{TAIL ~ Process} and {HEAD ~ catalyst} for determining nitrogen in a sample according to the Kjeldahl principle 
{ TAIL ~ Process } and { HEAD ~ catalyst } for determining nitrogen in a sample according to the Kjeldahl principle
TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH