Analysis of PCDD/Fs and dioxin-like PCBs in atmospheric deposition samples from the Flemish measurement network: correlation between the CALUX bioassay and GC-HRMS.

Since the CALUX (Chemically Activated LUciferase gene eXpression) bioassay is a fast, sensitive and inexpensive tool for the analysis of a high number of samples, the use of this technique in routine analysis of atmospheric deposition samples may be a valuable alternative for GC-HRMS. In this study, a validated CALUX method was used for the analysis of PCDD/Fs and dioxin-like PCBs in more than 90 atmospheric deposition samples for different locations in Flanders. The samples were taken in residential and agricultural areas, where a threshold limit of 21pgWHO-TEQm(-2)d(-1) for the sum of PCDD/Fs and dioxin-like PCBs was set, and in industrial zones and natural reserves, where no official threshold limit is available. The results from the Flemish measurement program showed correlation between CALUX and GC-HRMS for all the samples, originating from the different areas (R(2) of 0.81, 0.53 and 0.64 for dl-PCBs, PCDD/Fs and sum of both fractions, respectively). Median CALUX/GC-HRMS ratios of 2.0, 0.9 and 1.3 were reported for the PCDD/Fs, dioxin-like PCBs and the sum of both fractions, respectively. The results show that the CALUX bioassay is a valuable alternative tool for the classic GC-HRMS analysis of atmospheric deposition samples in the Flemish measurement network.

Analysis of PCDD/Fs and dioxin-like PCBs in atmospheric deposition samples from the Flemish measurement network: Optimization and validation of a new CALUX bioassay method.

Since the CALUX (Chemically Activated LUciferase gene eXpression) bioassay is a fast, sensitive and inexpensive tool for the analysis of a high number of samples, validation of new methods is urgently needed. In this study, a new method for the analysis of PCDD/Fs and dioxin-like PCBs in atmospheric deposition samples with the CALUX bioassay was developed, optimized and validated. The method consists of 4 steps: filtration, extraction, clean up and bioassay analysis. To avoid the use of large amounts of toxic solvents, new techniques were used for filtration and extraction: a C18 filter was used instead of a liquid/liquid extraction and an Accelerated Solvent Extractor (ASE) was used instead of the traditional soxhlet extraction. After pre-oxidation of the sample extract, clean up was done using a multi-layer silica gel column coupled to a carbon column. The PCDD/F and PCB fractions were finally analyzed with the H1L7.5c1 and/or the H1L6.1c3 mouse hepatoma cell lines. The limit of quantification was 1.4pg CALUX-BEQm(-2)d(-1) for the PCBs and 5.6pgCALUX-BEQm(-2)d(-1) for the PCDD/Fs, when using the new sensitive H1L7.5c1 cell line. The GC-HRMS recovery for all PCDD/F congeners was between 55% and 112%, with a mean recovery of 90%. CALUX recoveries of spiked procedural blanks were between the accepted ranges of 80-120%. Repeatability and reproducibility were satisfactory and no interferences from metals were detected. The first results from the Flemish measurement program showed good correlation between CALUX and GC-HRMS.

Laboratory and field validation of a combined NO2-SO2 Radiello passive sampler.

A combined NO2-SO2 Radiello radial-type diffusive sampler was validated under controlled laboratory conditions and compared with NO2-SO2 results of 3 other type of samplers in a field comparison at two locations Ghent-Mariakerke and Borgerhout in Flanders. Laboratory exposures at different temperatures (-5, 10 and 30 degrees C) and relative humidities (0, 50 and 80% RH) in combination with varying concentration levels and exposure times were carried out, with a focus on extreme conditions. Concentration level and exposure time were changed together following suppliers linear working range of samplers and assuring absolute amounts of compounds on the sampler corresponding to those of environmental levels. The average uptake rate for NO2 for 24 hour exposures at 10 degrees C and 50% RH and tested concentration levels (+/-73, 146 and 293 ppb NO2) was 0.076 +/- 0.011 ng ppb(-1) min(-1). Uptake rates during all experiments were lower than the uptake rate given in the instruction manual of the sampler. A significant effect of temperature and relative humidity on NO2 uptake rate was observed. The temperature effect from 10 to 30 degrees C corresponds to the temperature effect given by the supplier of the samplers. High relative humidity (70 to 80%) caused a strong non-reproducible decrease of uptake rate for NO2 at 24 hour experiments but this effect was not observed at longer exposures except for the tests at -5 degrees C. At the tested temperature below zero in combination with high relative humidity the sampler showed anomalous behaviour for NO2. The possible effect of concentration level and exposure time for NO2 needs further research. The average uptake rate for SO2 calculated from all exposures is 0.478 +/- 0.075 ng of sulfate ion each ppb min of SO2 and accords to suppliers uptake rate. No clear effects of temperature, relative humidity or concentration level/exposure time on the uptake rate for SO2 were found, partly due to the large scatter of results. Although NO2 accuracy of Radiello samplers was better during field campaigns than during laboratory validation, IVL and OGAWA samplers gave better results for NO2. In the field, IVL samplers showed best agreement with the continuous analyzers for both NO2 and SO2.

Sulphite and sulphate concentrations in weathering products of sandy limestone and in deposition samples.

The sulphite and sulphate concentrations in weathering products of limestone and in wet and total deposition samples were measured by the modified West-Gaeke method and by ion chromatography. The sulphite content in the weathering crust and in the runoff rainwater of two historical buildings in Belgium, was always much lower than the sulphate content. The maximum sulphite to sulphate ratio was 2.5%. The sulphite concentration in wet and total deposition samples was in the low or sub ppm range except during two misty periods when the sulphite concentration was 6.8 and 21 mg litre(-1). In those samples a high sulphate concentration was also found (nl. 57 and 137 mg litre(-1), respectively).

Dietary selenium intake in Belgium for different population groups at risk for deficiency.

An estimation of the dietary selenium intake in different population groups in Belgium has been carried out. 24 h duplicate meals and food consumption statistics combined with concentration levels in different foods, as determined by hydride generation atomic absorption spectrometry, are used. Dietary intake of selenium is low to very low, especially for vegetarians (12.7 +/- 9.1 micrograms) and patients on long-term total parenteral nutrition (1.2 +/- 0.8 microgram). The different intakes are discussed and compared with intakes published for other countries, while the importance of bioavailability of the selenium in food in the risk of deficiency is stressed.

Daily intake of selenium by bottle-fed infants in Belgium.

The selenium content of commercial infant formulae, processed milk and beikost was measured by hydride generation atomic absorption spectrometry after previous wet acid digestion. The median daily intake by infants (1-6 months) fed milk, soya or cereal-based infant formulae was 3.0-7.8 micrograms/day; lower than the mean daily intake by Belgian breast-fed infants (6.1-8.6 micrograms/day) and cow's milk bottle-fed infants (7.6-10.8 micrograms/day).

Trace elements in human milk, selenium a case study.

Longitudinal changes of the trace element (Fe, Cu, Zn, Mn, Mo, Cr, Co, As, Se) composition of human milk are discussed. The mean daily intake of breast fed infants is compared with the intake of infants fed cow's milk and with recommended dietary allowances. Parameters which can be used to check the selenium status are discussed. Clinical consequences of selenium deficiency are discussed.

Longitudinal study of the selenium content in human breast milk in Belgium.

The selenium content of expressed human milk obtained at different stages of lactation from 32 lactating mothers was measured by hydride generation atomic absorption spectrometry after previous wet acid digestion. The highest selenium level was found in colostrum (14.8 ng/g; wet weight), subsequently the content declined and plateaued off after one month (9.4 ng/g; wet weight). The daily selenium intake for Belgian infants of 3 months of age was found to be 7.1 micrograms (girls) and 8.1 micrograms (boys), which is lower than the values obtained in most other countries and lower than the recommended safe and adequate daily intake of 10 to 40 micrograms/day for the same age group.