Abstract
Average molecular weights of asphaltenes from Colombian Barrancabermeja asphalts were determined using freezing point depression and MALDI TOF methods. Asphaltenes from different sources were used: fresh Barrancabermeja asphalt and recovered asphalt of the same origin that had been used as paving during five years. The results obtained using both techniques are consistent and show that the average molecular weight of asphaltenes from fresh asphalt is lower than the weight of asphaltenes from recovered asphalts. The freezing point depression method using benzene as solvent proved to be reliable and accurate when the temperature changes are measured with an uncertainty of ±0.001 K. The matrix preparation for the MALDI TOF method was modified using silver trifluoroacetate as ionization promoter.
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References
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