removing the activated chemical test pad from the sealed package while said {HEAD ~ plastic packet} remains within {TAIL ~ the sealed package} 
remains within
removing the activated chemical test pad from the sealed package while said { HEAD ~ plastic packet } remains within { TAIL ~ the sealed package }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL