A new microdialysis unit for flow injection analysis

Summary A new dialysis unit optimized for FIA is described. It contains both a dialysis cell and a manifold for reagent addition. Both parts are included in the same module. For test purposes, a colorimetric determination of chloride — both with and without dialysis — has been carried out. For the conditions given in the experimental setup, the dialyzing efficiency was ca. 11 %. The dilution loss factor, i.e., dilution caused by the dialysis cell, was ca. 9. The dispersion coefficient (D) for the manifold — excluding the dispersion caused by dialysis — was calculated to 2.2. The analytical performance expressed as repeatability is around 1.3% r.s.d., and the sample throughput is around 80 – 90 samples/h. Potential application areas cover a wide range of possibilities, e.g., foods and feeds, dairy products, soils and plants, water and waste water analysis and fermentation products.

---

Neue Mikrodialyseeinheit für die Fließinjektionsanalyse

     

FIA-Fluorimetric assembly for the determination of noradrenaline hydrochloride by a solid-phase reactor with immobilized hexacyanoferrate(III)

An FIA assembly provided with immobilized hexacyanoferrate(III) is proposed for the fluorimetric determination of noradrenaline hydrochloride. The oxidative reagent is immobilized by means of a strong anion-exchange resin. The FIA manifold is very simple and the calibration graph is linear over the range 0.5–75mgl^–1 noradrenaline hydrochloride with an r.s.d of 0.88% (17 replicates) and a sample throughput of 84h^–1. Foreign compounds such as NaCl, sucrose, lactose and sodium sulfate caused no significant errors. The procedure is applied to the determination of noradrenaline in a medicinal formulation.     

Amperometric and spectrophotometric determination of carbaryl in natural waters and commercial formulations

The work presented describes the development and evaluation of two flow-injection analysis (FIA) systems for the automated determination of carbaryl in spiked natural waters and commercial formulations. Samples are injected directly into the system where they are subjected to alkaline hydrolysis thus forming 1-naphthol. This product is readily oxidised at a glassy carbon electrode. The electrochemical behaviour of 1-naphthol allows the development of an FIA system with an amperometric detector in which 1-naphthol determination, and thus measurement of carbaryl concentration, can be performed. Linear response over the range 1.0×10^–7 to 1.0×10^–5 mol L^–1, with a sampling rate of 80 samples h^–1, was recorded. The detection limit was 1.0×10^–8 mol L^–1. Another FIA manifold was constructed but this used a colorimetric detector. The methodology was based on the coupling of 1-naphthol with phenylhydrazine hydrochloride to produce a red complex which has maximum absorbance at 495 nm. The response was linear from 1.0×10^–5 to 1.5×10^–3 mol L^–1 with a detection limit of 1.0×10^–6 mol L^–1. Sample-throughput was about 60 samples h^–1. Validation of the results provided by the two FIA methodologies was performed by comparing them with results from a standard HPLC–UV technique. The relative deviation was <5%. Recovery trials were also carried out and the values obtained ranged from 97.0 to 102.0% for both methods. The repeatability (RSD, %) of 12 consecutive injections of one sample was 0.8% and 1.6% for the amperometric and colorimetric systems, respectively.     

Direct acetylation followed by solid-phase disk extraction and GC-ITDMS for the determination of trace phenols in water

Summary A rapid, accurate and sensitive method is described for the analysis of phenolic compounds, including phenol, alkylphenols, halogenated phenols and nitrophenols in tap, ground and river water samples. The method consists in direct acetylation of the aqueous phenols with acetic anhydride, extraction of the phenol acetates with a C₁₈ disk and analysis by gas chromatography with an ion-trap detector mass spectrometer. Using this method, the sample preparation time was approximately 1.5 h for six 1-L water samples, and recoveries for most of the phenolic compounds studied were more than 80% at concentration levels of 0.1 and 1.0g L^–1. The detection limits were in the range 2 to 15 ng L^–1 for phenol, alkylphenols and halogenated phenols, and 25 to 50 ng L^–1 for nitrophenols.     

Organic mercury speciation in fish by capillary gas chromatography interfaced with atomic absorption spectrometry

Summary A rapid method for the speciation of mercury in fish has been described. Organomercurials in benzene extract were separated by glass capillary gas chromatography and detected by atomic absorption spectrometry. Spiked alkylmercury in fish yielded 95% recovery with one single extraction with benzene. The absolute detection limit was about 1.0×10^–10 g mercury. The method can be applied to the determination of 0.04 ppm of mercury in a 0.5 g sample.

---

Speziation von organischem Quecksilber in Fisch mit Hilfe der Capillar-Gas-Chromatographie in Verbindung mit AAS

     

An indirect sequential determination of phosphorus and arsenic in high-purity tungsten and its compounds by atomic-absorption spectrophotometry

Summary An indirect atomic-absorption spectrophotometric method based on selective extraction of heteropolymolybdic acids has been developed for determination of small quantities of P and As in highpurity tungsten metal and tungsten compounds. The method is suitable for determination of 5–100 ppm of phosphorus and arsenic. The relative standard deviation is 38–5% for P and 31–3% for As, depending on the concentrations.

---

Indirekte Bestimmung von Phosphor und Arsen in hochreinem Wolfram und dessen Verbindungen durch AAS

Zusammenfassung Eine indirekte, auf selektiver Extraktion der Heteropolymolybdänsäuren beruhende AAS-Methode zur Bestimmung kleiner Mengen Phosphor und Arsen in hochreinem Wolfram und seinen Verbindungen wurde ausgearbeitet. Das Verfahren eignet sich für 5–100 ppm Phosphor und Arsen. Die rel. Standardabweichung beträgt 38–5% für P und 31–3% für Arsen, je nach deren Konzentration.

     

Amberlite XAD resin solid-phase extraction coupled on-line to a flow injection approach for the rapid enrichment and determination of phenols in water and waste waters

A novel and expeditious approach for direct determination of phenols in water and waste waters based on solid-phase extraction coupled on-line to a flow injection analysis (FIA) manifold is described. The method employs on-line preconcentration of the phenols in an acidified sample (pH=2.0) onto a 3 cmx3 mm column packed with Amberlite XAD-4 resin. The phenols are subsequently eluted from the resin into a flowing system with an alkaline solution (pH=13) by actuating a switching valve; the eluted analytes were then quantified spectrophotometrically as the products of reaction with 4-aminoantipyrine (4-AAP) and potassium ferricyanide on passing through the flow-cell of a detector. The proposed method has a linear calibration range 0.01-1 mug ml(-1) of phenol, with a detection limit of 0.004 mug ml(-1) (S/N=3) and a sample throughput of 12 h(-1), investigated with a 4.4 ml sample volume. The relative standard deviation is 2.4% for 0.2 mug ml(-1) of the analyte. The sensitivity offered by the procedure was higher by a factor of 13 than that provided by a conventional flow injection analysis method. The analytical scheme of the proposed system is much simpler than its conventional manual counterpart due to the fact that it combines trace enrichment, sample clean-up, derivation and detection in one analytical set-up. The high speed, ease of use and automation, selectivity, and relative freedom from random contamination by sample handling make this method ideal for the phenols monitoring in water and waste waters.     

Neue Eichmethode zur Nitrat- und Nitrit-Spurenbestimmung in Lebensmittelproben

Zusammenfassung Ein neues Verfahren zur Nitrat- und Nitritspurenbestimmung in verschiedenartigen Lebensmittelproben wird beschrieben. Dazu wird die massenspektrometrische Isotopenverdünnungsanalyse unter Verwendung eines ¹⁵NO ₃ ^– - und ¹⁵NO ₂ ^– -Indicators sowie die Messung negativer NO ₂ ^– -Thermionen im Massenspektrometer eingesetzt. Als definitive Methode liefert dieses Verfahren vergleichsweise richtige Analysenergebnisse, weshalb es sich vor allem auch als Eichverfahren eignet. Es werden Nitratgehalte in verschiedenen Milchpulver- und Schinkenproben im Bereich 3–170 ppm sowie getrocknete Proben von Pflanzenmaterialien im Bereich 0,1–2 Gew.-% analysiert. Dabei kann die Bestimmung letztgenannter Proben auch als Mikroanalyse erfolgen. Soweit es sich bei den Lebensmitteln um homogenisierte Proben handelt, liegen bei Konzentrationen >100 ppm die relativen Standardabweichungen des Verfahrens im Bereich 0,2–1%, bei Gehalten von 10–100 ppm im Bereich 1,5–3%. Die entsprechende Reproduzierbarkeit für parallel zum Nitrat bestimmtes Nitrit liegt bei 2–6% für Gehalte im Bereich 1–50 ppm. Die Nachweisgrenze für Nitrat und Nitrit ist etwa 0,2 ppm.

---

New calibration method for the nitrate and nitrite trace determination in food samples

Summary A new analytical procedure for the determination of nitrate and nitrite traces in different food samples is described. Isotope dilution mass spectrometry is applied using a ¹⁵NO ₃ ^– and a ¹⁵NO ₂ ^– spike for the dilution technique and measuring negative NO ₂ ^– thermal ions in the mass spectrometer. This definitive method provides relatively accurate analysis results. Therefore, it is especially suitable as a calibration method. Nitrate contents in different milk powder samples and ham samples in the range of 3–170 ppm as well as dried samples of different plant materials in the range of 0.1–2% (by weight) are analysed. The determination of the plant material can also be carried out as micro analysis. So far as the food samples are homogeneous, the relative standard deviation of this method is in the range of 0.2–1% for nitrate contents of > 100 ppm and in the range of 1.5–3% for those of 10–100 ppm. The corresponding values for nitrite analysed in parallel to nitrate are 2–6% in the range of 1–50 ppm. The nitrate and nitrite detection limit is about 0.2 ppm.

---

---

Vortrag anläßlich des Symposiums Anorganische Anionenanalytik, Regensburg, 19.–21. 9. 1984

---

Der Deutsche Forschungsgemeinschaft und dem Fonds der Chemischen Industrie danken wir für die finanzielle Unterstützung.     

Zur gas-chromatographischen Bestimmung von Methylbromid neben Phosphin in Luft

Zusammenfassung Es wird ein gas-chromatographisches Verfahren zur Bestimmung von Methylbromid neben Phosphin in Luft angegeben. Der Zusammenhang zwischen der Peakhöhe und dem CH₃Br-Gehalt ist sowohl in Abwesenheit als auch in Gegenwart von 1–10 ppm Phosphin in einem Bereich von 5–50 ppm CH₃Br linear. Das dosierte Gasvolumen betrug 1 ml. Während sich die Eichfunktionen für die Methylbromid-Phosphin-Gemische statistisch nicht unterscheiden, konnte ein stark signifikanter Unterschied zu der für reines Methylbromid erhaltenen Eichgeraden nachgewiesen werden. Die Reproduzierbarkeit der Messungen betrug 1% für reines CH₃Br und ca. 2,5% im Gemisch mit Phosphin.

---

Determination of methyl bromide in combination with phosphine in air by gas chromatography

Summary The determination of methyl bromide in combination with phosphine in air by gas chromatography is described. For methylbromide singly as well as in combination with 1–10 ppm PH₃ a linear relation between peak height and the content of 5–50 ppm CH₃Br for a dosaged gas volume of 1 ml was found. The calibration-curves for the CH₃Br-PH₃ mixtures do not show statistical differences, while the difference to the calibration-curve for methyl bromide only is highly significant. The precision of the determination was 1% for pure methyl bromide and about 2.5% in mixture with PH₃.

     

Determination of the total calcium concentration of serum by ICAP-AES

Summary The determination of nitrate, nitrite, phosphate, chloride and sulphate in aqueous extracts of salads and vegetables by ion chromatography is described. The method is reliable and fast, and needs no derivatisation nor clean-up besides filtration. Without using a preconcentration column, the detection limits are 0.1 ppm for nitrate, nitrite and sulphate, 0.04 ppm for chloride and 0.4 ppm for phosphate. Calibration curves with reference to peak heights are linear within the concentration range usually obtained.

---

Bestimmung von Nitrat und anderen anorganischen Anionen (NO ₂ ^– , PO ₄ ^3– , Cl^–, SO ₄ ^2– ) in Salat und Gemüse durch Ionen-Chromatographie

Zusammenfassung Es wird die Bestimmung von Nitrat, Nitrit, Phosphat, Clorid und Sulfat in wässrigen Extrakten von Salat und Gemüse durch Ionen-Chromatographie beschrieben. Die Methode ist zuverlässig und schnell und bedarf neben der Filtration keiner weiteren Derivatisierungsoder Reinigungsschritte. Die Nachweisgrenze liegt für Nitrat, Nitrit und Sulfat bei 0,1 ppm, für Chlorid bei 0,04 ppm und für Phosphat bei 0,4 ppm, dies ohne Vorkonzentrierung. Im üblicherweise verwendeten Konzentrationsbereich sind alle Eichkurven linear.

     

Some applications of enthalpimetric detection in flow injection analysis

Summary A flow injection manifold is described based on a flow-through arrangement of thermistors for measuring heat effects of chemical reactions. Temperature changes down to 10^–3 °C can be measured reproducibly. The working range for the determination of a component is dependent on the reaction enthalpy and can vary from 10^–3 to 10 mol/l for acids and bases, from 10 to 1000 ppm for e.g., alkylhydroperoxides. Sample frequencies up to 150 samples per hour can be realized.

---

Einige Anwendungen der enthalpimetrischen Detektion in der Fließinjektionsanalyse

     

Multiple potentiometric system for continuous determination of chloride, fluoride, nitrate and ammonia in natural waters

Summary A flow-through system for the simultaneous determination of chloride (30–150 ppm), fluoride (0.08-0.4 ppm), nitrate (5–20 ppm) and ammonia (0.05-0.5 ppm) in water was developed. Solid-state chloride and fluoride electrodes, a nitrate PVC membrane electrode with solid silver contact and a gassensing ammonia ORION 95-10 electrode were employed. The air-segmented sample stream is mixed with appropriate buffering solutions before entering the measuring cells. Mean accuracy of the determinations is usually better than ± 10%.

---

Multiples potentiometrisches System zur kontinuierlichen Bestimmung von Chlorid, Fluorid, Nitrat und Ammoniak in natürlichen Wässern

Zusammenfassung Ein Durchflußsystem wurde entwickelt zur gleichzeitigen Bestimmung von Chlorid (30–150 ppm), Fluorid (0,08-0,4 ppm), Nitrat (5–20 ppm) und Ammoniak (0,05-0,5 ppm). Folgende Elektroden wurden eingesetzt: Festkörperelektroden für Chlorid und Fluorid, PVC-Membranelektrode für Nitrat und die ORION 95-10 Gassensor-Elektrode für Ammoniak. Der Luft-segmentierte Probestrom wird vor Eintritt in die Meßzellen mit geeigneten Pufferlösungen gemischt. Die mittlere Genauigkeit beträgt ±10%.

     

Schnellbestimmung von Cu, Ag und Pd in PbSn-Verzinnungsb?dern durch Atomabsorptions-Spektroskopie

Zusammenfassung Eine Absorptionsmethode zur direkten Bestimmung von Cu, Ag und Pd in Pb-Sn-Legierungen wurde erarbeitet. Für die Bestimmung vorteilhafte Absorptionslinien (Cu 324,7 nm, Ag 338,3 nm und Pd 276,3 nm) wurden ermittelt und auf diesen intermetallische Interferenzen von 0–500 ppm Cu, Ag und Pd sowie von 10000ppm Pb und Sn gemessen. 1g der Legierung wird in 10 ml HNO₃ (D 1,52) und 2 ml 50 % HF gelöst. Die Lösung wird in einer Acetylen-Luft-Flamme analysiert. Die Methode erlaubt Gehalte bis zu 3·10^–4 % Cu, 5·10^–4 % Ag und 8·10^–4% Pd (zweifache Blindwerthöhe) mit ausreichender Genauigkeit zu bestimmen.

---

Rapid determination of Cu, Ag and Pd in PbSn-tinning baths by atomic-absorption spectroscopy

An atomic absorption method for direct determination of Cu, Ag and Pd in Pb-Sn-alloys has been developed. For the determination favourable absorption lines (Cu 324.7 nm, Ag 338.3 nm and Pd 276.3 nm) were found out. Intermetallic interferences of 0–500 ppm of Cu, Ag and Pd as also 10000 ppm of Pb and Sn were measured on these lines. 1 g of the alloy is dissolved in 10 ml HNO₃ (d 1.52) and 2 ml of 50 % HF. The solution is analyzed in an acetylene-air flame. This method allows the analyzing of contents up to 3×10^–4 % Cu, 5·10^–4% Ag and 8×10^–4% Pd (twofold blank) with sufficient precision.

     

Determination of traces of lead, thallium, and cadmium in zinc salts by means of anodic stripping voltammetry

Summary A method is described by which it is possible to determine traces of lead, thallium, and cadmium in zinc salts by means of anodic stripping voltammetry in a concentration range of about 0.1 to 20 ppm, with a possible error of 10 to 20%. As far as could be investigated, no other elements interfere with the determination.

---

Zusammenfassung Eine Methode wird beschrieben zur Bestimmung von Blei, Cadmium und Thallium in Zinksalzen durch anodische Amalgamvoltammetrie. Das Verfahren ist geeignet für Gehalte von etwa 0,1–20 ppm, bei einem möglichen Fehler von 10–20%. Soweit nachgeprüft werden konnte, wird die Bestimmung von keinen anderen Elementen gestört.

     

Rapid spectrophotometric determination of chlorate with dimedone bisthiosemicarbazone monohydrochloride

Summary Dimedone bisthiosemicarbazone monohydrochloride has been examined to evaluate its usefulness as a reagent for rapid and sensitive Spectrophotometric determination of chlorate (0.5–5.0 ppm) by oxidation of the reagent in 70% perchloric acid medium and measurement of the yellow product. The molar absorptivity at 417 nm is 1.86×10⁴ l·mole^–1·cm^–1. The relative standard deviation is 1.6% for 2.5 ppm of chlorate.

---

Spektropbotometrische Bestimmung von Chlorat mit Dimedonbisthiosemicarbazon-monocblorhydrat (I)

Zusammenfassung Die Verwendbarkeit von I als Reagens für die rasche und empfindliche spektrophotometrische Bestimmung von 0,5–5,0 ppm Chlorat durch Oxydation von I in 70%iger Perchlorsäure und Messung des gelben Reaktionsproduktes wurde untersucht. Die molare Absorptivität bei 417 nm beträgt 1,86×10⁴ l·mol^–1·cm^–1. Die relative Standardabweichung beträgt 1,6% für 2,5 ppm Chlorat.

     

Determination of organosilicon compounds in water by atomic absorption spectroscopy

Summary An extraction technique is described for the determination of ppm concentrations of both hydrophobic and hydrophilic methylsiloxane compounds in water, based on a single extraction with a mixed solvent of (11) l-pentanol and methyl isobutyl ketone followed by the determination of the silicone compounds extracted into the mixed solvent by atomic absorption spectroscopy. The method is applicable over the concentration range 0.3–30 ppm Si. Standard deviation in the case of 10 ppm Si is 0.313.

---

Bestimmung von siliciumorganischen Verbindungen in Wasser mit Hilfe der Atomabsorptions-Spektralphotometrie

Zusammenfassung Zur Bestimmung von ppm-Konzentrationen an hydrophoben und hydrophilen Methylsiloxanverbindungen im Wasser wird ein Extraktionsverfahren beschrieben. Hierbei wird nach einfacher Extraktion mit l-Pentanol/Methylisobutylketon (11) das Silicium im Extrakt mit Hilfe der AAS bestimmt. Der erfaßbare Konzentrationsbereich liegt bei 0,3–30 ppm Si. Die Standardabweichung beträgt bei 10 ppm Si 0,313.

     

Bestimmung kleiner Hafniumgehalte in Zirkoniumoxid mittels Neutronenaktivierungsanalyse

Zusammenfassung Es wird ein Verfahren zur Bestimmung von Hafnium in Zirkoniumoxid mittels der Neutronenaktivierungsanalyse beschrieben, das keine besonderen Einrichtungen und Schutzmaßnahmen für den Umgang mit den aktivierten Proben erfordert. Es eignet sich besonders zur Bestimmung von 10–100 ppm HfO₂ in ZrO₂. Dabei beträgt die relative Standardabweichung 5–10%.

---

Summary A procedure is described for the determination of hafnium in zirconium oxide by neutron activation analysis. The special feature of the method is the use of low activities only. Therefore no extensive precautions are required. The method is specially suitable for the determination of 10–100 ppm of HfO₂ in ZrO₂. The relative standard deviation is 5–10%.

---

---

Wir danken Herrn Prof. W. Fischer für wertvolle Diskussionen, dem Laboratorium für Technische Physik der Technischen Hochschule München für die Durchführung der Bestrahlungen, dem Bundesministerium für Wissenschaftliche Forschung und dem Fonds der Chemischen Industrie für finanzielle Unterstützung.     

Extraction and Gas-Chromatographic Determination of Phenol and Cresols in Soil

The effects of the acidity of an aqueous solution, the time of moistening a soil sample, and the time of ultrasonic desorption on the extraction of phenols from soils were studied. The optimum conditions were found. A procedure was developed for the gas-chromatographic determination of 0.05–50 mg/kg of phenol and o- and p-cresols in soil with an error of 10–25%. The time of analysis was 40 min.     

Beitr?ge zur Bestimmung von Spurenverunreinigungen in UO2-Kernbrennstoff

Zusammenfassung Die für die Bestimmung geringer Gehalte an Phosphor, Silicium, Fluor, Chlor, Lithium, Natrium, Calcium und Kohlenstoff in UO₂-Kernbrennstoff angewandten chemischen Analysenverfahren werden beschrieben. Durch Kombination einfacher und blindwertfreier Abtrennungsverfahren (Extraktionen und Pyrohydrolysen) mit empfindlichen physikalischchemischen Bestimmungsmethoden (Spektralphotometrie, Flammenphotometrie, coulometrische Titration) lassen sich Nachweisgrenzen zwischen 0,1 und 10 ppm bei Probeneinwaage von 0,5–1 g UO₂ erreichen. Der Zeitaufwand für die Analysen kann durch simultane Bestimmung zweier oder dreier Elemente in einem Arbeitsgang niedriggehalten werden. Die beschriebenen Verfahren haben sich bei Reinheitskontrollen von Kernbrennstoffen gut bewährt.

---

Summary Analytical methods have been developed for the determination of trace amounts of phosphorus, silicon, fluorine, chlorine, lithium, sodium, calcium, and carbon in UO₂ of nuclear purity. By combination of simple and rapid separation procedures (extraction, pyrohydrolysis) with highly sensitive methods of determination (spectrophotometry, flame photometry, coulometric titration) detection limits of 0.1–10 ppm have been obtained with sample sizes of 0.5–1 g. In order to reduce the time needed for analysis, some of the above elements are determined simultaneously. The methods described have been successfully applied to the purity control of nuclear fuels.

---

---

Herrn Dr. W. Gebauhr danken wir für wertvolle Anregungen und Diskussionen.