>perl -wMstrict -le
"my $input = '12:00am, 5:00pm,8:30AM';
 while ($input =~ m/\W([1-9]|[01][0-2]|2[0-3]):[0-5][0-9][ap]m/gsi)
 {
         print qq{This is a valid time!\t$&};
 }
"
This is a valid time!    5:00pm
This is a valid time!   ,8:30AM