Determination of nutrients in seawater by segmented–flow analysis with higher analysis rate and reduced interference on ammonia

A microbore continuous-flow analyser was used to determine ammonia, nitrite, nitrate and phosphate in seawater. Ninety samples per hour were measured by optimizing the hydraulic conditions and using a cadmium coil for nitrate reduction. The analysis range was extended and the detection limit was reduced by using two analytical ranges with automatic range-changing. Interference from magnesium on ammonia was investigated and reduced by using a different complexing agent. The results correlated well with a Japanese reference method.