use strict;
use warnings;

my @array1 = (
    'abc abc abc abc abc',
    'abc abc abc2 abc3 abc4 abc5',
    'abc abc abc1 abc2',
    );
my @array2;

for (@array1) {
    push @array2, $_;
    $array2[-1] =~ s/\s+//g;
}

print "@array2";

##</code><code>##

abcabcabcabcabc abcabcabc2abc3abc4abc5 abcabcabc1abc2