Studies on an efficient method for determining ethyl carbamate in the workplace air

In relation to the proposal to introduce an occupational exposure limit value for ethyl carbamate (EC) in Poland, a need to develop a sensitive method for determination of this carcinogenic substance in the workplace air was emerged. In the presented paper, a new method for its determination by high-performance liquid chromatography (HPLC) with fluorescence detector (FLD) is proposed. The method is based on the adsorption of EC on the cellulose filter, its extraction with water, further reaction of EC with 9-xanthydrol in acidic solution. Determination of the obtained EC derivative (N-xanthyl ethyl carbamate) was then conducted in a reverse-phase system with acetonitrile and water mobile phase at a flow rate of 1 mL/min on an Ultra C18 column of 250 mm by HPLC–FLD. Measurement range of 0.1–2 µg/m³ for a 1440 L of air sample was appropriate to the established maximum admissible concentration value of 1 µg/m³. The limit of detection is 0.142 ng/mL, and the limit of quantification is 0.426 ng/mL, respectively. The developed quantitative method makes it possible to determine ethyl carbamate in workplace air, which in turn allows determining exposure indicators and facilitates occupational risk assessment for the employees.     

The assessment of environmental pollution caused by mining and metallurgy wastes from highly polluted post-industrial regions in Southern Poland

Stored metallurgy and mining wastes contain relatively high amounts of potentially toxic elements. To monitor the distribution of contaminants originating from dumps, the chemical and physical properties of the wastes must be characterised. In this study, the chemical properties of wastes deposited in two different locations in Southern Poland (Szklary and Zloty Stok) were evaluated. Heaps located in Zloty Stok contain wastes from gold mineralisation comprising arsenic while wastes in Szklary originate from a factory that produced an iron-nickel alloy. In Szklary the total concentrations of Ca, Mg, Fe, Zn, Mn, Cr, Co, Cu, Ni, Tl, Ag, Cd and Pb were determined, while in Zloty Stok also As is an important contaminant. To assess the risk of contamination of the surrounding environment and to select the proper method for removing the contaminants, information on the distribution of elements between operationally defined phases must be obtained. For this purpose, a six-step sequential extraction was used. The mobility of most elements in the wastes from Szklary and Zloty Stok was relatively low; however, the large amount of As, 40–180 mg L^?1, that could be released to environment in case of Zloty Stok was high. The results of fractionation studies indicated that Ag, Cd, Tl, Co, Cu, Cr, Pb, Zn and Mn may be released into environment under low pH and low redox potential conditions, which can be induced by bacterial activity.     

Cyclic and Dynamic Behavior of Sand–Rubber and Clay–Rubber Mixtures

Geotechnical and Geological Engineering - In this paper, the possibility of using fine scrap tyre rubber to improve the mechanical properties of soil subjected to cyclic loading is...