5 research outputs found
Identification of Tobacco-Specific Nitrosamines as Disinfection Byproducts in Chloraminated Water
Tobacco-specific
nitrosamines (TSNAs) exist in environmental waters;
however, it is unknown whether TSNAs can be produced during water
disinfection. Here we report on the investigation and evidence of
TSNAs as a new class of disinfection byproducts (DBPs). Using five
common TSNAs, including (methylnitrosamino)-1-(3-pyridyl)-1-butanone
(NNK) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) as
the targets, we first developed a solid phase extraction (SPE) and
liquid chromatography-tandem mass spectrometry (LC-MS/MS) method capable
of rapidly determining these TSNAs at levels as low as 0.02 ng/L in
treated water. Using this highly sensitive method, we investigated
the occurrence and formation potential (FP) (precursor test conducted
in the presence of chloramines) of TSNAs in treated water from two
wastewater treatment plants (WWTPs) and seven drinking water treatment
plants (DWTPs). NNAL was detected in the FP samples, but not in the
samples before the FP test, confirming NNAL as a DBP. NNK was detected
in the treated wastewater before the FP test, but its concentration
increased significantly after chloramination in two of three tests.
Thus, NNK could be a DBP and/or a contaminant in wastewater. Moreover,
these TSNAs were detected in FP tests of wastewater-impacted DWTP
plant influents in 9 of 11 samples. However, TSNAs were not detected
at full-scale DWTPs, except for at one DWTP with high ammonia where
breakpoint chlorination was not achieved. The concentration of the
sum of five TSNAs (0.3 ng/L) was 100-fold lower than NDMA, suggesting
that TSNAs have a minor contribution to total nitrosamines in water.
We examined several factors in the treatment process and found that
chlorine or ozone may destroy TSNA precursors and granular activated
carbon (GAC) treatment may remove the precursors. Further research
is warranted into the efficiency of these processes at different DWTPs
using sources of varying water quality
Determination of 14 Nitrosamines at Nanogram per Liter Levels in Drinking Water
<i>N</i>-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. <i>N</i>-Nitrosodimethylamine (NDMA), <i>N</i>-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
Identification of Tobacco-Specific Nitrosamines as Disinfection Byproducts in Chloraminated Water
Polymer–Ceramic Nanohybrid Materials
This review is dedicated to nanohybrid materials consisting of a polymer-based matrix and a disperse nanoscaled ceramic phase. Different preparation techniques for the synthesis of polymer–ceramic nanohybrid materials will be presented, such as blending techniques, sol–gel processing, in-situ polymerization, and self-assembly methods. Selected structural and functional properties of polymer–ceramic nanohybrid materials will be highlighted and discussed within the context of their dependence on parameters such as the homogeneity of the dispersion of the ceramic throughout the polymer matrix, the particle size of the ceramic phase, and the polymer–ceramic interface. Moreover, some advanced applications of polymer–ceramic nanohybrid materials will be addressed and compared with their polymeric counterparts