Determination of mercury at a dithizone-modified glassy carbon electrode by anodic stripping voltammetry

Luminescent Pyrene-based Schiff base Receptor for Hazardous Mercury(II) Detection Demonstrated by Cell Imaging and Test Strip

Qualitative and quantitative analysis of mercury at concentration levels as low as parts per billion (ppb) is a basic and practical concern. The vast majority of research in this field has centered on the development of potent chemosensor to monitor mercuric (Hg²⁺) ions. Mercury exists in three oxidation states, + 2, + 1 and 0, all of which are highly poisonous. In this study, (N¹E,N²E)-N¹,N²-bis(pyrene-1-ylmethylene)benzene-1,2-diamine (PAPM), a novel photoluminescent sensor based on pyrene platform was synthesized. Over the tested metal ions (Cd²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ni²⁺, K⁺, Na⁺, Zn²⁺, Sr²⁺, Pb²⁺, Al³⁺, Cr³⁺ and Fe³⁺) the sensor responds only to Hg²⁺ by showing high selectivity and sensitivity. After treatment with mercuric ions at room temperature, the luminescence intensity of probe was quenched at 456 nm. The quenching of fluorescence intensity of probe upon addition of mercury is due to the effect of "turn-off" chelation enhanced quenching (CHEQ) by the formation of 1:1 complex. The ESI-MS spectrum and the Job's experimental results confirm the formation of 1:1 complex between PAPM and Hg²⁺. The detection limit and association constant of sensor for mercury is computed using fluorescence titration data and were found to be 9.0 × 10^-8 M and 1.29 × 10⁵ M^-1 respectively. The practical application of sensor towards recognition of mercury(II) ions was explored through economically viable test strips and also using cell imaging studies.

Barbituric acid–triphenylamine adduct as an AIEE-type molecule and optical probe for mercury(ii)

A barbituric acid–triphenylamine adduct displayed interesting aggregation-induced emission enhancement (AIEE) features in a THF–water co-solvent system and can act as a fluorescence turn-on probe for Hg²⁺.

An ESIPT-based fluorescent probe for highly selective and ratiometric detection of mercury(ii) in solution and in cells

A highly selective and sensitive ratiometric fluorescent probe for mercury(ii) has been developed. It has been demonstrated that the probe is able to detect Hg²⁺ level in water samples and living cell.

Optimization of analytical procedures for the simultaneous voltammetric determination of total Hg(II) in presence of Cu(II) in environmental matrices

The present work reports the critical comparison about the employment of three different supporting electrolytes (0.1 mol L−1 HClO4, 0.01 mol L−1 EDTA-Na2 + 0.06 mol L−1 NaCl + 2.0 mol L−1 HClO4 and 0.1 mol L−1 KSCN + 0.001 mol L−1 HClO4) and their instrumental and chemical optimisation for the simultaneous voltammetric determination of total mercury(II) and copper(II) in sediments and sea water at gold electrode, especially discussing the reciprocal interference problems.

The differential pulse anodic stripping voltammetric (DPASV) measurements were carried out using a conventional three-electrode cell: a gold electrode (GE) as working electrode, a platinum wire and an Ag‖AgCl‖KClsat as auxiliary and reference electrodes, respectively.

The analytical procedure was verified by the analysis of standard reference materials: Estuarine Sediment BCR-CRM 277, River Sediment BCR-CRM 320 and Mercury in Water NIST-SRM 1641d.

Once set up on the standard reference materials, the analytical procedure was transferred and applied to sediments and sea waters sampled in a lagoon ecosystem connected with Adriatic Sea (Ravenna area, Italy).

Determination of trace amounts of mercury(II) in water samples using a novel kinetic catalytic ligand substitution reaction of hexacyanoruthenate(II)

A simple, sensitive, selective and rapid kinetic catalytic method has been developed for the determination of Hg(II) ions at micro-level. This method is based on the catalytic effect of Hg(II) ion on the rate of substitution of cyanide in hexacyanoruthenate(II) with nitroso-R-salt (NRS) in aqueous medium and provides good accuracy and precision. The concentration of Hg(II) catalyst varied from 4.0 to 10.0x10(-6)M and the progress of reaction was followed spectrophotometrically at 525nm (lambda(max) of purple-red complex [Ru(CN)(5)NRS](3-), epsilon=3.1x10(3)M(-1)s(-1)) under the optimized reaction conditions; 8.75x10(-5)M [Ru(CN)(6)(4-)], 3.50x10(-4)M [nitroso-R-salt], pH 7.00+/-0.02, ionic strength, I=0.1M (KCl), temp 45.0+/-0.1 degrees C. The linear calibration curves, i.e. calibration equations between the absorbance at fixed times (t=15, 20 and 25min) versus concentration of Hg(II) ions were established under the optimized experimental conditions. The detection limit was found to be 1.0x10(-7)M of Hg(II). The effect of various foreign ions on the proposed method has also been studied and discussed. The method has been applied to the determination of mercury(II) in aqueous solutions.

Screening for mercury in aqueous environmental samples and urine samples using thin layer chromatography

A method for screening based on thin layer chromatography (TLC) comprising silica gel 'G' as a stationary phase and benzene as a mobile phase was found to be most suitable for the detection of mercury in aqueous samples and spiked human urine, without digesting the samples. A broad range for the detection of mercury, from 20 microg/L (20 ppb) to 1000 mg/L (1000 ppm), was established, by optimizing the experimental conditions. In urine samples, mercury could be detected also, at levels as low as 50 microg/L (50 ppb) or above. Mercury was detected by complexation with dithizone followed by TLC, also in the presence of other heavy metals, including arsenic, cadmium, lead, copper, iron, zinc, and nickel. The method is simple, cheap, and has no interference of the matrix present in the natural water and aqueous industrial effluent samples obtained from the field. Further, no sophisticated instrument is needed for the detection of mercury.

Concentrations of cadmium and lead heavy metals in Dardanelles seawater

Cadmium and lead were determined simultaneously in seawater by differential pulse stripping voltammetry (DPSV) preceded by adsoptive collection of complexes with 8-hydroxyquinoline (oxine) on to a hanging mercury drop electrode (HMDE). In preliminary experiments the optimal analytical condition for oxine concentration was found to be 2.10(-5) M, at pH 7.7, the accumulation potential was -1.1 V, and the initial scannig potential was -0.8 V. The peak potentials were found -0.652 V for Cd and -0.463 V for Pb At the 60 s accumalation time. The limit of detection (LOD) and limit of quantitatification (LOQ) were found to be by voltammetry as 0.588 and 1.959 microg l(-1) (RSD, 5.50%) for Cd and 0.931 and 3.104 microg l(-1) (RSD, 4.10%) for Pb at 60 s stirred accumulation time respectively. In these conditions the most of the seawater samples are amenable for direct voltammetric determination of cadmium and lead using a HMDE. An adsorptive stripping mechanism of the electrode reaction was proposed. For the comparison, seawater samples were also analysed by ICP-atomic emission spectrometry method (ICP-AES). The applied voltammetric technique was validated and good recoveries were obtained.

Flotation-Spectrophotometric Determination of Mercury in Water Samples Using Iodide and Ferroin

This paper describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of trace amounts of mercury. The method is based on the flotation of an ion-associate of HgI4(2-) and ferroin between aqueous and n-heptane interface at pH 5. The ion-associate was then separated and dissolved in acetonitrile to measure its absorbance. Quantitative flotation of the ion-associate was achieved when the volume of the water sample containing Hg(II) was varied over 50 - 800 ml. Beer's law was obeyed over the concentration range of 3.2 x 10(-8) - 9.5 x 10(-7) mol l(-1) with an apparent molar absorptivity of 1 x 10(6) l mol(-1) cm(-1) for a 500 ml aliquot of the water sample. The detection limit (n = 25) was 6.2 x 10(-9) mol l(-1), and the RSD (n = 5) for 3.19 x 10(-7) mol l(-1) of Hg(II) was 1.9%. A notable advantage of the method is that the determination of Hg(II) is free from the interference of the almost all cations and anions found in the environmental and waste water samples. The determination of Hg(II) in tap, synthetic waste, and seawater samples was carried out by the present method and a well-established method of extraction with dithizone. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed in encountering with real samples.