Determination of trace selenium by solid substrate-room temperature phosphorescence enhancing method based on potassium chlorate oxidizing phenyl hydrazine-1,2-dihydroxynaphthalene-3,6-disulfonic acid system

A new method for the determination of trace selenium based on solid substrate-room temperature phosphorimetry (SS-RTP) has been established. This method was based on the fact that in HCl-KCl buffer solution, potassium chlorate could oxidize phenyl hydrazine to form chloridize diazo-ion after being heated at 100 degrees C for 20 min, and then the diazo-ion reacted with 1,2-dihydroxynaphthalene-3,6-disulfonic acid to form red azo-compound which could emit strong room temperature phosphorescence (RTP) signal on filter paper. Selenium could catalyze potassium chlorate oxidizing the reaction between phenyl hydrazine and 1,2-dihydroxynaphthalene-3,6-disulfonic acid, which caused the sharp enhancement of SS-RTP. Under the optimum condition, the relationship between the phosphorescence emission intensity (DeltaIp) and the content of selenium obeyed Beer's law when the concentration of selenium is within the range of 1.60-320 fg spot-1 (or 0.0040-0.80 ng ml-1 with a sample volume of 0.4 microl). The regression equation of working curve can be expressed as DeltaIp=13.12+0.4839CSe(IV) (fg spot-1) (n=6), with correlation coefficient r=0.9991 and a detection limit of 0.28 fg spot-1 (corresponding to a concentration range of 7.0x10(-13) g ml-1 Se(IV), n=11). After 11-fold measurement, R.S.D. were 2.8 and 3.5% for the samples containing 0.0040 and 0.80 ng ml-1 of Se(IV), respectively. This accurate and sensitive method with good repeatability has been successfully applied to the determination of trace selenium in Chinese wolfberry and egg yolk with satisfactory results. The mechanism of the enhancement of phosphorescence was also discussed.     

Atomic absorption spectrometric determination of trace zinc in alloys and biological samples after preconcentration with [1-(2-pyridylazo)-2-naphthol] on microcrystalline naphthalene

An atomic absorption spectrometric method for the determination of trace amounts of zinc after adsorption of its [1-(2-pyridylazo)-2-naphthol] complex on microcrystalline naphthalene has been developed. This complex is adsorbed on microcrystalline naphthalene in the pH range 3.5-7.5 from large volumes of aqueous solutions of various alloys and biological samples with a preconcentration factor of 40. After filtration, the solid mass consisting of the zinc complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Zinc can alternatively be quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent packed in a column and determined similarly. About 0.5 ng of zinc can be concentrated in a column from 200 ml of aqueous sample, where its concentration is as low as 2.5 pg ml-1. The calibration curve is linear in the range 0.1-6.5 ng ml-1 in dimethylformamide solution. Eight replicate determinations of 2 ng ml-1 of zinc gave a mean absorbance of 0.145 with a relative standard deviation of 1.5%. The sensitivity for 1% absorption was 0.061 ng ml-1. Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of zinc, have been studied in detail to optimize the conditions for the determination of zinc in various standard complex materials.     

Simple and sensitive method for determination of glycoalkaloids in potato tubers by high-performance liquid chromatography with chemiluminescence detection

A novel, simple and sensitive high-performance liquid chromatographic method for the determination of the potato glycoalkaloids, alpha-solanine and alpha-chaconine, based on the chemiluminescent reaction of tris(2,2'-bipyridine)ruthenium(III) has been developed. The calibration graph was linear in the range of 5 ng/ml-10 microg/ml for both alpha-solanine and alpha-chaconine. The detection limits of alpha-solanine and alpha-chaconine were 1.2 and 1.3 ng/ml, respectively. This method was successfully applied to a potato tuber sample without cleanup, pre-concentration, and derivatization steps. The recoveries (mean +/- standard deviation, %) of alpha-solanine and alpha-chaconine spiked in tuber pith at 10 microg/g (n = 6) were 101.0 +/- 4.4% and 103.6 +/- 7.1%, respectively.     

Determination of cadmium in biological samples by inductively coupled plasma atomic emission spectrometry after extraction with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide.

An inductively coupled plasma atomic emission spectrometric method for the determination of trace amounts of cadmium after extraction of the metal into isobutyl methyl ketone containing 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is described. The optimum extraction conditions were evaluated from a critical study of the effects of pH, concentration of extractant, shaking time and ionic strength. The detection limit for cadmium is 0.1 ng ml-1 and the calibration is linear from 0.2 to 140 ng ml-1. The relative standard deviation for ten replicate measurements is 2.9% for 2 ng ml-1 of cadmium. Results from the analysis of some certified biological reference materials are given.     

Determination of selenium in blood plasma and serum by flow injection hydride generation atomic absorption spectrometry

A flow injection hydride generation atomic absorption spectrometric (AAS) method has been used to determine the selenium concentrations of human serum and plasma samples following digestion with nitric, sulphuric and perchloric acids. In the hydride generation process, reduction was carried out by sodium tetrahydroborate to produce a hydride that was atomized in a flame-heated atomisation cell. The method had a detection limit of 1.2 ng ml-1 and a sensitivity of 2.1 ng ml-1. Within-run precisions of 5.8% at 20 ng ml-1 and 4.5% at 80 ng ml-1, and between-run precisions of 4.8% at 69 ng ml-1 and 3.4% at 80 ng ml-1 were obtained. An inter-laboratory comparison study with a graphite furnace AAS method was carried out and the results showed excellent agreement. The flow injection method of sample introduction allowed the use of a sample volume of 330 microliters with an injection rate of 90 injections per hour.     

鲁米诺—溴酸钠—羟基化学发光体系测定痕量钌的研究和应用

本文详细地研究了应用鲁米诺－ＮａＢｒＯ３－ＯＨ＾－化学发光体系流动测定痕量钌的最佳反应条件，探讨了该化学发光反应的机理，合理地解释了一些实验现象，建立了测定痕量钌的新方法，并有很好的选择性。方法已用于测定铬铁矿和镍铜锍扣中钌的测定，获得了满意的结果，其检出限达到０．８ｎｇ／ｍｌ，相对标准偏差为３％－７％，回收率在９４％－１０７％之间。     

Rapid quenchofluorimetric determination of nickel(II) in some real and environmental samples

A fluorimetric method for rapid determination of Ni at trace and ultratrace levels [1 ng/ml- 1 g/ml] has been developed. It is based on the efficient quenching action of Ni (II) on the native fluoresence [_ex(max) = 288 nm, _em(max) = 444.8 nm] of 4,7-diphenyl 1,10-phenanthrolinedisulfonate (bathophenanthrolinedisulfonate) solution at low acidities. The method is very simple, rapid and accurate with high precision (R.S.D. = 0.66% at 50 ng/ml). The method has been applied directly to mineralised solutions of several real and environmental samples and the results of nickel determinations are in excellent agreement with the certified values. It is a quick single-step method that requires no clean-up.     

Determination of nucleic acids with crystal violet by a resonance light-scattering technique

For the first time, Crystal Violet (CV) was used to determine nucleic acid concentrations using the resonance light-scattering (RLS) technique. Based on the enhancement of the RLS of CV by nucleic acids, a new quantitative determination method for nucleic acids in aqueous solutions has been developed. At pH 5.03 and ionic strength 0.005 mol kg-1, the interaction of CV with nucleic acids results in three characteristic RLS peaks at 344.0, 483.0 and 666.0 nm. With 4.0 x 10(-5) mol l-1 of CV, linear relationships were found between the enhanced intensity of RLS at 666.0 nm and the concentration of nucleic acids in the range 0-2.5 micrograms ml-1 for herring sperm DNA, 0-4.0 micrograms ml-1 for calf thymus DNA and 0-4.5 micrograms ml-1 for yeast RNA. The limits of determination were 13.8 ng ml-1 for herring sperm DNA, 36.8 ng ml-1 for calf thymus DNA and 69.0 ng ml-1 for yeast RNA. The assay is convenient, rapid, inexpensive and simple.     

Analysis of delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine by ion chromatography and pulsed amperometric detection

A novel high-performance liquid chromatography (HPLC) method is presented for the detection and trace level determination of the tripeptide delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine (ACV). The tripeptide, an intermediate in penicillin production, is derived from fungal fermentation. The technique relies on ion-exchange separation of the tripeptide on an anion-exchange column followed by detection by reduction on a gold electrode using pulsed amperometry. The sensitivity of direct determination of ACV is increased by employing pulsed amperometric detection (PAD) over direct ultraviolet detection. Choice of the working electrode and optimisation of electrode potentials was based on cyclic voltammograms recorded for the tripeptide in the mobile phase. A linear regression equation was obtained over the range 0-100 micrograms ml-1. The detection limit in fermentation broths was found to be 0.1 micrograms ml-1 whereas in buffer the detection limit was found to be 10 ng ml-1. A good correlation coefficient was observed when ACV concentrations determined by ion chromatography-PAD were compared with measurements obtained by pre-column derivatisation with fluoromethylorthochloroformate followed by HPLC separation on a reversed-phase C18 silica column with UV detection. The procedure has been applied to the measurement of natural levels of ACV in fermentation broths of selected strains of Aspergillus nidulans and Penicillin chrysogenum.     

Synthesis of meso-tetra-(3,5-dibromo-4-hydroxylphenyl)-porphyrin and its application to second-derivative spectrophotometric determination of lead in clinical samples

A new very sensitive and selective chromogenic reagent, meso-tetra-(3,5-dibromo-4-hydroxylphenyl)porphyrin [T(DBHP)P], was synthesized and studied for the determination of trace lead in detail. In 0.10 mol l-1 NaOH medium, lead reacts with T(DBHP)P to form a 1:2 yellow complex, which gives a maximum absorption at 479 nm; 0-0.48 microgram ml-1 Pb(II) obeyed Beer's law. The molar absorptivity of the complex and Sandell's sensitivity are 2.5 x 10(5) 1 mol-1 cm-1 and 0.000812 microgram cm-2, respectively. Second-derivative spectrophotometry is better than conventional spectrophotometry in sensitivity and selectivity, and its limit of quantification, limit of detection and relative standard deviation are 0.70 ng ml-1, 0.21 ng ml-1 and 1.0%, respectively. Ca (3250-fold), Mg (2000-fold), Sr (1000-fold), Ba (750-fold), Al (1000-fold), Bi (500-fold), Fe (2000-fold), Co (750-fold), Ni (1000-fold), Cu (750-fold), Zn (1250-fold), Cd (2500-fold) and Ag (550-fold) do not interfere with the determination of lead. The chromogenic system is remarkably superior to other reagents, especially porphyrin compounds. The influence caused by oxygen in air or in solution can be easily eliminated by adding Na2SO3. The reaction is very stable, the stability constant of the complex being 1.2 x 10(45). The chromogenic reaction is completed within 1 min at room temperature when 8-hydroxylquinoline is used as catalyst. The proposed method has been applied to the direct determination of trace lead in clinical samples. The accuracy and precision are both very satisfactory.     

溴酸钾氧化酸性铬深蓝催化动力学极谱法测定痕量钒

在0.15mol·L~(-1)H_2SO_4介质中,以酒石酸作活化剂,Ⅴ(Ⅴ)对溴酸钾氧化酸性铬深蓝的反应具有强烈的催化作用,以极谱法监测催化反应过程中酸性铬深蓝浓度的变化,建立了测定痕量钒的催化动力学新方法。钒的线性范围为0.10～7.0ng·ml~(-1),检出限为0.05ng·ml~(-1),应用于人发中痕量钒的测定,结果满意。并对酸性铬深蓝的极谱特性进行了初步的探讨。     

Studies on flow injection analysis of platinum metals: I. Flow injection catalytic determination of ruthenium by phthalin-hydrogen peroxide reaction

A new method has been developed for the determination of trace ruthenium by flow injection analysis. The proposed method is rapid, simple and sensitive. The method has a limit of detection for ruthenium of 0.020 μg/mL and permits 70 determinations per hour. The method has been applied to determine ruthenium in refined ore with satisfactory result.     

Extractive spectrophotometric determination of tungsten(VI) in alloy steels using ethopropazine hydrochloride.

Ethopropazine hydrochloride (EPH) has been proposed as a sensitive reagent for the spectrophotometric determination of tungsten(VI). The method is based on the formation of a chloroform-soluble yellow-colored ternary complex by the interaction of EPH and thiocyanate with tungsten(V). The complex exhibits the absorption maximum at 404 nm with Sandell's sensitivity value of 20.03 ng cm-2. The complex obeyed Beer's law in the concentration range of 1-15 micrograms ml-1 with an optimum concentration range of 2.3-12.9 micrograms ml-1. The effects of foreign ions in the determination of tungsten(VI) were investigated. The method has also been successfully applied to the analysis of alloy steels.     

Application of ruthenium catalyzed oxidation of [tris(2-aminoethyl)amine] in trace determination of ruthenium in environmental water samples

The ruthenium catalyzed oxidation of tris(2-aminoethyl)amine (TREN) by hexacyanoferrate(III) has been utilized for the development of a new and sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III). The reaction was followed spectrophotometrically by the decrease in absorbance at 420nm (lambda(max) of [Fe(CN)(6)](3-)). The CKM developed utilizes fixed time procedure under optimum reaction conditions where the change in absorbance (DeltaA(t)) versus ruthenium(III) concentrations is plotted. The calibration curve recommended for the method is linear in the concentration range 10.11-252.67ngml(-1) with very good accuracy and reproducibility and a maximum error 2.20%. The detection limits of the method for ruthenium(III) corresponding to 10, 15 and 20min are 8.02, 5.03 and 3.15ngml(-1), respectively. The ruthenium(III) has also been determined in the presence of several other interfering and non-interfering cations and anions and no foreign ions interfered in the determination of ruthenium(III) up to five-fold higher concentration of the foreign ions tested. The method is highly sensitive, selective and stable. It has successfully been applied for the determination of trace ruthenium(III) in some synthetic and environmental water samples. A review of most of the published catalytic kinetic and some other important methods for the determination of ruthenium has also been presented.     

石墨探针—原子吸收光谱法测定人发中痕量铟的研究

探针原子化技术是一种实现等温原子化,改善灵敏度的行之有效的方法。本文采用此方法对痕量钿进行了一系列条件试验,峰面积与钿浓度在0～50ng·ml~(-1)范围内呈线性关系,其特征量4.8pg,检出限21.5pg,相对标准偏差5.7％,并成功地测定了成人发中铟的含量,范围在12～159pg·g~(-1),回收率96.4％～103.2％。该方法灵敏度高,操作简单、快速,结果满意。     

Selectivity of catalytic methods of determination

By means of catalytic analytical methods, extremely low levels can be determined at low cost and with a high sensitivity that is equal to that of physical methods of trace analysis. The selectivity of the catalytic determinations, is, however, usually rather lower than that of other methods of trace analysis. The selectivity can sometimes be improved by modification of the indicator reaction through variation of the reagents and their concentrations, or by use of masking reagents or activators, or by combination with a separation method. Modification of the indicator reaction can be exemplified by the selective determination of osmium and ruthenium by their catalysis of the nitrate oxidation of 1-naphthylamine. By variation of the nitrate concentration and the use of 1,10-phenanthroline and 8-hydroxyquinoline as complexing agents it is possible to determine these two elements simultaneously. An especially significant increase in the selectivity is made possible by use of a preliminary separation step. If the ion to be determined is separated by solvent extraction and then catalytically determined directly in the extract, a very specific determination is possible; this technique has been called "extractive catalytic determination". This method has been used for determination of molybdenum (0.5 ng/ml) in sea-water, iron (5 ng/ml) in heavy metal salts, and copper (3 ng/ml) in the presence of numerous elements.     

Fluorimetric determination of aluminium in serum

A convenient fluorimetric method for the routine determination of aluminium in serum has been developed using lumogallion [4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulphonic acid]. Losses of aluminium during deproteinisation of the serum were prevented by treatment with a combination of 20 or 30% m/V trichloroacetic acid (TCA) and 5% m/VTCA. Iron(III) was removed by extraction into chloroform with capriquat (methyltrioctylammonium chloride) as an Fe3+-lumogallion-capriquat ternary complex. The interference from Cu2+ was eliminated by using thiosulphate as a masking agent. The detection limit was 3.6 ng ml-1 and the calibration graph was linear up to 1.4 micrograms ml-1 of aluminium. Using the proposed method, the average concentration of aluminium in the serum of healthy subjects was found to be 6.8 ng ml-1, in agreement with values reported in the literature.     

Determination of ruthenium originating from the investigational anti-cancer drug NAMI-A in human plasma ultrafiltrate, plasma, and urine by inductively coupled plasma mass spectrometry

We present a highly sensitive, rapid method for the determination of ruthenium originating from the investigational anti-cancer drug NAMI-A in human plasma ultrafiltrate, plasma, and urine. The method is based on the quantification of ruthenium by inductively coupled plasma mass spectrometry and allows quantification of 30 ng L(-1) ruthenium in plasma ultrafiltrate and urine, and 75 ng L(-1) ruthenium in human plasma, in 150 microL of matrix. The sample pretreatment procedure is straightforward and only involves dilution with appropriate diluents. The performance of the method, in terms of accuracy and precision, fulfilled the most recent FDA guidelines for bioanalytical method validation. Validated ranges of quantification were 30.0 to 1 x 10(4) ng L(-1) for ruthenium in plasma ultrafiltrate and urine and 75.0 to 1 x 10(4) ng L(-1) for ruthenium in plasma. The applicability of the method and its superiority to atomic-absorption spectrometry were demonstrated in two patients who were treated with intravenous NAMI-A in a phase I trial. The assay is now successfully used to support pharmacokinetic studies in cancer patients treated with NAMI-A.     

Comparison of HPLC, capillary electrophoretic and direct spectrofluorimetric methods for the determination of temoporfin-poly(ethylene glycol) conjugates in plasma.

High-performance liquid chromatographic (HPLC), capillary electrophoretic (CE) and direct spectrofluorimetric methods for the determination of temoporfin-poly(ethylene glycol) 2000 conjugate (m-THPC-PEG 2000) in plasma are described and compared. m-THPC-PEG 2000 in plasma was quantitatively extracted (recovery 101-107%) with CH3OH-DMSO (4 + 1 v/v). The supernatant after centrifugation was used for HPLC, CE or direct spectrofluorimetric determination. The major drawback of the HPLC method was that it gave a broad and split peak even under gradient elution conditions, resulting in difficulty in detection and quantification. This is because m-THPC-PEG 2000 consists of a group of compounds with an average molecular mass of approximately 8680 Da owing to the wide molecular mass distribution of PEG 2000 used in the synthesis of the drug. m-THPC-PEG 2000 gave a single and relatively sharp peak when separated by CE with sodium tetraborate buffer (pH 9.45) in the presence of sodium dodecyl sulfate as the running buffer. However, this method lacks the necessary sensitivity for detecting the drug in plasma extract because of the limited sample volume that can be injected. Direct spectrofluorimetry is the method of choice because of its simplicity, specificity and sensitivity. Using an excitation wavelength of 423 nm and the specific emission maximum of 657 nm, the fluorescence intensity could be sensitively measured. The calibration curve constructed by plotting fluorescence intensity against concentration was linear within the range 1.32-1056 ng ml-1. The detection limit (S/N = 3) was 1.32 ng ml-1 and the limit of quantification (S/N = 10) was 2.24 ng ml-1. The precision and reproducibility were assessed by repeated analysis (n = 24) of spiked plasma samples at 350.8 and 699.3 ng ml-1. The RSD was 4.5% and 1.6%, respectively.     

阳极溶出伏安法测定痕量汞的研究

痕量汞的测定方法有很多[1 ] 。原子吸收法虽然具有较高的灵敏性 ,但是仪器设备昂贵 ,分析步骤较繁琐。近年来 ,化学修饰电极阳极溶出伏安法在对汞痕量分析方面的研究报道也不少[2～3] ,测定的检测限一般在 1 0 - 6～ 1 0 - 9ｇ·ｍｌ- 1 ,但它容易产生记忆效应 ,洗脱不良。本文以玻碳电极为工作电极 ,在ＨＣｌ ＮａＣｌ Ｃｄ2 +中 ,示差脉冲阳极溶出伏安法 (ＤＰＳ)测定痕量汞 ,汞的平均回收率达80 %。1　实验部分1 1　主要仪器与试剂ＰＡＲ— 384极谱仪 (美国 ) ;三电极系统 :工作电极为玻碳电极 ,参比电极为Ａｇ/ＡｇＣｌ电极 ,对电极为…