He was elected to the Sejm on 25 September 2005, getting 9767 votes in 40 Koszalin district, as a candidate from the Civic Platform list.

He was listed on the flight manifest[1] of the Tupolev Tu-154 of the 36th Special Aviation Regiment carrying the President of Poland Lech Kaczyński which crashed near Smolensk-North airport near Pechersk near Smolensk, Russia, on 10 April 2010, killing all on board.

On 16 April 2010, Karpinuk was posthumously awarded the Commander's Cross of the Order of Polonia Restituta.

He attended the Mikolaj Kopernik secondary school in Kolobrzeg and studied law in Gdańsk.

Until his death, he lived for many years in a block of apartments at Waska street in Kolobrzeg.