A new triazene group reagent m-nitrophenylazo-2-aminothiazole (m-NPAAT) was first synthesized and characterized by elemental analysis, and 1H-NMR and IR spectra. This new reagent reacts with Ag (I) in a slightly basic medium to form an 1:1 complex, which exhibits intensive resonance-enhanced Rayleigh light-scattering (RLS) in the presence of Tween-20. A new method for the determination of Ag (I) by RLS based on this reaction is proposed. The intensity of the RLS at 456nm is proportional to silver (I) concentration in the range of 1.0-700μg l-1 with a detection limit of 0.5μg 1-1. Expect for I-, SCN-and PdII, no other ions interfere in the determination at 5-1000times the concentration of Ag (I). The method is thus sensitive and of good selectivity, and has been used for the determination of trace impurity silver in an anti-cancer drug and in chemical samples and for the measurement of the solubility product of silver chloride. 1999 Elsevier Science B.V. All rights reserved.

Copper (Ⅱ) can react with a new fluorescence reagent, 5-(4-chlorophenylazo)-8-aminoquinoline (APAQCL), forming a fluorescence product only in slightly acidic medium, while the fluorescence product of cobalt (Ⅱ) with APAQCL forms only in basic medium and in the presence of H2O2. Based on the di€erence of the reaction between cobalt (Ⅱ) and copper (Ⅱ) with APAQCL, a new flow injection method for the sequential determination of cobalt and copper in binary mixtures by use of a fluorimetric detector and APAQCL as reagent was proposed. Linear calibration graphs were obtained over the concentration range 0.010-1.20 (μg/ml) of cobalt (Ⅱ) and 0.050-5.00 (μg/ml) of copper (Ⅱ) with the detection limit of 0.0030 (μg/ml) of cobalt (Ⅱ) and 0.010 (μg/ml) of copper (Ⅱ), respectively. The applicability of the method to the sequential determination of cobalt (Ⅱ) and copper (Ⅱ) in food samples was demonstrated by investigating the potential interference and by the analysis of synthetic mixtures of copper (Ⅱ) and cobalt (Ⅱ). The method was successfully applied to the determination of copper and cobalt in food samples. #1999 Elsevier Science Ltd. All rights reserved.

The resonance Rayleigh light-scattering (RRLS) signal of a new triazene reagent; 1-(o-nitrophenyl)-3-(2-thiazolyl) triazene (o-NPTT), was firstly synthesized and characterized in this paper at 500-600nm wavelength range and can be enhanced remarkably by Pd2+. According to this phenomenon, a new method was developed for the determination of Pd2+ by the RRLS technique in the presence of Tween-80. The calibration graph showed good linearity over a concentration range of 5.0-700μg 1-1 with a detection limit of 1.0μg 1-1. There are almost no foreign ions interfered in the determination at a more than fivefold concentration of Pd2+. The method is relatively sensitive, of good selectivity and has been successfully used for the determination of trace palladium in the slag of fertilizer factories and catalyst samples.

The resonance Rayleigh light-scattering (RRLS) signal of a new triazene reagent, 1-(p-chlorophenyl)-3-(2-thiazolyl) triazene (p-ClPTT), is first synthesized and characterized in this paper, in the 450-550nm wave length range is enhanced remarkably by Au3+. A new method for the determination of Au3+ by the RRLS technique in the presence of Tween-20 has been developed. The calibration graph shows good linearity over a concentration range of 5.0-800 μg/l with a detection limit of 3.0μg/l. Except for IO4-, SCN-and Pd2+, no other foreign ions interfere in the determination at concentrationsless than 10-fold of Au3+. The method is thus simple, sensitive and of good selectivity, and has been successfully used for the determination of trace gold in the ore samples.

Three new 8-aminoquinoline-5-azo derivatives: 5-(3-fluo-4-chlorophenylazo)-8-aminoquinoline (FCPAQ), 5-(3-fluo–4-chlorophenylazo)-8-benzenesulfonamidoquinoline (FCPBSQ), 4, 4'-bis (8-aminoquinoline-5-azo)-biphenyl (BAQABP) have been synthesized, and were found to be good fluorescence reagents for the determination of copper (II). In slightly acidic or basic medium, copper (II) reacts with FCPAQ, FCPBSQ or BAQABP to form a chelate, which exhibits an intensive fluorescence in ultraviolet region. The fluorescence intensity is proportional to the concentration of copper (II) over the range of 4.0-140, 1.0-200 and 3.0-150μg 1-1 with the detection limits of 0.80, 0.20 and 0.50μg 1-1 for the FCPAQ, FCPBSQ and BAQABP systems, respectively. The methods have been successfully applied to the determination of trace amount of copper in ore, alloy, water and hair samples.

The catalytic effect of osmium on the oxidation reactions of three basic dyes: methylene blue (MB), butyl rhodamine B (BRB) and nile blue (NB), by KIO4 are investigated spectrophotometrically and applied for the kinetic determination of osmium (IV) in the acidic medium at 90±0.5℃. The above reactions are monitored spectrophotometrically by measuring the decrease in the absorbance at 660nm, 555nm and 600nm for the catalytic reactions of MB, BRB and NB, respectively. Under the optimum conditions, osmium (IV) can be determined at the concentration up to 3.2mg L-1 for MB method, 6.8mg L-1 for BRB method, and 10.0 μg L-1 for NB method with the respective detection limit of 0.020, 0.020 and 0.080μg L-1. The methods, which are of high sensitivity, good selectivity and stability, are free from most interference and have been successfully applied for the determination of trace amounts of osmium in some ore and catalyst samples. The kinetic parameters of the catalytic reaction were derived, and its mechanism was suggested.

A capillary zone electrophoresis method modified by β-CD was, for the first time, developed for the simultaneous determination of five anthraquinones (physcion, chrysophanol, aloeemodin, emodin and rhein) in rheum and rheum-containing preparations. The factors relevant to the run buffer media and their effects on the separation were studied. A buffer solution composed of 15mM sodium borate, 30mM β-CD, 20% acetonitrile and 1.0% ethanediol was found to be the most suitable electrolyte for separation, whereby the contents of the five anthraquinones in rheum and rheum-containing preparations could be easily determined in 20min at 20kV. The relative standard deviation for the determination of the five constituents in the samples varied form 0.16-5.47%, and the recovery ranged between 92.0 and 107.3%. Moreover the inclusion constants of the target compounds, except for rhein with β-CD, were also determined.

Three highly sensitive spectrophotometric methods have been developed for the determination of tellurium (Ⅳ), based on its colour reactions with tungstate and basic dyes (BD) in aqueous solution in the presence of poly (vinyl alcohol). Tellurium (Ⅳ) reacts with tung state and BD to form ionassociation complexes. The molar absorptivities are between 1.76×107 and 3.33×107dm3 mo-1 cm-1, the highest value being found with Nile blue. Suitable conditions for the reactions and the effects of foreign ions were investigated. The methods have been successfully applied to the spectrophotometric determination of trace amounts of tellurium (Ⅳ) in smoke ash samples.