use Modern::Perl;
use Text::CSV;

my @Sample_Ids_m;
my $csv = Text::CSV->new( { binary => 1 } )    # should set binary attribute.
  or die "Cannot use CSV: " . Text::CSV->error_diag();


while ( my $row = $csv->getline(*DATA) ) {
    push @Sample_Ids_m, $row->[6];            # Element 6 is the ID
}

say for @Sample_Ids_m;                         # Print the collected IDs

__DATA__
John Doe,G building,05-Aug-2012,08-Aug-2012,"New York City, NY",ABC2345,UCD23467, 
John Moe,H building,05-Aug-2012,08-Aug-2012,New York City,DEF2345,UCD80645,
John Slo,I building,05-Aug-2012,08-Aug-2012,New York City,GHI2345,UCD76765,
John Hor,j building,05-Aug-2012,08-Aug-2012,New York City,JKL2345,UCD87111,

##</code><code>##

UCD23467
UCD80645
UCD76765
UCD87111

##</code><code>##

use Modern::Perl;
use Text::CSV;

my @Sample_Ids_m;
my $csv = Text::CSV->new( { binary => 1 } )    # should set binary attribute.
  or die "Cannot use CSV: " . Text::CSV->error_diag();

open my $fh, "<", "Merged_CSVfiles.csv" or die "Merged_CSVfiles.csv: $!";
while ( my $row = $csv->getline($fh) ) {

    push @Sample_Ids_m, $row->[16];            # Element 16 is the ID
}
$csv->eof or $csv->error_diag();
close $fh;

say for @Sample_Ids_m;                         # Print the collected IDs