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UCL Home  /  Geography  /  Resources  /  Laboratory  /  Laboratory Methods  /  Lake Sediment Analysis  /  Loss on Ignition

Loss on Ignition

The percentage weight lost on ignition gives a crude measure of the organic content of the sediment. Generally, percentage loss on ignition values show an inverse relationship with percentage dry weight values.

Equipment

Clean, dry porcelain crucibles, spatula, balance weighing to 4 decimal places, furnace set to 550°C, desiccator.

Procedure

The dried (overnight at 105°C) sediment samples in crucibles are placed in the furnace and kept at 550°C for 2 hours. It is easier to pack the furnace (it will take up to 80 samples) when it is cold in which case a further ¾ hour should be allowed for heating up. After 2 hours the furnace door should be opened to allow some of the heat to disperse before removing the crucibles with long-handled tongs and placing them on an asbestos mat. When they have cooled slightly they should be placed in a desiccator and allowed to cool fully before re-weighing. The percentage of the dry weight lost on ignition can then be calculated. The remaining ash sample may then be used for carbonate analysis.