Anala normapur

N-hexane (≥95 %, PESTINORM®), acetone (Anala® NORMAPUR) and 2-propanol (Anala® NORMAPUR) were purchased as solvents from VWR Chemicals (Vienna, Austria). Ultra-pure water was obtained from a water purification system (Milli-Q gradient A 10, Milipore, Merck, Darmstadt, Germany). Norit® SAE SUPER (Cabot Norit Nederland B.V., Klazienaveen, The Netherlands) was used as activated carbon powder. Grade 50 filter paper was purchased from Whatman (GE Heathcare, Dassel, Germany). Copper wire (0.6 mm thickness) was from HSB Elektro (Uslar, Germany). DEHP (analytical standard) and DEHP-d4 (Pestanal®, analytical standard) were purchased from Merck (Darmstadt, Germany). DEHP and DEHP-d4 stock standards (each 5000 μg mL⁻¹) were prepared in 2-propanol. From these working standards of DEHP (50 μg mL⁻¹ and 500 μg mL⁻¹) and DEHP-d4 (50 μg mL⁻¹) were made in 2-propanol. All standards were stored at 4 °C in dark in amber brown glass vials closed with caps equipped with teflon septa. A 1 mM potassium chloride (KCl) solution was used as background solution to stabilise the ionic strength. PVC pellets were purchased from Industrie Generali spa (Samarate, Italy) and contained ∼35 % of DEHP. Each leaching or spiking experiment was conducted in triplicates, including three blanks.

Before analysis via Liaison^® XL, free urine cortisol was extracted by mixing 2 mL of urine with 4 mL of methylene chloride (≥99.5% (v/v) stabilized, Anala^® NORMAPUR^® for analyses, VWR) for 5 min. A total of 2 mL of organic solvent was then evaporated to dryness under nitrogen. The dry residue was solubilized with 400 μL of the assay buffer provided by Diasorin [2 ] before cortisol quantification using the Liaison^® XL immunoassay. The intra-day and inter-day precision and bias of the method are within recommended specifications [2 ,10 ,11 ,12 ].