Quantitation of guanidine derivatives as representative persistent and mobile organic compounds in water: method development

Abstract

Persistent and mobile organic compounds (PMOCs) are highly soluble in water, thereby posing a threat to water resource quality. Currently, there are no methods that can accurately quantify guanidine derivative PMOCs, other than 1,3-diphenylguanidine (DPG) and cyanoguanidine (CG), in aqueous media. In this study, we developed a quantitation method that combines solid-phase extraction and liquid chromatography (LC)-tandem mass spectrometry to detect seven guanidine derivatives in aquatic environments and applied it to environmental water samples. Five LC columns were examined, and among them, a hydrophilic interaction liquid chromatography column was chosen owing to its suitable instrument detection limit and retention factor. Method precision was assessed using seven replicate analyses of river water. The corresponding analyte recoveries ranged from 73 to 137% (coefficient of variation = 2.1–5.8%). DPG and CG were detected in ultrapure water samples at levels up to 0.69 and 150 ng L−1, respectively; DPG and CG levels up to 44 and 2600 ng L−1, respectively, were detected in lake water, river water, sewage effluent, and tap water sampled in Western Japan. This is the first reported detection of DPG in the surface water of Japan, revealing that DPG and CG are ubiquitous compounds in aquatic environments. Moreover, this is the first study to detect 1-(o-tolyl)biguanide and N,N′′′-1,6-hexanediylbis(N′-cyanoguanidine) in water. This study provides a foundation for further research on the distribution, fate, and emission source of these pollutants, which is critical to maintain high water quality and to determine regulatory limits for these pollutants. Graphical Abstract

Occurrence of Polymer Additives 1,3-Diphenylguanidine (DPG), N-(1,3-Dimethylbutyl)-N′-phenyl-1,4-benzenediamine (6PPD), and Chlorinated Byproducts in Drinking Water: Contribution from Plumbing Polymer Materials

“…Other chlorinated products, DTG, and 6PPD-quinone were not detectable in any of the samples. Observed concentrations of DPG in tap water in our study are similar to those reported in previous studies with one report from Japanese tap water showing maximum concentrations of 44 ng/L ( n = 2) and samples from a drinking water treatment plant from the Pearl River Delta region of China showing maximum concentrations of ∼36 ng/L …”

“…DPG was found to occur in 100% of the samples (median = 4.31 ng/L, max = 32.6, min = 0.25 ng/L). While other studies have reported potential contamination from laboratory materials during sample processing and even DPG presence in ultrapure water, , all blank samples processed during this study were below the method reporting limit. Out of the five large molecular weight chlorinated byproducts studied, only three were detected, with CC15 also occurring in 100% of analyzed samples (median = 1.67 ng/L, max = 11.2, min = 0.29 ng/L).…”

Polymer Additives to Go? Occurrence of the Rubber Additive 1,3-Diphenylguanidine (DPG) in Bottled Water

“…With its ubiquitous usage and occurrence, the detection of polymer additive chemicals can be challenging. Many materials commonly used in laboratory operation, even if not in direct contact with samples, can be a source of contamination, as recently described with DPG being found in blank samples. ,− As an example, rubber materials such as the one used for vial closures, syringes, and even certain glove types can be a source of contamination. , To minimize such contamination sources, procedures that involve minimal sample handling can serve as an alternative. Constant development in LC-MS/MS instrumentation has also served to improve instrument limits of detection and robustness, reducing the need for sample preparation and concentration.…”

“…Recently, one such polymer additive transformation product, 6PPD-quinone, has been associated with the mass mortality of fish species . Other additives such as 1,3-diphenylguanidine (DPG) are also found to occur in many drinking water sources due to urban runoff events and leaching from tire materials, with DPG being detected consistently among the highest concentrations for tire leachable organics. − Additionally, DPG and 6-PPDQ uses in different applications can also be significant sources to the environment and to human exposure. , In tap water samples, DPG was found with a 100% detection frequency with a median concentration of 4.3 ng/L and was also associated with nontire-related source materials present in plumbing systems . In human urine, DPG was recently found with a detection frequency of 73% and 20% for children and adults, respectively, and at a median concentration of 0.05 ng/mL for children’s samples …”

“…While DPG can be considered as a persistent and mobile organic chemical (PMOC), , its occurrence is not restricted to the aquatic environment, and it has also been reported in urban air and indoor household dust, with DPG concentrations surpassing the concentrations of other commonly studied chemicals such as PFOA, PFOS, and tetrabromobisphenol A (TBBPA) . While DPG effects on human and environmental health not are fully understood, some reports have suggested potential adverse effects. , Furthermore, recent studies have also shown potential genotoxicity associated with chlorinated transformation products of DPG that could be generated during drinking water treatment …”