thats just to bad.. I really hope the rest will survive!
That bit of air is probably the problem! I dont know how you did the whole sugarwater, peroxide thing, but I read a guide that I really think is a good guard against contamination, here is how it goes:
1. Put the seeds in 5% sugarwater in a small cup or glass, cover and leave for 12 hours or so.
2. Tak out your syringe and suck up as many seeds as you would like to sow (without the syringe).
3. Hold the syringe with the top pointing upwards (the seeds should be on the bottom - if not reverse) and push out as much sugarwater as possible.
4. Now suck up aprox 3 ml. peroxide. Now you need to get all bubbles out, you do this first of all by tapping the syringe, then you put your finger on the tip of the syringe (still without needle!!) and compress the peroxide and then make a vacuum (watch out it could spray out or suck in alot of air if you are not carefull!) do this a couple pf times till all bubbles are completely gone.
5. Leave the seeds in the peroxide for about ½ hour, and then puch out most of the peroxide, you can leave a bit behind (it will just turn into water and oxygen in the jar/flask)
6. Now you put on the needle and push until a bit of peroxide sprays out.
7. Disinfect the silicone plug in the lid of your jar/flask with alcohol and push the needle through, push out as many seeds as you like and tilt the jar/flask a bit to get the seeds dispersed.
8. Pull out the syringe and seal the silicone plug with a bit of silicone or tape.
In this way I think you are prety sure the seeds won't get contaminated when sowing. - At least I hope cause that's what I'm going to do :P
Christian