Occurrence of perchlorate (ClO4−), chlorate (ClO3−) and bromate (BrO3−) in public drinking, open well and surface water sources at 20 locations in the South-West coastal state of Kerala (India) is reported. The analysis was performed by high performance liquid chromatography interfaced with tandem mass spectrometry (HPLC–MS/MS). Irrespective of water source (public tap water, open well water and surface water) all the analyzed samples contained high levels of ClO4−, indicating its contamination throughout the region. The highest ClO4− level found was 91.4 μg/L, which is 3.7 times higher than US EPA recommendations. ClO3− and BrO3− were also detected in the samples, with highest concentrations of 177 and 5.34 μg/L respectively in tap water samples. Regression analysis showed moderate positive correlation between ClO4− and bromide (Br−) in tap water (r2=0.659) and open well water (r2=0.485) samples, respectively. Similar correlation was also observed between ClO4− and Cl− (r2=0.591) concentrations in well water samples, indicating sea water could be one of the probable sources in addition to ClO4− manufacturing in the area. This is the first report of high levels of ClO4− and ClO3− and detectable BrO3− in water samples from anywhere in India.
The excited state intra molecular charge transfer (ICT) property of fluorophores has been extensively used for the design of fluorescent chemosensors. Herein, we report the synthesis and properties of three donor–π-acceptor–π-donor (D–π-A–π-D) based molecular probes BP, BT and BA. Two heteroaromatic rings, pyrrole (BP), and thiophene (BT) and a non-heteroaromatic ring N-alkoxy aniline (BA) were selected as donor moieties which were linked to a bipyridine binding site through a vinylic linkage. The heteroaromatic systems BP and BT perform selective and ratiometric emission signalling for zinc ions whereas the non-heteroaromatic probe BA does not. The advantages of the D–π-A–π-D design strategy in the design of ICT based probes for the selective fluorescent ratiometric signalling of zinc ions in biological media is discussed. Further, the use of BP, BT and BA for imaging Zn(2+) ions from MCF-7 cell lines is demonstrated.
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