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 sulphur in selenium

Determination of trace amounts of sulphur as Methylene Blue after reduction of sulphate to sulphide by hydriodic and hypophosphorous acids in acetic acid solution is applied to the determination of trace amounts of sulphur in selenium after removal of the selenium by evaporation with hydrobromic acid. Samples of 100 mg or less of selenium are chosen if the sulphur content is greater than 5-10 ppm; the time required for the separation is about 1.5 hr; 100 ppm of sulphur has been determined with a coeffident of variation of 5.2%. If the sulphur content is less than 5 ppm, 1-g samples must be taken and the time required is then about 3 hr; 0.4 ppm of sulphur has been determined with a standard deviation of 0.13 ppm. The accuracy of the method seems to be well within the random error.     

Determination of trace amounts of Germanium in CdS

Summary By an indirect method germanium can be determined by application of flameless atomic-absorption spectrometry to germanomolybdic acid. With this procedure some difficulties inherent in the AAS determination of Ge can be avoided and the detection limits are improved. Furthermore there is an amplification reaction because of the 121 MoGe ratio in the germanomolybdic acid. Determination of Ge at the ppm level in CdS is possible and results for this are reported.

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Zusammenfassung Germanium kann auf indirektem Wege durch Anwendung der flammenlosen Atomabsorptions-Spektrometrie auf Germanomolybdänsäure bestimmt werden. Damit können einige Schwierigkeiten vermieden werden, die der Germaniumbestimmung mit Hilfe der AAS anhaften, außerdem werden so die Nachweisgrenzen verbessert. Darüber hinaus handelt es sich hier infolge des Verhältnisses MoGe=121 in der Germanomolybdänsäure um eine Verstärkungsreaktion. Die Bestimmung von ppm-Mengen Germanium in CdS ist auf diesem Wege möglich. Über Ergebnisse wurde berichtet.

     

Determination of toxic trace residues in penicillins

Summary The Chromatographic determination of residues ofN,N-dime-thylaniline and formaldehyde in penicillins is described.N,N-Di-methylaniline can be extracted from alkaline solutions inton-hep-tane in one step and determined by HPLC (ultraviolet detector) or by gas chromatography (FID or N-P FID) without further treatment. HPLC and GC with N-P FID proved to be equivalent. The detection limit is in the subg/g range, and the time for the chromatographic separation is only a few min. Formaldehyde can be detected by chromatography only as a derivative at trace levels. Formaldoxime, produced by reaction with hydroxylammonium chloride is determined by GC (N-P FID) at the/g level.

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Bestimmung toxischer Rückstände in Penicillinen

Zusammenfassung Die chromatographische Bestimmung von Rückständen anN,N-Dime-thylanilin und Formaldehyd in Penicillinen wurde beschrieben. Ersteres kann aus alkalischen Lösungen mitn-Heptan in einem Schritt extrahiert und ohne weitere Probenbehandlung mittels HPLC (UV-Detektor) als auch GC (FID oder N-P FID) bestimmt werden. HPLC und GC mit N-P FID erwiesen sich als gleichwertig. Die Nachweisgrenze liegt im sub-ppm-Be-reich, die chromatographische Bestimmung nimmt nur wenige Minuten in Anspruch. Formaldehyd ist im Spurenbereich chromatographisch nur in Kombination mit einer Derivatisierung nachweisbar. Das mit Hydroxyl-ammoniumchlorid gebildete Formaldoxim kann gaschromatographisch mit einem N-P FID im ppm-Bereich bestimmt werden.

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

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 mercury in rock samples

Summary A precise and accurate method is described for the measurement of ng quantities of mercury in inorganic samples such as rock, mineral ores and soil. The mercury is distilled from pulverized samples and collected on a silver gauze absorber. The mercury is then rapidly desorbed from the silver element using heat, and it is carried by gas entrainment into the measuring cell of an ultraviolet absorption analyzer. Readout of the mercury content can be made by measurement of peak heights on a strip chart recording, but more elegantly and accurately by the digital printout from a GC integrator. Calibration of the instrumental assembly, by injection of measured quantities of saturated mercury vapor, is simple, rapid and accurate.

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Zusammenfassung Eine genaue Methode zur Bestimmung von Nanogrammengen Quecksilber in anorganischem Material wie Gesteinen, Erzen und Bodenproben wurde beschrieben. Aus den gepulverten Proben wird das Hg abdestilliert und auf einem Silberdrahtnetz gesammelt. Dann wird es rasch durch Erwärmen desorbiert und mit einem Gasstrom in die Meßzelle eines UV-Ab-sorptionsgerätes geleitet. Die Ermittlung des Quecksilbergehaltes kann aus der Peakhöhe eines Schreibers, besser mit dem Digitalzähler eines GC-Integrators erfolgen. Die Eichung des Gerätes durch Einleiten gemessener Mengen von gesättigtem Quecksilberdampf ist einfach rasch und genau.

     

Determination of trace amounts of calcium in caustic soda

Summary A procedure is described for the determination of as little as 2 ppm of calcium in 50% commercial solutions of caustic soda. It is based on a preliminary separation and concentration of calcium from a large volume of neutralized sample on Dowex A-1 chelating resin, followed by elution with dilute hydrochloric acid, and titration at P_H 12.2 with standard EDTA solution to the calcein/thymolphthalein mixed indicator visual endpoint. Magnesium, iron, copper, manganese, barium, nickel, mercury, and aluminium do not interfere when triethanolamine is used as a masking agent.

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Zusammenfassung Es wird eine Methode für die Bestimmung von mindestens 2 ppm Calcium in 50% igen, käuflichen Ätznatronlösungen beschrieben. Die Methode beruht auf einer Vortrennung und Anreicherung von Calcium aus einem großen Volumen der neutralisierten Probe mit Dowex A-1 Chelating Resin, anschließender Elution mit verdünnter Salzsäure und Titration mit ÄDTA-Lösung bei p_H 12.2 zum visuellen Endpunkt des Mischindicators von Calcein und Thymolphthalein. Magnesium, Eisen, Kupfer, Mangan, Barium, Nickel, Quecksilber und Aluminium stören die Bestimmung nicht, wenn Triäthanolamin als Maskierungsmittel verwendet wird.

     

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 trace amounts of polycyclic aromatic hydrocarbons in soil

A method for monitoring the contamination of soil with polycyclic aromatic hydrocarbons (PAHs) is introduced. Drying at elevated temperature is omitted to avoid losses of the more volatile constituents (primarily naphthalene). The soil sample, including its natural water content, is extracted with 2-methoxyethanol and cleaned up using a disposable C₈ cartridge and the PAHs are eluted with pentane, concentrated and measured by capillary gas chromatography with flame ionization detection. Determination limits between 15 and 35μg kg^?1 are obtained and the recovery is 80–90% measured at the 125 μg kg^?1 spike level, except for naphthalene (66%). Special attention is given to the design of the spiking technique, which simulates natural incorporation as far as possible, takes account of evaporation losses and therefore allows “real” recovery rates to be determined.     

Determination of trace amounts of polycylic aromatic hydrocarbons in soil

Summary A method is described for the determination of polycyclic aromatic hydrocarbons in natural soil. The soil is dried and extracted by ultrasonic agitation with dichloromethane. The extract is purified by liquid-liquid partitioning with dimethylformamide, water and hexane followed by high performance liquid chromatography on a silica column. Quantitative analysis of the purified extract is carried out by combined gas chromatography/mass spectrometry. The method yields reliable results at the ng/g level.

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Bestimmung von Spuren polycyclischer aromatischer Kohlenwasserstoffe in Boden

     

Determination of trace amounts of scandium by atomic absorption spectroscopy

Optimum instrumental conditions were investigated for the determination of trace quantities of scandium by atomic-absorption spectroscopy. Enhancement effects by organic solvents and by complex extractions were also studied. (46)Sc was used to establish the optimum extraction conditions. A sensitivity of 0.06 ppm of Sc was observed when using extraction into oxine-butanol and atomic absorption was measured with an acetylene-nitrous oxide flame.     

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 iron by catalytic-adsorptive stripping voltammetry

A highly sensitive and selective voltammetric procedure is described for the determination of trace amounts of iron. The procedure is based on the adsorptive collection of an iron-thiocyanate-nitric oxide complex on a hanging mercury drop electrode. The adsorbed complex catalyzes the reduction of nitrite in solution, which gives a detection limit of 40 ppt iron (30 s accumulation). The stripping current increases linearly with iron concentration up to 80 ppb. The relative standard deviations are 4.2% and 1.6% at 0.5 ppb and 40 ppb respectively. Most of the common ions, except cobalt, do not interfere with the determination of iron. The procedure is applied to determine iron in biological samples, natural waters and analytical-grade chemicals.     

阻抑动力学分光光度法测定痕量碘

研究了在稀H3PO4介质中,痕量碘离子对NO-2催化溴酸钾氧化吖啶橙的阻抑作用,建立了测定痕量碘离子的阻抑动力学光度分析的新方法。测定碘离子的线性范围为0～0.40μg/mL,检出限为7.3×10-9g/mL。已用于食品中的微量碘的测定。     

Determination of trace amounts of cobalt by solvent extraction--second derivative spectrophotometry

A sensitive derivative spectrophotometric method is described for the determination of microamounts of cobalt based on the integration of liquid-liquid separation and reaction, in dichloroethane, of the analyte with 3-(4-phenyl-2-pyridinyl)-5-phenyl-1,2,4-triazine (PPT) and 2,4,6-trinitro-phenol (picric acid). Cobalt was thus determined in the range 7.2-500 ng/ml. The method has a high selectivity with a detection limit of 2.2 ng/ml. The relative standard deviations were 3.2 and 1.5% for 20 and 100 ng/ml cobalt, respectively. The proposed method was applied to the determination of the analyte in vitamins.     

Determination of trace amounts of nickel by differential pulse adsorptive cathodic stripping voltammetry using calconcarboxylic acid as a chelating agent

A method for the determination of nickel(II) by stripping voltammetry is described. The method is based on the adsorptive accumulation of nickel(II) calconcarboxylic acid complex onto a hanging mercury drop electrode (HMDE), followed by the reduction of the adsorbed complex using differential pulse voltammetry. The optimum operating conditions and parameters were found to be 0.05 M NH₃/NH₄Cl buffer (pH = 9.5) as the supporting electrolyte, a ligand concentration of 1 × 10^?6 M, accumulation potential of ?0.5 V (vs. Ag/AgCl) and accumulation time of 60 s. At the optimized conditions, the peak current is proportional to the concentration of nickel in the range of 1.7 × 10^?9 to 4.7 × 10^?7 M (0.1–28 ng ml^?1) with a detection limit of 0.05 ng ml^?1. The relative standard deviation (n = 10) at nickel concentrations of 2, 10 and 15 ng ml^?1 varies in the range 0.76 to 2.1%. Possible interferences by metal ions, which are of great significance in real matrices, have been studied. The method was successfully applied to the determination of nickel content in a chocolate sample.     

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.     

Determination of trace amounts of mercury using hierarchically nanostructured europium oxide

This work reports a highly sensitive procedure for the determination of trace amounts of mercury, based on fluorescence quenching of thenoyltrifluoroacetone (TTA) capped hierarchically nanostructured europium oxide (cHN-Eu₂O₃). The HN-Eu₂O₃ consisted of nanometer-thick Eu₂O₃ sheets self-organized into nano- and micro-sized monoliths with a hierarchical architecture while retaining its desirable fluorescence properties. The fluorescence intensity of the cHN-Eu₂O₃ was 1000 times higher than that of commercial Eu₂O₃ nanoparticles (equivalent weight) when it was capped with TTA, suggesting that a synergetic effect, confining the longtime Eu³⁺ excitation within the nanostructure and light-harvesting effect of the capping agent, is responsible for this fluorescence enhancement. Excellent interaction between the cHN-Eu₂O₃ and solution species is expected owing to its large surface area, high surface-to-bulk ratio, and ultrahigh fluorescence intensity. As an example, aqueous suspensions of the cHN-Eu₂O₃ were used as sensing agent for the determination of trace amounts of mercury. A linear relationship between the concentration of mercury and fluorescence quenching was observed from 10 ppb to 10 ppm with a correlation coefficient of 0.997 and a detection limit of 5.0 ppb. Mercury in various samples was analyzed using the cHN-Eu₂O₃ suspension.