I should use TGA by applying the same temperature programme employed for biomass but I would like to know if microalgae decomposition (especially at high temperature, 200-900) could give some issues (i.e. high amount of H2 released)
What do you want to measure with loss on ignition using muffle furnace? If you want proximate measurement of organic matter, than you need to filter known volume of Spirulina culture on preweighed glass fibre filter and dry overnight at 100C, weigh and combust in muffle furnace at 550 for around 2 hours until you get black powder on filter, re-weigh on precision balance, the difference in weights before and after will give you an estimated organic matter. But for C analysis in muffle furnace you need to calculate correlation coefficient with some other methods, like biotector where C is analysed by wet combustion method. Usually C content of obtained by LOI in muffle furnace is 40-50% of organic matter at 550C.
moisture content can be obtained by- heating weighed amount (approximate 1.0 g) of sample between 105- 110 deg centigrade for 1 hr in silica crucible and then cooling to RT and taking Weight difference and its %. then heating (for 7 min)same sample to 760 deg centigrade keeping it closed with lid and finally getting the weight of ash combust completely ?(open the lid for air)and get % of ash. add all three and deduct from 100 to get fixed carbon content.