The 28-year-old clocked his fastest time of 2012 in Geneva at the start of the month, winning the B final in 45.47seconds, but he's still to duck under the A standard for London 2012.
While Tobin is still chasing that landmark, Martyn Rooney, Conrad Williams, Nigel Levine and Luke Lennon-Ford have all achieved it, giving them a sizeable advantage ahead of this weekend's Aviva 2012 Trials.
Tobin may have to make do with a spot in the 4x400m relay - no slap in the face with the GB quartet set to contend the medals - having been part of the foursome that finished fourth at Beijing 2008 as well as the team that won world silver in 2009 and European silver in 2010.
But Tobin is determined to secure his shot at individual glory at London, as well as a relay berth.
"It is frustrating that I didn't quite make the qualifying time in Geneva, it would have been nice to get it out of the way and then solely focus on my performance at the trials," he said.
"But my fastest times this year are coming down by a big margin every time I race so I believe it is coming, I just can't afford to lose too much ground on my rivals.
"There is a lot of competition for places and that does bode well for the relay, I think we will have a very strong relay team but I do want to get an individual spot. I've done the individual at some major events before but it's in the relays where my medals have come.
"At the start of the season I was finding that I just wasn't going out quick enough but I'm beginning to get that part of the race right now and so it's about building up the strength to be able to keep going to the line."