If you are only concerned about the leading and trailing whitespace in the 4th field, I suggest the following (or something similar):

  my @record = split( /,/);
  my $field4 = $record[3];
  $field4 =~ /^\s*//;
  $field4 =~ /\s*$//;
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I know that this isn't exactly a sophisticated regex but we are only working with one field. This is still faster than performing the replacement on all fields, I'm sure.

Mick