For in-process and on-line measurements of heavy metal content in industrial samples there is no time
for special and time consuming laboratory-type sample preparation.
All sample preparation must be done continuously in one step:
In SEIBOLD on line analysers this most important step is achieved by using our unique and proprietary reagents (buffers and dye).
- Interference influences must be eliminated.
- Oxidation stages have to be taken into account (or separated and excluded).
- Complexes have to be destroyed to free the heavy metal ions for measurement.
- Suspended particles must become dissolved again (or separated and excluded).
- Total Iron Fe(2+/3+) Analyser.
How is the term TOTAL HEAVY METAL defined?
Total heavy metal content is the sum of both dissolved and suspended heavy metals in all oxidation
stages in the water.
What has to be measured depends on the industrial needs and regulations where limit
and target values are very clear specified. In some industries the most important is free heavy metal form
because of its greater mobility and biological activity. Suspended heavy metal particles are typically
previously removed by special filters.
Therefore content of dissolved heavy metals is always part of the
total heavy metal amount.
What do SEIBOLD on-line analysers measure?
Clear samples containing dissolved heavy metals can be analysed immediately by SEIBOLD analysers
without any pre-treatment step. The reason for this is that SEIBOLD development strategy is based on the
chelate complex formation, the complexometric reaction between heavy metals and an organic ligand.
Stability of such chelate complex is very high comparing to stability complexes of heavy metals
with the following organic ligands acetate, citric acid, dimethylglyoxime, EDTA, glycine,
hydroxyquinoline, oxalate, salycilic acid, tartaric acid, thiourea, triethanolamine.
SEIBOLD unique and proprietary buffer has a very important role for chelate complex formation.
It contains chemical compounds that release heavy metals from its labile complexes and prepare them
for binding to a dye with strong complex stability. Such formed complexes are stable over hours, even days.
What are the requirements for accurate sample measurement?
Heavy metal analysis is accurate only when the sample is truly representative of the solution
Therefore, the importance of sampling and sample handling prior to delivery to the
analyser is of great importance for reliable results. Sample must fully represent the substance to be
Once sample is taken for analysis chemical and biological reactions can occur changing the sample composition.
Sample analysis must be as fast as possible without sample preservation.
The only requirements for on line heavy metal analysis are that sample must be homogenized without
suspended solids and no turbidity and no colour. Filtration at the time of sample will reduce these
negative influences. For special purposes acidic pre-treatment and heating of the sample is done by
SEIBOLD process analysers continuously in order to dissolve resistant particles.
Special tasks need special on-line analysers:
- COMPOSER for Cr (III) and Cr (VI), exclusive and total.
- COMPOSER for Fe (II) only, for fish farming.
- COMPOSER for total Cu and Cu particles, for industrial waste water.
- COMPOSER for total Cyanide, free Cyanide and Weak Acid Dissociable Cyanide (WAD CN).