Bethany Firth set a world best in the SM14 200m individual medley twice in one day at the British Para-Swimming International Meet in Glasgow.
The 19-year-old swimmer set a time of two minutes 22.67 seconds in the heats, beating the old record by 1.43 seconds.
Firth, from Northern Ireland, improved her time to 2:22.14 in the final.
Among the other Britons who achieved the World Championship qualifying marks on Friday were Ollie Hynd in the SM8 200m individual medley.
|Swimmers to achieve World Championship qualifying times|
|Bethany Firth (SB14 100m breaststroke, SM14 200m medley)|
|Claire Cashmore (SB8 100m breaststroke)|
|Hannah Russell (S13 100m freestyle)|
|Scott Quin (SB14 100m breaststroke)|
|Ollie Hynd (SM8 200m medley)|
|Ellie Simmonds (SM6 200m medley)|
|Sascha Kindred (SM6 200m medley)|
|Hannah Russell (S12 50m freestyle)|
|Jack Thomas (SM14 200m medley)|
Hynd, 20, won Commonwealth Games gold in the Tollcross pool last summer.
"I've got some good memories of this pool from last summer. It's a pool I like and I enjoy racing here," he said.
"It is always a stressful time around trials to hit the times you need but doing it this morning took the pressure off. It would have been nice to swim faster this evening but that's life."
Also securing qualifying times were Ellie Simmonds (SM6 200m medley), Sascha Kindred (SM6 200m medley), Hannah Russell (S12 50m freestyle) and Jack Thomas (SM14 200m medley).