A simple fluorophore-imine ensemble for colorimetric and fluorescent detection of CN- and HS- in aqueous solution.

Colorimetric and fluorescent detection of cyanide and hydrogen sulfide ions has been effected using a simple organic probe in H2O:DMSO (20:80, v/v) medium. The probe exhibits a colour change from pale-yellow to red upon addition of these analytes under normal light and fluorescent change from green to red under UV lamp. Other competitive ions show no observable colour or fluorescence change. The binding constants of cyanide and hydrogen sulfide ions with the probe determined using fluorescence titration data are found to be 2.1 × 104 and 1.6 × 104 M-1, respectively. The probe fluorimetrically detects the analytes in a wide pH range (4-10). 1H and 13C NMR studies suggest that the probe senses cyanide ion through deprotonation and nucleophilic addition mechanism and hydrogen sulfide ion via deprotonation mechanism. Detection limits of cyanide and hydrogen sulfide are determined to be 0.15 and 1 µM, respectively. The practical utility of the probe has been demonstrated by same dual mode detection of cyanide in food materials like bitter almond, cassava flour and sprouting potato.

Rational design and application of a fluorogenic chemodosimeter for selective detection of cyanide in an aqueous solution via excimer formation.

A new quinone-benzothiazole imine based chemodosimeter (R) was rationally designed, synthesized and characterized using NMR and mass spectral techniques. The receptor colorimetrically senses cyanide in aq. HEPES buffer: DMF (2:8 v/v) solution with an instantaneous colour change from yellow to bluish green. An enhancement of fluorescence intensity at 429 nm with excimer formation is also observed after addition of cyanide to the receptor, which is accompanied with a colour change from yellow to blue under UV lamp. Nucleophilic addition of cyanide to imine C-atom inhibits intra-molecular charge transfer (ICT) transition, which is responsible for the excimer formation. This chemical reaction is confirmed by 1H NMR titration. The receptor binds with two equivalents of cyanide with a binding constant of 5.55 × 104 M-1. The limit of detection (LOD) of cyanide by the receptor is found to be as low as 69 nM, which is much lower than the acceptable limit of cyanide in drinking water as set by the WHO (1.9 µM). Electrochemical studies support the termination of ICT transition upon addition of cyanide ion. Theoretical studies substantiate experimental findings and excimer formation. The receptor fluorometrically detects cyanide present in tap water and food materials such as cassava flour, almond and potato.

Neonatal Bartter syndrome.

Bartter syndrome is an inherited renal tubular disorder with hypokalemia, hypochloremic metabolic alkalosis, normal blood pressure with hyper-reninemia and increased urinary loss of sodium, potassium and chloride. We report an infant with neonatal Bartter syndrome, who improved with potassium supplements.

Hypocalcemia due to vitamin D deficiency in exclusively breastfed infants.

This report is based on observations during the conduct of a study of hypocalcemia in infants and children. In a study of 50 cases, 13 exclusively breast fed infants manifesting with hypocalcemic seizures were confirmed to have vitamin D deficiency. None of the 13 infants had received vitamin D supplementation. All of them had biochemical evidence of hyperparathyroidism and low levels of 25 (OH) Vit D3 and promptly responded to therapy with vitamin D and calcium. All the mothers of these 13 infants had low levels of 25 (OH) Vit D3. Mothers of 5 infants had reported reduced exposure to sunlight due to religious reasons. This report emphasizes the need to supplement Vitamin D in exclusively breast fed infants and also to encourage exposure to sunlight in them and their mothers.