He played for Assam at different age-levels such as Under-14, Under-16 and Under-19, before making his first-class debut in 2008.
In November 2014, Purkayastha returned to the Assam team during the 2014–15 Vijay Hazare Trophy.
In his first match of the Ranji Trophy of the season, he picked no wickets.
This bowling performance gave Assam an innings win and was his first ten-wicket haul for which he won the man of the match award.
[2] In his fourth match of the season, he picked 5/69 and 6/76 against Goa at Porvorim.