Fe3O4@Ionic liquids β-cyclodextrin polymer(Fe3O4@ mono-6- deoxy-6- (1-ethyl- imidazolium)-β-cyclodextrin iodide polymer, ILs-β-CDCP) was prepared. A novel method based on Fe3O4@ILs-β-CDCP solid phase extraction coupled with fluorescence spectrophotometry for Rhodamine B (RhB) determination, was investigated. Results were shown that RhB was adsorbed on Fe3O4@ILs-β-CDCP and eluted with sodium dodecyl sulfate (SDS) (1.0%) rapidly. Different parameters, such as pH, adsorption time and volume, eluent volume and time were studied. This method introduced linearity for RhB between 0.01–9.00 μg/mL−1 , the limit of detection was 5.2 ng/mL−1 , correlation coefficient (R) was >0.9987 and the relative standard deviation (RSD) was 3.1% (n = 3, c = 4.00 μg/mL). The mechanism of adsorption of RhB on Fe3O4@ILs-β-CDCP was studied through the FTIR analysis and the inclusion constant of Fe3O4@ILs-β-CDCP-RhB. This method was applied successfully for determination of RhB in real samples with satisfactory results.

Fe3O4@ionic liquids β-cyclodextrin polymer(Fe3O4@mono-6-deoxy-6-(1-ethyl-imidazolium)-β-cyclodextrin iodide polymer, Fe3O4@ILs-β-CDCP) was prepared. Magnetic solid phase extraction coupled with high-performance liquid chromatography for the separation/analysis of congo red (CR) in water and drysaltery was established. Fe3O4@ILs-β-CDCP showed a higher adsorption capacity toward CR. CR was adsorbed rapidly by Fe3O4@ILs-β-CDCP (adsorption efficiency: 95%) and eluted by ethanol (elution efficiency: 96%) at room temperature. Under the optimal conditions, preconcentration factor of the proposed method was 20-fold. The linear range, correlation coefficient (R2), detection limit (DL) and relative standard deviation were found to be 0.005–100.00 µg mL−1, 0.9910, 1.8 g L−1 and 0.61% (n = 3, c = 5.00 µg mL−1), respectively. The adsorption mechanism of CR on Fe3O4@ILs-β-CDCP was studied through the FTIR analysis. The accuracy of the developed method was confirmed by spiking city water, lake water, pond water and drysaltery. Fe3O4@ILs-β-CDCP can be used repeatedly for 10 times. This proposed method had been successfully applied to the determination of CR in real samples.

Core-shell nanoparticles (NPs) of the type Fe3O4@SiO2 were prepared, coated with 3 different ionic liquids, and tested for their capability of extracting bisphenol A (BPA). The results showed BPA is best extracted by NPs of the type Fe3O4@SiO2@[OMIM] (where OMIM stands for 1-octyl-3-methylimidazole hexafluorophosphate). Following desorption with methanol, BPA was quantified by HPLC with fluorescence detection in the UV. The following figures of merit were found under optimal conditions: A linear range from 0.5 to 2.0 × 104 μg·L‾1, a detection limit of 90 ng·L‾1, a relative standard deviation of 1.2 % (for n = 3 and 10 μg·L‾1), and a pre-concentration factor of 25. The NPs can be re-used up to 10 times. The method was successfully applied to the determination of BPA in plastic tableware.

The ionic liquid-immobilized expanded perlite (IL-EP) as a novel solid phase extraction adsorbent coupled with fluorescence spectroscopy for the separation/analysis of bisphenol A (BPA) was established. The results showed that BPA was rapidly adsorbed on IL-EP and separated/recycled from aqueous solution without centrifugation. It was worth mentioning that methanol as eluent could give a significant enhancement to the fluorescence of BPA. Moreover, the pseudo-second-order model fitted the adsorption kinetics data well, which indicated that chemisorption controlled the adsorption of BPA on IL-EP. The linear calibration curve for BPA was obtained over the concentration ranges of 0.01–10.0 μg mL−1 with the detection limits (LOD) of 0.3 ng mL−1. This method was applied to determinate BPA in food packaging material with reasonable results.

A novel method for the separation/analysis of linuron in fruit and vegetable samples is described. The work is based on the utilization of ionic liquid ([C6min][PF6])-loaded β-cyclodextrin cross-linked polymer (IL-β-CDCP) for the effective adsorption of linuron coupled with ultraviolet spectrophotometry. The inclusion interaction of IL-β-CDCP with linuron is studied with FTIR and inclusion constants. Under optimum conditions, the preconcentration factor achieved for this method is approximately 10. Linear range, limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation are 0.08–15.00 μg/mL, 5.8 ng/mL, 17.5 ng/mL and 0.96 % (n = 3, c = 4.0 μg/mL), respectively. This technique is successfully applied for determination of linuron in real samples.

•A novel method for the analysis of ulipristal acetate (UPA).•The hydrophobic IL [C8 mim] [PF6] as extraction solvent in UA IL-DLLME.•UPA easily migrated into IL phase without any dispersive solvent.•25-Fold enrichment factor was obtained.•This method was applied for the analysis of UPA in samples with satisfactory results.In this paper, a simple and efficient ultrasound-assisted ionic liquid dispersive liquid–liquid microextraction (UA IL-DLLME) coupled with high-performance liquid chromatography for the analysis of ulipristal acetate (UPA) was developed. UPA could be easily migrated into 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] IL phase without dispersive solvent. The research of extraction mechanism showed that hydrophobic interaction force played a key role in the IL-DLLME. Several important parameters affecting the extraction recovery were optimized. Under the optimized conditions, 25-fold enrichment factor was obtained and the limit of detection (LOD) was 6.8 ng mL−1 (tablet) or 9.3 ng mL−1 (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.03–6.0 µg mL−1. The proposed method was successfully applied to the UPA tablets and the real mice serum samples.The ER was all over 90.0% in three ILs and a higher ER was obtained when [C8mimPF6] was used as the extraction solvent. Adsorption capacity of three ILs for UPA was 1.99 mg g−1 ([C4mimPF6]), 9.33 mg g−1 ([C6mimPF6]) and 18.80 mg g−1 ([C8mimPF6]).

•A new method of magnetic solid phase extraction (MSPE) coupled with UV spectrometry for separation/analysis of linuron.•Linuron adsorbed rapidly on Fe3O4@SiO2@[OMIM]PF6 and eluanted by ethanol.•Preconcentration factor of the proposed method was 10-fold.•This method has been successfully applied to the determination of linuron in real samples.Three hydrophobic ionic liquids (ILs) including 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6), 1-hexyl-3-methyl-imidazole hexafluorophosphate ([HMIM]PF6), and 1-octyl-3-methylimidazole hexafluoro-phosphate ([OMIM]PF6) coated Fe3O4@SiO2 nanoparticles with core–shell structure to prepare magnetic solid phase extraction agent (Fe3O4@SiO2@ILs) and establish a new method of magnetic solid phase extraction (MSPE) coupled with UV spectrometry for separation/analysis of linuron. The results showed that linuron was adsorbed rapidly by Fe3O4@SiO2@[OMIM]PF6 and eluanted by ethanol. Under the optimal conditions, preconcentration factor of the proposed method was 10-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.04–20.00 μg mL−1, 5.0 ng mL−1, 0.9993 and 2.8% (n = 3, c = 4.00 μg mL−1), respectively. The Fe3O4@SiO2 nanoparticles could be used repeatedly for 10 times. This proposed method has been successfully applied to the determination of linuron in food samples.Fe3O4@SiO2@ILs with adsorbed target linuron was separated from the solution by an external magnetic field. The residual linuron in the supernatants was determined by UV–vis at 246 nm. Elinuron% was gradually increased with the loaded IL cation alkyl chain growth and Elinuron% on Fe3O4@SiO2@[OMIM]PF6 showed the highest extraction efficiency.

In this paper, a multifunctional platform for detection and degradation of prohibited colorants based on AgI/Ag hybrid nanocomposites through a facile wet-chemical route was successfully fabricated. The AgI/Ag hybrid nanocomposites were characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), energy-dispersive spectroscopy (EDS) and UV-vis diffuse reflectance spectra (DRS). The surface-enhanced Raman scattering (SERS) performance and photocatalytic activity of the AgI/Ag hybrid nanocomposites were investigated. The results showed that the AgI/Ag hybrid nanocomposites exhibit good SERS performance for malachite green (MG) and excellent photocatalytic activity of rhodamine B (RB). The proposed method has advantages in terms of providing a simple and rapid method for the sensitive analysis of prohibited additive colorants.

•SDS/IL ATPS for theseparation/analysis dutasteride.•ATPS not only extracted dutasteride but also sensitized its fluorescence intensity.•Synergistic effect of SDS and IL was investigated.•The proposed method was applied to dutasteride in real sample.A novel separation/analysis method was developed for the determination of dutasteride in a pharmaceutical formulation and biological samples, which based on surfactant dodecyl sodium sulfate (SDS)/ionic liquid 1-hexyl-3-methylimidazolium bromide (IL, [C6min]Br) aqueous two-phase system (ATPS) extraction coupled with spectrofluorimetry. The ATPS was formed owing to new ordered molecular assembly SDS/IL, which not only extracted dutasteride but also sensitized its fluorescence intensity due to synergistic sensitizing effect. Under optimum conditions, a linear calibration curve was obtained in the range of 0.016–0.64 μg mL−1 with r = 0.9991 (n = 8). The detection limit was 2.2 ng mL−1. The preconcentration factor was 7.5. The proposed green analytical procedure was satisfactorily applied to the analysis of dutasteride in dutasteride soft gelatin capsule and human serum with the recovery of 96.7–108.0%. The obtained results of this work were in good agreement with the results of HPLC. The extraction mechanism ATPS-based was also discussed.The fluorescence intensity of dutasteride after extraction was about 10 times than that of before extraction. The fluorescence sensitization is possibly caused by (1) concentration enrichment of dutasteride after extraction; (2) the sensitized effect of SDS/IL on fluorescence intensity.

A novel procedure is presented for the speciation of Cr(III)/Cr(VI) involving directly suspended single droplet microextraction combined with electrothermal atomic absorption spectrometry. In this method, Cr(III) can be extracted with 1-decanol at pH 6.0 due to the formation of a hydrophobic complex, Cr(III)-8-hydroxyquinoline (8-HQ), whereas Cr(VI) remains in the aqueous solution. The Cr(VI) concentration was calculated by subtracting the concentration of Cr(III) from the total chromium concentration after reducing Cr(VI) to Cr(III) by addition of hydroxylamine hydrochloride. Different factors affecting the extraction of Cr(III), such as pH, 8-HQ concentration, stirring rate, extraction temperature and time, and interfering ions, were schematically evaluated. Under the selected conditions, the limit of detection for Cr(III) was 0.03 ng mL−1 with a relative standard deviation of 4.7% (C = 1.0 ng mL−1, n = 5). The calibration curve was highly linear for the Cr(III) concentration range of 0.10–2.0 ng mL−1. The proposed method was validated against certified reference materials of environmental water (GSBZ50027-94, GBW(E)080642), and successfully applied in the speciation of chromium in well and tap water samples.

Fluorescence quenching by copper(II) of a Schiff base derivative of p-tert-butylcalix[4]arene (SANCAX) in 0.1% polyethylene glycol tert-octylphenyl ether (Triton X-100) medium was investigated. The fluorescence of SANCAX is quenched by Cu2+ due to the formation of a weaker fluorescent inclusion complex (Cu-SANCAX). The fluorescence quenching (ΔF = FSANCAX − FCu-SANCAX) is sensitized in Triton X-100. Under optimal conditions, the linear range calibration curve for the determination of Cu2+ is 0.005–0.08 μg mL−1. The detection limit is 3.05 ng mL−1 with an RSD of 1.55% (n = 3, c = 0.05 μg mL−1). The SANCAX fluorescence quenching mechanism was investigated by the Benesi–Hildebrand method, fluorescence quantum yield, and IR. The method has been applied in the determination of trace Cu2+ in real samples with satisfactory results.

•The investigation of the inclusion interactions of β-CDCP with quercetin.•The adsorption behavior of Qu on β-CDCP.•The β-CDCP could be used repeatedly for 30 times.•This technique had been successfully applied to the determination of Qu in real samples.A novel method for the separation/analysis of quercetin was described, which was based on the investigation of the inclusion interactions of β-cyclodextrin cross-linked polymer (β-CDCP) with quercetin (Qu) and the adsorption behavior of Qu on β-CDCP. The inclusion interaction of β-CDCP with Qu was studied through FTIR, TGA and 13C NMR. Under the optimum conditions, the preconcentration factor of the proposed method was approximately 8.8, the β-CDCP could be used repeatedly for 30 times and offered better recovery. The linear range, limit of detection (LOD) and the relative standard deviation (RSD) was found to be 0.10–12.0 μg mL−1, 4.6 ng mL−1 and 3.10% (n = 3, c = 2.0 μg mL−1) respectively. This technique had been successfully applied to the determination of Qu in real samples.Graphical abstractThere were some obvious changes of characteristic absorption peaks for the β-CDCP−Qu: (1) σCC peak (1612 cm−1) in β-CDCP−Qu vanished; the width of peak at 3390 cm−1 was larger in β-CDCP−Qu; which was demonstrated that the aromatic part in Qu was included into the hydrophobic cavity of β-CDCP. (2) The intensity of σCOH peaks at 1333 cm−1 and 1244 cm−1 in β-CDCP−Qu were much higher than that of β-CDCP, it was probably attributed to the fact that the hydrogen bond interactions played a crucial role in the inclusion of β-CDCP−Qu.

Functionalized β-cyclodextrin polymer, mono-6-deoxy-6-imidazole-β-cyclodextrin polymer (β-CDIMCP), was synthesized as a new solid phase adsorbent coupled with UV–visible spectroscopy to separate/analyze trace kaempferol. The results showed that kaempferol was adsorbed rapidly by β-CDIMCP (adsorption efficiency, 94.7 %) and then eluted by methanol (elution efficiency, 93.4 %). Under the optimum conditions, the calibration curve was linear in the concentration range from 0.10 to 14.0 μg/mL, with a correlation coefficient (R) of 0.9965. And the limit of detection was 0.028 μg/mL for kaempferol. The preconcentration factor of the method was tenfold. The molecular interaction between β-CDIMCP and kaempferol was studied through inclusion constant and FTIR analysis. The present method had been successfully applied to determine kaempferol in red wine samples.

A simple and rapid method based on dispersive liquid–liquid microextraction with room temperature ionic liquid 1,3-dibutylimidazolium hexafluorophosophate ([BBIM][PF6]) coupled to flame atomic absorption spectrometry was developed for the speciation of Mn(II)/Mn(VII) in tea samples. The main factors affecting dispersive liquid–liquid microextraction were investigated in detail. Mn(II) and total manganese [Mn(II)+Mn(VII)] were quantitatively extracted after adjusting aqueous sample solution to pH 10.0 and 7.0, respectively. Mn(VII) was calculated by subtraction of Mn(II) from total manganese. Under the optimized conditions, the limits of detection (3σ) for Mn(II) and Mn(VII) were 0.26 and 1.86 ng/mL, and their relative standard deviations were 2.6 and 4.8 % (n = 7, c = 25.00 ng/mL). The proposed method was validated by the determination of Mn(II) and Mn(VII) in the certified reference material [GBW(E)08513] of tea sample and different local tea samples with satisfactory results.

•A novel solid phase extraction material coupled with UV–vis spectrometry for the analysis of rutin.•CM-HP-β-CD polymer modified Fe3O4 nanoparticles (CM-HP-β-CDCP-MNPs) were synthesized/characterized.•The adsorption of rutin onto CM-HP-β-CDCP-MNPs was rapid, quantitative.•This technique was successfully applied to determine rutin in real samples.In this paper, carboxymethyl-hydroxypropyl-β-cyclodextrin polymer modified magnetic particles Fe3O4 (CM-HP-β-CDCP-MNPs) were prepared and applied to magnetic solid phase extraction of rutin combined with UV–visible spectrometry detection. The synthesized magnetic particles were characterized by element analysis, Fourier transform infrared spectra, thermal gravimetric analysis, and transmission electron microscopy. Several variables affecting the extraction and desorption of rutin such as pH, the amount of adsorbent, the type and volume of eluent, extraction and desorption time, and temperature were investigated. The maximum adsorption capacity was 67.0 mg g−1 for rutin with the equilibrium time of 30 min at room temperature, and the adsorbent could be reused for 10 times. A calibration curve was linear in the range of 0.05–8.00 μg mL−1 with a relative standard deviation of 2.9% (n = 5, c = 4.0 μg mL−1). The limit of detection was 7.0 ng mL−1. The interaction mechanism between the adsorbent and rutin was also studied. Feasibility of this method was validated by the analysis of rutin tablets and lotus plumule.The adsorption efficiencies of rutin with CM-HP-β-CDCP-MNPs as sorbent (curve a) was much higher than that with Fe3O4 (curve b) in the tested pH range.

The uniform spherical silver three-dimensional (3D) hierarchical structures consisting of dendrites were synthesized for the first time with a very facile, mild and cost-effective wet-chemical method employing potassium biphthalate as the structure-director in aqueous solution and at ambient conditions. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), infrared spectroscopy (IR) and energy dispersive X-ray spectroscopy (EDS). The investigation on the morphologies evolution revealed that potassium biphthalate was critical to control the assembly of the hierarchical Ag architectures. The hierarchical structure was shown excellent surface-enhanced Raman scattering (SERS) effect due to intensive hot spots.Graphical abstractHighlights► Uniform spherical silver hierarchical structures were synthesized for the first time. ► These silver hierarchical structures were constructed by dendrites. ► Potassium biphthalate was critical to control the assembly of the Ag architectures. ► Such hierarchical structures showed excellent SERS performance.

A simple method based on cloud point extraction (CPE) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection was proposed for the determination of species of aqueous-exchangeable selenium and unaqueous-exchangeable selenium. When the system temperature is higher than the cloud point extraction temperature (CPT) of the surfactant of p-octyl polyethyleneglycolphenyl ether (Triton X-100), the complex of selenium(IV)–diethyl-dithiocarbamate (DDTC) (total selenium and aqueous-exchangeable selenium) could be extracted into the surfactant-rich phase, an in situ separation of selenium(IV) could be realized. Unaqueous-exchangeable selenium concentration was obtained by respectively subtracting aqueous-exchangeable selenium from the total selenium. The chemical variables affecting the CPE were optimized. Under the optimized conditions, the limit of detection (LOD) and the relative standard deviations (RSD) was 0.10 ng/mL and 3.2% (c = 10.0 ng/mL, n = 11), respectively, for Se(IV). The proposed method was applied to the speciation of aqueous-exchangeable and unaqueous-exchangeable selenium in tea samples with satisfactory results.

A new wet-chemical approach to prepare surface-enhanced Raman scattering (SERS)-active substrates with pitaya-like silver nanostructures (PSNs) was proposed. It has been found that the morphology of as-prepared products is dependent on the reaction parameters. PSNs exhibit a high detection sensitivity of surface-enhanced Raman scattering for Rhodamine 6G (R6G) with a limit of detection of 1.0×10−13 mol L−1. This facile, large-scale, low-cost, and green chemistry synthesized Ag nanostructures make it a perfect choice for practical SERS detection applications.Highlights►Pitaya-like silver nanostructures (PSNs) were obtained by a facile chemical method. ► The morphology of as-prepared products is dependent on the reaction parameters. ► PSNs exhibit a high detection sensitivity of SERS for rhodamine 6G (R6G). ► The PSNs can be used for the analysis of R6G.

A novel spectrofluorimetric method to determine abiraterone acetate and its active metabolite, abiraterone was developed, based on the fact that fluorescence intensity of abiraterone acetate and abiraterone could be enhanced in β-cyclodextrin (β-CD) due to the formation of the inclusion complex. The inclusion interaction of β-CD and abiraterone acetate and the β-cyclodextrin sensitized spectrofluorimetry was examined. The various factors influencing fluorescence were discussed in details. The results showed that under the optimized conditions, the linear range of calibration curve for the determination of biraterone acetate and abiraterone was 0.20 ~ 6.0 μg/mL, and the detection limit (LOD) was 6.8 (r = 0.997) or 6.6 ng/mL (r = 0.996), respectively. No interference was observed from common co-existing substances or pharmaceutical excipient. The method was successfully applied to the analysis of abiraterone acetate in pharmaceutical formulation and abiraterone in human serum/urine.

The sensitizing effect of ionic liquid surfactant (ILS) media on the determination of zinc by spectrophotometry was developed. The main parameters influencing the analysis of zinc, such as pH value, the amount of ILS, the concentration of 2-[(5-bromo-2-pyridyl)-zao]-5-(diethl-amino) phenol (5-Br-PADAP) were optimized. The limit of detection (LOD) and the linear range of calibration curve obtained under the optimal conditions were 2.7 ng·mL− 1 and 0.02–1.00 μg.mL− 1, respectively. The sensitivity of Zn(II) analysis in ILS (C14mimBr) was higher than that in water(εin C14mimBr 1.25 × 105 > ε in H2O 6.25 × 104 L·mol− 1·cm− 1 ), with the enhancement factor of this method (the ratio of the slope of calibration curves) of 3.0. Moreover, the sensitized mechanism was primarily discussed with the critical micelle concentration (CMC) of ILS and distribution coefficient (KD) of 5-Br–PADAP. The method has been applied to the determination of zinc in water reference material, tap water, calcium–zinc gluconate oral solution and milk powder with satisfactory results.Highlights► Ionic liquid surfactant (ILS) as sensitized agent for the spectroscopic method. ► ILS (C14mimBr) could obviously improve the sensitivity of Zn(II) analysis. ► εin C14mimBr 1.25 × 105 > εin H2O = 6.25 × 104 L·mol− 1·cm− 1. ► The mechanism of sensitizing effect was first discussed with CMC of ILS and KD.

The fluorescence quenching effect of emodin (EMO) on the derivatives of p-tert-butyl-calix[4]arene with o-phenanthroline (TBCP) in 1.0% hexadecyl trimethyl ammonium bromide (CTAB) medium was investigated. The fluorescence of TBCP was quenched by EMO due to the formation of the weak fluorescent inclusion complex (EOM-TBCP), and the fluorescence quenching (ΔF = FTBCP–FEMO–TBCP) was sensitized in CTAB. Under the optimal conditions, the linear range of calibration curve for the determination of EMO was 1.17–23.40 μg/mL. The detection limit estimated and RSD was 0.34 μg/mL, 3.63% (n = 3, c = 4.74 μg/mL). The quantum yield Yu of TBCP was approximately 2.0 times higher in the presence of CTAB than that in the absence of CTAB. The method has been applied for the determination of EMO in samples with satisfactory results.Graphical abstractThe fluorescence emission spectra of TBCP (present of or absent of EMO) in CTAB and H2O media were shown in Fig. 2. It could be seen that (1) the fluorescence intensity of TBCP (FTBCP) was enhanced in presence of CTAB and the maximum emission wavelength was red shifted (curve 1 and 3); (2) the fluorescence intensity of TBCP (FTBCP,FTBCP-CTAB) was diminished when EMO was added (curve 2 and 4); and the ΔF1 = FTBCP–CTAB–FEMO–TBCP–CTAB was larger than that ΔF2 = FTBCP-FEMO–TBCP with the same concentration of EMO; (3) the FTBCP-CTAB gradually decreased with an increase of EMO concentration (auxiliary Fig. 2, curve 1–5). Curve 5 was the fluorescence spectrum of EMO–TBCP with the excess EMO, which indicated that inclusion complex of TBCP–EMO had the weak fluorescent property. Hence, there was the sensitizing effect in CTAB.Highlights► A novel method for the analysis of emodin (EOM). ► FTBCP was quenched by EMO due to the formation of EOM-TBCP. ► ΔF = FTBCP–FEMO–TBCP was sensitized in CTAB. ► Yu of TBCP was approximately 2.0 times higher in the presence of CTAB than that H2O. ► This method was applied for the analysis of EOM in samples with satisfactory results.

A novel adsorbent of carboxymethyl-β-cyclodextrin modified nanometer TiO2 (CM-β-CD/TiO2) was prepared and used as a solid-phase extraction (SPE) material coupled to fluorescence spectroscopy determination of l-tryptophan (l-Trp) in biological samples. The experimental conditions for modified nanometer TiO2 separation/preconcentration of l-Trp were optimized. The adsorption capacity of CM-β-CD/TiO2 for l-Trp was 75.2 μg/g. The linear range, detection limit (DL), and the relative standard deviation (RSD) were 0.10–1.20 μg/mL, 18.8 ng/mL, and 0.67% (n = 3, 1.0 μg/mL), respectively, with a preconcentration factor of 10. The developed method was applied to determination of l-Trp in real samples and the recoveries were found to be in the range of 99.2–100.3%. For validation, a comparison material of NIC-140686 sample was analyzed and the determined value was in good agreement with the certified value.

A novel β-cyclodextrin (β-CD) sensitized fluorescence quenching method for the determination of l-tyrosine (l-Tyr) with Mo(VI)-phenyl-fluorone (PF) as a fluorescence probe has been developed. The fluorescence intensity of Mo(VI)-PF–β-CD was diminished as the l-tyrosine was added, the fluorescence quenching value ΔF = Fβ-CD–Mo-PF − Fβ-CD–Mo-PF–l-Tyr was enhanced in β-CD and there was a linear relationship between the ΔF and the concentration of l-Tyr. Under the optimal conditions, the linear range of calibration curve for the determination of l-tyrosine was 0.3–20.0 μg mL−1; the detection limit was 0.094 μg mL−1. NaOH (10%, w/v) is the best reagent of hydrolysis in sample preparation. The sensitized mechanism of β-cyclodextrin was discussed. The method has been applied to the determination of l-tyrosine in spirulina and food samples with satisfactory results.

The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid-phase extraction material to preconcentrate/analysis bovine serum albumin (BSA) coupled with UV–vis spectroscopy. The method based on the complex (BSA–phenylfluorone (PF)) adsorbed on β-CDCP. Adsorption kinetics and various factors of the formation procedure of BSA–PF and its retention on β-CDCP were investigated. The linear range and detection limit (DL) was 20.0–200.0 and 0.03 mg/L, respectively. Moreover, the β-CDCP could be used repeatedly. The proposed method has been applied to analysis serum albumin with satisfactory results.

In this article the interaction between methyl violet (MV) and bovine serum albumin (BSA) was studied with spectroscopy. The results indicated that the fluorescence intensity of BSA was quenched strongly by MV through a static quenching procedure. The association constants, the number of binding sites and basic thermodynamic parameters were obtained based on fluorescence quenching data. The effect of MV on the conformation of BSA had been investigated with synchronous fluorescence spectroscopy and circular dichroism (CD) spectrum.

A sensitive method for the separation/analysis of Co(II) was described. The β-cyclodextrin cross-linked polymer (β-CDCP) was synthesized and used as solid phase extraction material (SPE) to separate/pre-concentrate trace cobalt coupled with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of Co(II). The method was based on α-pyridylazo-β-naphthol (PAN) as the complexing agent for Co(II)-PAN at neutral condition and the adsorption behavior of Co(II)-PAN on β-CDCP was studied. Further, p-octylpolyethylene-glycolphenyl ether (Triton X-100) as environment-friendly eluant was used. The linear range, detection limit (DL) and the relative standard deviation (R.S.D.) was 5.0–160.0 ng/mL, 5.84 ng/L and 2.27% (n = 3, c = 30.0 ng/mL) respectively. The enhancement factor was 10. Moreover, the β-CDCP could be used repeatedly and offered better recovery and estimation of standard samples.

This work describes a new analytical procedure for trace vanadium by graphite furnace atomic absorption spectroscopy coupled to cloud point extraction (CPE) as the separation-preconcentration method. The CPE behavior of vanadium using methylene blue as complex agent and Triton X-100 as a surfactant was investigated systematically. Under the optimized conditions, the detection limit was 0.7 ng · mL−1, and the relative standard deviation was 4.3% for vanadium (c = 50.0 ng · mL−1, n = 5). The recovery of vanadium was in the range of 98.9–102.8%. The method was applied to the analysis of vanadium in certified reference materials and real samples. The results obtained were in good agreement with the certified values.

In this paper, a simple and sensitive flow injection analysis (FIA) for the determination of protein with spectroscopic probe was developed. This method was based on the investigation of the interaction of tetrachloride fluorescein (2,4,5,7-tetrachloro-3,6-fluorandiol)–bovine serum albumin (BSA), the coupling reaction of protein with tetrachloride fluorescein (TCFS) which was used as a spectroscopic probe in the presence of β-cyclodextrin (β-CD). The interaction mechanism and the main factors affecting the determination were investigated in details. Under the optimum conditions, the linear range and detection limit were 0.0–28.0 μg mL−1 and 0.76 μg mL−1, respectively. The proposed method has been used to determine albumin in serum albumin with satisfactory results.

A new spectrofluorimetric method to determine epristeride (EP) has been developed, which based on the EP has a strong ability to quench the intrinsic fluorescence of bovine serum albumin (BSA). There was the relationship between the fluorescence quenching intensity of BSA (ΔF = FBSA − FBSA–EP) and the concentration EP. The quenching mechanism was investigated with the quenching type, the association constants, the number of binding sites and basic thermodynamic parameters. The method had been successfully applied to the analysis of EP in real samples and the obtained results were in good agreement with the results of official method-HPLC.

The inclusion interactions of β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) with dyes were developed by spectrofluorimetry, and the inclusion constants of inclusion complexes were determined by direct fluorescence technique. The main factors (the host molecule, the guest molecule, and the pH) for the inclusion interaction were discussed in detail. At the same time, the inclusion interaction of HP-β-CD and vitamin B6 (VB6) was investigated with the competitive fluorescence inclusion method and the inclusion constant of HP-β-CD and vitamin B6 (VB6) was obtained by indirect fluorescence technique. On the basis of the linear relationship between the change of fluorescence intensity (ΔF) and the concentration of VB6, a competitive fluorescence inclusion method was used to the determination of VB6. The method has been successfully applied to the analysis of VB6 in synthetic samples, tablets and injections with satisfactory results.

A new method based on cloud point extraction (CPE) separation and graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of inorganic tin species. When the system temperature is higher than the cloud point extraction temperature (CPT) of the mixed surfactant of p-octyl polyethyleneglycolphenyl ether (Triton X-100) and sodium dodecyl sulfate(SDS), the complex of Sn(IV) with 1-(2-pyridylazo)-2-naphthol (PAN) could be extracted into the surfactant-rich phase, whereas the Sn(II) remained in the aqueous phase. Thus, an in situ separation of Sn(IV) and Sn(II) could be realized. The main factors affecting the cloud point extraction were investigated systematically. Under the optimized conditions, the determination limit for Sn(IV), as low as 0.51 ng mL−1, was obtained by preconcentrating a 10 mL sample solution, and the relative standard deviation (n = 10; c = 1.0 mg L−1) was 3.6%. The proposed method was applied to the speciation analysis of tin in different water samples and the recovery of total Sn was in the range of 98.9–100.7%. In order to verify the accuracy of the method, a certified reference water sample was analysed and the results obtained were in good agreement with the certified values.

A novel procedure is presented for the speciation of Cr(III)/Cr(VI) involving directly suspended single droplet microextraction combined with electrothermal atomic absorption spectrometry. In this method, Cr(III) can be extracted with 1-decanol at pH 6.0 due to the formation of a hydrophobic complex, Cr(III)-8-hydroxyquinoline (8-HQ), whereas Cr(VI) remains in the aqueous solution. The Cr(VI) concentration was calculated by subtracting the concentration of Cr(III) from the total chromium concentration after reducing Cr(VI) to Cr(III) by addition of hydroxylamine hydrochloride. Different factors affecting the extraction of Cr(III), such as pH, 8-HQ concentration, stirring rate, extraction temperature and time, and interfering ions, were schematically evaluated. Under the selected conditions, the limit of detection for Cr(III) was 0.03 ng mL−1 with a relative standard deviation of 4.7% (C = 1.0 ng mL−1, n = 5). The calibration curve was highly linear for the Cr(III) concentration range of 0.10–2.0 ng mL−1. The proposed method was validated against certified reference materials of environmental water (GSBZ50027-94, GBW(E)080642), and successfully applied in the speciation of chromium in well and tap water samples.

Fluorescence quenching by copper(II) of a Schiff base derivative of p-tert-butylcalix[4]arene (SANCAX) in 0.1% polyethylene glycol tert-octylphenyl ether (Triton X-100) medium was investigated. The fluorescence of SANCAX is quenched by Cu2+ due to the formation of a weaker fluorescent inclusion complex (Cu-SANCAX). The fluorescence quenching (ΔF = FSANCAX − FCu-SANCAX) is sensitized in Triton X-100. Under optimal conditions, the linear range calibration curve for the determination of Cu2+ is 0.005–0.08 μg mL−1. The detection limit is 3.05 ng mL−1 with an RSD of 1.55% (n = 3, c = 0.05 μg mL−1). The SANCAX fluorescence quenching mechanism was investigated by the Benesi–Hildebrand method, fluorescence quantum yield, and IR. The method has been applied in the determination of trace Cu2+ in real samples with satisfactory results.