinogenic risk assessments of oral exposure to nine nitrosamines were performed based on the monitoring results. EI-GC-MS/MS performed the best for the simultaneous analysis of these nine nitrosamines with respect to overall linearity, trace analysis limit of detection (less than 1 μg), recovery (average 108.66 ± 9.32%), and precision (less than 6%), compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) (APCI and ESI) methods. Using the EI-GC-MS/MS method, these nine nitrosamines eluted into artificial saliva from 54 rubber-type products were monitored. Based on the monitoring data, risk assessment was performed by calculating the margin of exposure (MOE) for the respective nitrosamines detected. As a result, these nitrosamines were confirmed to be safe with regard to both non-carcinogenic and carcinogenic risks.

Low-Level Determination of Mutagenic Nitrosamine Impurities in Drug Substances by LC–MS/MS

Since the detection of N-nitrosodimethylamine (NDMA) in a batch of valsartan in 2018, at levels exceeding ICH acceptable intake limits for mutagenic impurities, the analysis of nitrosamines has become an intense focus point for the pharmaceutical industry. The identification and low-level determination of nitrosamines in potentially affected materials is challenging and requires the application of highly sensitive analytical techniques. This article reviews the chronological development of the story and the regulatory landscape that has evolved. It will then discuss the development of analytical methods for the determination of a series of nitrosamines referenced by regulatory authorities, demonstrating separation of these compounds from the active pharmaceutical ingredient (API) and looking at how mass spectrometry (MS) can be applied to ensure that the required detection limits can be reached.

Progress in the pretreatment and analysis of N-nitrosamines: an update since 2010

As highly toxic substances, N-nitrosamines (NAs) have been proved to cause carcinogenesis and mutagenesis in humans. Therefore, to carefully monitor safety and preserve human health, the development of rapid, accurate, and high-sensitivity determination methods of NAs is of substantial importance. This review provides a current-status comprehensive summary of the pretreatment and determination methods of NAs in various samples since 2010. Common pretreatment methods that have been used to extract and purify targets include solid-phase extraction, liquid-liquid extraction and various microextraction methods, such as solid-phase microextraction and liquid-phase microextraction, among others. Determination methods include liquid chromatography, gas chromatography, supercritical fluid chromatography and electrochemical methods, among others. In addition, we discuss and compare the advantages and disadvantages of various pretreatment and analytical methods and examine the prospects in this area.