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

Rapid determination of trace level N-nitrosamine precursors in secondary-treated wastewater by using two dimensional-ion chromatography

Nowadays, drinking water treatment involves large usage of chloramines making control of N-nitrosamines formation very challenging. Detecting and removing N-nitrosamine precursors in water is the most effective method to reduce N-nitrosamine formation. Therefore, it is essential to develop methods to detect N-nitrosamine precursors. In this paper, a method based on two-dimensional ion chromatography (2D-IC) is presented for detecting the trace levels of N-nitrosamines precursors, including dimethylamine, trimethylamine, diethylamine, methylethylamine, morpholine and piperidine, in relatively short time with minimized sample preparation. The 2D-IC method exhibits better sensitivity for analytes suffering from matrix interference, by eliminating interfering sample matrix ions, than conventional one-dimensional (1D) IC. Detection limits of the six amines were within the range of 0.035 μg/L to 0.1 μg/L. Excellent linearity was achieved for all the target amines with the method developed. The proposed method in this study was applied in the analysis of real wastewater samples. High recoveries ranging from 91.7 to 109.8% and relative standard deviation of less than 5.3% were obtained. The fully automated and simple method shows high selectivity against interfering metal ions and low detection limits, making routine detection of N-nitrosamines precursors practical.

Probabilistic health risk assessment of nitrosamines in drinking water of Shaoxing, Zhejiang, China

Nitrosamines (NAms) are potent genotoxic and carcinogenic but widely detected in drinking water. This study aimed to investigate the occurrence of major types of NAms in drinking water in Shaoxing, China, and to conduct multi-pathway probabilistic cancer risk (CR) assessment to residents based on age-dependent adjustment Chinese exposure factors. Results showed that concentrations of NAms in water varied from not detected (ND) to dozens of nanograms per liter level. N-Nitrosodimethylamine (NDMA) was detected most frequently (93.06%), followed by N-nitrosodiethylamine (NDEA) (64.08%)-with the highest cancer risk among NAms. The CR of NAms came mainly through the oral exposure pathway. The 95th percentile of the total CR of five major NAms was 1.06 × 10^-4, exceeding the maximum acceptable lifetime CR (1 × 10^-4) recommended by US EPA. Exposure to NDEA contributed the highest to the total CR. The CR of the five NAms through ingestion was 2.5 times higher using the Chinese exposure factors than that of the Americans. The most important variables related to CRs were concentrations of NAms in drinking water, exposure duration, drinking water ingestion rate, and exposure time during bathing. Our findings suggest the urgent need to develop and enforce effective regulatory policies to control the contamination of NAms in drinking water in China. Graphical abstract.

pH-regulated synthesis of CuOx/ERGO nanohybrids with tunable electrocatalytic oxidation activity towards nitrite sensing

CuO_x/ERGO nanohybrids with diverse morphologies prepared by pH-regulated synthesis display tunable electrocatalytic ability towards nitrite sensing.