The suction probes with cups made of open-grained, hydrophile polyethylene structure and ployamid diaphragm (pore size 0.45 µm) have been specially developed for the detection of heavy metals in the soil water. These are absorbed at the ceramic  surfaces  leading  to a falsification of the heavy metal concentration in the sample. PE and polyamid do not absorb heavy metals so that the heavy metal concentration in the soil is trans- ferred into the sampling vessel cleanly.  The  higher  permeability of the plastic cups compared to the ceramics also permits larger sample quantities to be taken in a shorter period.

The acrylic glass standpipe (Ø 25 mm) serves as collector. This means that the suction probe can be used completely autonomous- ly and the soil solution is stored at the natural ambient conditions.

A  separate  sampling  vessel  can be  connected  without  problem. By separating the feed and vacu- um line, the percolate cannot be drawn back by the soil moisture tension. The suction cups are also available without standpipe for underground installation.

The PE tube is then laid under- ground from the suction cup to the site of sampling so as to gua- rantee the storage of the sample at ambient conditions which are as natural as possible.

Advantages

• no influence on heavy metal concentration
• can be operated autonomously
• percolate cannot flow back
• sample stored at soil temperature