while(<DATA>){
        chomp(); #optional
        #s/[^\w\.\,\-]//g;
        tr /0-9.-e ,//dc; #another possibility..
	my ($field1, $field2) = (split /[\s,]+/)[0,1];
	print "\"$field1\"\t\"$field2\"\n";
}
__DATA__
"-0.500, 4.502e-6"
"-0.499, 4.474e-6"
"-0.498, 4.458e-6"
"-0.497, 4.445e-6"
"-0.496, 4.433e-6"
"-0.495, 4.421e-6"