Ternary Ion-association Complex Research Articles

C60 Mediated Ion Pair Interaction for Label-Free Electrochemical Immunosensing with Nanoporous Anodic Alumina Nanochannels.

Label-free biosensing based on the nanoporous anodic alumina (NAA) membrane emerged as a versatile biosensing platform in the recent decade. In the present work, we developed a new immunosensing strategy based on the nanochannels of NAA and the ion pair interaction mediated by electrochemistry of C60. The NAA served as the matrix for the immobilization of the capture antibodies. The incubation of target antigens resulted in the formation of the immunocomplexes and thus an increase of the steric hindrance of the nanochannels. Therefore, the concentration of the redox probe transported through the nanochannels decreases, which can be detected at the working electrode modified with C60. Herein, we initially found that the cathodic peak ascribed to the reduction of C60 to C60- was obviously enhanced by the presence of the redox probe K3[Fe(CN)6] and which was contributed to the formation of a ternary ion association complex among C60, tetraoctylammonium bromide, and K3[Fe(CN)6]. Therefore, the transportation of K3[Fe(CN)6] though the NAA-based bionanochannels can be detected by a C60 modified electrode with an amplified signal. Choosing human epididymis protein 4 (HE4) as the model target, a linear range of 1.0 ng mL-1 to 100 ng mL-1 can be established between the peak current obtained from the differential pulse voltammetric response of the platform and the concentration of HE4. The detection limit was 0.2 ng mL-1. This study not only provides a new avenue to develop the other nanochannel-based biosensing platform for a variety of other disease biomarkers but also contributes to the electrochemistry of fullerene.

Highly sensitive and selective fluorescent assay for guanine based on the Cu2 +/eosin Y system

A fluorescent probe has been developed for the determination of guanine based on the quenched fluorescence signal of Cu2+/eosin Y. Cu2+ interacted with eosin Y, resulting in fluorescence quenching. Subsequently, with the addition of guanine to the Cu2+/eosin Y system, guanine reacted with Cu2+ to form 1:1 chelate cation, which further combined with eosin Y to form a 1:1 ternary ion-association complex by electrostatic attraction and hydrophobic interaction, resulting in significant decrease of the fluorescence. Hence, a fluorescent system was constructed for rapid, sensitive and selective detection of guanine with a detection limit as low as 1.5nmolL−1 and a linear range of 3.3–116nmolL−1. The method has been applied satisfactorily to the determination of guanine in DNA and urine samples with the recoveries from 98.7% to 105%. This study significantly expands the realm of application of ternary ion-association complex in fluorescence probe.

Extraction-Spectrophotometric Method for Determination of Gallium(III) in the Form of Ion Associate with a Monotetrazolium Salt

The possibility of application of the ternary ion-association complex of gallium(III), 4-(2-pyridyl azo)resorcinol (PAR) and 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) for extraction-spectrophotometric determination of gallium(III) was studied. The liquid–liquid extraction system Ga(III)–PAR–TTC–H2O–CHCl3 was applied for this purpose. The effect of the foreign ions on the extraction was investigated. Based on the obtained results, a sensitive, relatively simple, and inexpensive method for determination of gallium(III) in a model mixture was developed, which can be implemented in industrial, biological, medical, and pharmaceutical samples.

Complex formation and liquid–liquid extraction of anionic chelate of cobalt(II)-4-(2-thiazolylazo)resorcinol with 1,4-diphenyl-3-(phenylamino)-1H-1,2,4-triazole

The complex formation of anionic chelate of Co(II)–4-(2-thiazolylazo)resorcinol (TAR) with 1,4-diphenyl-3-(phenylamino)-1H-1,2,4-triazole (Nitron, Nt) in the liquid–liquid extraction system Co(II)–TAR–Nt–H2O–CHCl3 was studied. The optimum conditions for the formation of ternary ion-association complex Co–TAR–Nt were determined. The molar ratio of the reagents was determined by independent methods. Based on it, reaction scheme and general formula of the complex was suggested. The extraction equilibriums were investigated and quantitatively were characterized by the equilibrium constants and recovery factor with the aid of independent methods. The effect of various foreign ions and reagents on the complex formation between the anionic chelate Co(II)-TAR and the nitronium cation was studied. The validity of beer’s law was checked and some analytical characteristics were calculated.

Study on erythrosine-phen-Cd(II) systems by resonance Rayleigh scattering, absorption spectra and their analytical applications

In pH 7.0–8.0 KH2PO4–Na2HPO4 buffer solution, Cd(II) reacted with 1,10-phenanthroline to form chelate cation [Cd(phen)3]2+, which further reacted with anion of erythrosine to form ternary ion-association complex through electrostatic attraction and hydrophobic effect. This process could result in remarkable absorption spectra change and produce obvious fading reaction at 528nm. Absorbance change (ΔA) of system was directly proportional to the concentration of Cd(II). Hereby, a highly sensitive spectrophotometric method for the determination of Cd(II) was established. The molar absorption coefficient was 2.29×105Lmol−1cm−1 and the detection limit of Cd(II) was 26.5ngmL−1. Furthermore, the resonance Rayleigh scattering (RRS) of this system with two peaks located at 371 and 590nm enhanced significantly, and second-order scattering (SOS) and frequence doubling scattering (FDS) of this system changed notably at 640 and 350nm, respectively. Under the optimum conditions, the scattering intensities (ΔIRRS, ΔIDWO-RRS, ΔISOS and ΔIFDS) had good linear relationship with the concentration of Cd(II) in certain ranges. The detection limits of Cd(II) were 1.27ngmL−1, 1.39ngmL−1, 4.03ngmL−1, 5.92ngmL−1 and 14.7ngmL−1 for dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS), RRS (371nm), RRS (590nm), SOS and FDS, respectively. In addition, the suitable reaction conditions and effects of coexisting substances were investigated. The methods had been successfully applied to the determination of Cd(II) in environmental water samples. The recovery range was between 93.0% and 103.0% and the relative standard deviation (RSD) was between 2.5% and 4.3%. The results were in agreement with those obtained from atomic absorption spectroscopy.

The Resonance Rayleigh Scattering Spectrum Characteristic of Tb<sup>3+</sup>-GMFX-AR and the Determination of Gemifloxacin

A new method for the determination of Gemifloxacin (GMFX) by using Resonance Rayleigh scattering was put forward. In HAc-NaAc buffer solution of pH 5 - 6, terbium (III) and antibiotics GMFX could form cationic complexes, which coulf further form 1 :2 : 1 (Tb3+ : GMFX :AR) ternary ion association complexes by the reaction with Alizarin Red (AR) anion through electrostatic and hydrophobic interaction. The new Resonance Rayleigh scattering (RRS) spectra would appear, and the two scattering peaks were located at 370nm and 590 nm. At 370 nm, the scattering enhancement (ΔI) was proportional to GMFX of certain concentration and its linear range and detection limit (3σ) were 0.005 ~ 4.00 μg.mL-1and 14.5 ng.mL-1. This method is simple, fast, with good selectivity and reproducibility, and it can be used for determination of GMFX drug in various body fluids.

Retention Profile and Selective Separation of Trace Concentrations of Phenols from Water onto Iron(III) Physically Loaded Polyurethane Foam Solid Sorbent: Kinetics and Thermodynamic Study

Phenols are included in the list of potential toxins for motor neurons. Thus, fast and selective method for removal of phenols has been developed. The method was based upon the extraction of iron (III) phenolate complex anions [Fe(phenolate)6]3- by tri-n-butylphosphine (TBP)-plasticized iron(III) immobilized polyurethane foam (PUF) from the test aqueous solution adjusted to pH≈1 followed by subsequent formation of ternary ion association complex of these species with the protonated urethane and/or ether linkages on the PUF solid phase extractor (SPE). The rate of removal of phenols from the aqueous solution by TBP plasticized iron (III) immobilized PUF were studied in batch conditions employing a series of kinetic models. Initially, phenols uptake onto plasticized iron (III) treated PUF was fast followed by kinetically pseudo-second order rate equation with an overall rate constant (k) of 0.014 and 0.018 g (mg min)-1 for phenol and 2-chlorophenol (2-CP), respectively. Endothermic nature of phenols sorption is governed by the positive value of ΔH where as the negative values of ΔG dictate that the uptake of the analyte onto the sorbent is spontaneous phenomena. The positive values of ΔS for both phenols may be indicative of moderate sorption step of the complex anion [Fe(C6H5O)6]3- and ordering of ionic charges with a compensatory disordering of the sorbed species onto the sorbents. PUF sorbent provides efficient removal of phenols traces from various water samples.

Study on interaction between palladium(ІІ)–Linezolid chelate with eosin by resonance Rayleigh scattering, second order of scattering and frequency doubling scattering methods using Taguchi orthogonal array design

Linezolid reacted with palladium to form 1:1 binary cationic chelate which further reacted with eosin dye to form 1:1 ternary ion association complex at pH 4 of Walpole’s acetate buffer in the presence of methyl cellulose. As a result not only absorption spectra were changed but Resonance Rayleigh Scattering (RRS), Second-order Scattering (SOS) and Frequency Doubling Scattering (FDS) intensities were greatly enhanced. The analytical wavelengths of RRS, SOS and FDS (λex/λem) of ternary complex were located at 538nm/538nm, 240nm/480nm and 660nm/330nm, respectively. The linearity range for RRS, SOS and FDS methods were 0.01–0.5μgmL−1, 0.1–2μgmL−1 and 0.2–1.8μgmL−1, respectively. The sensitivity order of three methods was as RRS>SOS>FDS. Accuracy of all methods were determined by recovery studies and showed recovery between 98% and 102%. Intraday and inter day precision were checked for all methods and %RSD was found to be less than 2 for all methods. The effects of foreign substances were tested on RRS method and it showed the method had good selectivity. For optimization of process parameter, Taguchi orthogonal array design L8(24) was used and ANOVA was adopted to determine the statistically significant control factors that affect the scattering intensities of methods. The reaction mechanism, composition of ternary ion association complex and reasons for scattering intensity enhancement was discussed in this work.

Extraction-spectrophotometric investigations on two ternary ion-association complexes of gallium(III)

Abstract Complex formation and liquid-liquid extraction were studied in systems containing Ga(III), azoderivative of resorcinol {4-(2-pyridylazo)resorcinol (PAR) or 4-(2-thiazolylazo)resorcinol (TAR)}, 2,3,5-triphenyltetrazolium chloride (TTC), water and chloroform. The optimum conditions w.r.t. pH, extraction time, concentration of ADR and concentration of TTC for the extraction of Ga(III) as an ion-associate complex were found.. The composition of the extracted complexes, (TT+)[Ga(PAR)2] (I), (TT+)[Ga(TAR)2] (II) or (TT+)2[Ga(OH)(TAR)2] (III), and the constants of association (β) between 2,3,5-triphenyltetrazolium cation (TT+) with corresponding anionic chelates were established by several methods. The constants of distribution (KD) and extraction (Kex) of the principal species I and III were determined as well. The apparent molar absorptivities of the chloroform extract at the optimum extraction-spectrophotometric conditions were ɛ′510=9.5×104 L mol−1 cm−1 (I) and ɛ′530=4.6×104 L mol−1 cm−1 (III). The validity of Beer’s law was checked and analytical characteristics that were calculated are reported herein.

Resonance Rayleigh scattering spectra of Cu2+–adenine–WO42− system and its analytical application

In pH 6.6-7.2 Tris-HCl buffer, Cu(2+) could react with adenine (A) to form a 1:1 coordination cation [CuA](2+), which only resulted in minor change of the absorption spectrum. However, when this cation further combined with WO(4)(2-) to form a 1:1 ternary ion-association complex [CuA]WO(4), the absorption spectrum changed a lot, and the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) enhanced significantly. The maximum wavelengths of RRS, SOS and FDS were located at 310, 592 and 395 nm, respectively. The enhanced intensities of the three methods were proportional to the concentration of adenine in certain ranges, and the detection limit of the most sensitive RRS method was 7.4 × 10(-9) mol L(-1) (1.0 ng mL(-1)), indicating that this method could detect trace adenine. In this work, the optimum reaction conditions and the influencing factors have been studied, some potential interferences and the composition of the ion-association complex have been investigated. Meanwhile, the construction of the product and the reaction mechanism have been investigated by atomic force microscopy, transmission electron microscope and quantum chemical calculation. Accordingly, a novel RRS method for determination of adenine has been proposed and applied to detect adenine in real samples with satisfactory results.

Ternary ion-association complexes between the indium(III) - 4-(2-pyridylazo)resorcinol anionic chelate and some tetrazolium cations

AbstractComplex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), tetrazolium salt (TZS), water and chloroform. Two different TZS were used: 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT). The optimum conditions for extraction of In(III) as a ternary complex, (TT+)[In(PAR)2] or (MTT+)[In(PAR)2], were found: pH, extraction time, concentration of PAR and concentration of TZS. The constants of extraction (Kex), constants of association (β), constants of distribution (KD) and recovery factors (R%) were determined. The apparent molar absorptivities in chloroform were calculated to be ɛ′520=6.6×104 L mol−1 cm−1 and ɛ′515=7.1×104 L mol−1 cm−1 for the systems with TTC (I) and MTT (II), respectively. Beer’s law was obeyed for In(III) concentrations up to 3.4 µg mL−1 in both the cases. The limits of detection (LOD=0.07 µg mL−1I and LOD=0.12 µg mL−1II), limits of quantification (LOQ=0.24 µg mL−1I and LOQ=0.41 µg mL−1II) and Sandell’s sensitivities (SS) were estimated as well.

Study on the ternary ion-association complex nanoparticles of palladium(II)-famotidine and halogen-fluorescein dyes by the resonance Rayleigh scattering and their application

In pH 3.5-4.7 NaAc-HAc buffer medium,famotidine(FMTD)reacted with palladium(Ⅱ)(Pd(Ⅱ))to form chelate cation,which further reacted with halogen-fluorescein dyes(HF)such as dichlorofluorescein(DCF),dibromofluorescein(DBF),diiodofluorescein(DIF),Erythrosine(ER),eosine(EY)and eosin(EE)to form ternary ion-association complexes[Pd(FMTD)]·(HF)2.It further aggregated to form average diameter of about 9 nm nanoparticles by hydrophobic forces and Van der Waals forces.As a result,the absorption bands of DCF,DBF,DIF,ER,EY,EE were shifted,the fluorescences of them were quenched and the resonance Rayleigh scattering(RRS) were enhanced greatly.The maximum absorption wavelengths of[Pd(FMTD)·(HF)2]were located at 476 nm(DCF system),540 nm(DBF system),553 nm(DIF system),560 nm(ER system),547 nm(EY system),549 nm(EE system)and the maximum RRS wavelengths of those were located at 302-361 nm.The ΔI was proportional to the FMTD concentration in a certain range and the detection limit was 1.0-2.6 ng/L.Based on it,a high sensitive,good selective,rapid and new molecular spectrum method had been proposed to determine FMTD.It could be applied to determine FMTD in pharmaceutical preparation such as tablets,gelatin capsule and injection.In this work,the optimum reaction conditions,the influences of coexisting substances and the properties of analytical chemistry were investigated.Moreover,the mechanism of ion-association reaction and the reasons of enhancement for RRS were also discussed by the change of absorption,fluorescence and the formation of nanoparticles.

Determination of Trace Bi(Ⅲ) in Environmental Water Samples with Alizarin Red-Bi(Ⅲ)-CTMAB System by Resonance Light Scattering Spectroscopy

In hydrochloric acid solution with pH=4.1,Bi(Ⅲ) can react with alizarin red(AR) and cetyltrimethylammonium bromide(CTMAB) to form ternary ion-association complexe particles(the combination proportion was defined as n(Bi(Ⅲ)):n(AR) :n(CTMAB)=1:3:3).In this case,the resonance light scattering(RLS) intensities are enhanced greatly.The maximum RLS wavelength locates at 364 nm.The optimal conditions of the reaction,influence factors and the effect of coexisting substances were investigated.In addition,the reaction mechanism of the ternary ion-association complex was discussed.Under the optimal experimental conditions of 2.5 mL 1.0×10-4 mol/L alizarim red and 2.0 mL 1.0×10-4 mol/L CTMAB,the resonance scattering intensity(ΔI364 nm) was linearly related to the concentration of Bi(Ⅲ) in the range of 0～0.384 mg/L with a detection limit of 5.898×10-8 g/L.The method can be applied to the determination of Bi(Ⅲ) in water samples.The result was satisfactory and the recoveries were 99.5%～100.2% at the concentrations ranging from 0.552 to 0.831 μg/L,and the relative standard deviation was less than 2.7%.A sensitive,simple and new resonance light scattering method for determination of trace amount of Bi(Ⅲ) in environment was set up using the alizarin red as a spectrum probe.

Study on the interaction between palladium(II)-chlorpromazine hydrochloride and sodium tungstate by the resonance Rayleigh scattering, second-order scattering and frequency doubling scattering spectra and its analytical application

The interaction between palladium(II)-chlorpromazine hydrochloride and sodium tungstate was investigated by ultraviolet-visible absorption, resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS) spectroscopy. In pH 5.3 Britton-Robinson (BR) buffer medium, chlorpromazine hydrochloride (CPZ) reacted with Pd(II) to form 2:1 cationic chelate, which further reacted with Na2WO4 to form a 1:1 ternary ion-association complex ([Pd(CPZ)2]·WO4). As a result, the signal intensities of RRS, SOS and FDS were enhanced greatly, and the enhancements of scattering were proportional to the CPZ concentration in a certain range. Their maximum wavelengths were located at 310 nm, 570 nm and 391 nm, respectively and the detection limits (3σ) were 1.6 ng/mL (RRS method), 3.2 ng/mL (SOS method) and 5.6 ng/mL (FDS method). The optimum reaction conditions, the influences of coexisting substances and analytical application were mainly investigated by RRS method due to its highest sensitivity. A highly sensitive, simple, rapid and new method had been proposed to determine CPZ in the pharmaceutical form and residue of CPZ in pork. In addition, the Gibbs free energy change (δGf) of ion-association reaction was computed by using B3LYP/3-21g*/LanL2dz method. The formation of ion-association and the reasons for the enhancement of RRS were also discussed.

Determination of Promethazine Hydrochloride with Palladium(II) and Na2WO4 by Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Spectra

ABSTRACT In a weak acidic medium, promethazine hydrochloride (PMZ) reacted with Pd(II) to form 2:1 cationic chelate ([Pd(PMZ)2]2+), it further reacted with Na2WO4 by virtue of electrostatic attraction and hydrophobic force to form 1:1 ternary ion-association complex ([Pd(PMZ)2] · ()), which can result in the large-scale enhancement of the resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum RRS, SOS and FDS peaks of [Pd(PMZ)2] · were located at 310 nm, 570 nm and 391 nm, respectively, and the enhancements of scattering were proportional to the concentration of PMZ in the range of 0.0081–2.6 µg mL−1 (RRS method), 0.02–3.0 µg mL−1 (SOS method) and 0.08–2.6 µg mL−1 (FDS method). Above three methods' detection limits (3σ) were 2.1 ng mL−1, 4.4 ng mL−1 and 6.6 ng mL−1 respectively. Using Pd(II) and Na2WO4 as probe, we have developed three new, sensitive, and rapid methods for the determination of PMZ. The RRS method was applied in the determination of PMZ in the pharmaceutical form with satisfactory results. In this work, the optimal reaction conditions and the influences of coexisting substances were investigated, the composition of ion-association complex and the reaction mechanism were also discussed by the RRS method.

The interaction between furosemide-palladium (II) chelate and basic triphenylmethane dyes by resonance Rayleigh scattering spectra and resonance non-linear scattering spectra and their analytical applications

In pH 4.5–7.0 Britton-Robinson buffer solution, furosemide (FUR) reacted with Pd (II) to form a 1:1 anionic chelate. This chelate could further react with such basic triphenylmethane dyes (BTPMD) as ethyl violet (EV), crystal violet (CV), methyl violet (MV), methyl green (MeG) and brilliant green (BG) to form 1:1 ion-association complexes. This not only resulted in the change of absorption spectra, but also led to the significant enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum RRS wavelengths were located at 324 nm for the EV, CV and MV system, and 340 nm for the BG and MeG system. The maximum SOS wavelengths were located at 550 nm for the EV, CV, BG and MeG system, and 530 nm for the MV system. The maximum scattering peaks of all the systems were at 392 nm for FDS. The enhanced RRS, SOS and FDS intensities were directly proportional to the concentration of FUR. The detection limits for the different dye systems were 0.3–4.9 ng mL−1 for the RRS method, 3.2–33.1 ng mL−1 for the SOS method and 9.0–85.7 ng mL−1 for the FDS method. These methods could be used for the determination of trace amounts of FUR. The effects of the formation of ternary ion-association complexes on the spectral characteristics and intensities of absorption, RRS, SOS and FDS have been investigated. The optimum conditions of these reactions, the influencing factors and the analytical properties have been tested. The influences of coexisting substances were tested by RRS method and the results showed that this method exhibited a high sensitivity. Based on the aforementioned research, the highly sensitive, simple and rapid methods for the determination of trace amounts of FUR by resonance light scattering technique have been established, which could be applied to the determination of FUR in tablet, injection, human serum and urine samples. The composition and structure of the ternary ion-association complex and the reaction mechanism were discussed.

The resonance Rayleigh scattering of the interaction of copper(II)-bleomycinA2 with DNA and its analytical application

The forming of bleomycinA2-Cu(II) cationic chelate and the interaction of the chelate with DNA have been investigated by using resonance Rayleigh scattering (RRS), molecular absorption and fluorescence spectra. The result shows that in aqueous solution, bleomycinA2 (BLMA2) can react with Cu(II) to form 1:1 cationic chelate which contributes to the changes of the absorption spectra and the quenched fluorescence of BLMA2. When the cationic chelate further bound with DNA to form ternary ion-association complexes, the remarkable enhancement of the RRS intensity was observed. In this work, the optimum conditions for the coordination reaction of BLMA2 with Cu(II) and some influencing factors have been investigated. The reaction mechanism of BLMA2-Cu(II) binding with DNA was suggested and a binding model was proposed. In addition, the fluorescence quenching type of BLMA2 was investigated. A highly sensitive, simple and rapid new method for the determination of DNA by using BLMA2-Cu(II) as RRS probe has been developed. The detection limits (3σ) are 7.2 ng/mL for ctDNA, 7.1 ng/mL for sDNA and 18 ng/mL for hsDNA. The method can be applied to the determination of trace amounts of DNA.

Resonance Rayleigh scattering spectra of ion-association nanoparticles of [Co(4-[(5-Chloro-2-pyridyl) azo]-1, 3-diaminobenzene) 2] 2+-sodium dodecyl benzene sulfonate system and its analytical application

In pH 1.8–3.0 Britton–Robinson (BR) buffer solution, cobalt (II) reacts with 4-[(5-Chloro-2-pyridyl) azo]-1, 3-diaminobenzene (5-Cl-PADAB, L) to form a cationic chelate [CoL 2] 2+. When interacting with anionic surfactants (AS) such as sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS) or sodium dodecyl sulfonate (SLS), the chelate can only react with SDBS to form ternary ion-association complexes ([CoL 2][SDBS] 2). By virtue of the extrusion action of water and Van der Waals force, the hydrophobic ion-association complexes draw close to each other and further aggregate to form {[CoL 2][SDBS] 2} n nanoparticles with an average diameter of 30 nm. As a result, resonance Rayleigh scattering (RRS) is enhanced greatly and new RRS spectra appear. Under the same conditions, both SDS and SLS exhibit no similar reactions and do not result in obvious change of RRS. Therefore, SDBS can be determined selectively by RRS method in the presence of SDS or SLS. The wavelength of 516 nm was chosen as a detection wavelength, the linear range and the detection limit (3 σ) are 0.05–6.0 μg mL −1 and 0.015 μg mL −1 for the determination of SDBS, respectively. The characteristics of RRS spectra of the [CoL 2] 2+–SDBS system, the optimum conditions of the reaction and the influencing factors have been investigated. The effects of coexisting substances have been examined too, indicating a good selectivity of the method for the determination of SDBS. The method can be used for the determination of SDBS in waste water and river water samples, and the results are satisfactory compared with those of standard samples of SDBS. Based on the formation of {[CoL 2][SDBS] 2} n nanoparticles, a sensitive, simple and rapid method has been developed for the determination of SDBS in environmental water samples using a RRS technique. Moreover, the reaction mechanism was discussed.

Effects of interaction of folic acid with uranium (VI) and basic triphenylmethane dyes on resonance Rayleigh scattering spectra and their analytical applications

In pH 4.2–4.8 HAc–NaAc buffer solution, folic acid (FA) could react with uranium (VI) to form a 2:1 anionic chelate which further reacted with some basic triphenylmethane dyes (BTPMD) such as Ethyl Violet (EV), Methyl Violet (MV) and Crystal Violet (CV) to form 1:2 ion-association complexes. As a result, not only the absorption spectra were changed, but also the intensities of resonance Rayleigh scattering (RRS) were enhanced greatly and the new RRS spectra were observed. The maximum RRS wavelengths were located at 328 nm for EV system, 325 nm for MV system and 328 nm for CV system. The fading degree (Δ A) and RRS intensities (Δ I) of three systems were different. Under given conditions, the Δ A and Δ I were all directly proportional to the concentration of FA. The linear ranges and the detection limits of RRS methods were 0.0039–5.0 μg mL −1 and 1.2 ng mL −1 for EV system, 0.0073–4.0 μg mL −1 and 2.2 ng mL −1 for MV system, 0.014–3.5 μg mL −1 and 4.7 ng mL −1 for CV system. The RRS methods exhibited higher sensitivity, so they are more suitable for the determination of trace FA. The optimum conditions, the influencing factors and the effects of coexisting substances on the reaction were investigated. The method can be applied to the determination of FA in serum and urine samples with satisfactory results. The structure of the ternary ion-association complex and the reaction mechanism were discussed in this work.

Ternary ion-association complex based ion imprinted polymers (IIPs) for trace determination of palladium(II) in environmental samples

A new ion imprinted polymer (IIP) material was synthesized by co-polymerization of palladium–iodide–vinyl pyridinium/palladium–thiocyanate–vinyl pyridinium ion ternary ion-association complex taken in methanol/DMSO with 2-hydroxyethyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (crosslinking monomer) in the presence of 2,2′-azobisisobutryonitrile (initiator). The imprinted anionic species [PdI 4] 2− or [Pd(SCN) 4] 2− were removed by leaching the dried and powdered materials particles for 18 h with 6 M HCl to obtain leached IIP particles. Non-imprinted/control polymers were also prepared in a similar fashion without the template. Various parameters that influence the percent extraction of palladium, viz. concentration of KI or KSCN, pH, weight of polymer particles, preconcentration and elution times, aqueous phase volume, etc., were systematically studied for both the systems, i.e., in batch as well as flow injection modes. As the on-line flow injection-flame atomic absorption spectrometric (FI-FAAS) allow offer higher enrichment factor, better precision and can analyze more samples for a given time, compared to batch method, this procedure is preferred for the analysis of palladium present in the street/fan blade dust samples collected from busy cities of India and the values obtained were compared with the standard ICPMS values.