•Hydrotalcite-like compounds modified bentonite has successfully synthesized.•Ben-HTlc shows better adsorption properties for Pb2+, Cu2+ and MO than some of other adsorbents.•The adsorption capacities sequencing of adsorbent for pollutants is Pb2+ > MO > Cu2+.•Lanthanum ions in hydrotalcite-like compounds have significantly improved the adsorption capacity of Ben-HTlc.Hydrotalcite-like compound (HTlc) which contained lanthanum cation was prepared successfully. The title compound was characterized by thermogravimetry analysis, element analysis, X-ray fluorescence, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, as well as specific surface area. The study sought to investigate the adsorption of heavy metals and dye (Pb2+, Cu2+ and methyl orange) in aqueous solution on Ben-HTlc. For optimization of adsorption behavior of the three elements, the pH value, contact time, adsorbate concentration were optimized. As for Pb2+, Cu2+ and methyl orange (MO), the single-component adsorption generally reached the maximum quantity in first 20 min and their respective adsorption capacities were 384.6 mg g−1, 156.3 mg g−1 and 333.3 mg g−1 (pH = 6.5 ± 0.1), the adsorption affinities were in the following sequence Pb2+ > MO > Cu2+. The repeated adsorption and regeneration studies showed the promising application of Ben-HTlc. The breakthrough experimental consequence had shown that the synthesized Ben-HTlc could efficiently remove heavy metals and dye from water, suggesting the potential utilization of Ben-HTlc in pollutants removal.Synthesis route of Ben-HTlc and the adsorption procedure of heavy metals and methyl orange in aqueous solution.Download high-res image (196KB)Download full-size image

•A highly sensitive method of RRS and FL are firstly applied to analyzing the two nootropic drugs.•The method has been applied to determine Nootropic drugs in human urine sample.•Quantum chemistry calculation and Valence bond theory were used to discuss the reaction mechanism.•This work can provide more effective detection method for Nootropic drugs than other methods.A highly sensitive detection approach of resonance Rayleigh scattering spectra (RRS) is firstly applied to analyzing nootropic drugs including piracetam (PIR) and oxiracetam (OXI). In HCl-NaAc buffer solution (pH = 3.0), the OXI chelated with palladium (II) to form the chelate cation [Pd2·OXI]2 +, and then reacted with Congo red (CGR) by virtue of electrostatic attraction and hydrophobic force to form binary complex [Pd2·OXI]. CGR2, which could result in the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λex = λem = 375 nm. This mixture complex not only has higher RRS, but also makes contribution to significant increase of fluorescence, and the same phenomena also were discovered in PIR. The enhanced RRS intensity is in proportion to the PIR and OXI concentration in the range of 0.03–3.0 μg mL− 1, and the detection limit (DL) of RRS method for PIR and OXI is 2.3 ng mL− 1 and 9.7 ng mL− 1. In addition, the DL of fluorescence method for PIR and OXI is 8.4 μg mL− 1 and 19.5 μg mL− 1. Obviously, the RRS is the highly sensitive method, and the recoveries of the two kinds of nootropic drugs were range from 100.4% to 101.8.0% with RSD (n = 5) from 1.1% to 3.1% by RRS method. This paper not only investigated the optimum conditions for detecting nootropics with using RRS method, but also focused on the reasons for enhancing RRS intensity and the reaction mechanism, which in order to firm and contract the resultant. Finally, The RRS method has been applied to detect nootropic drugs in human urine samples with satisfactory results.

•A simple, fast, costless, sensitive method of Resonance light scattering coupled with HPLC for the analysis of 6-mercaptopurine in human urine was established.•There were no complicated derivatization procedure involved in the proposed method.•The reation mechanism and possible reasons for enhancement of RLS were fully discussed in this work.A simple, fast, costless, sensitive and selective method of resonance light scattering coupled with HPLC was established for the determination of 6-mercaptopurine in human urine sample. In a Britton–Robinson buffer solution of pH 5.5, the formation of coordination complex between 6-mercaptopurine and metal palladium (II) led to enhance the RLS intensity of the system. The RLS signal was detected by fluorescence detector at λex = λem = 315 nm. The analytical parameters were provided by the coupled system, the linear of 6-mercaptopurine response from 0.0615 to 2.40 μg L− 1 and the limit of detection (S/N = 3) was 0.05 μg L− 1. The presented method has been applied to determine 6-mercaptopurine in human urine samples which obtained satisfactory results. Moreover, the reaction mechanism and possible reasons for enhancement of RLS were fully discussed.When 6-mercaptopurine reacted with palladium chloride to form the neutral complex, a hydrophobic interface was formed between the coordination complex and the aqueous phase, which is advantageous to the enhancement of RLS. The congregated complex formed by the squeezing effect of aqueous phase and Vander Waals force is the main reason for the enhancement of scattering since congregation enlarges the volume of the scattered molecular. Coordinated product was validated by the application of Job's method of continuous variation and molar ratio method. It showed that the reaction was produced by mixing the two substances in the composition ratio of 2:1. Based on mole ratio and infrared spectra, the following reaction was speculated:

In pH 2.55 HCl solution, vitamin C (VC) could deoxidize [Fe(CN)6]3− producing [Fe(CN)6]4−, which reacted with Zr (IV) to form Zr[Fe(CN)6] complex, then aggregated to produce {Zr[Fe(CN)6]}n nanoparticles by virtue of hydrophobic force and van der Waals force. The intensity of RRS at 340 nm is directly proportional to the concentration of VC in the range of 0.1–1.45 μg mL−1, and the detection limit (3 s/k) is 0.128 ng mL−1. In this work, the spectral characteristics of RRS, the optimum condition, the reaction mechanism of the reaction, and their influencing factors especially the effect of organic solvent have been studied. The sensitive, rapid, and simple method based on resonance Rayleigh scattering was successfully applied to determine trace amount VC in VC injection and tablet.

A highly selective and sensitive method of high performance liquid chromatography combined with resonance Rayleigh scattering spectra was developed for the detection of six psychotropic drugs, including Doxepin, Promethazine, Imipramine, Amitriptyline, Chlorpromazine and Clomipramine. This method was based on the weak intensity of the RRS of six drugs and its significant enhancement after combined with Erythrosine (Ery) in a pH 4.0–4.7 BR buffer solution. The linear range was between 0.05 and 20 μg mL−1 with correlation coefficients (r) all above 0.9916. The limits of detection (S/N = 3) were in the range of 0.42 and 21.05 ng mL−1. Because the RRS detection wavelength was special (the excitation wavelength was equal to the emission wavelength, λex = λem = 295 nm) and some other substances in human urine do not form ion-association complex with the Ery, no interference from the matrix was observed. The proposed method was successfully applied to real human urine samples analysis.

A rapid high-performance liquid chromatography (HPLC) technique incorporating resonance Rayleigh scattering (RRS) detection was developed for the determination of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DOTC). This method was based on the weak intensity of the RRS of the TCs and its enhancement with the addition of titan yellow (TY) and CuSO4 in a pH 3.5 Britton–Robinson buffer solution. The RRS signal was detected at λex = λem = 450 nm. The chromatographic separation used (25:75, v/v) methanol–phosphate buffer (pH 3) as the mobile phase. The analytical technique was validated for intra- and inter-day variations and the detection limits of the assay were 0.668 μg mL−1 for TC, 0.342 μg mL−1 for OTC, 0.480 μg mL−1 for CTC and 0.132 μg mL−1 for DOTC at a signal-to-noise ratifo of 3.0. The conditions for separation and detection were optimized and the reasons for the RRS enhancement were evaluated. The developed method was validated for the analysis of TCs in water samples. The recoveries were acceptable (ranging from 97.4–102.4%).

In the present study, an ultrasensitive electrochemical aptasensor for the simultaneous detection of thrombin (TB) and ochratoxin A (OTA) was fabricated by using exonuclease-catalyzed target recycling and DNA concatemers for signal amplification. The previously hybridized double-stranded DNAs (SH-cTBA/TBA and SH-cOBA/OBA) were self-assembled on a gold electrode. In the presence of targets, the formation of aptamer–target complexes would lead to not only the dissociation of aptamers (TBA and OBA) from the double-stranded DNAs but also the transformation of the complementary DNAs (SH-cTBA and SH-cOBA) into hairpin structures. Subsequently, owing to employment of RecJf exonuclease, which is a single-stranded DNA-specific exonuclease to selectively digest the appointed DNAs (TBA and OBA), the targets could be liberated from the aptamer–target complexes for recycling of the analytes. Thereafter, probe DNAs (T1 and T2) were employed to hybridize with SH-cTBA and SH-cOBA respectively to provide primers for the concatemer reaction. After that, when four auxiliary DNA strands S1, anthraquinone-2-carboxylic acid (AQ)-labeled S2, S3, S4, as well as hemin were introduced, extended dsDNA polymers with lots of AQ moieties and hemin–G-quadruplex complexes could form on the electrode surface. Then, based on the signal of the AQ and hemin–G-quadruplex complex, an electrochemical aptasensor for the simultaneous detection of TB and OTA was successfully fabricated.

A series of dyes based on a porphyrin donor and a cyanoacrylic acid anchor/acceptor group for solar cell application are investigated with regards to varied-length π-spacers affecting the photo-to-electric conversion efficiency (PCE). Investigations are firstly performed on three porphyrin sensitizers with 1–3 conjugated phenylethynyl (PE) units, which have experimentally proved that the efficiency of power conversion decreases systematically with increasing spacer length. The distances and amounts of charge transfer after photoexcitation are calculated. In the PE bridged porphyrin dyes, the calculated electron injection driving forces and the regeneration driving forces gradually decrease as the distance of the π-spacer increases. Our theoretical calculations can reproduce well the experimental conclusion, showing that the photo-to-electric efficiency has a strong distance dependence for the electron-rich phenyl spacer. Then we replace the phenyl group with a pyrimidyl (PM) group to uncover how the characteristics of the π-spacer affect the performance of optical absorption, charge separation, and the regeneration process, to further improve the power conversion. We find that the adoption of electron-deficient pyrimidyl can break and even remove the distance dependence of the π-spacer. Some integral factors affecting the dye performance, such as short-circuit photocurrent, open-circuit voltage and charge collection efficiency are analyzed. It would help to interpret what role the electron deficient π-spacers with varied lengths will play and how they are expected to behave in the performance of sensitizers. In this regard, this study presents us with a promising way to design novel functional dyes and to utilize the potential advantages of the lengthy spacer dyes.

A simple and rapid reversed-phase high performance liquid chromatography method, using resonance Rayleigh scattering detection, for the determination of neomycin sulfate in serum samples was developed. Separation was performed on a Synergi Hydro-RP column with water solution which contained 0.18% TFA (v/v) as the mobile phase. Separation variables were optimized and discussed. In acid medium, neomycin sulfate could react with trypan red to form ion-association complexes, there is a stoichiometric ratio of 1:1 between the reaction of the neomycin sulfate with trypan red by Job plot analysis and the molar ratio method. Scanning electron microscopy revealed that these aggregates were spherical gathered particles with an average size of 45 nm, which was in agreement with the theoretical results. The analytical parameters were provided by the system, limit of detection (LOD) of 56 ng mL−1 (3σ), linear correlation of 0.9990 and linear range response from 0.48 to 23.52 μg mL−1. The precision of the method was <4%. Herein we demonstrated a novel method for the determination of neomycin sulfate which obtained satisfactory results.

A reliable and novel high performance liquid chromatography (HPLC) incorporating resonance Rayleigh scattering (RRS) detection was developed for the determination of procaine (Pro) and lidocaine (Lid). This method was based on the weak intensity of RRS of procaine and lidocaine, which can be enhanced by the addition of Erythrosin Yellowish (E-Y) in pH 4.4 acidic medium. The RRS signal was detected at λex = λem = 370 nm. The conditions of separation and detection were optimized (pH, proportion of organic phase, flow rate, reaction temperature, concentration of E-Y and the length of reaction tube). The shape of ion-association complexes was observed by scanning electron microscopy. The reasons for RRS enhancement and the nature of the ion-association complexes were discussed by quantum chemistry calculation, scanning electron microscopy and absorption spectroscopy. The calibration curves of procaine and lidocaine were linear in the range from 0.005 to 15.375 μg mL−1 and the limit of detection (S/N = 3) was 2.3 ng mL−1 for procaine and 15 ng mL−1 for lidocaine. The developed method was validated for the assay of procaine and lidocaine in human plasma samples. The recoveries were between 97.8% and 105.9% which is within acceptable limits.

In the present letter we investigate the noncovalent interactions in the mixed coaggregates of 1,3,5-triphenyl-2-pyrazoline (TPP) and 1,4-dicyanonaphthalene (DCN) and their influence on the excited-state properties of the TPP–DCN. The theoretical results show that the π–π stacking interactions play an important role in the noncovalent interactions of the TPP–DCN coaggregates. The effect of the π–π interactions on the excited-state properties of the TPP–DCN is also fully investigated, and the results indicate that the TPP and DCN do not form an intermolecular charge-transfer complex in the ground state, whereas they form an exciplex in the excited state.Graphical abstractHighlights► The ground and excited state geometries of the mixed aggregates are obtained. ► The effect of the π–π stacking interaction on the excited-state properties of the mixed. ► TPP–DCN coaggregates is also fully investigated through analysing the absorption and fluorescence spectra and the frontier molecular orbitals. ► The nature of the noncovalent interactions is described.

A simple and novel reversed-phase high performance liquid chromatography (HPLC) method coupled with resonance Rayleigh scattering (RRS) was developed to analyze isepamicin (ISP) in rat plasma. The chromatographic separation was achieved at 30 °C on a reverse phase column of Synergi Hydro-RP (150 mm × 4.6 mm; 4 μm), with (15:85, v/v) methanol–water (containing 0.15% TFA (v/v)) as the mobile phase. The flow rate was 0.4 mL min−1. The RRS signal was detected at λex = λem = 372 nm. Netilmicin (NTL) was used as the internal standard. The new analytical technique was validated for the intra- and inter-day variation, the linear range of the standard curve of ISP and the limit of detection (S/N = 3). The results indicated that HPLC coupled with RRS was a reliable and valuable technique for quantitative analysis of ISP in rat plasma. The method shows a better linear relationship and lower analysis time.

In view of the fact that many substances generally exhibit very little ultraviolet absorbance and the absence of native fluorescence, a new strategy with simple instrumentation and excellent analytical performance combining high performance liquid chromatography (HPLC) with resonance Rayleigh scattering (RRS) was developed. It was validated for the quantification of aminoglycosides (AGs). This fact was also carefully calculated by quantum chemistry. However, the sensitivity was probably limited by the volume of flow-through cell. Therefore, the result calls for a suitable one to ensure optimal RRS signal. Interestingly, when serum or urine samples of analytes were analyzed by this method, they were all well resolved without any interference, which would hold a new perspective to be applied in the determination of substances in biological matrix.Graphical abstractTheoretical and experimental analysis had proved that aminoglycosides reacted with Congo red to form binary compounds simultaneously, which led to a novel HPLC–RRS strategy being applied in substances which are not fluorescing and not UV absorbed.Highlights► A novel HPLC–RRS strategy was shown in this study. ► Theoretical and experimental analysis had proved the feasibility of this method. ► Because of its specificity, no interference from the matrix was observed. ► The analytes in biological matrix were all well resolved without any interference. ► It provided new insights for analytes lack of useful spectroscopic and electrochemical properties.

A simple and novel LC method has been developed for determination of isepamicin (ISP) in rat plasma, an aminoglycoside antibiotic agent. After protein precipitation and clean-up procedure to remove lipophilic contaminants, ISP is derivatized by pre-column with 9-fluorenylmethyl chloroformate for fluorescence detection. Chromatographic separations are achieved using a C18 column and mobile phase consisting of water and acetonitrile (68/32, v/v). Amikacin was used as an internal standard. The calibration curve was linear over a concentration range of 0.625–15 μg mL−1. The limit of quantification was 0.45 μg mL−1. The intra- and inter-day variabilities of ISP were both less than 5%. Both derivatives were stable for at least a week at ambient condition. This assay procedure should have useful application in therapeutic drug monitoring of ISP. The limit of detection was 0.10 μg mL−1. The specificity, assay linearity, low level assay linearity and assay repeatability were also investigated. The established method provides a reliable bioanalytical method to carry out isepamicin pharmacokinetics in rat plasma.

High-performance liquid chromatography with fluorescence detection has been used for simple and efficient analysis of the aminoglycoside kanamycin in human plasma. Kanamycin sulfate was derivatized with 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer (0.2 M, pH 8.5) for 30 min at 25 °C. The derivative was chromatographed on a 150 mm × 4.6 mm, 5-μm particle, C8 column with 70% acetonitrile in water as mobile phase at a flow rate of 1.0 mL min−1. Under these conditions the retention time of kanamycin-FMOC was 6.2 min. The fluorescence excitation and emission wavelengths were 268 and 318 nm, respectively. Recoveries ranging from 92.3 to 100.8% were obtained. The correlation coefficient was >0.999 over the range 0.1–4.0 μg mL−1. The within-day precision of the method, as coefficient of variation, was 2.9–5.5% (n = 5). The kanamycin-FMOC derivative was stable in the reaction solution for 24 h at room temperature. Validation of the method is reported.

A rapid high-performance liquid chromatography (HPLC) technique incorporating resonance Rayleigh scattering (RRS) detection was developed for the determination of tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DOTC). This method was based on the weak intensity of the RRS of the TCs and its enhancement with the addition of titan yellow (TY) and CuSO4 in a pH 3.5 Britton–Robinson buffer solution. The RRS signal was detected at λex = λem = 450 nm. The chromatographic separation used (25:75, v/v) methanol–phosphate buffer (pH 3) as the mobile phase. The analytical technique was validated for intra- and inter-day variations and the detection limits of the assay were 0.668 μg mL−1 for TC, 0.342 μg mL−1 for OTC, 0.480 μg mL−1 for CTC and 0.132 μg mL−1 for DOTC at a signal-to-noise ratifo of 3.0. The conditions for separation and detection were optimized and the reasons for the RRS enhancement were evaluated. The developed method was validated for the analysis of TCs in water samples. The recoveries were acceptable (ranging from 97.4–102.4%).

A simple and rapid reversed-phase high performance liquid chromatography method, using resonance Rayleigh scattering detection, for the determination of neomycin sulfate in serum samples was developed. Separation was performed on a Synergi Hydro-RP column with water solution which contained 0.18% TFA (v/v) as the mobile phase. Separation variables were optimized and discussed. In acid medium, neomycin sulfate could react with trypan red to form ion-association complexes, there is a stoichiometric ratio of 1:1 between the reaction of the neomycin sulfate with trypan red by Job plot analysis and the molar ratio method. Scanning electron microscopy revealed that these aggregates were spherical gathered particles with an average size of 45 nm, which was in agreement with the theoretical results. The analytical parameters were provided by the system, limit of detection (LOD) of 56 ng mL−1 (3σ), linear correlation of 0.9990 and linear range response from 0.48 to 23.52 μg mL−1. The precision of the method was <4%. Herein we demonstrated a novel method for the determination of neomycin sulfate which obtained satisfactory results.

A reliable and novel high performance liquid chromatography (HPLC) incorporating resonance Rayleigh scattering (RRS) detection was developed for the determination of procaine (Pro) and lidocaine (Lid). This method was based on the weak intensity of RRS of procaine and lidocaine, which can be enhanced by the addition of Erythrosin Yellowish (E-Y) in pH 4.4 acidic medium. The RRS signal was detected at λex = λem = 370 nm. The conditions of separation and detection were optimized (pH, proportion of organic phase, flow rate, reaction temperature, concentration of E-Y and the length of reaction tube). The shape of ion-association complexes was observed by scanning electron microscopy. The reasons for RRS enhancement and the nature of the ion-association complexes were discussed by quantum chemistry calculation, scanning electron microscopy and absorption spectroscopy. The calibration curves of procaine and lidocaine were linear in the range from 0.005 to 15.375 μg mL−1 and the limit of detection (S/N = 3) was 2.3 ng mL−1 for procaine and 15 ng mL−1 for lidocaine. The developed method was validated for the assay of procaine and lidocaine in human plasma samples. The recoveries were between 97.8% and 105.9% which is within acceptable limits.

A simple and novel reversed-phase high performance liquid chromatography (HPLC) method coupled with resonance Rayleigh scattering (RRS) was developed to analyze isepamicin (ISP) in rat plasma. The chromatographic separation was achieved at 30 °C on a reverse phase column of Synergi Hydro-RP (150 mm × 4.6 mm; 4 μm), with (15:85, v/v) methanol–water (containing 0.15% TFA (v/v)) as the mobile phase. The flow rate was 0.4 mL min−1. The RRS signal was detected at λex = λem = 372 nm. Netilmicin (NTL) was used as the internal standard. The new analytical technique was validated for the intra- and inter-day variation, the linear range of the standard curve of ISP and the limit of detection (S/N = 3). The results indicated that HPLC coupled with RRS was a reliable and valuable technique for quantitative analysis of ISP in rat plasma. The method shows a better linear relationship and lower analysis time.