SQL script

Hi guys,

I am running out of ideas on how to exclude records with letters in between right after dots like below.

when i run the following script 

select mmatter ,SUBSTRING (mmatter,8,8),LEN(SUBSTRING (mmatter,8,8)) from matter where mmatter like '%F%'

i get :-

019032.F0003F00035
019032.F0010F00105
019032.F0011F00115  

The script i am working on feeds a table and it is suppose to exclude those numbers with letters in between. The letters could be from A to Z. Please help. thanks.