Highly sensitive and selective spectrophotometric method for determination of trace gold in geological samples with 5-(2-hydroxy-5-nitrophenylazo)rhodanine

Abstract

A excellent sensitive and selective method for spectrophotometric determination of trace gold has been developed, the method is based on the color reaction of gold(III) with new reagent 5-(2-hydroxy-5-nitrophenylazo)rhodanine (HNAR). Under optimal conditions, HNAR reacts with gold(III) to form a 1:5 orange complex, which has an maximum absorption peak at 480 nm. Maximum enhancement of the absorbance of the complex was obtained in the presence of the mixed surfactant of Triton X-100 and CTMAB; the reaction completed rapidly and the absorbance is stable for 5 h at least at 20 degrees C; 0-48 microg L(-1) Au(III) obeyed Beer's law. The apparent molar absorptivity of the complex, Sandell's sensitivity, the limit of quantification, the limit of detection and relative standard deviation were found to be 2.0x10(6) L mol(-1) cm(-1), 0.000,098,483 micro g cm(-2), 1.02 ng mL(-1), 0.35 ng mL(-1) and 1.09%, respectively. The effect of co-existing ions was studied seriously; most metal ions can be tolerated in considerable amounts. Its sensitivity and selectivity are remarkably superior to other reagents in the literature. The proposed method was used successfully to determine trace gold in geological samples. Moreover, the synthesis, characteristics and analytical reaction of HNAR with gold are also described in detail.

Surface‐initiated atom transfer radical polymerization of a new rhodanine‐based monomer for rapid magnetic removal of Co(II) ions from aqueous solutions

“…The arylidene derivatives of rhodanine have also broad biological activities, including antiviral, antimicrobial, cardiac, anti‐inflammatory, and antifungal effects . Some of the rhodanine‐based compounds have been used to determine and extract of the metal cations from standard or sample solutions . For example, Liu et al reported the synthesis and application of rhodanine‐bonded silica gel for the preconcentration and separation of Ag(I), Au(III), and Pd(II) ions.…”

“…13 Some of the rhodanine-based compounds have been used to determine and extract of the metal cations from standard or sample solutions. [13][14][15][16] For example, Liu et al reported the synthesis and application of rhodanine-bonded silica gel for the preconcentration and separation of Ag(I), Au(III), and Pd(II) ions. The results showed that trace amounts of the metal ions can be efficiently adsorbed by rhodanine-bonded silica gel from acidic solution without interfering common coexisting ions to the preconcentration and determination.…”

A Simple and Selective Spectrophotometric Method for the Determination of Trace Gold in Real, Environmental, Biological, Geological and Soil Samples Using Bis (Salicylaldehyde) Orthophenylenediamine

“…A simple sensitive and selective method for determination of trace gold has been required. Sophisticated techniques, such as inductively coupled plasma mass spectrometry (ICP-MS) ( Juvonen et al 2002 ), inductively coupled plasma atomic emission spectrometry (ICP-AES) ( Wu et al 2004 ), electrochemical ( Kavanoz et al 2004 ), spectrophotometry ( Zaijun et al 2003 ), neutran activation analysis ( Nat et al 2004 ) and atomic absorption spectrophotometry (AAS) ( Medved et al 2004 ) have widely been applied to the determination of gold in various samples. Some factors such as initial cost of instrument, technical know-how, consumable and costly maintenance of technique restrict the wider applicability of these techniques, particularly in laboratories with limited budget in developing countries and for field work.…”

Investigation of the Reaction of Gold(III) with 2‐[2‐(4‐Dimethylamino‐Phenyl)‐Vinyl]‐1,3,3‐Trimethyl‐3H‐Indolium. Application for Determination of Gold

“…18 The method also does not require the use of a surfactant. 16 Conditions: 1.0´10 -4 mol L -1 DATI; pH 3; l = 10 mm.…”

“…Separation and preconcentration steps are frequently required for the determination of gold. [3][4][5][6][7][8] Spectrophotometry is often used for gold determination in combination with various organic reagents, such as 5-(4-carboxylphenyl-azo)-8-hydroxyquinoline, 9 5-(4-carboxylphenylazo)-8-aminoquinoline, 10 5-(p-amino-benzylidene)-thiorhodanine, 11,12 5-(2-hydroxy-4-nitrophenylazo)thiorhodanine, 13 2-carboxyl-1-naphthalthiorhodanine, 14 5-(2-hydroxy-4-nitrophenylazo)-rhodanine, 15 5-(2hydroxy-5-nitrophenylazo)-rhodanine, 16 2-aminoacetophenone isonicotinoyl hydrazone, 17 ethopropazine hydrochloride and isothipendyl hydrochloride, 18 N,N-dimethylp-phenylene-diamine, 19 Nile blue, 20 Methylene blue 21 and 4-hydroxy-1-naphthalrodanine. 22 One interesting method described for the determination of gold utilised chemical amplification reactions based on oxidation with aqueous potassium periodate in a solution of gold(I), the masking of unreacted periodate with molybdate, and then the iodometric determination of the iodate and gold(III) produced.…”