A highly sensitive fluorimetric method for the determination of fluoride in biological material with Al3+-calcein complex

A highly sensitive fluorimetric method for the determination of fluoride was established. The method was based on quenching of the fluorescence of the Al³⁺-calcein complex in CCl₃COOH-CH₃COOK buffer solution by fluoride. The fluorescence emission was measured at λ_ex/λ_em 480/503 nm, and the experimental variables and interference in this determination were studied. The linear calibration range was 0.8 ng/mL to 150 ng/mL and the detection limit was 0.2 ng/mL. The method was applied to determine fluoride in biological materials. The recovery was in the range of 96.3% to 104.7% and the relative standard deviation was 4.6%. The results obtained from the certified reference material by the present method agreed with the certified values.     

A catalytic-kinetic method for the determination of traces of fluoride in biological material

A catalytic-kinetic method for the determination of nanogram amounts of fluoride, based on its inhibiting action on the catalyst in the zirconium-catalyzed reaction between perborate and iodide, is described. The rate measurements are accomplished very simply by using a Landolt reaction system with a biamperometric detection of the induction period. The standard deviation in the working range 19–190 ng of fluoride (1–10 nmol) is ± 2 ng. The method can be made specific by combining it with a separation of the fluoride by microdiffusion. This has been demonstrated by analyzing biological material and comparing the results with the fluoride contents obtained with other methods.     

A highly sensitive method for the determination of adriamycin and adriamycinol in human plasma using HPLC with fluorimetric detection

Summary A simple and very sensitive HPLC method, for the simultaneous determination in human plasma of adriamycin and its metabolite adriamycinol, is described. Plasmas from patients were stored frozen. Thawed samples were extracted by absorption of anthracyclin onto a small C18 column. After evaporation of the eluate and reconstitution of the residue with methanol (100L), 30 to 40L of the mixture were injected into the chromatograph. Separation was obtained using an RP 8 column with a mobile phase of formate buffermethanol-acetonitrile (502327, v/v). A spectrofluorimeter was used as detector. The limit of sensitivity of the assay was 50 pcg/ml of plasma.     

铟的灵敏光度测定法

我国对微量铟的显色反应研究得较少.最常用的是碱性染料萃取光度法,但操作冗繁而且苯的毒性较大.因此寻找灵敏度高而又能在水相测定铟的新方法是很有必要的. 用苯荧光酮(2,3,7-三羟基-9-苯基-6-荧光酮,PF)作显色剂的胶束增溶分光光度法已应用于锗、钼、锡、镓等的测定,但用类似的方法测铟则尚未见报道.我们的实验证明,在pH为7.7～8.9的醋酸-氢氧化铵缓冲介质中,铟与PF及氯化十六烷基吡啶(OPC)生成玫瑰红色的三元配合物,其配合比为In(III):PF:CPC=1:2:2,表观稳定常数为8.6×10~(10),摩尔吸收系数达1.28×10~5.提出用乙酸乙酯萃取分离杂质.利用本显色反应测定微量铟,方法灵敏且稳定,准确度和精密度均较好.     

Simplified sample preparation for fluoride determination in biological material

A simple and rapid preparation method for the determination of fluoride in biological materials (blood and food) of various origins, is described. A homogenized sample was placed in a plastic diffusion cell and calcium phosphate added, it was then dried at 55 degrees C and treated with 70% HClO4 and 40% AgClO4. After digestion for 24 h at 55 degrees C, the fluorides released were fixed on the upper part of a diffusion cell containing a thin layer of NaOH. The analyses of the diffused fluoride were carried out with an ion-selective electrode. The proposed microdiffusion method, without mineralization, enables quantitative separation of the fluoride from the biological samples.     

Semi-automated fluorimetric determination of nanogram quantities of selenium in biological material

A semi-automated method, based on the solvent extraction and fluorescence of 4,5-benzopiazselenol, is described for the determination of selenium in biological material. Samples, in batches of up to 150, are digested in a mixture of nitric and perchloric acids in temperature-controlled aluminium blocks. Selenate formed in the perchloric acid is reduced to selenite with hydrochloric acid. Metal ion interferences, including hydroxide adsorption of selenite, are prevented by ethylenediaminetetraacetic acid. Sulphate above 50 mM precipitates the 2,3-diaminonaphthalene, so wool digests were diluted accordingly. The digests are analysed from their digestion tubes at the rate of 40 per hour by the semi-automated method. Results for blood and a variety of food samples compare favourably with those obtained by other methods including hydride/atomic absorption and instrumental neutron-activation analysis.     

A highly sensitive and selective method for the extraction-spectrophotometric determination of cobalt

The method is based on the highly sensitive reaction between cobalt and 4-(5-bromo-2-pyridylazo)-l,3-diaminobenzene. The cationic complex in slightly acidic solution is quantitatively extracted into chloroform as an ion pair with anthraquinone sulfonate; interfering ions are retained in the aqueous phase by selected masking agents. The cobalt complex is then rapidly back-extracted into 2.4 M HCl and measured at 573 nm (? = 1.16 × 10⁵ l mol^-1 cm^-1).     

A rapid spectrophotometric method for determination of fluoride in silicates with the zirconyl-xylenol orange complex

A critical study has been made of the effect of acid concentration and of polymerized and depolymerized zirconyl ions on the formation of ZrO-XO complexes and their stabilities. At an optimum acidity of 0.5-0.6M hydrochloric acid, most of the common cations occurring in silicates do not interfere. Maximum colour development is almost instantaneous for the depolymerized ZrO-XO complex, but takes a few hours for the polymerized complex; the colour is stable for several hours. The absorbance is highest for the depolymerized ZrO-XO complex and decreases with an increase in polymerization of the zirconyl ions. Dissolved oxides of nitrogen affect the stability of the ZrO-XO complex but can be eliminated with urea. A simple, rapid and sensitive spectrophotometric method has been worked out for use of this complex in determination of fluoride in silicates, without separation, after fusion of the sample with sodium hydroxide at 450-550 degrees.     

A highly selective and sensitive perylenebisimide-based fluorescent PET sensor for Al determination in MeCN

A novel ‘turn-on’ fluorescent probe with perylene tetracarboxylic bisimide (PBI) as the fluorophore and di(2-(salicylideneamino))ethylamine (DSEA) as the metal ion receptor was designed. The capability of the prepared probe to detect metal ions was evaluated by the changes in its emission intensity. The probe demonstrated a considerable emission enhancement (ca. 110-fold) in the presence of Al³⁺ in MeCN with high selectivity and sensitivity. Furthermore, the considerably ‘off–on’ fluorescence response concomitantly led to the apparent color change from colorless to brilliant yellow, which could also be identified by naked eye easily under UV lamp.     

A method for quantitative determination of deuterium content in biological material

A method was developed for quantitative determination of deuterium incorporated into live organisms or biological macromolecules. The deuterated biological material was mixed with a bovine serum albumin (BSA) supporter to make a homogeneous sample for which the deltaD value (vs. VSMOW) was analyzed using a dual-inlet gas isotope mass spectrometer. The method is described in detail, and the equation for calculation of deuterium content is presented, i.e., CbioD=1/500 x k x RVSMOW x CBSAH x 10(6) ppm. Deuterated hepatitis A virus (HAV) RNA and BSA were systematically investigated. The results demonstrate that the method is capable of direct measurement of deuterium content, and is highly repeatable and reliable with a standard deviation of +/-3 per thousand. It is stressed that the quantity of deuterated sample required is extremely small as a result of using BSA as supporter. The method may be applied in many fields, and has the strengths of simplicity, relative cheapness, and robustness.     

A sensitive and highly selective extractive spectrophotometric method for the determination of palladium

Summary A Sensitive and Highly Selective Extractive Spectrophotometric Method for the Determination of Palladium Palladium forms an anionic chelate with 4-(2-pyridylazo)resorcinol (PAR, H₂R) which is extractable with xylometazolonium cation (XMH) into chloroform in the pH range 7.2–7.8 giving an intensely pinkish red coloured solution. The coloured species exhibits maximum absorbance at 520 nm with molar absorptivity 3.34×10⁴1·mole^–1·cm^–1 and obeys Beer's law in the range 0.8–5.30g/ml of palladium. The composition of the extracting species is found to be 111 for Pd(II)PARXMH. Large concentrations of EDTA and oxalate have no interference in the spectrophotometric determination of palladium by this procedure. Based on this a highly selective and sensitive method for the determination of palladium in the presence of Zn(II), Cd(II), Hg(II), Fe(III), Mn(II), Co(III), Mo(VI), Ru(IV), Sb(III), Al(III) is described. The application of this method for the determination of palladium in synthetic mixtures corresponding to the composition of jewel alloy and stibiopalladinite mineral is also demonstrated.     

A highly sensitive spectrophotometric method for determination of micro amounts of arsenic

A highly sensitive spectrophotometric method for determination of arsenic, based on the formation of an ion-association complex between arsenoantimonomolybdenum blue and Malachite Green, has been developed. The ion-association complex is soluble in the presence of Triton X-305, so arsenic can be determined directly in aqueous solution. The apparent molar absorptivity for arsenic is 1.13 x 10(5) l.mole(-1).cm(-1) at 640 nm. Beer's law is obeyed for 0-5 mug of arsenic. The lower limit of determination (absorbance = 0.01) is 4 ng ml in the final solution.     

A fluorimetric method for the determination of traces of gallium

A fluorimetric method for the determination of gallium, based on the formation of a fluorescent 1:1 chelate with benzyl-2-pyridylketone-2-pyridylhydrazone, is described. In 90% ethanol, the fluorescent species has excitation and emission maxima at 469 and 545 nm, respectively, and the calibration graph is linear over the range 1.4–350 ppb Ga at pH 5. Methods of removing interferences are discussed.     

A highly selective and sensitive fluorescent turn-on chemosensor for Al3+ based on a chromone Schiff base

A Schiff-base fluorescent sensor, 7-methoxychromone-3-carbaldehyde-(3′,4′-dimethyl)pyrrole hydrazone (MCPH), was synthesized. The new sensor showed high selectivity for Al³⁺ over other metal ions examined in acetonitrile. Upon binding Al³⁺, a significant fluorescence enhancement with a turn-on ratio over 101-fold was triggered. The detection limit of MCPH for Al³⁺ was 2.5?×?10^?7?mol?L^?1.     

A highly sensitive colorimetric and ratiometric sensor for fluoride ion

A new benzoimidazole-naphthalimide derivative 4 was synthesized and its photophysical properties were studied. This compound showed highly selectively and sensitive colorimetric and ratiometric sensing ability for fluoride anion.     

Determination of vitamin B12 in pharmaceutical preparations by a highly sensitive fluorimetric method

A fluorimetric method for the determination of vitamin B12 has been developed. The fluorescence emission was measured at lambda(ex)/lambda(em)275/305 nm in phosphate buffer solution (pH 7.0), and the experimental variables and possible interference were studied. The linear calibration range was 1.000 ng/mL to 100.0 ng/mL with a correlation coefficient of 0.9994 and a detection limit of 0.1 ng/mL. The method is rapid, simple and highly sensitive. It was used to determine vitamin B12 in pharmaceutical preparations. The recovery was 96%-98% and the relative standard deviation was in the range of 1.8%-2.7%. The results agreed with those obtained by spectrophotometry.     

Determination of vitamin B12 in pharmaceutical preparations by a highly sensitive fluorimetric method

A fluorimetric method for the determination of vitamin B₁₂ has been developed. The fluorescence emission was measured at λ_ex/λ_em275/305 nm in phosphate buffer solution (pH 7.0), and the experimental variables and possible interference were studied. The linear calibration range was 1.000 ng/mL to 100.0 ng/mL with a correlation coefficient of 0.9994 and a detection limit of 0.1 ng/mL. The method is rapid, simple and highly sensitive. It was used to determine vitamin B₁₂ in pharmaceutical preparations. The recovery was 96%–98% and the relative standard deviation was in the range of 1.8%–2.7%. The results agreed with those obtained by spectrophotometry. Received: 17 July 2000 / Revised: 4 September 2000 / Accepted: 7 September 2000     

A novel and highly sensitive catalytic method with oscillopolarographic detection for the determination of ultratrace amounts of iridium

Iridium(IV) has a strong catalytic effect on the slow redox reaction between Malachite Green and periodate ion in pH 4.2 acetate buffer solution at 100 degrees , and Malachite Green exhibits a sensitive single-sweep oscillopolarographic wave at -0.65 V vs. SCE. This provides the basis for a novel and highly sensitive and selective catalytic method with oscillopolarographic detection for iridium. The effect of pH, potassium periodate and Malachite Green concentrations, reaction temperature and reaction time and other variables are investigated. The detection limit is 8 ng/l. with a fixed-reaction time of 10 min. A linear calibration graph from 24 to 1600 ng/l. is obtained. Possible interferences by co-existing ions are examined.     

分子印迹固相萃取-电化学发光检测牛奶中氯霉素

基于氯霉素(CAP)能强烈抑制Ru(bpy)32+/TPA体系的电化学发光(ECL)信号,结合分子印迹固相萃取(MISPE)样品前处理技术,建立了一种高灵敏度检测牛奶中CAP残留量的方法。在最优实验条件下,体系的ECL猝灭值ΔI与CAP浓度呈良好线性关系,线性范围为1.0×10-13～1.0×10-11g/mL,检测限为3×10-12g/mL,精密度和准确度好,可用于牛奶中CAP残留量的测定。     

A new and sensitive method for the spectrophotometric determination of ethion in environmental and biological samples

A new and sensitive spectrophotometric method is described for the determination of sub ppm levels of the organophosphorus pesticide ethion based on the oxidation of ethion by potassium permanganate in phosphoric acid to sulphones and its hydrolysis under acidic condition at 100°C to release formaldehyde, which is then determined by a reaction with 1,3,5-trihydroxybenzene (phloroglucinol) in alkaline medium. Beer's law is obeyed in the range of 0.1–0.8 ppm of ethion at 460 nm. The analytical parameters have been optimized.