A toxic reagent-free method for normal-phase matrix solid-phase dispersion extraction and reversed-phase liquid chromatographic determination of aldrin,dieldrin, and DDTs in animal fats

A method for the determination of aldrin, dieldrin, DDT, DDE, and DDD contamination in animal fats (beef tallow, lard, and chicken fat) without using toxic reagents is developed, that uses high-performance liquid chromatography after the sample has been prepared by matrix solid-phase dispersion (MSPD) with acidic alumina oxide. A reversed-phase C₁-silica column with a mobile phase of 50% (v/v) ethanol solution (in water) and a photo-diode array detector were used for the determination. Average recoveries of the target compounds (0.2–5.0 g g^–1) ranged from 84–98%, with coefficients of variation of <5%. The limits of quantitation were 0.16 g g^–1 for AD, 0.10 g g^–1 for DD, 0.06 g g^–1 for DDT, 0.07 g g^–1 for DDE, and 0.05 g g^–1 for DDD. No toxic reagents were used at all.     

Development and Validation of an HPTLC–Densitometric Method for Determination of ACE Inhibitors

A high-performance thin layer chromatographic method coupled with densitometric analysis has been developed for measurement of benazepril and cilazapril, both pure and in their commercial dosage forms. The active substances were extracted from tablets with methanol (mean recovery 102%) and chromatographed on silica gel 60 F₂₅₄ HPTLC plates in horizontal chambers with ethyl acetate–acetone–acetic acid–water, 8:2:0.5:0.5 (v/v), as mobile phase. Chromatographic separation of these ACE inhibitors was followed by UV densitometric quantitation at 215 nm. Calibration plots were constructed in the range 0.4 to 2.0 g L^–1 for benazepril (2.0–10.0 g spot^–1) and from 0.5 to 1.5 g L^–1 for cilazapril (4.0–12.0 g spot^–1) with good correlation coefficients (r 0.990). The method was used to determine benazepril and cilazapril in pharmaceutical preparations with satisfactory precision (1.4% < RSD < 5.6%) and accuracy (1.7 < RE < 5.1).     

Die Bestimmung von 800 bis 30μg Blei(II) durch potentiometrische Titration mit Molybdat

Zusammenfassung Die Bestimmung von 800 bis 30g Pb(II) durch potentiometrische Titration mit Molybdat unter Verwendung einer bleispezifischen Elektrode wurde untersucht. Unter geeigneten Bedingungen sind mit 4·10^–3 M Molybdat 800 bis 300g Pb(II) in wäßriger Lösung mit einer Genauigkeit von ±0,57% bzw. 0,45% und einer Reproduzierbarkeit von ±0,43% bzw. ±0,30% (Standardabweichung=0,25% bzw. 0,17%) je nach Titrationsart automatisch bzw. manuell bestimmbar.Zur Bestimmung von Pb(II)-Mengen <300g ist eine 2·10^–3 M Molybdatlösung zu verwenden. 300 bis 100g Pb(II) sind in wäßriger Lösung mit zufriedenstellenden Resultaten bestimmbar, jedoch verbessert eine Titration in 40% igem Ethanol nicht nur die Genauigkeit in diesem Bereich, sondern erlaubt auch noch 30g Pb(II) mit einer Genauigkeit von ±1% und einer Reproduzierbarkeit von ±2% (Standardabweichung aus 20 Titrationen von 100g Pb(II)= 0,60%) zu bestimmen.Die Titration von 300–800g Pb(II) in wäßriger Lösung und von 30–300g Pb(II) in 40% igem Ethanol läßt sich auch in 0,1M NaNO_3– 0,1M NaClO_4– Lösung durchführen und ermöglicht somit auch zuverlässige Bleibestimmungen in organischen Verbindungen nach Mineralisierung mit HNO₃–HClO₄–H₂O₂.

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The determination of 800 to 30 g lead(II) by potentiometric titration with molybdate

Summary The determination of 800 to 30g Pb(II) by potentiometric titration with molybdate by using a lead(II)-selective electrode was investigated. Under suitable conditions, 800 to 300g Pb(II) in aqueous solution by automatic or manual titration with 4·10^–3 M molybdate can be determined with an accuracy of ±0.57% and ±0.45% and a precision of ±0.43% and 0.30% (standard deviation=0.25% and 0.17%, resp.).For determining amounts of Pb(II) below 300g, a 2·10^–3 M molybdate solution has to be used. Although 300 to 100g Pb(II) are determinable again in water with satisfactory results, the titration in 40% ethanol is however more reliable: in this medium, amounts of 300 to 30g Pb(II) can be determined with an accuracy of ±1% and a precision of ±2% (standard deviation from 20 titrations of 100g Pb(II)=0.60%).The titration of 300–800g Pb(II) in water and of 30–300g Pb(II) in 40% ethanol is also possible in 0.1M NaNO_3– and 0.1M NaClO_1– medium and can be used in the lead determination in organic compounds after mineralization with HNO₃-HClO₄-H₂O₂.

     

Fällungsanalyse im Mikrogrammbereich: Eine neue Methode

Zusammenfassung Eine neue Methode zur Durchführung gravimetrischer Bestimmungen im Mikrogrammbereich wurde beschrieben; diese beruht im wesentlichen darauf, daß der Niederschlag nicht mehr zusammen mit dem Filter, sondern nach Überführen mit einem geeigneten Lösungsmittel in einem separaten Wägegefäß gewogen wird.Die dazu nötigen Geräte und deren Herstellung wurden beschrieben. Nach dieser Methode wurden folgende Bestimmungen mit zufriedenstellender Richtigkeit durchgeführt: 2,5–25g Al, 5–50g Cu und 5–50g Zn mit Oxin, 2,5–25g Fe(III) und 2,5–25g Ti(IV) mit N-Benzoyl-phenylhydroxylamin, 5–50g Ni und 5–50g Cu mit Salicylaldoxim, 2,5–50g Co(II) und 2,5–50g Fe(III) mit -Nitroso--naphthol sowie 5–50g Chlorid als Silberchlorid.

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Precipitation analysis in the microgram-scale: A new method

Summary A new method for gravimetric determinations in the microgram-scale is described. This method is based on the fact that the precipitate is not weighed together with the filter but is transferred to a separate weighingvessel using a suitable solvent. The necessary simple devices and their use are described. The following determinations were carried out with satisfying accuracy: 2,5–25g Al, 5–50g Cu and 5–50g Zn with Oxine, 2,5–25g Fe and 2,5–25g Ti withN-benzoylphenylhydroxylamine, 5–50g Ni and 5–50g Cu with salicylaldoxime, 2,52–50g Co and 2,5–50g Fe with -nitroso--naphthol and 5–50g chloride as silver chloride.

     

Extractive spectrophotometric determination of dioxouranium(VI) with the sodium salt of hexamethyleneiminecarbodithioate

The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml^–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×10³ l mol^–1 cm^–1 with Sandell's sensitivity of 0.04 g cm^–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955.     

The application of XRF analysis in the determination of113mCd

The overall recovery of the separated^113mCd with added Cd carrier from 50 samples of natural water was determined by a secondarysource tube excited energy dispersive X-ray fluorescence spectrometer measuring the amount of cadmium in the final CdS+CuS coprecipitate on a 25 mm diameter Millipore filter. The method enables to determine 1–20 g Cd in 100 sec. with a limit of detection of 0.8 g.Presented at the 7th Czechoslovak Spectroscopic Conference and VIIIth CANAS, eské Budjovice, June 18–22, 1984.     

Simultaneous determination of neodymium and erbium in rare earth mixture with 5,7-dibromo-8-hydroxyquinoline and TX-100 by third-derivative spectrophotometry

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 5,7-dibromo-8-hydroxyquinoline in the presence of octylphenol poly(ethyleneglycol)ether have been studied by normal and third-derivative spectrophotometry. The proposed method is free of interference of other rare earths. The calibration graphs were linear up to 18 g/ml of neodymium and 21 g/ml of erbium (in the final solution). The derivative molar absorptivities are 395 l.mol^–1.cm^–1 for neodymium and 3421.mol^–1.cm^–1 for erbium. The corresponding values of Sandell's sensitivity were 0.36 and 0.49 g.cm^–1, respectively. The relative standard deviations evaluated from ten independent determinations of 2.5 g/ml of neodymium and erbium are 1.5 and 3.8% for neodymium and 1.8 and 4.1% for erbium in absence and presence of 70 g of lanthanum, respectively. The detection limits (signal to noise ratio=2) are 0.23 g/ml for neodymium and 0.30 g/ml for erbium. The method has been used for the determination of neodymium and erbium in mixed rare earths with satisfactory results.     

Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins

Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL^–1 for bovine serum albumin (BSA), 0.01–6.0 g mL^–1 for human serum albumin (HSA), 0.05–8.0 g mL^–1 for -globulin (-G), and 0.04–4.0 g mL^–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL^–1 BSA, 1.90% for 1.0 g mL^–1 HSA, 1.65% for 1.0 g mL^–1 -G, and 2.32% for 1.0 g mL^–1 ovalbumin.     

Spectrophotometric determination of cyanide ions through ligand exchange reaction in solution

Summary A simple spectrophotometric method for the determination of trace amounts of cyanide ions in aqueous medium, using a heterocyclic azo dye complexed with mercury(II) for the first time, is described. The visual comparative method has been used in which a stronger complexing anion displaces a coloured reagent from the metal-ligand complex. Ammonium (2-amino-3-hydroxy-pyridyl-4 azo)benzene-4-arsonate (AHP-4A) complexed with mercury(II) has been used for the determination of 0.13–1.46g/ml of cyanide ions with fair accuracy. The anion has also been determined, when cyanide ion reacts with mercury(II)-(AHP-4A) complex, probably forming a bridged complex. The increase in absorbance is proportional to the cyanide ion concentration in the range of 0.04–0.37g/ml, but this method is not very precise. The effect of foreign ions has also been studied. The sensitivities of other mercury(II) complexes in the determination of cyanide ions have been compared.

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Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Spuren Cyanid in wäßrigem Milieu mit Hilfe eines mit Hg(II) komplexierten heterocyklischen Azofarbstoffes wurde beschrieben. Hierbei verdrängt ein stärker komplexierendes Anion das Farbreagens aus dem Metallkomplex. Ammonium(2-amino-3-hydroxypyridyl-4-azo)benzol-4-arsenat (AHP-4A) in komplexer Verbindung mit Hg(II) wurde für die genaue Bestimmung von 0,13–1,46g CN^–/ml verwendet. Das Anion wurde auch nach der Reaktion von Cyanid mit Hg(II)-(AHP-4A)-Komplex (wahrscheinlich zu einer Brückenverbindung) bestimmt. Der Anstieg der Extinktion ist der Cyanidkonzentration im Gebiet 0,04–0,37g/ml proportional, aber dieses Verfahren ist nicht sehr genau. Der Einfluß von Fremdionen wurde untersucht. Die Empfindlichkeit anderer Hg(II)-Komplexe wurde zum Vergleich herangezogen.

     

Assessment of the essential element and heavy metal content of edible fish muscle

The aim of this work was to determine the concentrations of some essential and toxic elements in the muscle of ten species of commercial fish consumed in Portugal. We combined two different techniques for determination of the elements—energy-dispersive X-ray fluorescence (EDXRF) was used to quantify K, Ca, Fe, Zn, Se, Rb, and Sr and flame atomic-absorption spectrometry for analysis of Cr, Ni, Cu, Cd, Hg, and Pb. The latter technique was used because of its higher sensitivity, because these elements were not detected by EDXRF. The results obtained show a similar pattern for the trace elements. K and Ca are present at the highest concentrations in all the samples studied, from 0.6–1.3% and from 0.04–0.08%, respectively, followed by Zn, Fe, Sr, Se, and Rb. Sr is present at higher concentrations than Rb in all the species studied except meagre. Concentrations of the elements in octopus do not follow this pattern—Fe is present at a higher concentration than Zn. Low concentrations of Cr (0.66–1.5 g g^–1), Ni (0.11–0.24 g g^–1), Cd (0.01–0.08 g g^–1), Hg (0.49–2.74 g g^–1), and Pb (0.02–0.06 g g^–1) were observed in all the samples analysed. The concentration of Hg was highest in Helicolenus dactylopterus—5.4 g g^–1 in one sample.     

TLC technique for the detection and determination of gamma- BHC in biological material

Summary Five isomers present in technical benzene hexachloride were successfully separated by TLC on silica-gel G impregnated with silver nitrate solution. The -isomer was identified by running a control sample of -BHC. Measurement of the spot area was found suitable for the estimation of 5–20g of-BHC, and was applied to analysis of autopsy tissues. The limit of identification is 0.1g.

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Zusammenfassung Auf mit Silbernitratlösung imprägniertem Kieselgel G konnten dünn-schichtchromatographisch fünf Isomere aus technischem Hexachlorbenzol erfolgreich getrennt werden. Das-Isomere wurde mit Hilfe einer Vergleichsprobe identifiziert. Die Planimetrie der Flecken eignet sich zur Schätzung von 5–20 g-Hexachlorbenzol. Die Methode wurde zur Untersuchung von Autopsieproben angewendet. Die Nachweisgrenze beträgt 0,1g.

     

Bestimmung flüchtiger organischer Verbindungen in atmosphärischen Aerosolproben durch thermische Desorption und FID-Detektion

Zusammenfassung Staub- und Aerosolproben werden im Stickstoffstrom im Temperaturbereich 25–420° C einer temperaturprogrammierten thermischen Desorption unterworfen. Die flüchtigen organischen Komponenten werden mittels FID summarisch als volatile organic carbon (VOC) bestimmt. Die Eichung des Analysators erfolgt durch ein Aliphaten-Standardgemisch. Bei Probemengen von 50–100g Aerosol ist eine Bestimmung des VOC-Gehaltes mit einer Reproduzierbarkeit vons=3,5–7 rel.% möglich. Die Nachweisgrenze der Methode liegt für Aerosolproben bei 0,3g VOC.

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Determination of volatile organic components in atmospheric aerosol samples by thermal desorption and FID-detection

Summary Atmospheric dust and aerosol samples are treated in a nitrogen carrier gas stream at the temperature range 25–420° C by temperature programmed desorption. The volatile organic components are detected by FID. Calibration of the analyzer is carried out with a standard mixture of aliphatic hydrocarbons. The result is expressed as volatile organic carbon (VOC). The reproducibility of the method for aerosol samples (sample weight 50–100g) is in the range of 3,5–7% r. s. d. The detection limit of the method is 0,3g VOC.

     

Empfindliche Silberbestimmung in Blei

Zusammenfassung Eine empfindliche spektrophotometrische Methode zur Bestimmung von Silber wurde beschrieben (Molarextinktion =1,8×10⁶). Das Lambert-Beersche Gesetz wird zwischen 43×10^–4 und 38,8×10^–3 g/ml gut befolgt. Salicylsäure wird in Gegenwart von Ammoniumpersulfat, 2,2'-Dipyridyl und Silber als Katalysator oxydiert, wobei sich ein gelbbrauner Farbstoff bildet, der bei 410 nm ein Maximum der Absorption zeigt.Die Methode eignet sich zur Bestimmung von Silberspuren in Blei, da sich dieses in großen Mengen mit ÄDTA maskieren läßt.

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A sensitive determination of silver in lead

Summary A sensitive method of spectrophotometric determination of silver is described (molar extinction =1.8×10⁶). Lambert-Beer's Law is valid between 43×10^–4 g/ml and 38.8×10^–3 g/ml. Silver as catalyst oxidizes salicylic acid in the presence of ammonium persulfate and 2,2'-dipyridyl as activator producing a yellow-brown color that shows a maximum of absorption at 410 nm.This method seems to be adequate for the determination of traces of silver in lead because lead can be masked in great quantities with EDTA.

     

The automated assay of SH-groups in the range below 50μmole/l

Summary The manual method of Stockhausen, using 6,6'-dithiodinicotinic acid as a specific reagent for SH-groups, has been modified to give an automated kinetic assay. Readings are performed with the LKB Reaction Rate Analyzer 8600 in a volume of 1–2 ml at a rate of 60 samples per hour. For reduced glutathione (as a standard), concentrations between 3 and 60mole/l can be measured with a mean relative standard deviation of 4.2%; the limit of detection is 1.5mole/l. Interferences are discussed.

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Die automatische Bestimmung von SH-Gruppen in der Gröenordnung unter 50Mol/l

Zusammenfassung Die manuelle Methode von Stockhausen zur Bestimmung von SH-Gruppen mit 6,6'-Dithiodinicotinsäure wurde als Grundlage für ein automatischkinetisches Bestimmungsverfahren verwendet. Die Messung in einem Volumen von 1–2 ml erfolgt im LKB Reaction Rate Analyzer 8600 und mit einer Durchsatzgeschwindigkeit von 60 Proben je Stunde. Bei Verwendung von reduziertem Glutathion als Standard liegt der Meßbereich zwischen 3 und 60Mol/l mit einer durchschnittlichen relativen Standardabweichung von 4,2%; die Erfassungsgrenze liegt bei 1,5Mol/l. Die Störung der Methode durch verschiedene Verbindungen wird diskutiert.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Accurate reflectance measurements in the infrared spectral range using an integrating sphere

An integrating sphere is used together with a Fourier transform spectrometer for directional-hemispherical reflectance measurements in the spectral range from 1m to 15m. Comparisons with PTB's fundamental sphere reflectometer around 1m show that the uncertainty of the infrared measurements is ±0.01.     

Determination of Triphenyltin and Its Metabolite Diphenyltin in Culture Medium by High-Performance Liquid Chromatography with UV detection

A method for the determination of triphenyltin and diphenyltin was developed by reversed-phase high-performance liquid chromatography with UV detection. Triphenyltin and diphenyltin were separated using a reversed-phase Symmetry C₁₈ column (150 × 3.9 mm, 5 m) with tetrahydrofuran-water-acetonitrile-glacial acetic acid (13:25:5:7, v/v) containing 0.05% triethylamine and 1.0% sodium acetate as mobile phase at 0.50 mL min^–1 and detection at 257 nm. The calibration curves were linear from 0.26 mol L^–1 to 1100 mol L^–1 for triphenyltin with a correlation coefficient of 0.9999 (n=12) and from 0.60 mol L^–1 to 1200 mol L^–1 for diphenyltin with a correlation coefficient of 0.9991 (n=12), respectively. The detection limits of triphenyltin and diphenyltin were 0.2 mol L^–1 and 0.4 mol L^–1, respectively. The method was successfully applied to the determination of triphenyltin and its metabolite diphenyltin in culture medium. The recoveries of triphenyltin and diphenyltin were in the ranges of 97.7% to 103.3% and 85.5% to 91.6%, respectively.     

Protonation of Os3(μ-H)(CO)9(μ3-σ,η2-C≡C-R) clusters (R=CMe2OH,C(Me)=CH2)

Protonation of triosmium clusters Os₃(-H)(CO)₉(₃-,²-CC-R) (R=CMe₂OH, C(Me)=CH₂) affords a cationic complex containing a six-electron propargyl ligand which has been detected for the first time.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1144–1145, June, 1993.     

Chemical properties of bile acids: III. Bile acid structure and solubility in water

The temperature dependence of the solubilities in water at pH 3.00 of a representative series of ten cholanoic acids (bile acids) were measured over the temperature range 10 to 50°C. The solubilities ranged from 5×10^–8M for 3-hydroxy-5-cholanoic acid (lithocholic acid) to 2×10^–3M for 3-7-12-trihydroxy-5-cholanoic acid (ursocholic acid). The solubilities increased with temperature and were found to be dependent on the number, position, and orientation of the hydroxyl groups. The hydroxyl groups affect solubility both by forming hydrogen bonds with the solvent and by reducing the hydrophobic area of the steroid nucleus. The enthalpic H⁰ and entropic S⁰ contributions to ⁰ associated with the dissolution process were obtained from the temperature dependence of the solubilities. A qualitative interpretation of the thermodynamic parameters in relation to bile acid structure is also presented.     

Thorium in man and environment uptake and clearance

The intake and tissue distribution of thorium (^{2 3 2}Th) was studied in an urban (Bombay) population in India. From the analysis of 16 whole diet samples, the average daily intake through food was found to be 2 g (range 0.8–4.3 g·d^–1). The estimated intake through drinking water and inhalation comes out to be 0.03 and 0.02 g per day. From the analysis of human autopsy tissue samples it is observed that the concentration ranges in lungs and bone are 1.5–16 g/kg and 0.2–9.0 g/kg fresh weight respectively. The average urinary concentration is 12 ng/1 (range 7–22 ng/l for 10 samples). Among the different body tissues, pulmonary lymph nodes were found to contain the highest concentration (geometric mean 53.4 g/kg, range 31.4–85.5 g/kg for 6 samples). Analysis of the samples was done by the neutron activation technique. 311.8 keV gamma photons of^{2 3 3}Pa which is the activation product of^{2 3 2}Th, were counted after chemical separation. A 54 cm³ intrinsic Ge detector coupled to 1024-channel analyser was used. Using the average lung content and the daily average intake values of thorium through inhalation, the clearance half-time from lung was estimated.