Determination of trace scandium by ion-exchanger phase spectrophotometry withp-nitrochlorophosphonazo

Ion-exchanger phase Spectrophotometry withp-nitrochlorophosphonazo (CPApN) has been developed for the determination of scandium. The linear range is 1–8 g of scandium in 50 ml of solution, using 0.8 g of resin, with an apparent molar absorptivity of 2.76 × 10⁵ 1 mol^–1 cm^–1. Aluminum and rare earth elements in reasonable amounts do not interfere. The method has been applied successfully to the determination of scandium in alloys, with relative standard deviations of 2–4%.     

Determination of uranium(VI) in seawater by ion-exchanger phase absorptiometry with arsenazo III

An ion-exchange phase absorptiometric method with Arsenazo III has been developed for the determination of uranium (VI). A flow cell with 0.1 ml of anion exchange resin was employed to achieve a detection limit for uranium of 0.16 microg/l. in 100 ml of a seawater sample. The sensitivity is about 300 times higher than for corresponding solution spectrophotometry.     

Determination of nitrite in sea-water by ion-exchanger colorimetry

Summary A microdetermination method (at theg/l level for nitrite) has been developed, based on ion-exchanger colorimetry. The nitrite is reacted with sulphanilamide andN-(1-naphthyl)ethylenediamine to form an azo dye which is then sorbed on Dowex 50W-X2. The resin phase absorbance at 550 and 800 nm is measured directly. The relative detection limit is 0.27g/l and the distribution ratio is 2.6×10⁴. The method has been applied to determination of nitrite in 500-ml sea-water samples and compared with a conventional technique.

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Bestimmung von Nitrit in Meerwasser durch Ionenaustausch-Kolorimetrie

Zusammenfassung Eine Mikromethode zur Bestimmung von Mikrogramm Nitrit/Liter mit Hilfe der lonenaustausch-Kolorimetrie wurde ausgearbeitet. Zu diesem Zweck wird Nitrit mit Sulfanilamid und N-(1-Naphthyl)ethylendiamin zu einem Azofarbstoff umgesetzt, der an Dowex 50W-X2 adsorbiert wird. Die Absorbanz der Harzphase wird unmittelbar bei 550 und 800 nm gemessen. Die relative Nachweisgrenze beträgt 0,27g/l, das Verteilungsverhältnis 2,6×10⁴. Das Verfahren wurde zur Bestimmung von Nitrit in 500-ml-Proben Meerwasser verwendet und mit konventionellen Methoden verglichen.

     

Determination of neodymium by ion-exchanger absorptiometry with the f-f electron transition band

Summary Ion-exchanger absorptiometry, based on the direct measurement of light absorption by neodymium in the cation-exchange phase, has been developed for metal determination. In the presence of ethylenediaminetetraacetic acid (EDTA) about 99% of the neodymium in a 200-ml sample solution (pH 2.2 to 2.5) was concentrated in 0.50 g Muromac 50W-X12 cation exchanger within 15 min. EDTA does not interfere with the sorption of neodymium ions on the resin but suppresses spectrophotometric interference by ferric ions and ion-exchange saturation by ferric and thorium cations. The resin-phase attenuations at 740.5 nm and of the resin background at 620 nm were used for measurements with a 5-mm cell. Neodymium in the range 0.1 – 10 mg could be simply and rapidly determined without interference from other rare earths and the proposed method was used to analyse the rare-earth minerals and alloys.

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Bestimmung von Neodym durch Ionenaustauscherharz-Absorptiometrie mit Hilfe der f-f-Elektronenübergangsbande

     

Determination of submicrogram amounts of gallium by ion-exchanger fluorimetry Determination of gallium in natural waters

A method for microdetermination of gallium at ng/ml level has been developed, based on ion-exchanger fluorimetry. The gallium reacts with salicylidene-o-aminophenol to give a highly fluorescent complex, which is fixed on a dextran-type cationic resin. The fluorescence of the resin, packed in a 1-mm silica cell, is measured directly with a solid-surface attachment. The range of concentration of the method is 2.0-10.0 ng/ml, the RSD 1.3% and the detection limit 0.3 ng/ml. The method has been applied to the determination of gallium in natural waters. The gallium content found in tap water was higher than that in raw water. This is related to the use of commercial aluminium salts in the water-treatment plant.     

Determination of beryllium trace contents in mineral waters after preconcentration on a chelating ion-exchanger

Summary A separation-preconcentration procedure for the determination of Be traces in mineral waters is described. The precision and the accuracy of the procedure were checked by the use of artificial as well as of real samples by AAS-ETA and AES-ICP. On the basis of the results and of their statistical evaluation, the proposed procedure allows to obtain reliable results with the necessary limit of determination and can provide important, till now not accessible information on Be-concentration in waters.     

Enhancement of sensitivity of ion-exchanger absorptiometry by using a thick ion-exchanger layer

Enhancement of the sensitivity of ion-exchanger absorptiometry by the use of much thicker ion-exchanger layers than those previously employed has been investigated. Because the background attenuance due to light-scattering from the solid particle layer increases only moderately, whereas the net absorbance of the sorbed sample species increases greatly when the cell length is increased, a cell with at least 10-mm path-length may be effectively used without difficulty in most commercial spectrophotometers, giving at least ten times the sensitivity obtainable with a 1-mm cell. Since the background attenuance depends on the optical geometry, it can be lowered to some extent by using a particular type of spectrophotometer, and by placing a cylindrical mirror between the cell and the light-detector window or by setting the cell as close as possible to the window. The use of such long cells has been found to improve the sensitivity in the chromium-diphenylcarbazide, iron-1,10-phenanthroline, nickel-PAN, cadmium-PAR, bismuth-chloride and uranium-thiocyanate systems. Other methods may be similarly improved.     

Application of ion-exchanger phase photoacoustic spectroscopy to flow analysis of trace amounts of iron in water

Ion-exchanger phase photoacoustic spectroscopy has been applied to the flow analysis of trace amounts of iron in water. The reaction product of iron(II) with 4,7-diphenyl-1,10-phenanthroline-disulphonate, introduced into a carrier solution stream in the flow system, was concentrated on a small amount of QAE-Sephadex gel settled in a fused silica glass tube (1.5 mm i.d.) of a photoacoustic cell. The photoacoustic signal produced by pulsed laser irradiation of the gel beads at 532 nm was detected by a cylindrical piezoelectric transducer which was attached outside the glass tube. When 3.7 ml of a sample solution was introduced into the flow system, the sensitivity of this method was 590 times higher than that of the corresponding solution photoacoustic spectrometry and the detection limit of iron was 0.33 ng/ml. Because the coloured complex was desorbed from the cell with a desorbing agent solution, the present method could afford repeated analyses of natural water samples containing iron at ng/ml levels without any preconcentration procedures.     

固相萃取-气相色谱-质谱法测定利多卡因代谢物单乙基甘氨酰二甲苯胺的血药浓度

建立了固相萃取-气相色谱-质谱(GC-MS)测定利多卡因代谢物单乙基甘氨酰二甲苯胺(MEGX)血药浓度的方法。血清中的MEGX采用固相萃取小柱萃取、GC-MS测定。色谱条件为：HP-5MS毛细管柱(15 m×0.25 mm×0.1 μm),初始柱温100 ℃,保持1 min后以40 ℃/min速率升温至200 ℃,保持0.5 min;进样口温度250 ℃;分流进样,分流比1∶1,进样量2 μL;载气为氦气,流量为1.0 mL/min。质谱条件为:离子源温度230 ℃,电子轰击电离,电子能量70 eV,选择离子检测（m/z 58(MEGX)、 m/z 86(普鲁卡因,内标)）。结果表明,MEGX在血清中的浓度在1.562～25 ng/mL范围内的线性关系良好,相关系数0.9981,最低检测限为0.5 ng/mL,不同浓度MEGX的萃取回收率在80.1%～85.7%之间。实验证明该方法快速、准确,选择性好,灵敏度高,适合用于血清中微量MEGX的测定。     

Application of the opal-glass method for ion-exchanger spectrophotometry

A simple and precise method for the measurement of the net absorbance of colored species sorbed on ion-exchange resins is reported. Identical opal-glass plates are inserted on the transmission sides of both the sample-cell and blank-cell compartments of the spectrophotometer. Absorbances of sample-resin layers are measured against a blank-resin layer as reference. Scattering effects caused by resin particles are almost eliminated by using opal glass. For the determination of chromium(VI) with diphenylcarbazide reproducible calibration lines were obtained without tedious compensation methods.     

Microdetermination of vanadium by ion-exchanger colorimetry

A microdetermination method for vanadium by ion-exchanger colorimetry has been developed. Vanadium is sorbed on the anion-exchanger Dowex 1-X8 as vanadium-benzohydroxamic acid complex in 3 M HCl medium. The resin-phase absorbance at 516 and 800 nm is measured directly. The detection limit is 0.28 μg/liter and the distribution ratio is 340. It is possible to enhance the sensitivity by increasing the sample volume.     

去氢甲睾的血药浓度检测

用气相色谱(GC)的内标定量法(ISTD)对拟作为饲料添加剂的去氢甲睾(DHMT),于9名志愿者口服50 mg后,设定时间点抽血,测定血药浓度.实验结果的以药后时间(h)为序1,2,3,6,9,11,14,24,48,72,浓度为(μg/mL)0.25±0.05,4.2±0.19,7.8±1.05,11.5±1.09,15.8±2.00,10.5±0.97,10.7±0.92,9.3±1.36,4.4±0.18,0.44±0.07.数据表明达峰时间为9h,峰值为15.8±2.00(μg/mL),显示DHMT在血中吸收及消除较为缓慢,如果连续用药,必须考虑累积效应.     

Selectivity of voltammetric determination at an ion-exchanger modified electrode

An expression of the selectivity value for the voltammetric determination of an ionic analyte in the presence of interfering component(s) at an electrode chemically modified with an ion-exchanger has been developed and applied to the analysis of a model metal-ion mixture. Using distribution coefficient values, the predicted selectivity value was calculated and compared with that obtained experimentally. The approach allows a choice of the ion-exchange resin and experimental conditions for a given analytical task.     

Determination of N-nitrosomethylaniline and methylaniline in the gas phase

A method is described for selective sampling and determination of gaseous N-nitrosomethylaniline (NMA) and methylaniline (MA) in air without artifacts. Therefore a denuder system is developed to distinguish between the amine and the nitroso compound during sampling. A spatial separation of the gas phase of these compounds is realized. The detection is performed after gas Chromatographic separation with a thermal energy analyzer (TEA) for the nitrosamine and with flame ionization detector (FID) for the amine and nitrosamine. Besides the sampling technique, the extraction of the samples and detection principles are described. To prove that the formation of artifacts does not appear, the influence of humidity and nitrogen oxides was investigated.Dedicated to Professor Dr. H. Malissa on the occasion of his 75th birthday     

Interpretation of the selectivity and detection limit of liquid ion-exchanger electrodes

An equation has been derived which describes the e.m.f. of a liquid ion-exchanger membrane electrode in conditions of low concentration levels of the primary and interfering ions. The equation is based on the assumption that if the external solution contains no excess of ions which may exchange with the organic phase, then the concentration of the exchanger at the interface decreases, and this is responsible for formation of a diffusion layer inside the membrane. Therefore the potential response depends on the initial concentration of the ion-exchanger in the membrane phase, on the thicknesses of the diffusion layer on both sides of the interface, and on the diffusion coefficients of the species in both phases. This equation explains the non-Nernstian behaviour of the electrode in the presence of interferents, as well as the variation of the conditional selectivity coefficients. The parameters mentioned also influence the detection limit of an electrode. The electrode behaviour has been tested in unstirred solutions and in solutions stirred at different rates. Through its influence on the diffusion layer thickness, the stirring also influences the electrode potential and the characteristics of the electrode.     

Interaction of dispersed phase with concentration polarization

The effect of a dispersed phase in reducing the concentration polarization in a membrane tube has been studied. The presence of a dispersed phase seems to have an effect in controlling the size of eddy formation and the rate of energy dissipation in the fluid medium. The role of eddy length and the energy dissipation rate on the mass transfer coefficient is discussed. Theoretical results obtained for the mass transfer coefficient and for the concentration polarization in the case of gelatin ultrafiltration are compared with the existing experimental results. The theoretical predictions seem to be in good agreement with the experimentally observed results.     

Selective ion-exchanger behaviour of neutral carrier ion-selective electrode membranes

Radiotracer experiments confirm that neutral carrier ion-selective electrodes made from plasticized PVC are low-capacity selective ion-exchangers. The ion-exchange selectivity is closely correlated to potentiometric selectivity.