how to split a non-fixed size string

Hi Guys

I have a lots of user account SIDs string like , what i want is to get the string between the first " and the first"," symbol

$string = "S-1-5-XXXXX-XXXXX-XXXX-XXXX,CN=contoso,CN=com"

for simplicity , i need to get the S-1-5-xxx-xxxx-xxxx-xxxx from the $string , how can i achieve this ?