Purdy's time of one minute 22.10 seconds wasn't up to his personal standards, but he was satisfied with the technical aspects of his swim.
"The speed wasn't there," said the 34-year-old, who returned to competitive swimming last season after an eight-year absence. "Technically I am doing a lot of different things in my stroke."
Added the three-time Paralympian: "The mindset I've now got is to get into controlled, efficient swimming. It takes a little bit more time. The sets I have been working on is to try to make sure that I've got what I need for when I need to have it."
Montreal's Aurelie Rivard finished the meet by winning the S10 100 freestyle in 1:01.51 and placed second in the S10 100 backstroke in 1:21.95, leaving her feeling confident heading into the summer.
"This sets me up very well and I'm really looking forward to a great summer," said Rivard.
Nathan Stein of Maple Ridge, B.C., won the S10 100 freestyle in 54.08 seconds.
Danial Murphy of Bedford, N.S., had a productive meet, breaking three of his own Canadian records.
Murphy swim the S5 50 butterfly in 48.52, the 200 freestyle in 3:01.52 and the 100 freestyle in 1:27.62.
Canada's Para-swimmers will compete in two major international meets this summer — the IPC Swimming World Championships in Glasgow, Scotland, and the Toronto Parapan American Games.
The athletes selected to the world championships and nominated to Parapan Am Games team will be announced Monday.