Thermochemistry of hydrated rare earth orthophosphates

The hydrated rare earth orthophosphates LnPO₄ ·xH₂O (Ln=La-Dy) contain zeolitic water in the structural channels, which is released reversibly up to 300°. The thermal stabilities of the hydrates depend upon the nature of the Ln atom. The dehydration temperature decreases with decreasing ionic radiusr of Ln³⁺, according to the general equation=(r–a)/b (where is the DSC and/or DTG dehydration peak temperature, anda andb are empirical constants depending on the experimental conditions).The contracting-area rate equation was valid for linearization of the isothermal vs. time plots in the range 0; 0.65. Kinetic values ofE, A, H ⁺ and S⁺ were calculated and the kinetic stabilities of the hydrates are discussed.

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Zusammenfassung Die hydratisierten Seltenerdiphosphate LnPO₄·xH₂O (Ln=La bis Dy) enthalten in Kanälen ihrer Struktur zeolithisches Wasser, das reversibel bis 300 °C abgegeben wird. Die thermische Stabilität der Hydrate hängt von der Natur des Ln ab. Die Entwässerungstemperatur sinkt mit abnehmendem Ionenradiusr der Ln3+-Ionen gemäss:=(r–a)/b (a undb sind empirische Konstanten, die von den experimentellen Bedingungen abhängen). Die isotherme Entwässerung lässt sich im Umsatzbereich 0 0,65 mit der Gleichung für kontrahierende Fläche (zweidimensionale Phasengrenzreaktion) beschreiben. Die kinetischen Grössen AktivierungsenergieE, -enthalpieH ^*, und -entropieS ^* wurden berechnet und die kinetische Stabilität der Hydrate wird diskutiert.

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LnPO4·xH2O (Ln=La-Dy) , 300°. . r =(r-)/b, 9 — , a b — , . — <0; 0,65>. , , ^* S ^* .

     

Simultaneous determination of copper,mercury and lead by first-order derivative spectrophotometry using dithizone as reagent

A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) g present in 40 ml of aqueous phase with detection limits of 5 g/L (Cu) and 20 g/L (Hg and Pb). The R.S.D.s for 100 g/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy.     

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.

     

Certified reference materials (CRM 408 and 409) for quality control of main components (ammonium, calcium, hydronium, magnesium, nitrate, potassium, sodium and sulphate) in simulated rain water

Analyses of rainwater are routinely performed by a number of organisations to monitor the contribution from rainwater to the component occurrences in the environment and the acidification of the environment. To control the quality of such determinations, the Community Bureau of Reference (BCR) has organised a certification campaign to produce two simulated rainwater reference materials (CRM 408, low mineral content and CRM 409, high mineral content). The materials were carefully prepared (addition of pro analysis and supra pure reagents with the mentioned elements to silica-free deionised water) and its homogeneity and long-term stability were verified. The materials were certified for their contents of ammonium (106 mol/kg) (CRM 409), calcium (7.68 and 15.5 mol/kg), chloride (67.3 and 113 mol/kg), hydronium (16.6 and 48.0 mol/kg), magnesium (6.14 and 12.3 mol/kg), nitrate (20.1 and 78.1 mol/kg), potassium (4.25 mol/kg) (CRM 409), sodium (42.0 and 82.9 mol/kg) and sulphate (10.5 and 53.2 mol/kg). Indicative values (not certified) are given for ammonium and potassium in CRM 408. This paper presents the certification work performed, as well as the analytical work for the certification of the contents of relevant species.     

Isocratic high-performance liquid chromatographic determination of plasma adenosine

Summary Due to manifold physiological and cardioprotective actions of adenosine, the demand for a simple but accurate method to determine its concentration in plasma is increasing. The aim of this study was firstly to develop a simple isocratic method instead of the gradient elution or peak-shifting techniques used earlier and secondly to check conflicting data on the composition of stop-solution, added to the sample in order to prevent changes in adenosine concentration. Isocratic elution improved signal to noise ratio and concentrations of 100 mol L^–1 dipyridamole and 2.5 mol L^–1 erythro-9(2-hydroxy-3-nonyl)adenine in the blood sample effectively prevented both adenosine formation and degradation, even without the use of a 5-ecto-nucleotidase inhibitor. Lowering the concentration of dipyridamole to 25 mol L^–1 caused more than a tenfold increase of adenosine concentration in two out of five cases and even 100 mol L^–1 dipyridamole alone is not sufficient to inhibit adenosine deaminase in blood samples.     

Untersuchungen zur Bestimmung von Spurenelementen in Blutserum mit Hilfe der Totalreflexions-R?ntgenfluoreszenzanalyse

Summary The quantitative determination of trace elements in human blood serum by Total Reflection X-Ray Fluorescence Analysis (TXRF) is influenced by absorption- and reflection-effects caused by the organic (proteins) and inorganic (P, S, Na, K, Ca, Cl) matrices. To minimize these effects we have developed a sample preparation technique based on the decomposition of the organic matrix and followed by the separation of the trace elements from the organic matrix by ion-exchange. The described method enables the simultaneous determination of K (1584 g), Ca (666 g), Fe (22 g), Cu (9.6 g), Zn (8.8 g), Se (0.97 g), Sn (1.3 g), Pb (0.12 g) and Rb (1.6 g) (obtained values in parentheses).

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Herrn Prof. Dr. G. Tölg zum 60. Geburtstag gewidmet     

Semiquantitative estimation of the mycotoxins citrinin, Ochratoxin A, Aflatoxin M1 and penicillic acid on thin-layer chromatograms with a grey scale

Summary Spots of citrinin, ochratoxin A, aflatoxin M₁ and penicillic acid on thin-layer chromatograms can be semi-quantitatively estimated by using a grey scale, commonly used in photo laboratories. The detection limits are 0.01 g for citrinin, 0.006 g for ochratoxin A, 0.002 g for aflatoxin M₁ and 0.01 g for penicillic acid. Standard curves for these mycotoxins are given.

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Halbquantitative Bestimmung der Mycotoxine Citrinin, Ochratoxin A, Aflatoxin M₁ und Penicillinsäure auf Dünnschicht-Chromatogrammen mit Hilfe eines Graukeils

Zusammenfassung Mit Hilfe eines in Photolabors gebräuchlichen Graukeils können dünnschicht-chromatographische Flecke der obengenannten Mycotoxine halbquantitativ bestimmt werden. Die Nachweisgrenzen betragen 0,01 g für Citrinin, 0,006 g für Ochratoxin A, 0,002 g für Aflatoxin M₁ und 0,01 g für Penicillinsäure. Eichkurven werden angegeben.

     

Preparation of micron-size monodisperse polymer particles by seeded polymerization utilizing the dynamic monomer swelling method

Utilizing a new type of monomer swelling method, 6.1 m-size monodisperse polymer particles were prepared by seeded polymerization. 1.8 m-size monodisperse polystyrene (PS) seed particles (1.8 m in size) were prepared by dispersion polymerization in ethanol-water (80/20, v/v) medium in the presence of poly(acrylic acid) as stabilizer with 2,2-azobisisobutyronitrile as initiator. The PS seed dispersion was mixed with ethanol-water (60/40, v/v) solution dissolving styrene (S) monomer, benzoyl peroxide as initiator, and poly(vinyl alcohol) as stabilizer. By slow, continuous, dropwise addition of water with a micro feeder into the mixture, the PS particles absorbed the many S monomers, which were separated from the medium and swelled from 1.8 m to 8.4 m while keeping the monodispersity high. We named this procedure the dynamic swelling method. Then, the seeded polymerization of the absorbed S monomer was carried out in the presence of NaNO₂ as water-solube inhibitor.Part CXXII of the series Studies on Suspension and Emulsion.     

Synthesis,characterization and crystal structures of heterometallic trinuclear carbonyl sulfido clusters (η5-Cp)MoFeCo- (CO)8(μ3-S) and [(η5-Cp)Mo]2Fe(CO)7(μ3-S)

HFe2Co(CO)9(3-S) reacts with (5-Cp)Mo(CO)3Cl in refluxing THF to give heterometallic trinuclear clusters (5-Cp)MoFeCo(CO)8(3-S) and [(5-Cp)Mo]2Fe(CO)7-(3-S), which have been characterized by elemental analyses, i.r., 1H- and 13C-n.m.r. and X-ray crystal structure determination. An electrophilic addition–elimination sequence is proposed for their formation.     

Nuclear interferences of uranium and thorium in a reactor neutron activation analysis determination of cerium using the radionuclides141Ce and143Ce

The interference contributions of uranium and thorium to the determination of cerium based on radionuclides¹⁴¹Ce and¹⁴³Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for¹⁴¹Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10^–3 g Ce/g Th, and for¹⁴³Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10^–3 g Ce/g Th.     

Determination of Promedol (Trimeperidine) and Ketamine in Blood Using Gas Chromatography–Mass Spectrometry

A procedure was developed for the gas-chromatographic determination of promedol (trimeperidine) and ketamine in whole blood with mass-selective detection. The detection limit for trimeperidine and ketamine in blood is 0.05 g/mL. The analytical range is 0.1–5.0 g/mL. The maximum within-series errors in the determination of the studied compounds are no higher than 14.1% for concentrations of 0.10 g/mL and 7.47% for concentrations of 1.0 g/mL. The maximum between-series relative errors are 5.75% for concentrations of 0.10 g/mL and 2.7% for concentrations of 1.0 g/mL. The procedure can be used in toxicological and clinical analyses.     

Study of Na-A molecular sieve degeneration by thermal analysis

The degenerations on heat treatment and the thermal stabilities of Na-A molecular sieve zeolites of different crystallinities were studied by thermal analysis. The degenerations of the sieves were computed from the decreases of the zeolitic water content. The thermal stabilities were determined from the commencement of the exothermic peaks. Heating at 600 causes considerable degeneration of these sieves. The degeneration and thermal stability depend on the crystallinity of the sieve. Poorly-crystalline sieves are degenerated to a greater extent than well-crystaline ones. The thermal stabilities on poorly-crystalline sieves also decrease during heating at 600.

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Zusammenfassung Die infolge der WÄrmebehandlung auftretende Degenerierung und die HietzebestÄndigkeit von Na-A Molekularsiebzeolithen verschiedener KristallinitÄt wurden durch Thermoanalyse untersucht. Die Degenerierung der Siebe wurde an der Abnahme des Zeolithwassergehaltes gemessen. Die HitzebestÄndigkeit. wurde aus dem Anfang des exothermen Peaks abgeleitet. Aufheizen auf 600 verursacht eine bedeutende Degenerierung der Siebe. Degenerierung und HitzestabilitÄt hÄngen von der KristallinitÄt der Substanzen ab. Wenig kristalline Siebe werden in höherem Ma\e degeneriert als hochkristalline. Die HitzebestÄndigkeit wenig kristalliner Spezies wird durch Aufheizen auf 600 ebenfalls herabgesetzt.

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Résumé On a étudié, par analyse thermique, la dégénération causée par traitement thermique ainsi que la stabilité thermique de tamis moléculaires aux zéolithes Na-A de cristallinité différente. On a mesuré la dégénération des tamis à partir de la diminution de la teneur en eau zéolithique. On a déterminé la stabilité thermique à partir du commencement du pic exothermique. Le chauffage à 600 cause une dégénération considérable des tamis. La dégé nération et la stabilité thermique dépendent de la cristallinité des tamis. Des tamis à faible cristallinité dégénèrent plus fortement que ceux à haute cristallinité. La stabilité thermique des tamis à faible cristallinité diminue également lors du chauffage à 600.

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Na- -, . , . - . 600 - . , - . , . - 600.

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The authors thank Mr. G. C. Bhattacharyya and Mr. A. A. Naqvi for their help in X-ray analysis.     

Trace analysis of cationic surfactants in water using HPLC with conductometric detection

Summary A simple and fast determination of trace amounts of commercially used cationic surfactants is described. After extraction from water cationic surfactants are separated by HPLC and detected by conductometry. The detection limit is 3 g/l for distearyldimethylammonium chloride, 16 g/l for ditallowimidazolinium methosulphate, and 6 g/l for dodecylpyridinium chloride.     

Human prostate specific antigen (hPSA) purification and establishment of hPSA radioimmunoassay

Human prostate specific antigen (hPSA) RIA was developed with hPSA and anti-PSA prepared in our laboratory. Its standard curve was linear with a sensitivity of 0.5 g/L. Serum PSA levels of 130 normal males ranged from 0 to 3.5 g/L (1.15±0.93 g/L), which are consistent with the results of other conventional RIA. The recovery, intra- and inter-assay coefficients of variation conform to the demands of RIA, and the results of 41 samples obtained by both the PSA RIA and PSA RIA of DPC were well correlated (=0.990). PSA level of 23 patients with prostatic carcinoma was 10400 g/L.     

Depth profile studies of ZrTiN coatings by laser ablation inductively coupled plasma mass spectrometry

The feasibility of depth profiling was studied by using a 193-nm ArF* excimer laser ablation system (GeoLas, MicroLas, Goettingen, Germany) with a lens array-based beam homogenizer in combination with an ICP-QMS Agilent 7500. Two ablation cells (20 and 1.5 cm³) were compared at the laser repetition rate of 1 Hz, laser beam energy of 135 mJ and the carrier gas flow rate 1.5 L min^–1 He + 0.78 L min^–1 Ar. The ablation cell dimensions are important parameters for signal tailing; however, very small cell volumes (e.g. 1.5 cm³) may cause memory effects, which can be probably explained by dominant inertial losses of aerosol on cell walls with its delayed mobilization. The 20-cm³ ablation cell seems to be appropriate for depth profiling by continuous single-hole drilling. The study of the influence of the pit diameter magnitude on the waning and emerging signals under small crater depth/diameter aspect ratios, which range between 0.75 and 0.0375 for the 3-m-thick coatings and pit diameters 4–80 m, revealed that the steady-state signals of pure coating and pure substrate (out of interface) were obtained at crater diameters between 20 and 40 m. Depth resolution defined by means of slopes of tangents in the layer interface region depend on the pit diameter and has an optimum value between 20 and 40 m and gives 0.6 m for the 20-m pit. In-depth variation of concentration of coating constituent (Ti) was proved to be almost identical with two different laser/ICP systems.Viktor Kanický performed this work while on leave at ETH Zurich     

The composition of volatile and particulate hydrocarbons in urban air

Summary The hydrocarbon composition of the particle and gas phases in the urban atmosphere has been studied by filtration and parallel adsorption on active charcoal and polyurethane foam (PUF). Gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS) have been used for the analysis of the organic matter extracts obtained with each system. In the case of the particle and PUF samples these extracts were fractionated into aliphatic and aromatic compounds. This approach has allowed to identify up to 247 hydrocarbon molecules showing that C0–C5 alkylbenzenes are the major compounds in the charcoal extracts whereas C14–C23 n-alkanes, C0–C4 alkylnaphthalenes, C0–C4 alkylbiphenyls and C3–C5 alkylbenzenes are those predominantly found in the PUF materials. The particles essentially contain C17–C38 n-alkanes and parent polycyclic aromatic hydrocarbons (PAH). These qualitative differences are paralleled by a progressive concentration decrease from the more to the less volatile hydrocarbons. Thus, the total charcoal extracts average 80 g/m³, the PUF compounds represent 4 /m³ and the particle hydrocarbons 0.7 g/m³. These latter airborne materials are essentially composed of petrogenic residues 0.6 g/m³ (aliphatic fraction) whereas the pyrolytic PAH only involve 0.08 g/m³.     

Comparison of various semiempirical MO LCAO methods

In an orthogonalized basis, the diagonal element F of the Fock operator, for a number of semiempirical MO LCAO methods, can be represented by a trinomial which is quadratic with respect to the Mulliken charge. The coefficients differ for different methods, depending on the manner in which the interelectronic interaction is taken into account. From a study, in general form, of the influence of change in the coefficients of the trinomial F on the bond order matrix, an explanation has been given for certain familiar calculation results: the equalization of the -charges on going from the Hückel method to the more advanced techniques, and the decrease in the covalent character of metal-ligand bonds when allowance is made for the interelectronic interaction in the calculations for complexes.In conclusion, we wish to thank V. D. Sutula and L. I. Chernyavskii for much valuable discussion.     

Fallout analysis of atmospheric water precipitations

Summary A rapid ion-exchange method for the determination of ¹⁴⁴Ce, ¹³⁷Cs, ⁸⁹Sr, ⁹⁰Sr and ¹⁴⁰Ba in 2–30 liter samples of atmospheric water precipitations is described. The samples, containing up to 300 mg of calcium, are sorbed on a specially shaped column filled with Dowex 50, X-8 or Dowex 50W, X-8. Radio-cerium and radio-caesium are stripped from the column with 0.6 M ammonium glycolate/ 0.2 M NaCl, pH 5, radio-strontium and radio-barium with 0.15 M ammonium citrate, pH 7.5. The isolated radio-nuclides are counted on a low-background beta-counter: ¹⁴⁴Ce as CeO₂, ¹³⁷Cs as Cs-dipicrylaminate, ⁸⁹Sr/⁹⁰Sr as SrCO₃, ⁹⁰Y as Y₂O₃, and ¹⁴⁰Ba as BaCO₃. The mean chemical yields amount to 95% for cerium, 85% for caesium, 95% for strontium, 95% for yttrium and 65% for barium. With parallel determinations at levels of a few picocuries, the deviations of the results from the respective mean values generally do not exceed ± 5%. With a 30 l sample the limit of detection amounts to 0.005 Ci/l for ¹⁴⁴Ce, 0.006 Ci/l for ¹³⁷Cs, 0.005 Ci/l for ⁹⁰Sr, and 0.006 Ci/l for ¹⁴⁰Ba.

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Zusammenfassung Es wird eine schnelle Ionenaustauschmethode für die Bestimmung von ¹⁴⁴Ce, ¹³⁷Cs, ⁸⁹Sr, ⁹⁰Sr und ¹⁴⁰Ba in 2–30 l Proben von atmosphärischen Wasser-Niederschlägen beschrieben. Die Proben, mit einem Calciumgehalt bis zu 300 mg, werden in eine besonders gestaltete, mit Dowex 50, X-8 oder Dowex 50 W, X-8 gefüllte Säule eingewaschen. Radio-Cer und Radio-Caesium werden mit 0,6 M Ammoniumglykolat/0,2 M NaCl, pH 5, Radio-Strontium und Radio-Barium mit 0,15 M Ammoniumcitrat pH 7,5 eluiert. Die isolierten Radio-Nuklide werden in einem Beta-Antikoinzidenzzähler gemessen: ¹⁴⁴Ce als CeO₂, ¹³⁷Cs als Cs-dipikrylaminat, ⁸⁹Sr/⁹⁰Sr als SrCO₃, ⁹⁰Y als Y₂O₃ und ¹⁴⁰Ba als BaCO₃. Die mittlere Rückgewinnung der zugesetzten Träger beträgt für Cer 95%, 85% für Caesium, 95% für Strontium, 95% für Yttrium und 65% für Barium. In Parallelbestimmungen mit Gehalten von einigen Ci/l, überschreiten die Abweichungen der Ergebnisse von den entsprechenden Mittelwerten im allgemein nicht 5%. Bei einer 30 l-Probe beträgt die untere Nachweisgrenze 0,005 Ci/l für ¹⁴⁴Ce, 0,006 Ci/l für ¹³⁷Cs, 0,005 Ci/l für ⁹⁰Sr und 0,006 Ci/l für ¹⁴⁰Ba.