Loss on Ignition (LOI) Testing

What is Loss on Ignition?

Loss on Ignition is a wet chemical analysis method used in inorganic analytical chemistry, and it describes the process of measuring the weight change of a sample after it has been heated to high temperature causing some of its content to burn or to volatilise. The method involves 'igniting' the sample at a specified temperature to allow the volatile substances in the sample material to escape until the mass of the sample no longer changes. This process is usually performed in air, but can also be performed in other inert or reactive atmospheres. The volatile materials lost during the analysis usually consist of water and carbon dioxide from carbonates. In environmental monitoring, LOI testing are widely employed to measure the organic content in samples such as soil, cement, sludge and waste. The volatiles lost during the analysis usually consist of water (e.g. hydrates) and carbon dioxide from carbonates. In addition, it can be used as a quality control test to ensure that volatile organics have been removed from the sample. At BOC Sciences, our LOI testing service can provide various specimens to be ashed, monitored and recorded over a wide temperature range of 50 to 1000°C. Our experts monitor the weight change of the sample during the heating process and determine the content of organic substances in various materials such as sediment, sludge, soil and waste. In addition, inorganic materials such as cement, lime, calcined bauxite and refractory materials can also be tested by ignition on loss.

Figure 1. Median and range of LOI of 5 samples of the 'mixed sediment' exposed to 550 °C. (Oliver, H.; et al. 2001)

Application of LOI Testing for Soil Organic Carbon Determination

Soils are made up of minerals, organisms, water and more organic matter. Soil productivity is influenced by the organic matter content. In agricultural soils, high organic matter helps improve the water holding capacity, increases the soil's ability to withstand pH changes, and provides nutrients for the soil's organisms. Therefore, monitoring soil organic matter can help guide soil management in agriculture, and using the LOI method to determine the quality of soil organic matter is a useful procedure

LOI Testing Services

LOI Testing Process

• Firstly, the sample is placed into a crucible and weighed
• The sample is then placed into a drying oven to dry the sample material
• After cooling, the crucible is re-weighed and the difference is the moisture content of the sample
• The sample is then ignited for the necessary length of time
• After cooling, the crucible is weighed again and the difference between this weight and the dry weight is the organic content

LOI Calculation

Loss on Ignition of a sample is reported as the elemental or oxide analysis of the mineral. It is calculated by comparing the weight of the sample before and after it has been subjected to high temperatures during ignition. The loss on ignition calculation represents the amount of organic matter in the sample.

LOI Testing Equipment

• Flat bottom crucible-suitable for ignition at 550°C; made of nickel, porcelain, silica, or platinum
• Muffle furnace-capable of maintaining a temperature of (550 ± 25)°C
• Desiccator-with active drying agent, such as silica gel
• Analytical balance-with an accuracy of 1 mg or better

Figure 2. Loss-on-ignition, magnetic susceptibility and 14C dating results. (Saarse, L.; et al. 2009)

BOC Sciences' LOI Testing Features

• High performance and ease of operation of equipment instruments
• Advanced accuracy and integrity of measurements
• Automatic determination of moisture and ash values