A Study of the Mechanisms and Characteristics of Fluorescence Enhancement for the Detection of Formononetin and Ononin.

In this work, the origins for the spectral difference between two isoflavones, formononetin (F) and ononin (FG), are revealed via a comparison study of the fluorescence molecular structure. The fluorescence enhancement of FG in hot alkaline conditions is reported for the first time. For F, there is almost no fluorescence under acidic conditions, but when the pH is >4.8, its fluorescence begins to increase due to the deprotonation of 7-OH. Under a pH between 9.3 and 12.0, the anionic form of F produces a strong and stable fluorescence. The fluorescence quantum yield (Yf) of F is measured to be 0.042. FG shows only weak fluorescence in aqueous solutions under a wide range of pH until it is placed in hot alkaline solutions, which is attributed to the cleavage reaction of the γ-pyrone ring in FG. The Yf of FG is determined to be 0.020. Based on the fluorescence sensitization methods of F and FG, the quantitative analysis and detection of two substances can be realized. The limit of the detections for F and FG are 2.60 ng·mL-1 and 9.30 ng·mL-1, respectively. The linear detection ranges of F and FG are 11.7~1860 ng·mL-1 and 14.6~2920 ng·mL-1, respectively. Although the structural relationship between F and FG is glycoside and aglycone, under hot alkaline conditions, the final products after the cleavage and hydrolysis reactions are essentially different. The different fluorescence characteristics between F and FG pave a way for further identification and a quantitative analysis of the corresponding components in Chinese herbal medicine.

Fluorescence, Absorption, Chromatography and Structural Transformation of Chelerythrine and Ethoxychelerythrine in Protic Solvents: A Comparative Study.

Chelerythrine (CH) and ethoxychelerythrine (ECH) are chemical reference substances for quality control of Chinese herbal medicines, and ECH is the dihydrogen derivative of CH. In this study, their fluorescence and absorption spectra, as well as their structural changes in different protic solvents were compared. It was observed that their emission fluorescence spectra in methanol were almost the same (both emitted at 400 nm), which may be attributed to the nucleophilic and exchange reactions of CH and ECH with methanol molecules with the common product of 6-methoxy-5,6-dihydrochelerythrine (MCH). When diluted with water, MCH was converted into CH, which mainly existed in the form of positively charged CH+ under acidic and near-neutral conditions with the fluorescence emission at 550 nm. With the increase of pH value of the aqueous solution, CH+ converted to 6-hydroxy-5,6-dihydrochelerythrine (CHOH) with the fluorescence emission at 410 nm. The fluorescence quantum yields of MCH and CHOH were 0.13 and 0.15, respectively, and both the fluorescence intensities were much stronger than that of CH+. It is concluded that CH and ECH can substitute each other in the same protic solvent, which was further verified by high-performance liquid chromatography. This study will help in the investigation of structural changes of benzophenanthridine alkaloids and will provide the possibility for the mutual substitution of standard substances in relevant drug testing.

Time-resolved fluorescence and chemometrics-assisted excitation-emission fluorescence for qualitative and quantitative analysis of scopoletin and scopolin in Erycibe obtusifolia Benth.

This paper presents a new strategy for qualitative identification of scopoletin and scopolin in Erycibe obtusifolia Benth using time-resolved (lifetimes) fluorescence and quantitative analysis with chemometrics-assisted excitation-emission matrix (EEM) fluorescence. Due to the significant spectral overlapping among analytes and interference, the use of the more selective time-resolved fluorescence is proposed for qualitative identification in quality control of traditional Chinese medicine (TCM) for the first time. Using the strategy of combining EEM fluorescence with second-order calibration method, i.e. parallel factor analysis (PARAFAC), the simultaneous quantification of scopoletin and scopolin in the complex system of Erycibe obtusifolia Benth was achieved successfully. The predicted concentrations were compared with the values obtained using high performance liquid chromatography-coupled to fluorimetric detector (HPLC-FLD), and no significant differences between them were observed. Therefore, the proposed methods using time-resolved fluorescence for qualitative analysis and EEMs coupled with second-order calibration for quantitative analysis in TCM are comparable and provide a suitable alternative to the chromatography-based method.

A comparison of several second-order algorithms for simultaneous determination of neomangiferin and mangiferin with severe spectral overlapping in Anemarrhenae Rhizoma.

This work presents a greener approach for simultaneous determination of neomangiferin and mangiferin, the major bioactive constituents with severe spectral overlapping in Anemarrhenae Rhizoma, combining the sensitivity of molecular fluorescence and the selectivity of chemometric multivariate calibration algorithms. In this study, we compared the analytical performance of two group chemometric algorithms including trilinear algorithms such as parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD), self-weighted alternating trilinear decomposition (SWATLD) and alternating penalized trilinear decomposition (APTLD), and PLS-based methods such as unfolded partial least-squares or the multi-dimensional partial least-squares, both combined with residual bilinearization (U-PLS/RBL, N-PLS/RBL). The statistical parameters for the validation set of the second calibration were evaluated through the relative error of prediction (REP%), the average recovery (Rec%), and the root mean square error of prediction (RMSEP). Prediction results for the validation set by trilinear algorithms showed that the values were satisfactory for neomangiferin, and higher and not acceptable values for mangiferin, while U-PLS and N-PLS predictions were very successful for two analytes. Therefore, U- and N-PLS/RBL were chosen to determine neomangiferin and mangiferin in more complex real samples simultaneously, and U-PLS/RBL algorithm showed the best performance. The predicted concentrations by proposed methods were satisfactorily compared with those obtained using high performance liquid chromatography with ultraviolet detection.

Design of a Novel Apparatus to Enrich Analytes via a Diffuse-Evaporation Process for HPLC-FTIR Analysis.

HPLC-FTIR analysis using a novel apparatus with CuO powder as an interface is reported. This apparatus initially serves as a reservoir for the dilute eluted solution of HPLC, and then acts as an enrichment device by combining diffusion and evaporation processes. It can be used not only to effectively remove the mobile phase of the eluted solution, but also to enrich the analyte within a tiny spatially resolved separated sample spot whose size is suitable for obtaining spectra using an FTIR microscope. An experimental demonstration using benzamide and sodium dodecyl benzene sulfonate shows that this apparatus is readily applicable in the analysis of real-world mixture samples.

Simultaneous determination of α-asarone and ß-asarone in Acorus tatarinowii using excitation-emission matrix fluorescence coupled with chemometrics methods.

A chemometrics-assisted excitation-emission matrix (EEM) fluorescence method was proposed for simultaneous determination of α-asarone and ß-asarone in Acorus tatarinowii. Using the strategy of combining EEM data with chemometrics methods, the simultaneous determination of α-asarone and ß-asarone in the complex Traditional Chinese medicine system was achieved successfully, even in the presence of unexpected interferents. The physical or chemical separation step was avoided due to the use of "mathematical separation". Six second-order calibration methods were used including parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD), alternating penalty trilinear decomposition (APTLD), self-weighted alternating trilinear decomposition (SWATLD), the unfolded partial least-squares (U-PLS) and multidimensional partial least-squares (N-PLS) with residual bilinearization (RBL). In addition, HPLC method was developed to further validate the presented strategy. Consequently, for the validation samples, the analytical results obtained by six second-order calibration methods were almost accurate. But for the Acorus tatarinowii samples, the results indicated a slightly better predictive ability of N-PLS/RBL procedure over other methods.

A new 4-Amino-7-Nitro-2,1,3-Benzoxadiazole (ANBD)-Based Fluorescent Probe for the Detection of Hg2.

Based on the photoinduced electron transfer (PET) principle, 4-amino-7-nitro-2,1,3-benzoxadiazole (ANBD) has been used as a fluorophore to develop a new fluorescent probe, 4-(2-N,N-dimethylthioacetamide)amino-7-nitro-2,1,3-benzoxadiazole (2), for the detection of Hg2+. Upon the addition of Hg2+, a 46-fold fluorescence enhancement occurs. Moreover the probe 2 exhibits a high selectivity and sensitivity to Hg2+, even in the presence of other common metal ions. Under optimal reaction conditions, a good linearity can be obtained in the range of 0.5-2.5 µM, and the detection limit is 0.05 µM. In addition, the desulfurization reaction mechanism is proposed based on electrospray ionization mass spectrum. The present study is not only a supplement to the detection method of Hg2+, but also a merit to the development of ANBD-based fluorescent probes.

[Fabrication and Characterization of Planar Luminescent Solar Concentrator Waveguides Based on LR305 Dye].

Photovoltaic power generation is one of the best ways to utilize solar energy, but the cost of electricity is very high. To reduce the cost of photovoltaic power generation, in this paper, a type of planar luminescent solar concentrator waveguides based on Lumogen F Red 305 (LR305) dye with each size of 50 mm×50 mm×5 mm was proposed with radical polymerization method. The optical properties and photo-electricity outputs of the waveguides were characterized.

[Study on Fluorescence Properties of Flavanone and Its Hydroxyl Derivatives].

Flavanone derivatives are important active ingredients of natural medicine, so the synthesis of these compounds is one of the research hotspots of organic synthesis. Nevertheless, there is little research on fluorescence properties of these compounds up to now. Fluorescence properties of flavanone and 6 kinds of hydroxyl derivatives are studied in this paper. It is found that aqueous solutions of flavanone (FV), 7-hydroxyflavanone (7HF) and 6-hydroxyflavanone (6HF) have fluorescence, but aqueous solutions of 2'-hydroxyflavanone (2'HF), 4'-hydroxyflavanone (4'HF), naringenin and pinocembrin basically have no fluorescence. In three dimensional fluorescence spectra, excitation wavelengths λex of FV are located at 235, 265 and 340 nm, emission wavelength λem is at 386 nm; λex of 7HF are at 230, 276 and 315 nm, λem is at 391 nm; λex of 6HF are at 260 and 356 nm, em is at 482 nm. Influences of pH on fluorescence of FV, 7HF and 6HF are studied, and the reasons of pH affects on fluorescence are discussed from the viewpoint of molecular structure. The UV-absorption spectra of 7HF and 6HF at different pH are studied, and the proton ionization constants (pKa) of 7HF and 6HF are determined respectively to be 7.26±0.05 and 9.90±0.02, by a pH-absorption method. Influences of solvent (methanol) on fluorescence of FV, 7HF and 6HF are studied, and find that the fluorescence of FV and 7HF in methanol are weaker than that in water, but the fluorescence of 6HF in methanol is much stronger. In ordered media (SDS, CTAB and ß-CD), fluorescence of FV and 7HF decreased than that in water, but the fluorescence of 6HF enhanced in the media of ß-CD or CTAB. Using quinine sulfate or L-tryptophane as reference, fluorescence quantum yields of FV and 7HF aqueous solutions are measured to be 0.057 and 0.012, respectively; fluorescence quantum yields of 6HF in methanol or in aqueous solution containing 1.62 mg·mL-1 ß-CD are measured to be 0.064 or 0.012, respectively.

Design of a New Concentration Series for the Orthogonal Sample Design Approach and Estimation of the Number of Reactions in Chemical Systems.

A new concentration series is proposed for the construction of a two-dimensional (2D) synchronous spectrum for orthogonal sample design analysis to probe intermolecular interaction between solutes dissolved in the same solutions. The obtained 2D synchronous spectrum possesses the following two properties: (1) cross peaks in the 2D synchronous spectra can be used to reflect intermolecular interaction reliably, since interference portions that have nothing to do with intermolecular interaction are completely removed, and (2) the two-dimensional synchronous spectrum produced can effectively avoid accidental collinearity. Hence, the correct number of nonzero eigenvalues can be obtained so that the number of chemical reactions can be estimated. In a real chemical system, noise present in one-dimensional spectra may also produce nonzero eigenvalues. To get the correct number of chemical reactions, we classified nonzero eigenvalues into significant nonzero eigenvalues and insignificant nonzero eigenvalues. Significant nonzero eigenvalues can be identified by inspecting the pattern of the corresponding eigenvector with help of the Durbin-Watson statistic. As a result, the correct number of chemical reactions can be obtained from significant nonzero eigenvalues. This approach provides a solid basis to obtain insight into subtle spectral variations caused by intermolecular interaction.

4,4'-Bipyridine-1,1'-diium acetylenedicarboxylate: a new member of the (H2bipy)[Cu(ox)2] (bipy is 4,4'-bipyridine and ox is oxalate) family.

4,4'-Bipyridine-1,1'-diium (H2bipy) acetylenedicarboxylate, C10H12N2(2+)·C4O4(2-), (1), is a new member of a family of related structures with similar unit-cell parameters. The structures in this family reported previously [Chen et al. (2012). CrystEngComm, 14, 6400-6403] are (H2bipy)[Cu(ox)2] (ox is oxalate), (2), (H2bipy)[NaH(ox)2], (3), and (H2bipy)[H2(ox)2], (4). Compound (1) has a one-dimensional structure, in which H2bipy(2+) cations and acetylenedicarboxylate (ADC(2-)) anions are linked through a typical supramolecular synthon, i.e. R2(2)(7), and form linear `-cation-anion-' ribbons. Through an array of nonclassical C-H...O hydrogen bonds, adjacent ribbons interact to give two-dimensional sheets. These sheets stack to form a layered structure via π-π interactions between the H2bipy(2+) cations of neighbouring layers. The supramolecular isostructurality of compounds (1)-(4) is ascribed to the synergistic effect of multiple interactions in these structures. The balanced strong and weak intermolecular interactions stabilizing this structure type include strong charge-assisted N-H...O hydrogen bonds, C-H...O contacts and π-π interactions.

[Fluorescence enhancement of flavoxate hydrochloride in alkali solution and its application in pharmaceutical analysis].

Fluorescence enhancement reaction of flavoxate hydrochloride (FX) in strong alkali solution was studied, the mechanism of the reaction was investigated, and a novel fluorimetric method for analysis of FX in drug sample was established. FX has no intrinsic fluorescence, but it can slowly produce fluorescence in strong alkali solution. Heating can promote the fluorescence enhancement reaction. In 3D fluorescence spectra of the decomposition product of FX, two fluorescence peaks, located respectively at excitation wavelengths λex/ emission wavelength λem =223/410 nm, and 302/410 nm, were observed. Using quinine sulfate as a reference, fluorescence quantum yield of the decomposition product was measured to be 0.50. The structural characteriza- tion and spectral analysis of the decomposition product reveal that ester bond hydrolysis reaction of FX is firstly occurred during heating process, forming 3-methylflavone-8-carboxylic acid (MFA), then a cleavage reaction of the γ-pyrone ring of MFA occurred, producing α, ß-unsaturated ketone. This product includes adjacent hydroxyl benzoic acid group in its molecule, which can form intramolecular hydrogen bond under alkaline condition, so that increase the conjugate degree and enhance the rigidity of the molecule, and thereby cause fluorescence enhancement. Based on this fluorescence enhancement reaction, a fluorimetric method was proposed for the determination of FX. A linear calibration curve covered the concentration range 0.020 3-0.487 µg · mL. The regression equation was I(F) = 23.9 + 5357.3 c, with correlation coefficient r = 0.999 7 (n = 8), detection limit D = 1.1 ng · mL(-1). The method was applied to the analysis of FX tablets, with a spiked recovery rate of 100.2%. The reliability of the method was verified by a UV-spectrophotometric method.

[Synthesis and characterization of chromium doped Y3Al5O12 compound pigment].

The authors synthesized a new kind of green pigment via co-precipitation method by doping Y3Al5O12 with Cr+. The size of the pigment particles is around 200 nm as observed under scanning electron microscope. XRD results demonstrate that the pigment crystalline form of the pigment is yttrium alluminium garnet. UV-Vis spectra were used to investigate the coordination states and transition behavior of the doping ions. In addition, the colour feature was measured by CIE L* a* b* chroma value. The pigment was blended with polypropylene and then polypropylene fiber was produced using the polypropelene-pigment composite via molten spinning process. The distribution of the pigment particles in the polypropylene fibers was characterized by Xray computed tomography (CT) technique on the Beijing synchrotron radiation facility. The result states that the composite oxide pigment particles are homogeneously dispersed in the polypropylene fibers. The pigments are stable, non-toxic to the environment, and may be applied in non-aqueous dyeing to reduce waste water emitted by textile dyeing and printing industry.

[Synthesis and characterization of mixed metal oxide pigments].

In the present work, aluminum chloride and various soluble salts of doping ions were dissolved in water. In addition, urea and polyvinyl pyrrolidone (PVP) were also dissolved in the above aqueous solution under supersonic treatments. Then the solutions were heated to induce the hydrolysis of urea so that soluble aluminum and doping ions convert into insoluble hydroxide or carbonate gels. After calcinations, the obtained gels change to mixed metal oxide pigments whose color is related to type and concentrations of the doping ions. XRD characterization demonstrates that the diffraction patterns of the products are the same as that of alpha-alumina. Diffuse reflectance spectra of samples of the samples in UV-Vis regions show that the absorption bands for d-d transitions of the doping ions undergo considerable change as the coordinate environments change. In addition, L*, a* and b* values of the pigments were measured by using UV-Vis densitometer. SEM results indicate that the size of the pigment powders is in the range 200-300 nm. The pigments are quite stable since no evidence of dissolution was observed after the synthesized pigment is soaked for 24 hours. ICP test shows that very little amount of doped metal occurs in the corresponding filtrate. The above results suggest that these new kinds of mixed metal oxide pigments are stable, non-toxic, environmental friendly and they may be applicable in molten spinning process and provide a new chance for non-aqueous printing and dyeing industry.

[Fluorimetric analysis of camptothecin in Chinese herbal medicine common Camptotheca fruit].

Three-dimensional (3D) fluorescence spectra and thin layer fluorescence chromatogram of common Camptotheca fruit (CCF) crude drug, camptothecin (CPT) and 10-hydroxycamptothecin (HCPT) have been studied, and a novel fluorimetric method for determination of CPT in CCF crude drug has been established. In 3D fluorescence spectra, CPT presented 3 fluorescence peaks with excitation wavelengths lambdaex of 215, 255 and 365 nm, separately, and all peaks with emission wavelength lambdaem of 430 nm. HCPT presented 4 fluorescence peaks with lambdaex of 220, 265, 325 and 375 nm, separately, and all peaks with lambdaem of 555 nm. The fluorescence of CPT is much stronger than that of HCPT. Comparison of 3D fluorescence spectra and analysis of thin layer fluorescence chromatogram revealed that the main fluorescent component of CCF is CPT. HCPT and other components basically do not interfere with the fluorescence of CPT. Under the condition of pH 3.0-6.7, CCF aqueous solution can produce strong and steady fluorescence. Using methanol as solvent, the extracting solution of CCF was prepared, and diluted properly with water, then measured fluorescence intensity at lambdaex/lambdaem = 365/430 nm to determine the content of CPT. A linear calibration curve covered the concentration range 0.002 35-0.235 microg x mL(-1). The regression equation was IF = 9 + 30,844 c, with correlation coefficient r = 0.999 (n=9). The method has been applied to the analysis of CPT in a CCF sample, with a result of 0.127% and a spiked recovery rate of 102%. The reliability of the method has been verified by a thin layer chromatography-fluorescence scanning method. Experimental results demonstrated that this method can be used for quality evaluation of CCF crude drug.

A simple and sensitive assay of gallic acid based on localized surface plasmon resonance light scattering of silver nanoparticles through modified Tollens process.

A simple, low toxic, sensitive strategy based on the localized surface plasmon resonance light scattering (LSPR-LS) properties of silver nanoparticles (AgNPs) is introduced for the detection of gallic acid (GA). It was found that the silver ammonium complex, [Ag(NH(3))(2)](+)(aq), could be reduced in the alkaline medium by GA at room temperature; this reaction formed dispersed AgNPs. Transmission electron microscopy analyses were performed to ascertain the formation of AgNPs. UV-visible spectra revealed the localized surface plasmon resonance (LSPR) absorption at 410 nm corresponding to the LSPR of AgNPs. On these basis, we could quantify the GA concentration in the range of 4 × 10(-7) - 5 × 10(-6) mol L(-1) in the optimized experimental conditions. This method was used for determining the concentration of GA in artificial samples with satisfactory results. The detailed mechanism underlying this special phenomenon was elucidated.

[Using barium fluoride fine particles as stationary phase for TLC/FTIR analysis].

In situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures. However, the progress in this technique was quite slow. The reason is that conventional stationary phase such as silica gel etc. has strong absorption in FTIR spectrum and thus brings about severe interference in the detection of samples. To solve the problem, the authors propose to use barium fluoride fine particles as stationary phase of TLC plate. The reasons are as follows: Barium fluoride wafer has been extensively used as infrared window in FTIR experiments and it has no absorbance in an IR region between 4 000 and 800 cm'. As a matter of fact, the atomic mass of barium and fluoride is quite large, thus the normal vibration of BaF2 lattice is limited in far-IR region and low frequency part of mid-IR region. Therefore, the interference caused by IR absorption of stationary phase can be resolved if BaF2 is used as stationary phase of TLC plate. Moreover, BaF2 is quite stable and insolvable in water and most organic solvents and it will not be dissolved by mobile phase or react with samples in TLC separation. Additionally, decreasing the particle size of BaF2 is very important in TLC/FTIR analysis technique. The reason is two-fold: First, decreasing the particle size of stationary phase is helpful to improving the efficiency of separation by TLC plate; second, decreasing the size of BaFz particle can improve the quality of FTIR spectra by alleviating the problem of light scattering. By optimizing the synthetic conditions, fine particles of barium fluoride were obtained. SEM results indicate that the size of the BaF2 particles is around 500 nm. FTIR spectrum of the BaF2 particles shows that no absorption of impurity was observed. Moreover, the elevation of baseline caused by light scattering is insignificant. The authors have developed a new technique named "settlement volatilization method" to prepare TLC plate without polymeric adhesive that may bring about significant interference in FTIR analysis. Preliminary TLC experiments proved that the TLC plate using BaF2 fine particles as stationary phase can separate rhodamine B from methylene blue successfully. Applications of barium fluoride fine particles as stationary phase have bright perspective in the development of new in-situ TLC/FTIR analysis techniques.

Asynchronous orthogonal sample design scheme for two-dimensional correlation spectroscopy (2D-COS) and its application in probing intermolecular interactions from overlapping infrared (IR) bands.

This paper introduces a new approach to analysis of spectra called asynchronous orthogonal sample design (AOSD). Specifically designed concentration series are selected according to mathematical analysis of orthogonal vectors. Based on the AOSD approach, the interfering portion of the spectra arising strictly from the concentration effect can be completely removed from the asynchronous spectra. Thus, two-dimensional (2D) asynchronous spectra can be used as an effective tool to characterize intermolecular interactions that lead to apparent deviations from the Beer-Lambert law, even if the characteristic peaks of two compounds are substantially overlapped. A model solution with two solutes is used to investigate the behavior of the 2D asynchronous spectra under different extents of overlap of the characteristic peaks. Simulation results demonstrate that the resulting spectral patterns can reflect subtle spectral variations in bandwidths, peak positions, and absorptivities brought about by intermolecular interaction, which are barely visualized in the conventional one-dimensional (1D) spectra. Intermolecular interactions between butanone and dimethyl formamide (DMF) in CCl(4) solutions were investigated using the proposed AOSD approach to prove the applicability of the AOSD method in real chemical systems.

Superconcentrated hydrochloric acid.

We report the discovery of a potentially useful superconcentrated HCl at ambient temperature and pressure by using a simple surfactant-based reversed micelle system. Surprisingly, the molar ratios of H(+) to H(2)O (denoted as n(H+)/n(H2O)) in superconcentrated HCl can be larger than 5, while the maximum achievable n(H+)/n(H2O) value for conventional saturated HCl aqueous solution (37 wt %) is only about 0.28. Furthermore, both NMR and FT-IR results indicate that a significant amount of HCl remains in the molecular form rather than being ionized into H(+) and Cl(-). The superconcentrated HCl may promote some organic reactions that are not feasible by using conventional 37 wt % HCl solution. For example, addition reaction between C═C and HCl occurs in superconcentrated HCl solution without using catalysts.

A localized surface plasmon resonance light scattering-based sensing of hydroquinone via the formed silver nanoparticles in system.

In this contribution, a simple strategy for the detection of hydroquinone (HQ) is proposed based on the localized surface plasmon resonance light scattering (LSPR-LS) of the silver nanoparticles (AgNPs) formed through the modified silver mirror reaction. The redox reaction between HQ and silver ammonia occurred in the coexistence of sodium hydroxide and ammonia at room temperature, where silver ammonia was reduced by HQ and resulted in the formation of AgNPs without adding the AgNPs seeds. The formed AgNPs were demonstrated to be monodisperse and uniform by transmission electron microscopy (TEM) image. We also studied the localized surface plasmon resonance absorption (LSPR-A) and LSPR-LS spectra using both a UV-vis spectrophotometer and a common spectrofluorometer, and obtained a good agreement between experiments. By carefully optimizing the amount of NaOH and ammonia of the reaction conditions, we were able to obtain the highest net intensity of LSPR-LS on the concentrations of HQ. On the basis of experimental studies, the LSPR-LS intensity enhanced linearly over the range 0.4-2.5 µmol L(-1) with the corresponding limits of determination (3σ) of 70.6 nmol L(-1). With that, the present approach was applied to detect HQ in water samples with satisfactory results.