Comparison of the sensitivities of seven N-nitrosamines in pre-screened waters using an automated preconcentration system and gas chromatography with different detectors

Nitrosamines crisis in pharmaceuticals - Insights on toxicological implications, root causes and risk assessment: A systematic review

The presence of N-nitroso compounds, particularly N-nitrosamines, in pharmaceutical products has raised global safety concerns due to their significant genotoxic and mutagenic effects. This systematic review investigates their toxicity in active pharmaceutical ingredients (APIs), drug products, and pharmaceutical excipients, along with novel analytical strategies for detection, root cause analysis, reformulation strategies, and regulatory guidelines for nitrosamines. This review emphasizes the molecular toxicity of N-nitroso compounds, focusing on genotoxic, mutagenic, carcinogenic, and other physiological effects. Additionally, it addresses the ongoing nitrosamine crisis, the development of nitrosamine-free products, and the importance of sensitive detection methods and precise risk evaluation. This comprehensive overview will aid molecular biologists, analytical scientists, formulation scientists in research and development sector, and researchers involved in management of nitrosamine-induced toxicity and promoting safer pharmaceutical products.

Current status and prospects of development of analytical methods for determining nitrosamine and N-nitroso impurities in pharmaceuticals

Nitrosamine impurities in pharmaceuticals have recently been concerned for several national regulatory agencies to avoid carcinogenic and mutagenic effects in patients. The demand for highly sensitive and specific analytical methods with LOQs in the ppb and sub-ppb ranges is among the most significant challenges facing analytical scientists. In addition, artifactual nitrosamine formation during sample preparation and injection leading to overestimation of nitrosamines has received considerable attention. Numerous analytical methodologies have been reported for quantifying nitrosamine impurities in active pharmaceutical ingredients and medicinal products at the interim limit criteria as preventive measures. In this review, we meticulously discuss those reported gas and liquid chromatographic methods for nitrosamine determination in pharmaceuticals in aspects of chromatographic conditions and sensitivity of detection. We also introduce the potential of novel fluorescence-based methods recently developed to rapidly screen nitrosamine impurities. In addition, the review assesses the nitrosation assay procedure (NAP test), which is expected to be a future preventive measure for screening potential nitrosation and identifying suspected contamination with N-nitroso or other potential mutagenic impurities during the drug development process.

N-nitrosamines in Qingdao dried aquatic products and dietary risk assessment

N-nitrosamines are human carcinogens commonly present in dried aquatic products. A method of gas chromatography - mass spectrometry combined with steam distillation was developed for the determination of 9 N-nitrosamines in dried aquatic products in Qingdao, China, with which 300 samples of fish, squid, shrimp and sea cucumber collected from Qingdao were analysed. A health risk assessment was conducted based on determined levels of N-nitrosamines by using estimated daily intake and slope factors. Results showed that fish products was the category with the highest content of N-nitrosamines, whereas squid and shrimp products were the categories with the highest frequency of presence of N-nitrosamines. The average estimated cancer risk of N-nitrosamines in dried aquatic products in Qingdao ranged from 3.57 × 10^-8 to 3.53 × 10^-5. Nitrosodimethylamine, N-Nitrosodiethylamine and N-Nitrosodibutylamine could be considered to pose a potential cancer risk to residents in Qingdao.

Development of multi-residue gas chromatography coupled with mass spectrometry methodologies for the measurement of 15 chemically different disinfection by-products (DBPs) of emerging concern in drinking water from two different Portuguese water treatment plants

In water treatment plants (WTPs), chemical agents, such as chlorine and ozone, might react with organic matter and anthropogenic contaminants, forming a high diversity of disinfection by-products (DBPs). Due to the potential toxicological effects, the identification of unregulated DBPs (UR-DBPs) is critical to help water managers in the selection of effective water treatment processes, contributing to improving water safety plans. Given the limited validated analytical methods to detect UR-DBPs, here we developed new multi-residue gas chromatography coupled with mass spectrometry methodologies for the detection and quantification of 15 UR-DBPs, including aldehydes, haloketones (HKs), nitrosamines and alcohols, in drinking water matrices. Solid-phase extraction (SPE), for the nitrosamine group, and solid-phase micro extraction (SPME), for the remaining DBPs, were used as sample preparation methods. The developed methodologies allowed the quantification of target UR-DBPs at trace concentration levels (ng L^-1), with method quantification limits (MQLs) ranging from 14.4 ng L^-1 to 26.0 ng L^-1 (SPE-GC-MS) and 2.3 ng L^-1 and 1596 ng L^-1 (SPME-GC-MS). The methods were applied to different drinking water matrices, considering distinct delivery points of EPAL - Empresa Portuguesa das Águas Livres WTPs. Overall, the aldehyde group, represented by decanal, nonanal and 2-ethylheaxanal, showed the highest occurrence, followed by HKs and nitrosamines. The results of this study suggested that the formation of these UR-DBPs should be further monitored in WTPs.

Development of a Sensitive Screening Method for Simultaneous Determination of Nine Genotoxic Nitrosamines in Active Pharmaceutical Ingredients by GC-MS

A worldwide crisis with nitrosamine contamination in medical products began in 2018. Therefore, trace-level analysis of nitrosamines is becoming an emerging topic of interest in the field of quality control. A novel GC-MS method with electron ionization and microextraction was developed and validated for simultaneous determination of nine carcinogenic nitrosamines (NDMA, NMEA, NDEA, NDBA, NMOR, NPYR, NPIP, NDPA, and N-methyl-npz) in active pharmaceutical ingredients (APIs): cilostazol, sunitinib malate, and olmesartan medoxomil. The method was validated according to the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines, demonstrating good linearity in the range of LOQ up to 21.6 ng/mL (120% of specification limit). The limits of detection for the nine nitrosamines were determined to be in the range 0.15–1.00 ng/mL. The developed trace level GC-MS method turned out to be specific, accurate, and precise. The accuracy of all the tested APIs ranged from 94.09% to 111.22% and the precision evaluated by repeatability, intermediate precision, and system precision was RSD ≤ 7.65%. Nitrosamines were not detected in cilostazol and sunitinib, whereas in olmesartan medoxomil NDEA was detected at the level of LOQ. The novel protocol was successfully applied for nitrosamines determination in selected APIs and can be used for the routine quality control of APIs under Good Manufacturing Practices rules, ensuring the safety and effectiveness of pharmaceutical products.

Absolute Quantitation of N-Nitrosamines by Coulometric Mass Spectrometry without Using Standards

Carcinogenic N-nitrosamines were recently found in the sartan family of drugs and caused many drug recalls. Both of their detection and quantification are therefore important. Methods reported for N-nitrosamine quantitation rely on the use of standards and are just applicable to simple N-nitrosamines. There is an urgent need to quantify N-nitrosamines derived from drugs with a complicated structure that lack standards. To tackle the issue, this study describes a novel absolute quantitation strategy for N-nitrosamines using coulometric mass spectrometry (CMS) without standards. In our approach, N-nitrosamine is first converted into electrochemically active hydrazine via zinc reduction under acidic condition and the resulting hydrazine can then be easily quantified using CMS. To validate our method, six simple N-nitrosamines, N-nitrosodiethylamine (NDEA), N-nitroso-4-phenylpiperidine (NPhPIP), N-nitrosodiphenylamine (NDPhA), N-nitrosodibutylamine (NDBA), N-nitrosodipropylamine (NDPA), and N-nitrosopiperidine (NPIP), were chosen as test samples, and they all were quantified with excellent measurement accuracy (quantitation error ≤1.1%). Taking this one step further, as a demonstration of the method utility, a drug-like N-nitrosamine, (R)-N-(2-(6-chloro-5-methyl-1'-nitroso-2,3-dihydrospiro[indene-1,4'-piperidin]-3-yl)propan-2-yl)acetamide (VII), was also synthesized and successfully quantified using our method at 15 ppb level in a complex formulation matrix, following solvent extraction, N-nitrosamine isolation, and reductive conversion. Because of the feature of requiring no standards, CMS provides a simple and powerful approach for N-nitrosamine absolute quantitation and has great potential for analysis of other drug impurities or metabolites.

Determination of N-Nitrosamines by Gas Chromatography Coupled to Quadrupole–Time-of-Flight Mass Spectrometry in Water Samples

An analytical method based on high-resolution quadrupole–time-of-flight (QToF) mass spectrometry has been developed as an alternative to the classical method, using a low-resolution ion trap (IT) analyzer to reduce interferences in N-nitrosamines determination. Extraction of the targeted compounds was performed by solid-phase extraction (SPE) following the United States Environmental Protection Agency (USEPA) -521 method. First, both electron impact (EI) and positive chemical ionization (PCI) using methane as ionization gas were compared, along with IT and QToF detection. Then, parameters such as limits of detection (LOD) and quantification (LOQ), linearity, and repeatability were assessed. The results showed that the QToF mass analyzer combined with PCI was the best system for the determination of the N-nitrosamines, with instrumental LOD and LOQ in the ranges of 0.2–4 and 0.6–11 ng mL−1, respectively, which translated into method LOD and LOQ in the ranges of 0.2–1.3 and 0.6–3.9 ng L−1, respectively. The analysis of real samples showed the presence of 6 of the N-nitrosamines in influent, effluent, and tap water. N-nitrosodimethylamine (NDMA) was quantified in all the analyzed samples at concentrations between 1 and 27 ng L−1. Moreover, four additional nitrosamines were found in tap and wastewater samples.

N-nitrosamines in drinking water and beer: Detection and risk assessment

Occurrence and risk related to nitrosamines, a group of carcinogenic compounds found in some drinking waters and beer, are studied. An analytical method using a solid-phase micro-extraction (SPME) along with gas chromatography (GC) and mass spectrometry (MS) was developed to determine seven N-nitrosamines in drinking water and beer, including N-nitrosomethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodimethylamine (NDMA), N-nitrosodi-n-propylamine (NDPA), N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip), and N-nitrosodinbutylamine (NDBA). The analysis can be completed in 70 min, and only a 4 mL sample is required, with a detection limit of 0.1-0.8 ng/L for the seven nitrosamines in water and 6-15.7 ng/L in beer. The method was applied to analyze water samples collected from 11 reservoirs and their associated drinking water treatment plants in Taiwan and 10 beer samples from 6 brands with factories located in 6 countries. In the drinking water samples, all seven N-nitrosamines were detected, with NDMA having the highest level at 10.2 ng/L. In the beer samples, NDMA was detected at much lower concentrations (0.12-0.23 μg/L) than the 5 μg/L US standard, while NPip was detected at much higher concentrations (4.1-5.3 μg/L) compared to NDMA. The risk assessment indicates that the risk associated with NDMA is the highest among the studied N-nitrosamines in Taiwan's drinking water, with an average cancer risk of 6.4 × 10^-06. For other nitrosamines, the risks are all below 10^-6. For the risks associated with N-nitrosamines in beer, NDMA, NDEA, NDPA, and NPip are in the range of 1.5 × 10^-05 to 4.6 × 10^-04, while that for other nitrosamines are much lower. As for beer, no information for NPip and no modern information for NDEA and NDPA have previously been available, more studies about nitrosamines in beer are suggested for better estimation and control of the risks associated with consumption of beer.

Evaluation of a method for the simultaneous quantification of N-nitrosamines in water samples based on stir bar sorptive extraction combined with high-performance liquid chromatography and diode array detection

A simple, sensitive, and reliable procedure based on stir bar sorptive extraction coupled with high-performance liquid chromatography was applied to simultaneously extract and determine three semipolar nitrosamines including N-nitrosodibutylamine, N-nitrosodiphenylamine, and N-nitrosodicyclohexylamine. To achieve the optimum conditions, the effective parameters on the extraction efficiency including desorption solvent and time, ionic strength of sample, extraction time, and sample volume were systematically investigated. The optimized extraction procedure was carried out by stir bars coated with polydimethylsiloxane. Under optimum extraction conditions, the performance of the proposed method was studied. The linear dynamic range was obtained in the range of 0.95-1000 ng/mL (r = 0.9995), 0.26-1000 ng/mL (r = 0.9988) and both 0.32-100 ng/mL (r = 0.9999) and 100-1000 ng/mL (r = 0.9998) with limits of detection of 0.28, 0.08, and 0.09 ng/mL for N-nitrosodibutylamine, N-nitrosodiphenylamine, and N-nitrosodicyclohexylamine, respectively. The average recoveries were obtained >81%, and the reproducibility of the proposed method presented as intra- and interday precision were also found with a relative standard deviation <6%. Finally, the proposed method was successfully applied to the determination of trace amounts of selected nitrosamines in various water and wastewater samples and the obtained results were confirmed using mass spectrometry.

Determination of N-nitrosamines by automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometry

An automated dispersive liquid-liquid microextraction integrated with gas chromatography and mass spectrometric procedure was developed for the determination of three N-nitrosamines (N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine) in water samples. Response surface methodology was employed to optimize relevant extraction parameters including extraction time, dispersive solvent volume, water sample pH, sodium chloride concentration, and agitation (stirring) speed. The optimal dispersive liquid-liquid microextraction conditions were 28 min of extraction time, 33 μL of methanol as dispersive solvent, 722 rotations per minute of agitation speed, 23% w/v sodium chloride concentration, and pH of 10.5. Under these conditions, good linearity for the analytes in the range from 0.1 to 100 μg/L with coefficients of determination (r(2) ) from 0.988 to 0.998 were obtained. The limits of detection based on a signal-to-noise ratio of 3 were between 5.7 and 124 ng/L with corresponding relative standard deviations from 3.4 to 5.9% (n = 4). The relative recoveries of N-nitroso-di-n-propylamine, N-nitrosopiperidine, and N-nitroso di-n-butylamine from spiked groundwater and tap water samples at concentrations of 2 μg/L of each analyte (mean ± standard deviation, n = 3) were (93.9 ± 8.7), (90.6 ± 10.7), and (103.7 ± 8.0)%, respectively. The method was applied to determine the N-nitrosamines in water samples of different complexities, such as tap water, and groundwater, before and after treatment, in a local water treatment plant.

Determination of 14 nitrosamines at nanogram per liter levels in drinking water

N-Nitrosamines, probable human carcinogens, are a group of disinfection byproducts under consideration for drinking water regulation. Currently, no method can determine trace levels of alkyl and tobacco-specific nitrosamines (TSNAs) of varying physical and chemical properties in water by a single analysis. To tackle this difficulty, we developed a single solid-phase extraction (SPE) method with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for the determination of 14 nitrosamines of health concern with widely differing properties. We made a cartridge composed of a vinyl/divinylbenzene polymer that efficiently concentrated the 14 nitrosamines in 100 mL of water (in contrast to 500 mL in other methods). This single SPE-HPLC-MS/MS technique provided calculated method detection limits of 0.01-2.7 ng/L and recoveries of 53-93% for the 14 nitrosamines. We have successfully demonstrated that this method can determine the presence or absence of the 14 nitrosamines in drinking water systems (eight were evaluated in Canada and the U.S.), with occurrence similar to that in other surveys. N-Nitrosodimethylamine (NDMA), N-nitrosodiphenylamine, and the TSNA 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol were identified and quantified in authentic drinking water. Formation potential (FP) tests demonstrated that NDMA and TSNA precursors were present in (1) water samples in which tobacco was leached and (2) wastewater-impacted drinking water. Our results showed that prechlorination or ozonation destroyed most of the nitrosamine precursors in water. Our new single method determination of alkylnitrosamines and TSNAs significantly reduced the time and resource demands of analysis and will enable other studies to more efficiently study precursor sources, formation mechanisms, and removal techniques. It will be useful for human exposure and health risk assessments of nitrosamines in drinking water.

Histopathological lesions, P-glycoprotein and PCNA expression in zebrafish (Danio rerio) liver after a single exposure to diethylnitrosamine

The presence of carcinogenic compounds in the aquatic environment is a recognized problem. ABC transporters are well known players in the multidrug-resistance (MDR) phenomenon in mammals associated with resistance to chemotherapy, however little is known in fish species. Thus, the aim of this study was to induce hepatic tumours and evaluate long-term effects on P-glycoprotein (P-gp) and proliferating cell nuclear antigen (PCNA) proteins in Danio rerio liver, after exposure to diethylnitrosamine (DEN). Several hepatic histopathological alterations were observed in zebrafish after exposure to DEN including pre-neoplastic lesions 6 and 9 months post-exposure. After 3, 6 and 9 months of exposure to DEN, P-gp and PCNA proteins expression were up-regulated. In conclusion, this study has shown that zebrafish ABC transporters can play a similar role as in human disease, hence zebrafish can be used also as a biological model to investigate in more deep mechanisms involved in disease processes.

Screening of N-nitrosamines in tap and swimming pool waters using fast gas chromatography

N-Nitrosamines (NAms) are suspected human carcinogens that have been identified as drinking water and wastewater pollutants. In this work, a sensitive screening/confirmation method was proposed for the determination of the most toxic NAms that can be found in water samples (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine, N-nitrosomorpholine, N-nitrosopiperidine, and N-nitrosopyrrolidine). A sample volume of 250 mL was first preconcentrated in an automatic SPE unit and then the extract was concentrated to a final volume of 10 microL (providing a preconcentration factor of 25,000). Aliquots of the extract were subjected to a rapid screening process (1.6 min) by using a short capillary polar column (1.5 m length) and GC with nitrogen-phosphorous detection. In this way, the high number of samples to be tested routinely in a water laboratory is simplified due to a reduction in the analysis time. Thus, the screening method acts as a filter that indicates whether target analytes are present, above or below the cut-off level (3.8 or 10.4 ng/L), giving no false negatives at concentrations below the guide values for NAms in drinking water established by different countries. Positive samples (tap and swimming pool waters) were then confirmed by GC-MS detection.

Fullerenes for aromatic and non-aromatic N-nitrosamines discrimination

The detection of N-nitrosamines (NAms) in water supplies is an environmental and public health issue because many NAms are classified as probable human carcinogens. Non-aromatic (aliphatic and cyclic) NAms are more toxic than aromatic ones as their maximum admissible concentration is limited in drinking water (20-2000ngL(-1)). From that premise, a simple and novel method to discriminate between both fractions of NAms according to their toxicity was proposed. An automatic solid-phase extraction unit containing two sequential sorbent columns was constructed. A sample volume of 25mL was passed through a C(60) fullerene column in which only the aromatic fraction was retained, and the effluent was then passed through a Merck LiChrolut EN column where the non-aromatic fraction was retained. Following elution of the non-aromatic NAms with 150microL of ethyl acetate-acetonitrile (9:1), 1microL of the extract was injected into a GC/MS. A comparative study of C(60) and C(70) fullerenes and nanotubes revealed C(60) fullerene to be the best choice to selectively retain the aromatic fraction. The method exhibits a linear range of 15-20,000ngL(-1); limits of detection of 4-15ngL(-1); and an RSD of approximately 5%. Recoveries throughout the whole method were between 95% and 102% for six non-aromatic NAms spiked into several types of waters. Our study demonstrates that a simple and fast SPE system (10min per sample) with a customary GC-MS instrument permits the quantification of these amines in complex matrices with considerable sensitivity and selectivity.

Gas chromatographic determination of N-nitrosamines in beverages following automatic solid-phase extraction

A semiautomatic method for the determination of seven N-nitrosamines in beverages by gas chromatography with nitrogen-phosphorus detection is proposed. Beverage samples are aspirated into a solid-phase extraction module for preconcentration and cleanup. The influence of the experimental conditions was examined by using various sorbents among which LiChrolut EN was found to provide quantitative elution and the highest preconcentration factors of all. The proposed method is sensitive, with limits of detection between 7 and 33 ng/kg, and precise, with relative standard deviations from 4.3% to 6.0%. The recoveries of N-nitrosamines from beverage samples spiked with 0.5 or 1 microg/kg concentrations of these compounds ranged from 95% to 102%. The method was successfully applied to the determination of residues of the studied N-nitrosamines in beverages including beer, wine, liquor, whisky, cognac, rum, vodka, grape juice, cider, tonic water, and soft drinks. The analytes were only detected in beer samples, positives being confirmed by gas chromatography coupled with impact ionization mass spectrometry.