低温烘干土壤对金属结果的影响

应助达人

国标一般说是自然阴干，或者冷冻干燥。
现在烘干箱现在也有广泛使用，但没看到环境相关法规提及烘干温度。
美国环保署 方法200.7 11.3章节对金属总量样品处理有提及：“For the determination of total recoverable analytes in solid samples,
mix the sample thoroughly and transfer a portion (>20 g) to tared
weighing dish, weigh the sample and record the wet weight (WW).
(For samples with <35% moisture a 20 g portion is sufficient. For
samples with moisture >35% a larger aliquot 50-100 g is required.) Dry
the sample to a constant weight at 60?C and record the dry weight
(DW) for calculation of percent solids (Section 12.6). (The sample is
dried at 60?C to prevent the loss of mercury and other possible volatile
metallic compounds, to facilitate sieving, and to ready the sample for
grinding.) ”

所以认为除了汞外，其他金属60°应该没问题，至于65°的使用影响未见有相关法规文件。

章节12.6：“Note: If the data user, program or laboratory requires that the reportedpercent solids be determined by drying at 105°C, repeat the procedure given in200.7-37Section 11.3 using a separate portion (>20 g) of the sample and dry to constantweight at 103-105°C.”

7.6节：7.8 Standard Stock Solutions - Stock standards may be purchased or preparedfrom ultra-high purity grade chemicals (99.99-99.999% pure). All compoundsmust be dried for one hour at 105°C, unless otherwise specified. It isrecommended that stock solutions be stored in FEP bottles. Replace stockstandards when succeeding dilutions for preparation of calibration standardscannot be verified.

所以认为除汞外105°左右好像也可以，但说的不是很清楚，我国环境标准这方面我没有找到相关法规说温度的，通常都是说自然阴干