I am not chemist but you can try to find noc code here.
http://www23.statcan.gc.ca/imdb/p3VD.pl?Function=getVD&TVD=122372&CVD=122376&CPV=2211&CST=01012011&CLV=4&MLV=4
Your job title may be little different but for correct NOC code Make sure that your work experience's Job duties and responsibilities matches with that NOC code.