<?php
$str = "AdGroup update failed: [AdGroupServiceError.DUPLICATE_ADGROUP_NAME @ operations[6].operand.name; trigger:'prince2 training west yorkshire', AdGroupServiceError.DUPLICATE_ADGROUP_NAME @ operations[8].operand.name; trigger:'prince ii training and exam']";
preg_match_all("/trigger:'(.*?)'/im",$str,$match);
print_r($match[1]);