Analytical applications of organized molecular assemblies

Chelates in Analytical Chemistry

Sensitive determination of mercury in tap water by cloud point extraction pre-concentration and flow injection-cold vapor-inductively coupled plasma optical emission spectrometry

A novel spectrophotometric method for batch and flow injection determination of cyanide in electroplating wastewater

Monodisperse Ni/PS spheres with polystyrene (PS) core and nickel shell were fabricated by ultrasonic electroless plating. Hollow nickel spheres were consequently prepared by calcination and reduction of these Ni/PS spheres at high temperature. The samples were characterized by SEM, TEM, XRD, TG, TPR and EDX. The effects of sensitization time and agitation type on the preparation and dispersity of the Ni/PS spheres were examined. The results indicated that long sensitization time was necessary for the uniform deposition of nickel on the surfaces of the PS spheres. Ultrasonic waves could prevent the polystyrene spheres and Ni/PS spheres from agglomeration, and enhanced the rate of reaction in electroless plating. Optimum electroless plating conditions were found to be as that the polystyrene spheres were sensitized for 30 min, followed by electroless plating for 5 min in the presence of ultrasonic wave. The hollow nickel spheres were consequently obtained by calcining these Ni/PS spheres in air at 550 °C for 4 h and reducing in hydrogen at 550 °C for 3 h.

Preparation of monodisperse Ni/PS spheres and hollow nickel spheres by ultrasonic electroless plating

Mercuric ion with 5-Br-PADAP forms a 1:2 complex at pH 8.0–10, which, with the addition of Triton X-100, has a molar absorptivity of 1.10 × 105 at 565 nm. A method is described for the determination of mercury in industrial waste water and sludge.

Spectrophotometric Determination of Mercury Using 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol

The system Fe3+ -5-Br-PADAP, in the presence of Triton X-100, has been studied The molar ratio of Fe3+ /5-Br-PADAP in the complex is 1:2 at pH 2–6; the molar absorptivity is 864 × 104 at 595 nm and the apparent stability constant is 184 × 1013  A more sensitive spectrophotometric method for iron determination was developed The iron contents of Chinese leaf tea samples determined by this method are 0024% for Qimen Black Tea and 0037% for Tunxi Green Tea The results are in agreement with those obtained by the o-phenanthroline method

Spectrophotometric Determination of Iron by 2-(5-Bromo-2-pyridylazo) 5-diethylaminophenol

Indirect spectrophotometric determination of cyanide by means of the colour reaction of silver with cadion 2B in presence of triton X-100.

A spectrophotometric method has been developed for the determination of chromium in waste water with 5-Br-PADAP (2-(5-brorno-2-pyridylazo)-5-diethylaminophenol). Chromium(III) forms a blue-purple complex at pH 4.7 upon heating. The color is very stable and is highly sensitive for chromium. At 600 nm it obeys Beer's law in the concentration range of 0–15μg of Cr(III) per 25 ml. The sensitivity and molar absorptivity of the reaction are 0.00065μg of Cr(III) per cm2 and 7.93×1041 · mole−1 · cm−1, respectively. The continuous variation and molar ratio methods indicate that chromium forms 1∶2 complex with the ligand.

Spectrophotometric determination of microgram amounts of chromium(VI) and total chromium in waste water

The synthesis and characteristics of a new chromogenic reagent p-azobenzenediazoaminoazobenzene sulfonic acid (ADAAS) is reported. ADAAS forms a dark-violet red complex with cadmium in the presence of Triton X-100 and in ammonia medium. The molar absorptivity of the complex is 2.02 {times} 10{sup 5} 1 mol{sup {minus}1} cm{sup {minus}1} at 532 nm, and the formation constant of the complex is 6 {times} 10{sup 21}. Beer's law is obeyed for cadmium concentrations of between 3.6 {times} 10{sup {minus}8} M and 4.3 {times} 10{sup {minus}6} M. The effect of foreign ion can been eliminated completely by use of masking agents. The proposed method has been used for the determination of trace amounts of cadmium in water samples.

Zhu Yurui

Papers

Spectrophotometric Determination of Mercury Using 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol

Spectrophotometric Determination of Iron by 2-(5-Bromo-2-pyridylazo) 5-diethylaminophenol

Indirect spectrophotometric determination of cyanide by means of the colour reaction of silver with cadion 2B in presence of triton X-100.

Spectrophotometric determination of microgram amounts of chromium(VI) and total chromium in waste water

Synthesis of p-azobenzenediazoaminoazobenzene sulfonic acid and its application for spectrophotometric determination of cadmium