Volatile MeHg can be on-line ethylated by passing through a 0.45 µm Millex-HA filter impregnated with 50 µL of NaBEt4 (1% in Milli-Q water), then trapped on Tenex trap and analyzed by thermally desorbed-GC-AFS [45]. Gaseous MeHg can also be sampled by refluxing mist chamber ...