When I weighing air-dried peat sampel that passed through 0.25mm sieve on microbalance, it seems like the sampel weight keep decreasing unstopable. First of all, I thought it was probably due to interference of room condition. So, I did some setting accordancely. It was good with tin foil (blank) and tin foil+oxide, but when I transferred peat sampel on top of the tin foil, it happened again! I tried another approach that of using tin capsule and closed the open ended capsule with clamp (sample preparation for volatile materials) and walla...successful! Do you think that the oxidation could have occured on my air-dried peat sampel?
What is happening is that the sample is loosing additional moisture to the room in which the scale resides. In order to get a permanent weight dry the samples overnight in an oven at 105 degrees Celsius then store them in an incubator.
What are you analyzing (carbon, hydrogen, nitrogen, sulfur)?
Yes, it makes sense, but do you think that the oven dried organic soil coulf affects it chemical composition? Even several studies used different approaches to dry their soil sample. 1st air-dried, 2nd oven dried (105oC) and 3rd is oven dried (60oC). So what is the best approach then?
It depends on your molecule of interest. Even acetic acid will volatize in a vacuum oven at 60 degrees Celsius. What are you trying to do? Many soils are analyzed 'as is' so some molecules will not adhere (be dried on) surface particles.
want to figure out the chemical properties of the sampel. My study related to soil carbon depletion, soil respiration and the changing the land use.
Soil respiration requires the sample be tested as is, since soil respiration is due to microbial activity (which would be killed by oven drying). You can always oven dry a portion and correct back to the dried level.
Yes, I couldnt agree with you more..perhaps we can always compare and correct with statistical analysis between those methods. Thank you Mr. Neagle on your time.
Marshall , you can defunc the soil respiration emerging on account of microbes and organic matter , by following the procedural steps while analysing the soil for international pipette method. A soil having digested all the carbon and reducing the microbial activity to almost zero , will be a better reflection of soil chemical properties than with organic matter plus related ecological issues..?
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