Arquin, a summer signing who played in the fourth tier of French football last term, chose the perfect moment to grab his first goal in Bulls colours in what was only his second substitute appearance.
In truth, the result was tough on League One Brentford who deserved better but have now been knocked off of the competition at the first hurdle for the seventh time in the last eight seasons.
Sam Saunders forced a save from Bulls keeper Adam Bartlett after just 39 seconds, an early sign of the visitors' dominance in the opening 45 minutes.
Clayton Donaldson, Shaleum Logan and Karleigh Osborne all went on to test Bartlett, who had to be at his best to keep the hosts on level terms at half-time.
It was left for Arquin to snatch the tie from six yards in injury time following good work on the byline from Joe Colbeck, leaving Brentford's giantkilling over Everton last season a distant memory.
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