I would use a regular expression: 
while (<DATAFILE>) {
   unless (m{^(.*?)\s*,([\d:]+)}) {
       warn "$.: unrecognizable line: $_";
       next;
   }
   my $data = $1;
   my $time = $2;
   # ... continue processing ...
}
# output follows:
__END__
1.4567,11:00:00
1.4571,11:00:01
3: unrecognizable line:             ,             
1.4567,11:58:00
5: unrecognizable line: 1.4566 , 
1.5555,11:43:00
7: unrecognizable line:

[download]

Note, the regular expression is very liberal in what it will accept which is the way I like to do things. You can make it more exacting if you find it necessary.

In reply to Re: dealing with whitespace and using chop when reading delimited files by pc88mxer
in thread dealing with whitespace and using chop when reading delimited files by Conal

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