$parser = new SmalotPdfParserParser();
    $pdf    = $parser->parseFile('publication.pdf');

    $text = $pdf->getText();
    echo $text;

    $pattern = '/ECO-[.-^*-]{3,}| ECO-[.-^*-]{4,}sb[NMB]b|ECO-[.-^*-]{4,}sUP| ECO-[.-^*-]{3,}sUPs[B-N-M]{1}| ECO-[.-^*-]{3,}sRX/' ;
    preg_match_all($pattern, $text, $array);

    echo "<hr>";
    print_r($array);

Array ( [0] => Array ( [0] => ECO-698 [1] => ECO-CHI-522 [2]