Determination of Potassium Ferrocyanide in Foods by Resonance Rayleigh Scattering Method with Basic Triaminotriphenylmethane Dyes

In this work, a sensitive, rapid and simple method for the determination of trace amounts of potassium ferrocyanide in salinized foods and table salt using EV as a RRS probe is established. The detection limit （3σ） of the EV system is 7.8 ng/mL. This new method is more suitable for the determination of the trace amounts of potassium ferrocyanide in colour salinized foods and it can not be disturbed by the color of salinized foods.

Determination of Matrine and Oxymatrine in Radix Sophorae Flavescentis by Resonance Rayleigh Scattering, Second-order Scattering and Frequency Doubling Scattering Technique

In 0.1 mol/L HCl medium, 12-tungstophosphoric（TP） acid reacted with matrine（Mat） and oxymatrine（Oxy） to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scattering（FDS） appeared and their intensities were enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS were located at 370, 670 and 390 nm, respectively. The in-crements of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range. Based on this, the method for the determination of matrine and oxymatrine has been established. It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result. The reaction mechanism and reasons of RRS enhancement were discussed.

Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Methods for Determination of Methylene Blue with 12-Tungstophosphoric Acid

In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scatte- ring（FDS） are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity（△I） are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits（3s） for MB are 2.3 ng/mL（RRS method）, 5.6 ng/mL（SOS method） and 6.4 ng/mL（FDS method）, respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.

Interaction Between Mitoxantrone Metal Complex and Titan Yellow by Resonance Rayleigh Scattering Spectra and Its Analytical Application

In a pH 2.4 Britton-Robinson buffer medium, the anthracycline antibiotics mitoxantrone（MXT） could react with metal ions such as Pd（Ⅱ）, Co（Ⅱ） and Cu（Ⅱ） to form 1：2（molar ratio） cationic chelates, which further reacted with the anionic dye titan yellow to form 1：2 ternary ion-association complexes by electrostatic interaction. As a result, the intensity of resonance Rayleigh scattering（RRS） was enhanced greatly. These RRS spectral characteristics of various metal ion systems were similar, and the maximum RRS wavelengths were all located at 454 nm. But the increments of RRS intensities were different in the series of Pd（Ⅱ）〉Co（Ⅱ）〉Cu（Ⅱ）. The enhanced RRS intensities were proportional to the concentration of MXT in a range of 0.03-2.4μg/mL and the detection limit（3σ） was 0.009μg/mL for the Pd（Ⅱ） system. In this study, the optimum conditions of the reactions and the effects of foreign substances were investigated, in addition, the composition and reaction mechanism of ion-association complexes were discussed. Thus a highly sensitive, simple and rapid method is proposed for the determination of MXT in urine and serum samples.

Determination of Potassium Ferrocyanide in Foods by Resonance Rayleigh Scattering Method with Double-Charged Triaminotriphenylmethane Dyes

In pH 1.0 acidic medium, double-charged triaminotriphenylmethane dyes such as methyl green （MEG） and iodine green （IG） react with potassium ferrocyanide to form 2 ： 1 ion-association complexes by virtue of electrostatic forces and hydrophobic interaction. It results in the change of absorption and the great enhancement of resonance Rayleigh scattering （RRS） and the appearance of new RRS spectra. Two systems have similar spectral characteristics and their maximum RRS wavelengths are all located at 276 nm and smaller peaks are located at 332 and 457 nm, respectively. The intensity of RRS is directly proportional to the concentration of [Fe（CN）6]^4- in the range of 0.03-5.7 μg·mL^-1 （MeG system） or 0.04-5.9 μg·mL^-1 （IG system）. The RRS method has high sensitivity and the detection limit （3σ） for potassium ferrocyanide is 9.3 ng·mL^-1 （MeG system） or 11.2 ng·mL^-1 （IG system）. The optimum conditions, influencing factors and effects of foreign substances are investigated. The method also has a good selectivity. A sensitive, rapid and simple RRS method for the determination of potassium ferrocyanide in salinized food and table salt has been developed.

Absorption, Fluorescence and Resonance Rayleigh Scattering Spectra of Interaction of Papain with Calf Thymus DNA

In weak acidic medium, interaction between papain and calf thymus DNA （ctDNA） resulted in absorption spectral change, fluorescence quenching of papain and remarkable enhancement of resonance Rayleigh scattering （RRS） The interaction types and binding modes were discussed by characteristics of RRS, absorption, fluorescence and circular dichroism spectra combining thermodynamic data. Four interaction types include electrostatic attraction, hydrophobic force, hydrogen bonding and aromatic stacking interaction. Papain interacted with the major groove of ctDNA. Aromatic stacking interaction is the main reason of change of absorption spectrum and fluorescence quenching of papain. Surface enhanced scattering effect, resonance energy transfer effect, increase of molecular volume and conformational change make contribution to RRS enhancement. The enhanced RRS intensity （△I） is directly proportional to the concentration of ctDNA or papain, The detection limit （3σ） is 5.2 ng·omL^-1 for ctDNA and 5.6 ng·mL-1 for papain. This creates conditions for determination of papain and ctDNA.

Resonance Rayleigh Scattering Spectra of Thorium(IV)-bisazo Dye of Chromotropic Acidprotein Systems and Their Analytical Applications

In acidic medium, thorium(IV) can react with a bisazo dye of chromotropic acids such as arsenazo III (AA III), arsenazo M (AA M), chlorophosphonazo III (CPA III) and chlorosulphonphenol S (CSP S) to form an anionic chelate which further interacts with some proteins to produce a complex. This results in a significant enhancement of intensity of the resonance Rayleigh scattering (RRS) and the appearance of a new RRS spectrum. There are a few obvious RRS peaks in the range of 400-470 nm and the most intensive peak of them is located at 470 nm. The intensity of RRS is directly proportional to the concentration of protein in the range of 0-1.6 μg·mL -1 for Th(IV)-CPA III system, 0-2.8 μg·mL -1 for Th(IV)-AA M system, 0-2.0 μg·mL -1 for Th(IV)-AA III system and 0-0.28 μg·mL -1 for Th(IV)-CSP S system, respectively. The detection limits for BSA (3σ) are 10.7 ng·mL -1 for Th(IV)-CPA III, 6.3 ng·mL -1 for Th(IV)-CSP S, 13.6 ng·mL -1 for Th(IV)-AA III and 22.1 ng·mL -1 for Th(IV)-AA M, respectively. This new RRS method has high sensitivity and fairly good selectivity and can be applied to the direct determination of proteins in human serum with satisfactory results.

Resonance Rayleigh Scattering Method for the Determination of Raloxifene with Evans Blue

The intensity of resonance Rayleigh scattering (RRS) of Evans blue (EB) or raloxifene hydrochloride (Ralo) is very weak, but it can be enhanced significantly and a new RRS spectrum appears when both of them interact to form an ion-association complex in sodium acetate-hydrochloric acid buffer solution at pH 1.8. The intensity of RRS is directly proportional to the concentration of Ralo in the range of 0–8.3 μg · mL?1, and the detection limit for Ralo (σ = 3) is 18.9 ng·mL?1. The method has high sensitivity and fairly good selectivity. Based on the above evidences, a new facile method for the determination of trace amount of Ralo has been established with satisfactory results.

Determination of Hyoscine Butylbromide with Ag＋ and Dihalogenated Fluorescein Dyes in Capsules by Resonance Rayleigh Scattering Method Coupled with Flow Injection Analysis Techniquet

In pH 4.2-5.2 HOAc-NaOAc buffer solution, Ag＋ reacted with dihalogenated fluorescein （DHF） dyes to form a 1 ; 2 anionic complex. This anionic complex could further react with hyoscine butylbromide （HBB） to form 1 ： 1 ion-association complex, which resulted in the significant enhancement of resonance Rayleigh scattering （RRS） intensity. Therefore, a novel method for the determination of HBB by resonance Rayleigh scattering （RRS） coupled with flow injection analysis （FIA） technique has been established. The present method had been applied to determine HBB in capsules and the results were in good agreement with those obtained by the literature method.

Preparation and Characterization of Nano-Se/Silk Fibroin Colloids

A solution-phase approach to the synthesis of nano-Se/silk fibroin colloids（NSeSFC） by reducing selenious acid solution with silk fibroin（SF） was proposed, and the composites were in situ prepared by macrowave method. The nanocomposites were characterized with ultraviolet-visible（UV-Vis） absorption spectrometry, resonance Rayleigh scattering（RRS） spectrometry and transmission electron microscopy（TEM）. The nano-Se（0） solution exhibited the strongest resonance Rayleigh scattering at 579 rim. Through the RRS discussion, we found the best preparation and conservation condition of NSeSFC. The TEM image shows the sizes of the Se（0） particles were about 50 nm and dispersed equably. The resulted NSeSFC exhibited good stability, and it can be kept for a long period.

Influence of tip geometry on the spatial resolution of tip enhanced Raman mapping

In 2013,a breakthrough experiment pushed the Raman mapping of molecules via the tip-enhanced Raman scattering（TERS） technique to a sub-nanometer spatial resolution,going into the single-molecule level.This surprising result was well explained by accounting for the critical role of elastic molecule Rayleigh scattering within a plasmonic nanogap in enhancing both the localization and the intensity level of the Raman scattering signal.In this paper,we theoretically explore the influence of various geometric factors of the TERS system on the spatial resolution of Raman mapping,such as the tip curvature radius,tip conical angle,tip–substrate distance,and tip–molecule vertical distance.This investigation can help to find out the most critical geometric factor influencing the spatial resolution of TERS and march along in the right direction for further improving the performance of the TERS system.

Effects of Protein on the Detection of Chlorobenzenes in Fish and Their Elimination by Modified QuEChERS Method

Molecular fluorescence spectrometry, resonance Rayleigh scattering and gas chromatography-mass spectroscopy（GC-MS） were used to study the effect of pure fish serum albumin（FSA） as the model protein on the extraction of three chlorobenzenes（CBs： 1,3-DCB, 1,2-DCB and 1,2,4-TCB; DCB=dichlorobenzene; TCB=trichlorobenzene） in fish samples. The results show that there was a strong binding effect between CB and FSA. In an aqueous solution of 90%（volume fraction） acetone, a slow but full protein denaturation might take place, which would cause the unfolding of protein and the releasing of CBs. Based on these results, a QuEChERS（quick, easy, cheap, effective, rugged and safe） method was modified by replacing the traditional acetonitrile with acetone aqueous solution in the present work. This modified QuEChERS method was applied in the determination of CBs in fish samples. The spiked recoveries and the limits of detection were 80.4%--118.3% and 2.4--7.3 ng/g, respectively. This paper proposes a new strategy by slowing down the protein denaturation and releasing bound organic compounds to enhance the extraction efficiency of CBs in fish samples.