This method is intended for determination of basic nitrogen in gases in the range of 0.05 to several hundred weight parts per million. It can be used for liquefied gases, such as stabilizer gas and polymerization unit feed stocks; also for gases such as hydrogen recycle gas from catalytic hydrotreating units. A titrimetric analysis used for samples containing more than 3 wt-ppm nitrogen determines the sum of ammonia and amines. A spectrophotometric analysis used below 3 wt-ppm nitrogen determines only ammonia.