Determination of Nucleic Acids Sensitized by Emulsifier OP‐micelle Using Ethyl Rhodamine B as a Resonance Light‐Scattering Probe

Abstract

The resonance light scattering (RLS) spectra of ethyl rhodamine B with nucleic acid (calf thymus DNA and herring sperm DNA) have been studied. The effective factors and the optimum conditions have been studied, and the enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the range 0～5.00 µg mL^?1 for calf thymus DNA (ctDNA) and 0～3.50 µg mL^?1 for herring sperm DNA (hsDNA). The limits of detection are 3.42 and 3.14 ng mL^?1, respectively. Based on this, a RLS method for the determination of nucleic acids sensitized by emulsifier OP‐micelle was accordingly established. The binding mode concerning the interactions of ethyl rhodamine B with nucleic acids was also studied, and this method has good selectivity and high sensitivity and it has been applied to the determination of DNA in synthetic samples and real samples with satisfactory results.     

核酸-桑色素-铝(Ⅲ)三元荧光体系的研究

基于核酸对桑色素 铝 (Ⅲ )配合物的荧光增强作用 ,以桑色素 铝 (Ⅲ )为荧光探针 ,考察该探针与核酸的结合反应 ,建立了新的准确测定核酸的方法 ,并研究了该三元荧光体系的作用机理。在 pH 8 5时 ,fsDNA ,ctDNA ,smDNA和 yRNA的浓度与桑色素 铝 (Ⅲ )的荧光强度成线性关系 ,响应范围分别为 0 2 5～1 5 0 ,0 2 5～ 2 0 0 ,0 10～ 1 6 0和 0 2 5～ 2 0 0 μg·mL-1,检测限 (3σ/K)分别为 3,2 ,2和 3ng·mL-1。测定了合成样品 ,回收率 93 3%～ 10 7 9% ,相对标准偏差小于 3 6 %     

The Sensitive Determination of Nucleic Acids Using Fluorescence Enhancement of Eu<Superscript>3+</Superscript>-BenzoylacetoneCetyltrimethylammonium Bromide-Nucleic Acid System

A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu³⁺-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of nucleic acid in the range of 1.0 × 10⁻⁹ to 5.0 × 10⁻⁶ g/mL for herring sperm DNA (hsDNA), 3.0 × 10⁻⁹ to 1.0 × 10⁻⁶ g/mL for calf thymus DNA(ctDNA) and 8.0 × 10⁻⁹ to 1.0 × 10⁻⁶ g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated.     

Selective Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Silodosine in Dosage Form and Human Plasma. Application to Stability Studies and Content Uniformity Testing

A novel, sensitive and selective spectrofluorimetric method has been developed and validated for determination of silodosine (SLD) in its dosage form and human plasma. The method is based on nucleophilic substitution reaction of SLD with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride) in presence of 5.0 × 10^?4 M sodium carbonate (pH 10.50) to yield a highly fluorescent derivative that was measured at 435 nm after excitation at 347 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the range 30.0–200.0 ng ml^?1, with a correlation coefficient of 0.9979. The limits of detection (LOD) and quantification (LOQ) were found to be 5.44 and 16.47 ng ml^?1, respectively. The proposed method was validated according to ICH guidelines, and successfully applied to the assay of commercial capsules as well as content uniformity testing. The high sensitivity of the proposed method allowed its successful application to the analysis of SLD in spiked human plasma with % recovery of 92.88 ± 1.05–100.73 ± 0.75%, (n = 6). The application of the proposed method was further extended to stability studies of SLD after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines, where this work describe the first attempt for selective spectrofluorimetric determination of silodosine in plasma and in the presence of its oxidative degradation.     

Silver Nanoparticle Based Analysis of Aminoglycosides

Colorimetric silver nanoparticle sensor was developed for determination of aminoglycosides in milk. Silver nanoparticles were synthesized by using sodium borohydride as reducing agent and sodium dodecyl sulfate as stabilizer. Yellow color of silver turned into orange and red in proportion to the concentrations of analytes. Quantitative analyses were performed by using decrease in absorbance of silver nanoparticles at 394 nm. Linear ranges were 20–60 ng mL^?1, 23–60 ng mL^?1, and 60–100 ng mL^?1 for gentamicin, tobramycin, and amikacin, respectively. The method was optimized in terms of pH, ionic strength, and time. This simple and validated method was applied to milk samples and pharmaceutical preparations.     

Solid-Phase Extraction Using Polymer-Based Cartridge Modified with 2-(2-benzothiazolylazo)-3-hydroxyphenol for Preconcentration of Uranium(VI) Ions from Water and Real Samples

ABSTRACT

A highly sensitive, selective, and rapid method for the determination of ng mL^?1 level of U(VI) based on the rapid reaction of U(VI) with 2-(2-benzothiazolylazo)-3-hydroxyphenol (BTAHP) and the solid-phase extraction of the colored complex with a reversed-phase polymer-based C18 cartridge was developed. The BTAHP reacted with U(VI) to form a violet complex of molar ratio 2:1 [BTAHP to U(VI)] in the presence of 4.0 M of phosphoric acid solution and Triton X-114 medium. This complex was enriched by the solid-phase extraction with a polymer-based C18 cartridge. The enrichment factor of 200 was achieved. The molar absorptivity of the complex is 2.73 × 10⁶ L mol^?1 cm^?1 at 639 nm in the measured solution. The system obeys Beer's law in the range of 2.0–125 ng mL^?1, whereas the optimum concentration range obtained from Ringbom plot was 8.0–115 ng mL^?1. The relative standard deviation for 10-replicates sample of 100 ng mL^?1 level is 1.05%. The detection and quantification limits are 0.6 and 1.98 ng mL^?1 in the original sample. This method was applied to the determination of uranium(VI) in sea, tap, and waste waters, ore standard reference material, soil and sediment samples with good results comparing to the graphite furnace atomic absorption spectroscopy (GFAAS) method.     

Fluorescence Enhancement of the Silver Nanoparticales – Curcumin - Cetyltrimethylammonium Bromide-nucleic Acids System and its Analytical Application

It is found that silver nanoparticles (AgNPs) can further enhance the fluorescence intensity of curcumin (CU) - cetyltrimethylammonium bromide (CTAB) – nucleic acids and improve its anti-photobleaching activity. Under optimum conditions, the enhanced fluorescence intensity is proportion to the concentration of nucleic acids in the range of 2.0 × 10⁻⁸–1.0 × 10⁻⁶ g mL⁻¹ for fish sperm DNA (fsDNA), 2.0 × 10⁻⁸–1.0 × 10⁻⁶ g mL⁻¹ for calf thymus DNA (ctDNA), 1.0 × 10⁻⁸–1.0 × 10⁻⁶ g mL⁻¹ for yeast RNA (yRNA), and their detection limits (S/N = 3) are 8.0 ng mL⁻¹, 10.5 ng mL⁻¹ and 5.8 ng mL⁻¹, respectively. This method is used for determining the concentration of DNA in actual sample with satisfactory results. The interaction mechanism is also studied.     

RAYLEIGH LIGHT SCATTERING ENHANCING REACTION OF DIBROMOCHLOROARSENAZO AND PROTEINS SYSTEM AND ITS ANALYTICAL APPLICATION

Based on the enhancement effects of Rayleigh light scattering (RLS) on Arsenazo-DBC, a novel quantitative method for the determination of proteins in aqueous solutions has been proposed. The reaction of Dibromochloroarsenazo (Arsenazo-DBC) and five proteins (BSA, HSA, egg albumin, human γ-IgG, Lysozyme) has been studied. Under optimal conditions the dynamic ranges for proteins were 2.5–60.0 μg·ml^?1, and the detection limits for HSA and BSA were at 98.50 ng·ml^?1 and 88.10 ng·ml^?1, respectively. Comparing with other methods, the method is simple, practical and relatively free from interference from coexisting substances. The method was employed for the determination of total protein in human serum with satisfactory results.     

Synthesis,CMC Determination,Antimicrobial Activity and Nucleic Acid Binding of A Surfactant Copper(II) Complex Containing Phenanthroline and Alanine Schiff-Base

A new water-soluble surfactant copper(II) complex [Cu(sal-ala)(phen)(DA)] (sal-ala = salicylalanine, phen = 1,10-phenanthroline, DA = dodecylamine), has been synthesized and characterized by physico-chemical and spectroscopic methods. The critical micelle concentration (CMC) values of this surfactant–copper(II) complex in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 303, 308, 313. 318 and 323 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG⁰m, ΔH⁰m and ΔS⁰m). The interaction of this complex with nucleic acids (DNA and RNA) has been explored by using electronic absorption spectral titration, competitive binding experiment, cyclic voltammetry, circular dichroism (CD) spectra, and viscosity measurements. Electronic absorption studies have revealed that the complex can bind to nucleic acids by the intercalative binding mode which has been verified by viscosity measurements. The DNA binding constants have also been calculated (K_b?=?1.2?×?10⁵ M^?1 for DNA and K_b?=?1.6?×?10⁵ M^?1 for RNA). Competitive binding study with ethidium bromide (EB) showed that the complex exhibits the ability to displace the DNA-bound-EB indicating that the complex binds to DNA in strong competition with EB for the intercalative binding site. The presence of hydrophobic ligands, alanine Schiff-base, phenanthroline and long aliphatic chain amine in the complex were responsible for this strong intercalative binding. The surfactant–copper (II) complex was screened for its antibacterial and antifungal activities against various microorganisms. The results were compared with the standard drugs, amikacin(antibacterial) and ketokonazole(antifungal).     

Sensitive Chemiluminescence Assay for Patulin in Apple Juice by Flow Injection

Abstract

A sensitive chemiluminescence (CL) procedure for the determination of patulin by flow injection is described. It was found that patulin inhibits the CL generated from the luminol–dissolved oxygen system significantly. The decrement of chemiluminescence intensity was linear with the patulin concentration over the range from 0.04 to 10.0 ng mL^?1 with a detection limit of 0.01 ng mL^?1 (3σ_noise). At a flow rate of 2.0 mL min^?1, a complete analytical process could be performed within 0.5 min, including sampling and washing, with a relative standard deviation of less than 3.0% (n=5). The proposed method was applied successfully in the determination of patulin in apple juice, and the recovery was between 96.9% and 103.9%.     

UV–Vis Spectrophotometric Determination of Mercury Based on Room Temperature Ionic Liquids Enhanced Hollow-Fiber Liquid-Phase Microextraction

A novel method based on the enhancement effect of room temperature ionic liquids for hollow-fiber liquid-phase microextraction trace amounts of mercury combined with UV–Vis spectrophotometry for the determination of Hg was developed. The addition of room temperature ionic liquids led to 6.0 times improvement in the determination of mercury. Under optimized conditions, an enrichment factor of 120 could be obtained, and the detection limit for Hg was 0.2 ng mL^?1. The relative standard deviations for five replicate determinations of 20 ng mL^?1 Hg(II) was 5.4%. The proposed method was successfully applied to certified reference materials and environmental water samples with satisfactory results for the determination of Hg.     

Native Fluorescence Determination of Pyridoxine Hydrochloride (Vitamin B6) in Pharmaceutical Preparations After Sorption on Sephadex SP C‐25

A simple, batch mode, solid phase spectrofluorimetric procedure has been developed for the determination of pyridoxine hydrochloride (PY) (vitamin B₆). The method is based on the measurement of the native fluorescence of the analyte at 395 nm (λ_exc = 295 nm) sorbed on Sephadex SP C‐25 beads. The cation‐exchange gel, previously equilibrated with the sample solution, is packed in a 1‐mm quartz cell in which the measurements are performed (diffuse transmitted fluorescence).

The method responds linearly in the measuring range of 50–500, 10–100 and 5–40 μg·l^? 1 with detection limits of 9.5, 2.3 and 0.60 μg·l^? 1 for 10, 25 and 50 ml of sample volume, respectively.

The relative standard deviation (n = 10) for the determination of 100 (10 ml), 60 (25 ml) and 30 μg·l^? 1 (25 ml) of PY is 1.3%, 2.2% and 3.7%, respectively. The method, which shows increasing sensitivity as the sample volume increases, was satisfactorily applied to the determination of vitamin B₆ in pharmaceutical preparations using the procedure for 10 ml of sample.     

Vortex-Assisted Liquid–Liquid Microextraction for the Determination of Residual Sulfonamides in Meat Samples with Spectrofluorophotometer

A simple and fast extraction termed vortex-assisted liquid–liquid microrextraction coupled with molecular fluorescence spectroscopy has been developed and used for the detection of three sulfonamides (sulfadiazine sodium, sulfamethoxazole, and sulfaguanidine) in the meat samples. In the vortex-assisted liquid–liquid microrextraction method, 400 µL of nonanoic acid was used as extractant and directly injected into 10 mL centrifuge tube containing a derivative, which sulfonamides derived with o-phthaladehyde. And the extraction solvent was dispersed into the water phase under mechanical force with the vortex-mix. The polar side was reduced and the strong fluorescence produced at λ_ex = 295 nm. Variable parameters affecting the derivatization and vortex-assisted liquid–liquid microrextraction procedure were evaluated and optimized. The vortex-mix substituted effect of disperser solvent in this procedure. The limits of detection were 2.0 ng mL^?1 for sulfadiazine sodium and sulfamethoxazole, 0.5 ng mL^?1 for sulfaguanidine with the relative standard deviations of the method ranging from 2.5% to 6.1%. And the calibration graph was linear from 5 to 5000 ng mL^?1 with coefficient of determinations more than 0.9995. Recoveries of the three sulfonamides on spiked meat samples at different levels were 92.2–102.5%. Finally, the method has been successfully applied to the determination of sulfonamides from meat samples.     

Novel Method for Determination of Anthracene by Coupling Dispersive Liquid-Liquid Extraction to First-Derivative Synchronous Spectrofluorimetry

A novel method could be adopted successfully for determination of anthracene in environmental samples, utilizing dispersive liquid-liquid extraction followed by first-derivative synchronous fluorimetry at a constant wavelength difference Δλ?=?165 nm, where a linear calibration curve was obtained in a concentration range of 0.5–100 ng mL^?1 at 244 nm. The detection limit was 0.1 ng mL^?1. The method can be easily adopted for determination of anthracene in aqueous media including tap water and river water. The recoveries obtained were 85.40–108.02 %. The proposed method was validated according to International Conference of Harmonization (ICH) guide lines and successfully applied to determine anthracene in pure form and in water samples including real life water samples from different sources. All the results obtained were compared with those of published method, where no a significant difference was observed.     

Multipumping Nitrite Determination in Exhaled Breath Condensate

Abstract

A flow system based on multicommutation is proposed for the rapid, clean, and inexpensive determination of nitrites in small volumes of breath condensates. The procedure exploits the colorimetric detection of nitrite with the Griess reagent [0.03% naphthylethylene diamine dihydrochloride (NED), 0.5% sulpfhanilamide, and 3.0% phosphoric acid] in acidic medium at 540 nm correcting the variations of the baseline with measurements at 424 nm. The flow system was designed with a set of solenoid micropumps to minimize sample and reagent consumption and waste generation. The detection limit was estimated as 3.8 ng mL^?1 (99.7% confidence level) with a linear response ranging up to 500 ng mL^?1. The coefficient of variation was estimated as 0.7% for a solution containing 300 ng mL^?1 nitrite (n=9). Approximately 144 determinations can be carried out per hour, consuming only 678.4 µg Griess reagent and generating 1.184 mL of effluent per determination, thus providing an environmentally friendly alternative and a nonexpensive method. The procedure was successfully applied to determine nitrite in breath condensates.     

Determination of Cd in Water Samples by Hollow-Fiber–Supported Liquid-Membrane Extraction Coupled with Thermospray-Flame–Furnace Atomic-Absorption Spectrometry

ABSTRACT

A new method of hollow-fiber–supported liquid-membrane extraction (HF-SLME) coupled with thermospray-flame–furnace atomic-absorption spectrometry (TS-FF-AAS) for the determination of cadmium in water samples was developed. 1-Octanol was immobilized in the pores of the polypropylene hollow fiber as liquid membrane and used as the acceptor solution. Cd was selectively extracted from water samples into 1-octanol that filled the inner part of hollow fiber as the acceptor solution. The authors evaluated in detail some parameters that influence extraction and determination, such as the concentration of sodium diethyldithiocarbamate (DDTC), pH of samples, stirring rate, extraction time, flow rate of the pump, and interferences. Under optimized conditions, an enrichment factor of 146 could be obtained. In combination with thermospray-flame–furnace atomic-absorption spectrometry, a very low limit of detection (LOD) (5 ng L^?1) was achieved. The relative standard deviation (RSD) was 4.3% for five determinations of 0.1 ng mL^?1 cadmium. The accuracy of this method was validated by determination of certified reference water samples (GBW(E) 08607 and GSBZ(E) 50009-88). The proposed method was also applied to the determination of cadmium in tap water and river water, with the recoveries in the range of 90–96% for spiked samples.     

Sensitive Detection of Luteolin Using Thioglycolic Acid–Capped Cadmium Telluride/Cadmium Sulphide Quantum Dots as the Fluorescent Probe

ABSTRACT

A sensitive and simple method for the determination of luteolin (LTL) was developed based on the fluorescence quenching effect of LTL for thioglycolic acid–capped (TGA-capped) CdTe/CdS quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 0.3 to 20.0 µg · mL^?1 with a correlation coefficient of 0.9972, and the detection limit was 7.2 ng · mL^?1. The fluorescence quenching mechanism has been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-Vis) absorption, fluorescence (FL) spectroscopy. The proposed method was successfully applied to the determination of LTL in commercial capsules and human urine samples. It manifested several advantages such as high sensitivity, short analysis time, low cost, and ease of operation.     

吖啶橙-罗丹明B二聚体能量转移体系在DNA测定中的应用及机理研究

首次研究了吖啶橙 罗丹明B二聚体能量转移体系作为荧光探针用于DNA的测定 ,并对其机理进行了探讨。用于鲱鱼精DNA和小牛胸腺DNA的测定 ,线性范围分别为 0 33～ 1 33mg·L- 1 ,0 33～ 3 33mg·L- 1 ,检测限分别为 1 6 3× 10 - 3mg·L- 1 ,1 5 2× 10 - 3mg·L- 1 。对 1 0 0mg·L- 1 鲱鱼精DNA和小牛胸腺DNA的测定 ,相对标准偏差分别为 2 4 %和 2 0 %。     

The Mineral Content of Rhizona cyperi after Microwave-Assisted Digestion and Determination by AAS

ABSTRACT

Rhizoma cyperi (tuberal part of Cyperus rotundus Linn) obtained from 15 different zones of China was studied to determine the contents of 16 trace elements such as 4 minor (Ca, K, Mg, and Na), 9 trace (Co, Cr, Cu, Fe, Mn, Mo, Ni, V, and Zn), and 3 toxic (Ag, Cd, and Pb) elements. The concentration determination of 16 elements was performed by atomic absorption spectrophotometry (AAS) after microwave-assisted digestion. A microwave-assisted digestion procedure based on the mixture nitric acid–hydrogen peroxide was evaluated. The method was successfully validated with the good recoveries (97–105%) against CRM GBW07603 (bush twigs and leaves). The calibration curve furnished good linear correlation coefficients (r = 0.9956–0.9999), excellent recoveries (99.35–103.7%), and limits of detection (LOD = 1–50 ng·mL^?1) suitable to determine in Rhizoma cyperi. The results showed that K, Ca, Mg, and Na were the most abundant of the major elements in Rhizoma cyperi with average concentrations of K, 26,221 µg·g^?1; Ca, 1097 µg·g^?1; Mg, 714 µg·g^?1, and Na, 293 µg·g^?1, respectively. K element was determined for the first time in this plant.