Drc e icp ms

Nicotine in both the XAD-7 and solid surface samples was analyzed with an Agilent Model 7890 Gas Chromatograph (GC) coupled to an Agilent Model 5975C Mass Selective Detector (Agilent Technologies, Santa Clara, CA, USA). The XAD-7 and solid surface extracts were analyzed following ISO 16200-1 [48 ]. PG and glycerol in both the XAD-7 and solid surface samples were analyzed with an Agilent Model 6890 GC equipped with a Flame Ionization Detector. The XAD-7 and solid surface extracts were analyzed following ISO 16200-1 [48 ]. VOCs were analyzed with an Agilent Technologies Model 6890, GC equipped with a 5973 Mass Selective Detector (ISO 16000-6) [49 ]. Carbonyls were analyzed with an Agilent Model 1100 High Performance Liquid Chromatograph with a DAD-UV detector operated at 365 nm (ISO-16000-3) [50 ]. Selected trace elements were determined by Inductively Coupled Plasma-Mass Spectrometry with a Perkin Elmer DRC-e ICP-MS (EPA IO-2.1 and 3.5) [51 ,52 ]. All results for RAS are given as μg/m³. The limit of quantification (LOQ) for each compound is shown in Table 1. Results for surface samples are given as μg/cm².

To determine the Se content in egg yolks, the egg yolk samples were freeze-dried (Labconco Free Zone plus 6, Kansas, MO, USA) at −50 °C for 72 h and ground to a powder [61 (link),62 (link)]. Briefly, approximately 0.5 g egg yolk or tissue was digested in 5 mL of concentrated HNO₃ (Sigma-Aldrich, St. Louis, MO, USA) and 3 mL H₂O₂ (EMSURE^® ISO, Merck, Darmstadt, Germany). Then, the digest was diluted with deionized water to a final volume of 10 mL. The Se concentration was determined using a Perkin Elmer DRC-e ICP-MS with calibrations performed every 20 samples.

In January of 2017 during a field work in the Salar de Huasco National Park (Chilean Altiplano), water and sediment samples were taken from five different sites (previously described by Dorador et al., 2008 (link)). The Salar area is known for its heterogeneity, considering spatially as well as biodiversity and physicochemical characteristics. This ecosystem is mostly composed of streams, salt crusts, peatlands and shallow (permanent and non-permanent) lakes with a salinity gradient from north to south (H0 to H5; Dorador et al., 2008 (link)). Physicochemical parameters like temperature, salinity and pH were recorded in situ (HI 98192 and HI 2211 - HANNA Instruments). Total arsenic concentration was determined by the INQUISAL-CONICET service (San Luis, Argentina), through an ELAN DRC-e ICP-MS (PerkinElmer^®) following the ASTM “American Society for Testing and Materials” standard methods (TMECC: 04.12-B and 04.14).