The objective of the study was to measure the indoor air quality in classrooms with special emphasis on particulate matter (PM 10) and carbon dioxide (CO2) and the impact of cleaning and ventilation.Material and method: PM 10 was analysed via gravimetric method and by laser beam technology. CO2 was analysed by infrared sensors. Measurements were collected for 3 weeks; first week: "normal" cleaning (twice a week) and ventilation; second week: intensified cleaning (five times a week); third week: intensified cleaning and intensified ventilation.Results: Levels of PM 10 in the classrooms during the 3 weeks were 69 +/- 19 mu g/m(3) and they were dominated by Occupancy and the persons' activity. Intensified cleaning showed a significant decrease in all classrooms (79 +/- 22 to 64 +/- 15 mu g/m(3)) The effect of ventilation on levels of PM10 was inconsistent - levels of CO2 were very high in all schools and could be diminished by intensified ventilation (mean 1459 to 1051 ppm).Conclusion: Although further investigation is needed to study detailed characteristics of the PM 10 (size distribution, chemical identity) the data are sufficient to improve the cleaning and the ventilation in schools. (C) 2007 Elsevier GmbH. All rights reserved.

The derivatization of formaldehyde with 2,4-dinitrophenylhydrazine and the extraction of the product formalhydrazone is studied. The determination is carried out by HPLC. Applying a cryogenic sampling technique and a sampling volume of 300 l of air the detection limit of formaldehyde in air is 30 pptv and this is suitable for measurements of formaldehyde in the atmosphere.

For the determination of trace elements in water by neutron activation (NAA) two multielement-standards on the basis of calcium carbonate were prepared by freeze-drying from solutions after addition of calcium carbonate. Homogeneity was certified by NAA, and the content was tested by atomic absorption (AAS), NAA and X-ray fluorescence analysis (XFA). The multielement-standards were applied for trace element determination in standardized water samples and in Rhine water. Comparison with a monoelement-standard (iron) and with AAS showed good agreement of the results.

Der Spurenelementgehalt in standardisiertem Wasser, in Rheinwasser und Meerwasser wird durch Neutronenaktivierungsanalyse (NAA), Röntgenfluorescenzanalyse (RFA) und Atomabsorption (AAS, mit Ausnahme von Meerwasser) bestimmt. Die Voranreicherung erfolgt für NAA durch Gefriertrocknung und Schütteln mit einem Celluloseaustauscher (CA), für RFA durch Abtrennung in CA-Säulen, Filtration durch CA-Filter oder Schütteln mit CA. Die Ergebnisse werden verglichen und diskutiert.

By freeze-drying the following elements can be determined in natural water except sea water: Au, Ba, Br, Ca, Ce, Co, Cr, Eu, Fe, K, La, Mo, Na, Sb, Sc, Se, U, Zn. Some problems may arise with respect to As and Hg. Cu, Cd and Ni can only be determined if present in high concentrations. Separation by adsorption on charcoal in presence of complexing agents gives yields between 75 and 100% for the following elements in sea water: Ag, Au, Cd, Ce, Co, Cr, Eu, Fe, Hg, La, Mo, Sc, Se, U, Zn (As 67%, Sb 56%). Activation or use of labelled ions and study of exchange give information about mobility of trace elements in suspended matter.

A systematic study was undertaken in order to find out which of the most relevant elements can be determined in water under normal conditions by non-destructive neutron activation simultaneously using a suitable monostandard method. Standardized water samples as well as natural water of different kind were used, brought to dryness by freeze-drying and irradiated in quartz at a neutron flux of 1014 cm−2 s−1 for 1 day. The trace element content in quartz ampoules of different origin was determined separately. The following elements are discussed in detail including possible interferences: As, Au, Br, Ca, Cd, Co, Cr, Cu, Eu, Fe, Hg, K, La, Mo, Na, Ni, Sb, Sc, Se, U, Zn.