Application of magdala red as a fluorescence probe in the determination of nucleic acids

A fluorescence quenching method was developed for the rapid determination of DNA and RNA using magdala red as fluorescence probe. In weakly acidic ¶medium, the fluorescence of magdala red (λex>lem = 54055 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01–¶1.2 μg/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015–1.0 μg/mL for yeast RNA, respectively. The corresponding detection limits are ¶6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and ¶15.0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from coexisting substances in the determination of DNA was also examined. Real samples were determined with satisfactory results.     

Application of magdala red as a fluorescence probe in the determination of nucleic acids

A fluorescence quenching method was developed for the rapid determination of DNA and RNA using magdala red as fluorescence probe. In weakly acidic medium, the fluorescence of magdala red (lambdaex/lambdaem = 540/555 nm) can be largely quenched by DNA or RNA. The calibration graphs are linear over the range 0.01-1.2 microg/mL for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and 0.015-1.0 microg/mL for yeast RNA, respectively. The corresponding detection limits are 6.0 ng/mL for CT DNA, 7.0 ng/mL for SM DNA and 15.0 ng/mL for yeast RNA, respectively. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 3.18% for 400 ng/mL of CT DNA. Interference from coexisting substances in the determination of DNA was also examined. Real samples were determined with satisfactory results.     

Cationic cyanine as a near-infrared fluorescent probe for the determination of nucleic acids

A new method with a cationic near-IR cyanine as fluorescent probe was developed for the determination of nucleic acids. The near-IR cyanine shows maximum excitation and emission wavelengths at 765 and 790 nm, respectively, in aqueous solution. The method is based on the fluorescence decrease of near-IR cyanine in the presence of nucleic acids. Under optimal conditions, the ratio of fluorescence intensity in the absence and presence of nucleic acids was proportional to the concentration of ¶nucleic acids over the range 0.10–1.2 μg/mL for CT (calf thymus) DNA or SM (salmon sperm) DNA, and 0.10–¶1.6 μg/mL for yeast RNA. The detection limits were ¶30 ng/mL for CT DNA, 25 ng/mL for SM DNA and ¶70 ng/mL for yeast RNA. The relative standard deviation (n = 6) was 2.1% for 500 ng/mL CT DNA, 2.4% for ¶500 ng/mL SM DNA and 2.7% for 500 ng/mL yeast RNA, respectively.     

Cationic cyanine as a near-infrared fluorescent probe for the determination of nucleic acids

A new method with a cationic near-IR cyanine as fluorescent probe was developed for the determination of nucleic acids. The near-IR cyanine shows maximum excitation and emission wavelengths at 765 and 790 nm, respectively, in aqueous solution. The method is based on the fluorescence decrease of near-IR cyanine in the presence of nucleic acids. Under optimal conditions, the ratio of fluorescence intensity in the absence and presence of nucleic acids was proportional to the concentration of nucleic acids over the range 0.10-1.2 microg/mL for CT (calf thymus) DNA or SM (salmon sperm) DNA, and 0.10-1.6 microg/mL for yeast RNA. The detection limits were 30 ng/mL for CT DNA, 25 ng/mL for SM DNA and 70 ng/mL for yeast RNA. The relative standard deviation (n = 6) was 2.1% for 500 ng/mL CT DNA, 2.4% for 500 ng/mL SM DNA and 2.7% for 500 ng/mL yeast RNA, respectively.     

Determination of Nucleic Acids Using Rivanol as the Fluorescent Probe in the Presence of SDS

ABSTRACT

The quantitative method for nucleic acids using rivanol as the fluorescent probe in the presence of SDS was proposed. Under proper conditions, addition of nucleic acids to a mixture of rivanol and SDS resulted in enhanced fluorescence and spectral shifts of rivanol-SDS system. The calibration graph was linear in the range of 0–10.0 μg/ml for CT DNA and 0–9.0 μg/ml for yeast RNA, the limit of detection was 62 ng/ml for CT DNA and 156 ng/ml for yeast RNA. CT DNA could be determined in the presence of 20%(w/w) yeast RNA.     

A new selective reagent for the spectrofluorometric determination of beryllium

The fluorescence properties of the beryllium and aluminum complexes with 2, 4-dioxo-4-(4-hydroxy-6-methyl-2-pyrone-3-yl) butyric acid ethyl ester (Ligand) were studied and optimal conditions for their fluorometric determination were established. Beryllium can be determined in the linearity range of 0.5–2.0 μg/ml and aluminum 0.5–1.5 μg/ml. The effect of diverse ions on the determination of beryllium is discussed.A simple procedure for the fluorometric determination of beryllium in human blood plasma in the concentration range of 5–50 μg Be/ml is described.     

Determination of nucleic acids using calcein-neodymium complex as a fluorescence probe.

A novel fluorometric method has been developed for rapid determination of DNA and RNA with calcein-neodymium complex as a fluorescence probe. The method is based on the fluorescence enhancement of calcein-Nd(III) complex in the presence of DNA or RNA, with maximum excitation and emission wavelength at 489 nm and 514 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.5 - 3.0 microg/ml for both DNA and yeast RNA, 0.4 - 2.0 microg/ml for fish sperm DNA (FS DNA) and 0 - 3.0 microg/ml for calf thymus DNA (CT DNA). The corresponding detection limits are 15.1 ng/ml for DNA, 21.2 ng/ml for yeast RNA, 10.5 ng/ml for FS DNA and 8.9 ng/ml for CT DNA. The interaction mechanism for the binding of calcein-Nd(III) complex to DNA is also studied. The results of absorption spectra, fluorescence polarization measurements and thermal denaturation experiments, suggested that the interaction between calcein-Nd(III) complex and DNA is an electrostatic interaction.     

A Novel Method to Determine DNA by Use of Molecular “Light Switch” of Ru(phen)2(dppz)

A novel fluorimetric method was developed for selective determination of DNA with the molecular “light switch” complex of Ru(phen)₂(dppz)²⁺. The maximum fluorescence intensity was produced in the pH range 9.3–11.5, with the maximum excitation and emission wavelength of 453.0 and 598.0 nm, respectively. Under the optimum conditions, the fluorescence intensity was in proportion to the concentration of DNA. The linear range for calfthymus DNA, salmon sperm DNA, and herring sperm DNA are 0–0.9 μg/mL. The limits of detection for calfthymus DNA, salmon sperm DNA, and herring sperm DNA are 2.0, 1.8, and 5.4 ng/mL, separately. When the proposed method was used to determine DNA in the presence of some coexisting substances, a satisfactory result was obtained.     

Spectrofluorimetric determination of nucleic acids as 8-hydroxyquinoline/ yttrium ternary complexes

The formation of nucleic acids/8-hydroxyquinoline/yttrium(III) ternary complexes and their fluorescent properties have been studied. The nucleic acids studied include native and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of pH 7.6–8.5, controlled by NH₃-NH₄C1 buffer, ternary complexes are formed that fluoresce at different wavelengths with different nucleic acids. Based on the fluorescence reactions, sensitive spectrofluorimetric methods for nucleic acids are proposed. In optimal conditions, the calibration curves were linear in the range 0.5–4.0 gml^–1 for calf thymus DNA, 0.5–2.5 g ml^–1 for fish sperm DNA and 0.5–4.0 g ml^–1 for yeast RNA. The limits of determination (3 ) were 0.030 g ml^–1 for calf thymus DNA, 0.020 g ml^–1 for fish sperm DNA and 0.090 g ml^–1 for yeast RNA. Corresponding to the interferences of coexisting substances, six synthetic samples were constructed and the results of determination were satisfactory.     

Study on the interaction between nucleic acid and Eu3+-oxolinic acid and the determination of nucleic acid using the resonance light scattering technique

At pH 9.75, the resonance light scattering (RLS) intensity of OA–Eu³⁺ system is greatly enhanced by nucleic acid. Based on this phenomenon, a new quantitative method for nucleic acid in aqueous solution has been developed. Under the optimum condition, the enhanced RLS is proportional to the concentration of nucleic acid in the range of 1.0 × 10⁻⁹ to 1.0 × 10⁻⁶ g/ml for herring sperm DNA, 8.0 × 10⁻¹⁰ to 1.0 × 10⁻⁶ g/ml for calf thymus DNA and 1.0 × 10⁻⁹ to 1.0 × 10⁻⁶ g/ml for yeast RNA, and their detection limits are 0.020, 0.011 and 0.010 ng/ml, respectively. Synthetic samples and actual samples were satisfactorily determined. In addition, the interaction mechanism between nucleic acid and OA–Eu³⁺ is also investigated.     

Determination of Monochloroacetic Acid and Dichloroacetic Acid for Quality Control of Acetic Acid Chlorination Industry by Ion Chromatography

An ion chromatographic method is described for the purpose of quality control in the process of monochloroacetic acid production. Using 2.5 mM NaOH–10% methanol as eluent, the simultaneous determination of acetic acid, monochloroacetic acid, dichloroacetic acid, and Cl⁻ was obtained in a single run. Monochloroacetic acid and dichloroacetic acid showed good linearity in the range 0.1–20 and 0.15–20 μg/ml and correlation coefficients were 0.9999 and 0.9998, respectively. The detection limits (signal-to-noise ratio 3:1) of monochloroacetic acid and dichloroacetic acid were 17 and 25 ng/ml. This simple, sensitive, and time-saving method can be applied for composition analysis in acetic acid chlorination production.     

中性红荧光探针法测定生物大分子核酸

中性红 (NR)是一种吩嗪染料 ,至今已有许多关于 NR与 DNA相互作用的报道[1～ 5] .李克安[4 ] 和黄承志等 [5]利用共振光散射技术分别在酸性 (p H=2 .3 )和中性 (p H=7.6～ 7.8)条件下 ,建立了以 NR为探针测定痕量 DNA的方法 .我们 [2 ,3]曾利用荧光光谱方法研究了在 p H=7.4条件下 NR与 DNA之间的相互作用 ,发现利用吖啶橙和 NR之间的能量转移现象可以测定 DNA,但检出限偏高 ,且由于使用两种染料试剂 ,操作较繁琐 .为了克服吖啶橙、NR能量转移分析法的不足 ,本文建立了在 p H=4.5的条件下以单一染料 NR为荧光探针测定痕量核酸的…     

Simultaneous determination of paracetamol and chlorpheniramine in human plasma by liquid chromatography-tandem mass spectrometry

An analytical method for the determination of paracetamol and chlorpheniramine in human plasma has been developed, validated and applied to the analysis of samples from a phase I clinical trial. The analytical method consists in the extraction of paracetamol and chlorpheniramine with diethyl ether, followed by the determination of both drugs by an LC–MS–MS method, using 2-acetamidophenol as internal standard. The intra-assay and inter-assay precision and accuracy of this technique were good and the limit of quantitation was 0.5 μg/ml of plasma for paracetamol and 0.2 ng/ml for chlorpheniramine. The concentration working range was established between 0.5 μg/ml and 25 μg/ml for paracetamol and between 0.2 ng/ml and 50 ng/ml for chlorpheniramine. This method has been used for analyzing more than 1200 human plasma samples from a clinical study with 24 volunteers.     

Fluorometric determination of nitrite with acetaminophen

A simple, sensitive and selective fluorometric method for the determination of nitrite is described. The fluorometric determination is based on the reaction of acetaminophen with nitrite in an acidic medium followed by alkalinization of the reaction which yields a highly fluorescent product, exhibit (λ_ex/λ_em=325/430 nm). The optimum experimental conditions were studied. The fluorescene intensity is linear over a nitrite concentration of 0.08–1.3 μg/ml with a detection limit of 2.7 ng/ml (S/N=3). The effect of interferences from various metals/ions were studied. The proposed method is accurate, reproducible, shows satisfactory results and compares successfully with the reference method.     

Flow-Injection Spectrophotometric Determination of Hydrazine

A flow-injection spectrophotometric method for the determination of hydrazine is described. The method is based on the inhibitory effect of hydrazine on the reaction of thionine with nitrite in acidic media. The decolorization of thionine by the reaction with nitrite was used to monitor the reaction spectrophotometrically at 602 nm. The variables that affected the reaction rate were fully investigated and the optimum conditions were established. Hydrazine can be determined in the range 2.0–40.0 μg/ml with a limit of detection of 1.0 μg/ml. The relative standard deviation for 10 replicate determinations of 7.0 μg/ml hydrazine is 3.3%. The method is simple, rapid, and widely applicable.     

Fluorimetric determination of iron(III) by quenching the luminescence of the zinc-morin-Triton X-100 system

Summary Simple and highly sensitive fluorimetric methods for iron determination are described. The methods are based on quenching the fluorescence of an aqueous morin solution or zinc-morin-Triton X-100 ternary system. The fluorescence emission is measured at 500 and 503 nm (wavelength of excitation 420 and 433 nm) for morin and the ternary system, respectively. The quenching calibration graphs are linear over the range 0–250 and 0–55 ng Fe/ml and the iron detection limits are 20 and 5 ng/ml using morin and zinc-morin-Triton X-100 system, respectively. The influence of experimental variables such as pH, reagent and surfactant concentrations, temperature, standing time and diverse ions are studied to obtain the optimum conditions. The method has been applied to the determination of iron in aluminium metal.

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Fluorimetrische Eisen(III)-bestimmung durch Luminescenzlöschung des Systems Zink-Morin-Triton X-100

     

Indirect kinetic microdetermination of oxalate, citrate, and fluoride ions

An indirect catalytic method for the separate microdetermination of oxalate, citrate, and fluoride ions is described. The method is based on the inhibition action of oxalate, citrate, and fluoride ions on the catalytic oxidation reaction of 2,4-diaminophenol-hydrogen peroxide by iron(III).Procedures for the determination of 1.76 × 10⁻² to 17.6 × 10⁻² μg/ml for oxalate ion, 3.78 × 10⁻² to 30.24 × 10⁻² μg/ml for citrate ion, and 0.38 to 4.18 μg/ml for fluoride ion are given.Quantities of 1.76 × 10⁻² to 17.6 × 10⁻² μg/ml for oxalate ion, 3.78 × 10⁻² to 30.24 × 10⁻² μg/ml for citrate ion, and 0.38 to 4.18 μg/ml for fluoride ion could be determinated with a relative error of about 1–3.5% for oxalate and citrate ions and 1–2% for fluoride ion.     

Spectrophotometric and derivative spectrophotometric determination of nickel with hydroxynaphthol blue

The reaction of nickel(II) cation with hydroxynaphthol blue (HNB) in aqueous media at pH 5.2–6.0 results in a red complex that is stable for at least 2h. Beer's Law is obeyed up to 3.2 g/ml of nickel(II) with an apparent molar absorptivity of 1.38 × 10⁴l/mol/cm at 563 nm. This paper proposes procedures for nickel determination by ordinary and first-derivative spectrophotometry. The results demonstrate that the linear dynamic range is 0.08–3.20 g/ml with a limit of detection of 23 ng/ml for ordinary spectrophotometry, compared with 21–800 ng/ml and 6 ng/ml, respectively, for first-derivative spectrophotometry. Calcium(II), magnesium(II), barium(II), strontium(II), cadmium(II), lead(II), manganese(II), bismuth(III) and molybdenum(VI) ions do not interfere for at least 1001 mass ratios. The main interferents are cobalt(II), titanium(IV), aluminium(III), mercury(II) and copper(II). The interferences of titanium(IV), aluminium(III), zirconium(IV) and iron(III) can be masked by fluoride and mercury(II) and copper(II) with thiosulfate or thiourea. The derivative method is applied to nickel determination in standard brasses and the results demonstrate that there is no significant difference between the results and certified values at the 95% confidence level.     

Determination of strontium and its relation to other alkaline earth elements in human brain samples

Strontium content of five brain regions of five control and five Alzheimer's diseased (AD) patients and eight brain regions of three Hungarian control patients was determined. Microwave-assisted and high-pressure Parr-bomb digestions were used for sample dissolution. Strontium content of the digested samples was measured by ETAAS. The optimized parameters for digested human brain samples are: T_{pyrolysis, max}: 1500 °C, T_atomization: 2500 °C, 0.4% La(NO₃)₃ as a chemical modifier. The detection limit is 0.057 ng/ml and the characteristic mass is 1.0 pg. Calcium and magnesium content of the same digested samples were measured by ICP-OES. Accuracy of the applied methods was tested by analyzing NBS SRM1577 Bovine liver reference material, digested and measured with the samples together. Recovery measurements were done to eliminate the disturbing effect of the matrix. Strontium concentrations show great individual differences (20–450 ng/g, dry weight) independent of being either control or AD values, in contrast to the Mg (c_{control,Hungarian}: 590–675 μg/g, c_{control,German}: 620–675 μg/g, c_AD,German: 640–695 μg/g) and Ca (c_{control,Hungarian}: 270–390 μg/g, c_{control,German}: 310–400 μg/g, c_AD,German: 435–515 μg/g) concentrations.     

Fluorometric Determination of Traces of Nitrite with Rhodamine 6G

A simple and highly selective fluorometric method for determining nitrite with rhodamine 6G is described. The method is based on the oxidation of rhodamine 6G in sulfuric acid medium. A linear calibration graph passing through the origin was obtained in the range 0.02–0.4 μg/ml nitrite. The detection limit is 0.001 μg/ml. The method is free from interference by Fe(III) and Cu(II), which normally interfere with other methods. The method was applied successfully to the determination of nitrite in tap water, lake water, and milk samples.