Robotics & Automation
Sample preparation is the most important part of the laboratory process. To improve the reliability of this process Ultra Trace has installed a Robotic sample preparation cell. This is the first of its kind in the world capable of preparing large samples (3-4Kg) in a single stage mix and grind operation.
The cell utilises two robots feeding six Labtech-ESSA LM5 mills which have been modified by Ultra Trace so that the bowls can be removed.
The process is as follows:
The first robot takes a clean bowl and puck from a holding rack and places it in one of two infeed stations. The empty bowl and puck are weighed.
The operator enters the number of the next sample to be pulverised into the computer. The samples must be prepared in a pre-determined order and the operator is not prompted for the next sample to enter. This means that he must read the sample number from the sample bag and if the number he enters is not the next in sequence, the sample cannot be loaded into the bowl. This ensures that samples are prepared in order and mix-ups cannot occur.
The bowl, puck and sample are reweighed so that the sample weight can be determined. The robot returns the bowl, puck and sample to the holding rack.
The second robot takes the bowl, puck and sample and places it in the next available mill. Mills are loaded and unloaded in a sequential manner. The bowl lid is clamped in place and the sample is pulverised for a period of time based on the weight of sample. On completion of pulverising the lid is removed and air blast cleaned.
The second robot then removes the bowl, puck and sample from the mill and moves to the wash station where the puck is removed from the bowl. The puck is tipped on its side to any sample that may be resting on the puck surface falls back into the bowl and the puck is then washed with near boiling water.
The bowl and sample are then transported to the sampling station where a mid-stream .analysis. pulp (approx 300 g) is taken. The pulp feeds into a 8x4 paper packet and the residue feeds into a UV stabilised plastic bag. Both pulp and residue packets are barcode labelled at this point which eliminates the possibility of mis-labelling of samples. The plastic bag containing the excess pulverised sample is heat sealed for secure long term storage. All sub-sampler surfaces are air-blast and air-pulse cleaned to eliminate sample cross contamination.
The second robot takes the empty bowl to the wash station where it is also washed with near boiling water. The clean bowl and puck are then collected by the first robot and returned to the holding rack.
The major benefits of this system are:
- Operators work in a cleaner, safer environment.
- Possibility of switching of samples during preparation is eliminated.
- More consistent product from preparation because pulverising time is dependant on sample weight.
- Less cross contamination of samples because pucks and bowls are washed with very hot water rather than just air blast cleaned.
- Operator visually inspects the pulveriser bowl for cleanliness before the next sample is placed in it.
- All samples are bar-coded to ensure sample identity during analytical processing.
- Uses pulverising technology that is tried and proven. The robotic cell is an adaptation of existing technology rather than adoption of a new pulverising technique.