Determination of trace amounts of antimony in geological materials by atomic absorption spectrometry

For the determination of traces of antimony in rocks and soils, dried samples are heated with ammonium iodide to volatilize antimony triiodide, which is then taken up with 10% hydrochloric acid and extracted into TOPO-MIBK. Analysis is completed by atomic absorption spectrometry. The range is 1.0–40 p.p.m. Sb, the relative standard deviation being about 10–4%. Up to 20% iron and 2000 p.p.m. Cu, Pb, Zn. Sn, As or Hg do not interfere.     

Determination of trace amounts of organic acids in silage by liquid chromatography

Trace amounts of organic acids in silage may be determined rapidly and quantitatively by ion-exclusion chromatography. The method described uses a conductimetric microcell to monitor the aqueous eluate from the column. Examination of the results obtained shows that the method has a coefficient of variation of 6% when the sample is injected onto a column with the solvent running. It appears likely that the technique could be applied to mixtures of other acids.     

Determination of trace amounts of p-toluenesulfonic acid in organic materials

Summary p-toluenesulfonic acid is separated from the sample (e. g. glucose, glycollic acid, lactic acid, lactose, maltose) by extraction using liquid ion-exchanger Alamine 336 (tricaprylamine) and quantitated by liquid chromatography. Precision at the 5 ppm level characterized by a standard deviation is 0.458 ppm. Recoveries average 66.13% forp-toluenesulfonic acid determination in glucose, and 71.99% in glycollic acid. Calibration curves constructed by the aid of spiked samples are linear in the region studied, i. e. 1.4–13.3 ppm and can be used for evaluation in routine analysis. When only an occasional check for the presence ofp-toluenesulfonic acid is needed, one spiked sample is analyzed as a reference standard.

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Zusammenfassung p-Toluolsulfonsäure (I) läßt sich von Glucose, Glykolsäure, Milchsäure, Milchzucker, Malzzucker u. dgl. durch Extraktion mit dem flüssigen Ionenaustauscher Alamin 336 (Tricaprylamin) abtrennen und chromatographisch bestimmen. Die Genauigkeit bei 5 ppm entspricht einer Standardabweichung von 0,458 ppm. Bei Bestimmung von I in Glucose findet man durchschnittlich 66,13% der eingesetzten Menge, bei Bestimmung in Glykolsaure 71,99%. Die mit Hilfe von Bezugsproben, denen bekannte Mengen von I zugesetzt wurden, ermittelten Eichkurven verlaufen im untersuchten Bereich, d. h. zwischen 1,4 und 13,3 ppm linear und können im Routinebetrieb verwendet werden. Bei nur gelegentlicher Bestimmung von I bedarf es nur einer Vergleichsprobe als Bezugs-Standard.

     

Determination of trace amounts of chloramines by liquid chromatographic separation and amperometric detection

The detection of chloramines by monitoring electrochemical reduction processes on a glassy carbon electrode was investigated. Liquid chromatographic separation using a C₁₈ column followed by amperometric or spectrophotometric detection were compared. The results indicate that amperometric detection is the more sensitive, especially for dichloramine.     

Separation of four platinum metals by anion-exchange in hydrobromic acid medium

Distribution coefficients of Pt, Ir, Pd and Rh in the systems Dowex 1 [Br^?]?HBr plus 0.0035M bromine and Dowex 1 [Br^?]?HBr plus 2% N₂H₄·HCl, were determined with the aid of radioactive tracers by batch equilibration for the resins of nominal cross-linking 2, 4 and 8, respectively. Column experiments showed that Dowex 1X4 should be used for separations because of the favourable dynamics of the column process. Elution conditions for the quantitative separation of both trace and milligram amounts of Ir?Pt, Rh?Pt, Pd?Pt and Ir?Pd?Pt mixtures are given. Some data on the effect of temperature upon the quality of separation are also presented.     

Determination of trace amounts of beryllium using derivative spectrophotometry in non-ionic micellar medium

A rapid and sensitive method for the trace level determination of beryllium based on the formation of a 1:2 complex (λ_max 560 nm) with 1,4-dihydroxy-9,10-anthracenedione in an aqueous medium containing Triton X-100 is reported. Beer’s law is followed in the range 3.60–360 ng ml⁻¹ of Be(II). The molar absorptivity and Sandell’s sensitivity are 1.68×10⁴ l mol⁻¹cm⁻¹ and 0.54 ng cm⁻², respectively; detection limit is 0.23 ng ml⁻¹ of Be(II). Analysis of synthetic mixtures of composition similar to that of alloys and spiked samples of distilled water, gave results that are in agreement with their beryllium content.     

气泡富集-高效液相色谱法测定地表水样中微量土霉素

建立了气泡富集-高效液相色谱（HPLC）测定地表水样中微量土霉素的方法。采用新型样品前处理方法--气泡富集法,对水溶液中的微量土霉素进行富集,考察了气泡富集条件对富集效果的影响。研究发现,在优化的气泡富集和色谱条件下,土霉素的富集倍数可达37.06,土霉素含量测定的RSD为4.8%（n=11）,LOD为0.038 mg/L。将该方法用于地表水样中土霉素的测定,平均加标回收率为101.9%。可见,气泡富集法对土霉素的富集效果好,能与色谱结合用于地表水样中土霉素的快速、灵敏、准确检测。同时,在进行样品前处理时无需任何有机溶剂,而且装置简单、成本低廉、易操作。可见气泡富集法是一种非常有研究和推广价值的绿色样品前处理方法,有望用于复杂样品中其他微量甚至痕量物质的分析。     

Determination of peptaibol trace amounts in marine sediments by liquid chromatography/electrospray ionization-ion trap-mass spectrometry

Extraction followed by reverse phase liquid chromatography (LC)/electrospray ionization-ion trap-mass spectrometry (ESI-IT-MS) analysis has been successfully developed for the determination of peptaibols, fungal toxic metabolites, in marine sediments. Spiking experiments showed that the mean recovery of target compounds exceeded 85% at a spiking level of 10 ng/g of sediment (wet weight). Detection and quantification limits were 250 and 830 pg/g of sediment, respectively. The method developed constituted the first sensitive assay for quantification of peptaibol trace amounts in a natural environment. A concentration of 5 ng/g in sediment samples collected from Fier d'Ars was found.     

Determination of warfarin at trace-levels in water by solid-phase spectrofluorimetry

A new selective and sensitive spectrofluorimetric method for the determination of warfarin at trace levels (0.2-50.0 ng/ml) in water is proposed. Warfarin is fixed on Sephadex QAE A-25 gel (at pH = 7.0) and its fluorescence is measured directly in the solid-phase using a 1-mm silica cell at 312/385 nm with a detection/quantification limit of 0.06/0.2 ng/ml, a relative standard deviation of 2.3% and recoveries between 95 and 105%. The method is applied to the determination of warfarin residues in water.     

Determination of trace amounts of palladium by radiochemical displacement

A method has been developed for the determination of trace amounts of palladium using radioactive mercury dithizonate as the reagent. Experimental conditions for the quantitative displacement of mercury from the reagent, calibration graph and the interfering effects of various ions have been studied. The method is sensitive down to 2 g of palladium present in 10 ml of the aqueous solution.     

Determination of trace amounts of thorium by electroanalytical techniques

Trace amounts of thorium have been determined in the presence of uranyl nitrate and ammonium diuranate (as interferents) by cyclic voltammetry, differential-pulse polarography, differential-pulse voltammetry, square-wave voltammetry and anodic-stripping voltammetry. The determination is based on the substitution of thorium for copper, lead and cadmium in their EDTA complexes and voltammetric measurement of the displaced metal ion. The detection limits ranged between 2 x 10(-7) and 1 x 10(-6)M (r.s.d. 2-7%) for solutions free from the uranium compounds, and between 8 x 10(-7) and 5 x 10(-6)M (r.s.d. 3-5%) in the presence of the uranium compounds at concentrations up to about 1000 times that of thorium. The detection limits depend on both the particular technique and the EDTA complex employed. Anodic-stripping voltammetry gave detection limits of 8 x 10(-8) and 10(-7)M in the absence and presence of uranium respectively.     

Determination of trace amounts of nitrite by single-sweep polarography

A single-sweep polarographic determination of nitrite in 0.2 M sulphuric acid medium containing nickel(II) sulphate and ammonium thiocyanate is described. The ternary complex (NiSCNNO)⁺ which is formed in the solution is strongly adsorbed on the surface of the mercury electrode and an adsorptive polarographic wave at ?0.57 V (vs. SCE) is related to the concentration of nitrite in the range 2.0 × 10^?8-1.0 × 10^?6 M. The detection limit is 8 × 10^?9 M. The relative standard deviation is 1.5% and the regression coefficient is 0.998. Most common anions and cations do not interfere. The mechanism of the electrode process was studied by several electrochemical methods. The polarographic wave is attributed to the reduction of nitrogen monoxide in the adsorbed (NiSCNNO)⁺ complex to hydroxylamine. The procedure was applied to the determination of trace amounts of nitrite in sausage, water and nitrate.     

Determination of trace amounts of phosphate by flow-injection photometry

This paper describes a simple and rapid procedure for determination of traces of phosphate by means of molybdenum blue chemistry. The use of a cost-effective home-made flow cell with a long path length in combination with a light emitting diode (LED) and a photodiode (PD) is demonstrated as a simple absorbance detector for flow-injection analysis. In this method, a sample is injected into the carrier stream through an injection valve and mixed online with mixed reagent (a mixture of molybdate, bismuth, and ascorbic acid in sulfuric acid). The color intensity of the resulting association complex, molybdenum blue, is measured photometrically (_max 875 nm). The proposed method can be used to detect phosphate in the range 0.02–4.0 mg L^–1 and the precision of the proposed procedure is less than 5% at 0.1 mg L^–1 phosphorus as phosphate. The method has been successfully applied to a variety of natural water samples.     

Determination of boron with chromotropic acid by first-derivative synchronous spectrofluorimetry

Summary A method for the determination of traces of boron by first-derivative synchronous spectrofluorimetry is proposed. It is based on the formation of a fluorescent complex with chromotropic acid at pH 6.7. The constant wavelength difference chosen to optimize the determination is =_em–_ex=24 nm. The range of application is between 2.0 and 20.0 /l of boron, the detection limit 0.4 g/l and the relative standard deviation 3.2%. A study was made of the influence of several ions as potential interferents. The method has been satisfactorily applied to the determination of boron in plants, fertilizers and natural waters.     

Determination of warfarin at trace-levels in water by solid-phase spectrofluorimetry

A new selective and sensitive spectrofluorimetric method for the determination of warfarin at trace levels (0.2–50.0 ng/ml) in water is proposed. Warfarin is fixed on Sephadex QAE A-25 gel (at pH = 7.0) and its fluorescence is measured directly in the solid-phase using a 1-mm silica cell at 312/385 nm with a detection/quantification limit of 0.06/0.2 ng/ml, a relative standard deviation of 2.3% and recoveries between 95 and 105%. The method is applied to the determination of warfarin residues in water.     

Determination of nanogram amounts of boron in some antimony compounds

Summary A method has been developed for determining boron in antimony compounds in the range 10^–7–10^–6%. The method comprises the isolation of the boron by distillation as methyl borate and its determination fluorimetrically with dibenzoylmethane. For the three materials analysed, SbCl₃, Sb₂O₃, and SbCl₅, individual procedures of dissolution as well as distillation were developed. The results obtained are reproducible, the mean deviation being about 12% at boron concentrations of 10^–7–10^–6%.

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Zusammenfassung Ein Verfahren zur Bestimmung von 10^–7 bis 10^–6% Bor in Antimon-verbindungen wurde ausgearbeitet. Es umfaßt die Abtrennung des Bors durch Destillation als Methylborat und dessen fluorimetrische Messung mit Dibenzoylmethan. Für SbCl₃, Sb₂O₃ und SbCl₅ wurden jeweils eigene Arbeitsweisen der Auflösung und Destillation angegeben. Die Analysenergebnisse sind reproduzierbar; die mittlere Abweichung beträgt etwa 12% für Borkonzentrationen von 10^–7 bis 10^–6%.

     

碳糊修饰电极吸附伏安法测定食品中的锑

研制了溴邻苯三酚红 (BPR)作修饰剂的碳糊修饰电极 ,并用此电极作工作电极建立了测定痕量锑的吸附伏安法。在选定的实验条件下 ,峰电流与Sb(Ⅲ )浓度在 8.0× 1 0 -9～ 2 .0× 1 0 -7mol L范围内呈线性关系 ,检出限为 2 .0×1 0 -9mol L ,1 0次测定相对标准偏差为 2 .0 % ,不用分离 ,可直接测定食品中痕量Sb(Ⅲ ) ,测定的回收率为 90 %～ 1 0 3%。     

Determination of trace amounts of formaldehyde in acetone

A method to quantify sub-ppm levels of formaldehyde in acetone has been developed and it is reported here. In this method, the different reactivities and stabilities of sulfite with formaldehyde and acetone are used to separate the two carbonyl compounds. Sulfite reacts with formaldehyde to form hydroxymethanesulfonate (HMS), the non-volatile and stable nature of which allows its separation from bulk acetone solvent. The resulting HMS is then converted back to formaldehyde under basic conditions, and formaldehyde is derivatized with 2,4-dinitrophenylhydrazine (DNPH) and quantified in its DNP hydrazone form using high-performance liquid chromatography-UV detection. The method detection limit at the 99% confidence level was 0.051 mg L⁻¹. A batch of samples can be processed within 4 h. The method has been applied to quantify the amount of formaldehyde in an analytical-grade acetone and in a commercial nail polish remover and the level of formaldehyde was found to be 0.175 and 0.184 mg L⁻¹, respectively.     

Determination of trace amounts of manganese in nickel by fourth-derivative spectrophotometry

Fourth-derivative absorption spectra were used to determine trace amounts of manganese in nickel salts. Optimum conditions for the oxidation of microgram amounts of Mn(II) to MnO(-)(4) in the presence of large amounts of nickel were established. Fourth-derivative spectra provided good sensitivity and selectivity for this determination. Attention has been paid to the effect of instrumental parameters on the results obtained. Limitations of the peak-to-trough and zero-crossing measurement techniques have been examined. Manganese (1 x 10(-3)-2 x 10(-5)%) in nickel salts (nitrate, sulphate and chloride) and in nickel powder was determined with good precision and accuracy.