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A novel fluorescent chemosensor rhodamine B phenyl hydrazide (RBPH) for Hg(2+) was designed and synthesized. This probe is highly sensitive, selective, and irreversible for Hg(2+) and exhibits fluorescent response at 580 nm. RBPH also displayed detectable color change from colorless to pink upon treatment with Hg(2+). This property has been utilized as naked eye detection for Hg(2+) in various industrial samples. Fluorescence microscopic experiments demonstrated that this chemosensor is cell permeable and can be used for fluorescence imaging of Hg(2+) in cellular media. This probe can detect Hg(2+) with good linear relationships from 1 to 100 nM with r = 0.99983 and the limit of detection were found to be 0.019 nM with ± 0.91 % RSD at 10 nM concentrations.

A sensitive solvent-free extraction protocol for the quantification of arsenic at trace level has been described. It is based on the reaction of arsenic (V) with molybdate in acidic medium in presence of antimony (III) and ascorbic acid as a reducing agent to form a blue-colored arsenomolybdenum blue complex. The complex has been extracted into surfactant phase using Triton X-114, and its absorbance was measured at 690 nm. The detection limit, working range, and the relative standard deviation were found to be 1 ng mL⁻¹, 10-200 ng mL⁻¹, and 1.2%, respectively. The effect of common ions was studied, and the method has been applied to determine trace levels of As(III) and As(V) from a variety of samples like environmental, biological, and commercially procured chemicals.

The micellar mediated trace level estimation of mercury in industrial effluent sample by the rhodamine B hydrazide spirolactam ring opening process is described. The catalytic reaction of mercuric ion with colorless rhodamine B hydrazide to form pink colored rhodamine B through amide bond cleavage at pH 5 forms the basis of this reaction. The dye obtained was extracted from the aqueous phase into non-ionic surfactant using Triton X-114 through cloud point formation and its absorbance was measured at 556 nm. The reaction conditions such as concentrations of rhodamine B hydrazide and Triton X-114, effect of NaCl concentration on cloud point temperature and the efficiency of extraction were optimized. The selectivity of the method towards mercury in the presence of various ions was studied. The validity of the method was examined by spiking real samples with known amounts of mercury and carrying out recovery studies. The results obtained by the proposed method were compared with the standard dithiazone method. The preconcentration and enrichment factors were found to be 5 and 12 respectively. The limit of detection and the linear range were found to be 1.4 ng ml-1 and 10-100 ng ml-1 respectively. The relative standard deviation was found to be 0.35% at 20 ng ml-1.

A sensitive surfactant-mediated extractive spectrophotometric method has been developed, based on the reaction of ferric iron with sulfide to form ferrous iron and its subsequent reaction with ferricyanide to form Prussian Blue, to quantify trace levels of hydrogen sulfide/sulfide in environmental samples. The method obeys Beer's law in the concentration range 2-10 microg of sulfide in 25 mL of aqueous phase with molar absorptivity (epsilon) of 3.92 x 10(4) L mol(-1) cm(-1). The colored species has been extracted into isoamyl acetate in the presence of a cationic surfactant i.e. cetylpyridinium chloride, to enhance the sensitivity of the method with epsilon value 5.2 x 10(4) L mol(-1) cm(-1). The relative standard deviation has been found to be 0.69% for 10 determinations at 4 microg of sulfide and the limit of detection was 0.009 microg mL(-1). The interference from common anions and cations has been studied. The proposed method has been applied to the determination of residual hydrogen sulfide in the laboratory fume hood as well as ambient atmospheric hydrogen sulfide in the vicinity of open sewer lines after fixing the analyte in ionic form using suitable trapping medium.

A simple pH probe is developed based upon the covalent chemical derivatisation of carbon particles with anthraquinone. The amperometric response of electrodes constructed from this material is examined and shown to produce a Nernstian linear response to pH from 1 to 9, over a range of temperatures from 20 to 70 degrees C, consistent with a two-electron, two-proton electrochemical process.