Field evaluation of a tailor-made new passive sampler for the determination of NO2 levels in ambient air

This study describes the field evaluation of a tailor-made new glass passive sampler developed for the determination of NO(2), based on the collection on triethanolemine (TEA)-coated fibre filter paper. The sampler has been derived from a Palmes design. The overall uncertainty of the sampler was determined by using Griess-Saltzman ASTM D 1607 standard test method as a reference method. The agreement between the results of the passive sampler and the reference method was +/-7.90% with the correlation coefficient of 0.90. Method precision in terms of coefficient of variance (CV) for three simultaneously applied passive samplers was 8.80%. The uptake rate of NO(2) was found to be 2.49 ml/min in a very good agreement with the value calculated from theory (2.63 ml/min). Sampler detection limit was 1.99 microg/m(3) for an exposure period of 1 week and the sampler can be stored safely for a period of up to 6 weeks before exposure. A comparison of the sampler performance was conducted against a commercially available diffusion tube (Gradko diffusion tube). The results from the applied statistical paired t test indicated that there was no significant difference between the performances of two passive samplers (R (2) > 0.90). Also, another statistical comparison was carried out between the dark and transparent glass passive samplers. The results from the dark-colour sampler were higher than that from the transparent sampler (approximately 25%) during the summer season because of the possible photodegradation of NO(2)-TEA complex.     

Comparison study of five analytical methods for the fractionation and subsequent determination of aluminium in natural water samples

Five methods for aluminium fractionation used in different laboratories in Norway and Finland were compared using six control, 75 soil water and 10 lake water samples. Different fractionation principles [cation exchange, formation of the Pyrocatechol Violet (PCV) or quinolin-8-ol (oxine) complex], types of cation exchanger [Amberlite (Na/H) or Bond Elut (H)], reaction time (from 2.3 s), flow systems (flow injection analysis or segmented flow) and determination principles (molecular absorption spectrometry or ICP-AES) were tested. Determination of the 'labile' fraction was strongly dependent on the method used and the largest differences were observed between the ICP-AES method with cation exchange (Bond Elut H form) and the 'quickly reacting' method (oxine, 2.3 s). Different flow systems, both using cation exchange and determination of the PCV complex but with different reaction times and an extra acidification step, resulted in large differences in the 'reactive' and 'non-labile' fractions determined. However, the determination of the labile fraction gave similar results with both these methods. The two different types of cation exchanger used (with and without pH buffering and with different counter ions) in the ICP-AES methods resulted in differences, mainly because of a smaller 'non-labile' fraction in the non-buffered system. The two flow injection systems (oxine and PCV complexation) showed common trends, which may be connected with the short reaction times used. Comparison with theoretical equilibrium calculations using the model ALCHEMI suggested that the best correlation for the determination of the 'labile' fraction were obtained with the ICP-AES method with an Amberlite column.     

Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content

This paper provides additional data on a sewage sludge amended soil certified reference material, CRM 483, which was certified in 1997 for its EDTA and acetic acid extractable contents of some trace metals, following standardised extraction procedures. The additional work aimed to test the long-term stability of the material and the applicability of an improved version of the BCR three-step sequential extraction procedure on the sewage sludge amended soil (CRM 483). The paper demonstrates the CRM 483 long-term stability for EDTA and acetic acid extractable contents of Cd, Cr, Cu, Ni, Pb and Zn and gives the results (obtained in the framework of an interlaboratory study) for the extractable contents of the same elements in the CRM 483, following the BCR three-step sequential extraction scheme. The aqua regia extractable contents following the ISO 11466 Standard are also given. The data are given as indicative (not certified) values.