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A convenient method has been developed for the separation and determination of beeswax in propolis from beehives located in the Netherlands. The method is based on differences in specific density and involves the adding of water and microwave heating of a propolis sample. After cooling to room temperature, the resulting three phase system provides a full separation of the beeswax from the propolis in the upper layer. This layer can easily be collected to quantify the authentic beeswax content of the raw propolis sample. Confirmation of the identity of beeswax isolated from propolis with this procedure, was obtained using Near Infrared Spectroscopy (NIR).

Restricted access media (RAM) columns in the column mode and column switching (LC/LC) configuration represent a powerful approach for the analysis of acidic compounds in water samples with high levels of organic matter. This was gleaned from a study aimed at determining their performance in decreasing the humic acid interference in the trace analysis of acidic herbicides in water samples during the use of reversed-phase liquid chromatography with UV detection. The use of RAM columns permits the development of a rapid, sensitive and selective multiresidue procedure for the screening of a heterogeneous group of acidic herbicides.

This study investigated the potential of restricted access media (RAM) columns used as a first column in coupled-column LC hyphenated to thermospray tandem mass spectrometry (LC/LC-TSP/MS/MS) for the fast, selective, and sensitive determination of target drugs in serum samples. Because of their wide range in polarity, salbutamol and clenbuterol were chosen as model compounds and representatives of the class of [[Beta].sub.2]-agonists. Three types of RAM columns were tested: (i) Pinkerton ISRP (internal surface reversed phase, 5 [[micro]meter]), (ii) SPS (semipermeable surface, 5 [[micro]meter] C18), and (iii) RP-18 ADS (alkyl-diol silica, 25 [[micro]meter]). A 3-[[micro]meter] C18 column (50 mm x 4.6 mm i.d.) was chosen as the second column. Tandem mass spectrometric detection was carried out in the selected reaction monitoring (one parent[right arrow]one daughter) mode. With regard to retention and, moreover, the peak elution volume of the analytes, the ISRP material was found to perform best: a 50-mm x 4.6-mm i.d. ISRP column in combination with a 100% aqueous buffer (pH of 7.0 [+ or -] 0.2) allowed the injection of large volumes (up to 200 [[micro]liter]) of sample without additional band broadening of the analytes and provided sufficient preseparation between analytes and large-molecule serum constituents. Under the selected conditions, both analytes could be determined in serum samples up to a limit of quantification (LOQ) of 0.5 ng/mL, with a sample throughput of 7 and 5 [h.sup.-1] for salbutamol and clenbuterol, respectively. Method validation was carried out by analyzing, in the course of several days, calf and human serum samples spiked with the analytes. In the case of salbutamol, the overall recovery from serum samples spiked at levels between 0.5 and 50 ppb (n = 33) was 103.4%, with a repeatability of 12.7% and reproducibility of 14.3%. The overall recovery for clenbuterol was 99.6% (n = 15, spiked level 0.5-5 ppb), with a repeatability of 15.2% and reproducibility of 16.4%. The adopted LC/LC-TSP/MS/MS analyzer appeared to be very robust under the selected conditions, and, after the period of analysis involving the processing of more than 100 mL of serum, neither loss of chromatographic performance nor pressure increase of columns or of the interface was observed.

The Operational Priority Substances (OPS) model is part of the European Union System for the Evaluation of Substances (EUSES) and is used to estimate air concentrations and atmospheric depositions for risk assessment of chemicals. Traditionally, EUSES assesses environmental exposure using a standardized scenario based on explicit assumptions and default parameter settings. Under the new European Union REACH legislation-which stands for Registration, Evaluation, Authorisation, and restriction of Chemicals-industry is responsible for the risk assessment of chemicals. The current work investigates the potential impact and importance of source parameter refinement on the emission distribution and environmental fate of chemicals as modelled by OPS. In total, 60 scenarios with different combinations of (non) default values for emission heat content, emission source height, and emission source radius, were run for a typical particle-bound substance. Increasing heat content and emission source height reduced the modelled air concentrations and depositions and caused maximum air concentrations to occur further away from the emission source. Results show that estimated air concentrations and total depositions used for risk assessment can become more realistic by using more site-specific emission source parameters. This article proposes risk assessment refinement options and provides recommendations on future updates of EUSES. [ABSTRACT FROM AUTHOR]

Liquid chromatography coupled to tandem mass spectrometry with a triple quadrupole analyser was used to determine selected (medium) polar organic pollutants- isoproturon, diuron and pentachlorophenol, as the herbicides simazine, atrazine, terbuthilazine, alachlor, and metolachlor- in treated water from urban solid-waste leachates. Two millilitres of water was preconcentrated by on-line trace enrichment (solid-phase extraction liquid chromatography) which allowed rapid analysis, but still with a satisfactory sensitivity, as the limits of quantification were 0. 05 µg L-1, while the limits of detection were in the range of 0. 001-0. 01 µg L-1. Confirmation of the identity of compounds was ensured by the use of two tandem mass spectrometry transitions. Moreover, a study of matrix effects was thoroughly investigated by applying the developed procedure to different ground and surface waters. A simple dilution of the water sample with high-performance-liquid-chromatography-grade water was sufficient to minimize and/or remove this undesirable effect in all water samples tested, this approach being feasible due to the excellent sensitivity of the method. [ABSTRACT FROM AUTHOR]

Focuses on the development of column switching in liquid chromatography (LC) in many configurations. Discrimination of precolumn switching from coupled-column; Packing of precolumns with materials of larger particle size; Evidence of the high separation power of the analytical column of LC.

The bioavailability of polycyclic aromatic hydrocarbons (PAHs) for earthworms (Eisenia andrei) was experimentally determined in seven field-polluted soils and 15 soil--sediment mixtures. The pore-water concentration of most PAHs was higher than predicted. However, most of the compound was associated with dissolved organic carbon (DOC) and not directly available for uptake by earthworms. The apparent sorption could be reasonably predicted on the basis of interactions with DOC; however, the biota-soil accumulation factors (BSAFs) for earthworms were up to two orders of magnitude lower than predicted by equilibrium partitioning. The large variability between sites was not fully explained by differences in sorption. Experimental results indicate that the pool of freely dissolved PAHs in the pore water became partially depleted because of uptake by the earthworms and that bioaccumulation is thus also influenced by the kinetics of PAH desorption and mass transport. A pilot study with Lumbricus rubellus showed that steady-state body residues were well correlated to E. andrei. Current results show that depositing dredge spoil on land may lead to increased bioavailability of the lower-molecular-weight PAHs. However, risk assessment can conservatively rely on equilibrium partitioning, but accurate prediction requires quantification of the kinetics of bioavailability. [ABSTRACT FROM AUTHOR]