An RP LC-ESI-MS/MS method for the determination of the migration of 16 primary phthalic acid esters from plastic samples has been developed using distilled water, 3% acetic acid, 10% alcohol, and olive oil as food simulants. Detection limits were 1.6–18.5 μg/kg in distilled water, 1.4–17.3 μg/kg in 3% acetic acid, 1.4–19.2 μg/kg in 10% alcohol, and 31.9–390.8 μg/kg in olive oil. The RSDs were in the range of 0.07–11.28%. The real plastic products inspection showed that only few analyzed samples were phthalates contaminated. Bis-2-ethylhexyl ester and dibutyl phthalate were the common items migrated from the plastic products into food and feeds, but the migration concentrations were far below the limits set by European Union (1.5 mg/kg for bis-2-ethylhexyl ester and 0.3 mg/kg for dibutyl phthalate).

The preparative-scale separation of chiral compounds is vitally important for the pharmaceutical industry and related fields. Herein we report a simple approach for rapid preparative separation of enantiomers using functional nucleic acids modified gold nanoparticles (AuNPs). The separation of _DL-tryptophan (_DL-Trp) is demonstrated as an example to show the feasibility of the approach. AuNPs modified with enantioselective aptamers were added into a racemic mixture of _DL-Trp. The aptamer-specific enantiomer (_L-Trp) binds to the AuNPs surface through aptamer-_L-Trp interaction. The separation of _DL-Trp is then simply accomplished by centrifugation: the precipitate containing _L-Trp bounded AuNPs is separated from the solution, while the _D-Trp remains in the supernatant. The precipitate is then redispersed in water. The aptamer is denatured under 95 °C and a second centrifugation is then performed, resulting in the separation of AuNPs and _L-Trp. The supernatant is finally collected to obtain pure _L-Trp in water. The results show that the racemic mixture of _DL-Trp is completely separated into _D-Trp and _L-Trp, respectively, after 5 rounds of repeated addition of fresh aptamer-modified AuNPs to the _DL-Trp mixture solution. Additionally, the aptamer-modified AuNPs can be repeatedly used for at least eight times without significant loss of its binding ability because the aptamer can be easily denatured and renatured in relatively mild conditions. The proposed approach could be scaled up and extended to the separation of other enantiomers by the adoption of other enantioselective aptamers. Chirality 25:751–756, 2013. © 2013 Wiley Periodicals, Inc.

A homogeneous chemiluminescence (CL) reaction was initiated by ultrasound irradiation. Luminol sonochemiluminescence (SCL) reaction kinetics were determined under pseudo-first-order conditions, and the reaction followed the model for simple rise–fall kinetics. In addition, SCL quenching reactions induced by purines were also investigated in which the interactions between luminol and purines were analysed using the Stern–Volmer (S-V) mechanism. The results implied that the high rate constant of luminol CL quenched by purines may be attributed to ground state interactions originating from hydrogen bonding. Copyright © 2012 John Wiley & Sons, Ltd.

An HPLC system combining a chemiluminescence detector was applied to estimate the singlet oxygen (¹O₂) generation ability of di-sulfonic phthalocyanine zinc (ZnPcS₂) isomers. As photosensitizers, ZnPcS₂ produces ¹O₂ in air-saturated solutions under photoirradiation. The latter reacts with methyl Cypridina luciferin analogue (MCLA) to initiate chemiluminescence. This photoinduced chemiluminescence (PCL) of MCLA provides an easy method for evaluating the isomers' ¹O₂ generation ability during a simultaneous HPLC separation procedure. The cis-isomers and trans-isomers of ZnPcS₂ show different ¹O₂ generation abilities, which are in accordance with differences in their absorption spectra. Copyright © 2013 John Wiley & Sons, Ltd.

Two new iridium(III) complexes with good water-solubility and biocompatibility have been synthesized and characterized. These two iridium(III) complexes showed strong luminescence with high quantum efficiency. Preliminary experiments demonstrated the feasibility of sensing lectin by formation of iridium(III) complexes. These new iridium(III) complexes might open up new applications in biosensor and chemosensor.

The cover picture shows the structures of two novel water-soluble cyclometalated iridium(III) complexes with good water solubility, high quantum efficiency and biocompatibility. Preliminary experiments of cell viability and sensing of lectin show that iridium(III) complexes with appended sugar groups provide advantages of reducing the toxicity and of improving the solubility in water, and open up the possibility of molecular targeting of carbohydrate-binding domains in cells and tissues. Details are discussed in the Short Communication by M.-J. Li, G.-N. Chen et al. on p. 197.

Ergosterol and stigmasterol are the most common phytosterols in the traditional Chinese medicine. They are two major sterol compounds in Anoectochilus roxburghii (wall) Lindl (A. roxburghii) and have been proved to have many important biological activities. A method by using high-speed counter-current chromatography (HSCCC) has been successfully developed for separation and purification of ergosterol and stigmasterol in A. roxburghii simultaneously in this paper. The optimum conditions used in this method were as follows: The two-phase solvent system consisted of n-hexane–ethylacetate–butanol–methanol–water (3.5:0.3:0.5:2.5:0.3, v/v); the rotation speed was 900 rpm; the flow rate of the lower phase was 1.5 mL/min. About 36.5 mg of ergosterol and 43.6 mg of stigmasterol were obtained from 100 g of A. roxburghii. The purity of ergosterol and stigmasterol was examined to be 92.0 and 95.5%, respectively, by using HPLC. The chemical structures of these components were identified by UV spectra, FT-IR, MS, ¹H-NMR and ¹³C-NMR. The results demonstrated that high-speed counter-current chromatography was a feasible method to separate and purify ergosterol and stigmasterol from the herb. This separation and purification method was more effective than many other conventional techniques.

The interaction between tamibarotene and bovine serum albumin (BSA) was studied using fluorescence quenching technique and ultraviolet–visible spectrophotometry. The results of experiments showed that tamibarotene could strongly quench the intrinsic fluorescence of BSA by a dynamic quenching mechanism. The apparent binding constant, number of binding site and corresponding thermodynamic parameters at different temperatures were calculated respectively, and the main interaction force between tamibarotene and BSA was proved to be hydrophobic force. Synchronous fluorescence spectra showed that tamibarotene changed the molecular conformation of BSA. When BSA concentration was 1.00 × 10⁻⁶ mol L⁻¹, the quenched fluorescence ΔF had a good linear relationship with the concentration of tamibarotene in the range 1.00 × 10⁻⁶ to 12.00 × 10⁻⁶ mol L⁻¹ with the detection limit of 6.52 × 10⁻⁷ mol L⁻¹. Copyright © 2010 John Wiley & Sons, Ltd.

A novel method using microemulsion electrokinetic chromatography combining accelerated solvent extraction was developed for quantitative analysis of six phthalate esters (PAEs) including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, as well as dioctyl phthalate. The effect of each individual component within the microemulsions, i.e. oil phase, surfactant and co-surfactant on resolution of the analytes was systematically studied. Baseline separation of six PAEs was achieved within 26 min by using the microemulsion buffer containing a 60 mmol/L borate buffer at pH 9.0, 0.5% v/v n-octane as oil droplets, 100 mmol/L sodium cholate as surfactant and 5.0% v/v 1-butanol as co-surfactant. The purposed accelerated solvent extraction-microemulsion electrokinetic chromatography method was successfully applied to the determination of trace amount of PAEs in soil samples collected from three different fields in areas of Fujian Province and the contents of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate and dioctyl phthalate were 0.63–0.68, 0.32–0.63, 2.53–3.96, 0–1.75, 7.32–11.7 and 0–3.46mg/kg, respectively. It was validated that the results were consistent with those obtained by GC-MS method.

The interaction between quinidine sulfate (QDS) and congo red (CR) was studied using resonance light scattering (RLS) technique, ultraviolet–visual spectrophotometry and fluorimetry. In weak acidic medium, QDS reacts with CR to form a supermolecular complex which results in the enhanced RLS intensity. Some important interacting parameters, such as the solution acidity and CR concentration, salt effect and addition order of the reagents, were investigated and optimized. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of QDS in the range 0.2–8.4 µg mL⁻¹. The corresponding detection limit was 12.0 ng mL⁻¹. The results showed that this new method enabled simple, sensitive and rapid determination of QDS and was used for the determination of QDS in urine and simulated huamn serum samples. Copyright © 2009 John Wiley & Sons, Ltd.

A simple method was established to determine protoberberine alkaloids in Cortex Phellodendri and Rhizoma Coptidis based on an acidic potassium permanganate chemiluminescence (CL) system. The optimum conditions for the CL reaction between protoberberine alkaloids and potassium permanganate were studied in detail. Under the optimum conditions, the linear response ranges for berberine, palmatine and jatrorrhizine were 0.038–7.27, 0.031–18.1 and 0.012–3.61 μg/mL with detection limits of 0.005, 0.004 and 0.0007 μg/mL, respectively. This method was successfully applied to determine the content of protoberberine alkaloids (calculated using berberine as an index) in Cortex Phellodendri and Rhizoma Coptidis. In addition, a possible mechanism of this CL reaction was proposed on the basis of the investigation of CL, UV and fluorescent spectra of protoberberine alkaloids in acidic solution containing potassium permanganate. Copyright © 2009 John Wiley & Sons, Ltd.

A high-performance CE with amperometric detection (CE-AD) was employed for the kinetic study of keto-enol tautomerism of p-hydroxyphenylpyruvic acid (pHPP). Several factors (concentration of β-cyclodextrin (β-CD), concentration and pH of running buffer, separation voltage and injection time) affecting CE-AD were investigated and separation conditions were optimized. The kinetics of pHPP was performed in water solution and phosphate solution under different pH and temperature, the homologous ketonization rate constants and half-life were obtained. Also, the activation energy was calculated according to the rate constants under different temperature. The experimental results indicated that β-CD played an important role in the separation, therefore UV spectrometric method was applied for the study of complexation interaction between ketonic pHPP and β-CD. The results indicated that the stoichiometric ratio of the pHPP–β-CD complex was 1:1 and formation constant was determined. The obtained kinetic results are in correspondence with those reported by our group with CE-UV.

It was found that meloxicam could enhance the chemiluminescence (CL) of the tris(2,2'-bipyridine) ruthenium(II)–Ce(IV) system in the medium of sulfate acid. Based on this phenomenon a new flow-injection system with chemiluminescent detection has been proposed for determination of meloxicam. Under optimum conditions, meloxicam had a good linear relationship with the CL intensity in the concentration range of 6.0  10⁻⁴ to 1.0 µg/mL and the detection limit was 3.7 × 10⁻⁴ µg/mL. The proposed method was applied to detect meloxicam in tablets and a satisfactory recovery was obtained. The possible mechanism for this CL system is also discussed in this paper. Copyright © 2009 John Wiley & Sons, Ltd.

A simple, reliable, and reproducible method for separation and determination of five enkephalin-related peptides based on CE with amperometric detection (AD) is described in this paper. A potential of 1.0 V was applied to the carbon disk electrode, which was used as a working electrode in this system. At 15 kV of applied voltage, the five compounds were separated within 18 min in a 20 mmol/L phosphate buffer solution (PBS, pH 7.6) including 2.5% methanol v/v. LOD for five enkephalins were ranged from 6.31 to 54.3 nmol/L. The method was applied successfully to determine the five compounds added in the human cerebrospinal fluid (CSF) and the recoveries were in the range of 95.8–98.2%.

Flavones such as morin, rutin, quercitrin, quercetin and wogonin were found to be able to strongly enhance the electrochemiluminescence (ECL) of the Ru(bpy)₃²⁺ system. Based on this, a novel ECL method with good stability and reproducibility could be developed for determination of flavones. Under the optimum conditions, the enhanced ECL intensity was linear with the flavones concentration in a wide range. The detection limits (defined as S:N = 3) for morin, rutin, quercitrin, quercetin and wogonin were 3.2 × 10^–7 mol/L, 4.3 × 10^–7, 1.8 × 10^–7, 8.0 × 10^–8 and 1.0 × 10^–7 mol/L, respectively. In addition, the possible mechanism for the Ru(bpy)₃²⁺ ECL system in the presence of flavones is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.