10 Techniques for fast large-volume sampling of total gaseous mercury (TGM) in the air 11 and extracting the TGM with 5 mL acid solution were developed for stable mercury 12 isotope ratio measurements. A Big gold coated sand Trap (BAuT), a 45 mm i.d. × 300 13 mm length quartz tube containing 131 times more gold coated silica than a conventional 14 gold trap has, was used for the collection of a large amount of TGM from the air. The 15 collected TGM was then extracted by 5 mL reversed aqua resia in a 2L Tedler bag, and 16 the extract was analyzed by a cold-vapor generator coupled with a multi collector 17 inductively coupled plasma mass spectrometer for the isotopic compositions. The 18 sampling tests of BAuT showed 99.9% or higher collection efficiency during the 19 sampling time of 1-24 h under the flow rate of 20-100 L min-1. Recovery tests of the 20 bag extraction using 100 ng of NIST SRM 8610 exhibited nearly 100% of recovery 21 yields and agreement of the measured five stable mercury isotope ratios with the 22 reference values within 2  of uncertainty when using the trapping solution of 40% 23 reversed aqua resia with the extraction time of a day. The overall methodology tested in 24 the pilot field and laboratory studies demonstrated the successful analysis, promising 25 highly precise stable mercury isotopic data with the time resolution less than a day. Part 26 of the procedure can be automated, ideal for unmanned sampling at a remote site.