Racing at the Paavo Nurmi Games, he executed a strong opening three quarters of the race before clipping Antti Sainio in the lane outside him and losing his stride.
Chalmers cruised in and clocked 51.22s.
The Continental Tour race in Turku was won by Estonia’s Rasmus Magu in 48.42s.
There was also disappointment for Ireland’s Thomas Barr, another chasing the standard, when he finished fourth in 49.46s.
Chalmers now moves on to Switzerland for the ATLETICAGENEVE meeting on Saturday, before competing in the UK Athletics Championships on Saturday 29 and Sunday 30 June.
At the Boysen Memorial at the Bislett stadium in Norway, sprinter Abi Galpin continued her step up to the 400m in style.
She finished fourth with a new island record of 54.74s, lowering her previous best of 54.96s set in April.
The race was won by Gunta Vaicule in 53.18s.
