Trace 1310

Organic acids in urine were measured in a routine workflow of a clinical Biochemical Genetics laboratory (Department of Laboratory Medicine, Cliniques universitaires St Luc, UCLouvain, Brussels, Belgium). Briefly, urine was acidified by addition of hydrochloric acid and was extracted three times with ethyl acetate. The pooled organic phase was dried down under nitrogen flow, and organic acids were trimethylsilylated and analyzed by gas chromatography–mass spectrometry (ThermoScientific, Trace 1310) using an Agilent CP-Sil 8 CB-MS 30 m x 0.25 mm x 0.25 μm capillary column (43 ).

To determine the PAHs, the soil samples were extracted by means of a Soxhlet extractor. In brief, 10 ± 0.05 g of soil was mixed with 10 g of sodium sulfate anhydrous and then placed into a cellulose thimble. Thus, the soil samples were dived in an acetone–hexane mixture (1 + 1, v/v) at 140 °C for 60 min. After, the soil samples were washed with the solvent mixture vapors for 60 min. The extraction solvent was then recovered and dried under a gentle flow of nitrogen in a fume hood. Analytes were then recovered with 1.0 mL of n-hexane and an appropriate volume of the experimentally determined internal standard (octacosane, C₂₈H₅₈) was added. Then, 1 μL was injected into the gas chromatograph-mass spectrometer (gas chromatograph, Trace 1310, equipped with a triple quadrupole mass spectrometer, QqQ, 7000D, Agilent Technologies, Santa Clara, CA, USA) for the analysis. Quantification was carried out by means of calibration curves. Calibration curves were prepared by diluting a standard solution of PAHs in methanol/dichloromethane (1 + 1 v/v) (Certified Reference Material, CAPChem Ltd., Belgium). The chemical analyses were carried out in triplicate.