The analysis of the inorganic components is roughly divided in two parts: most cations are routinely measused with inductively coupled plasma (ICP), whereas mainly anionic nutrients are quantified with a segmented flow analyser.
With these analysers the nutrients are routinely measured in aqueous samples, such as surface and marine water, and in soil extracts. Both machines available (produced by Skalar, Breda, the Netherlands) are each adapted to its special purpose.
The first machine is a general-use analyser. It is able to measure (NO3+NO2), NO2, NH4, total dissolved N, PO4, SO4, and Cl. For most anions the measurement range falls within 10 to 2000 µmol/l, whereas the measurement range is lower for PO4 (0.2 to 16 µmol/l) and NO2 (2 to 70 µmol/l). The substrate is usually fresh water, but with some adaptations BaCl2- and K2SO4 extracts and saline samples can be analysed.
Our second and newer auto-analyser is dedicated to low concentrations of (NO3+NO2), NO2, NH4 and PO4. The measurement range of PO4 and NO2 is 0,1 to 1,0 µmol/l, for (NO3+NO2) it is 1 to 20 µmol/l and NH4 is quantified between 0.5 to 7 µmol/l . This analyser is fitted with detector-correction lines which allows the analyses of marine water samples. Out of range-samples can be diluted automatically.
Both systems are a segmented flow SAN++ auto-analyser manufactured by Skalar (Breda, the Netherlands).
Inductively Coupled Plasma (ICP) and Atomic Absorption Spectroscopy (AAS)
For the analysis of trace elements and heavy metals in acid digested soils or liquid samples.
Acid digestion of samples are typically performed with HNO3/ HCl with a microwave (Paar Physica Multiwave) or with HF/H2SO4 of soil or organic material
Perkin Elmer Optima 8000 Optical Emission Spectrometer with Perkin Elmer S10 autosampler (ICP-OES) and Perkin Elmer AAnalyst 400 (AAS) (Singapore).