Interlaboratory Study of Sample Homogeneity Impact on CHNS, Water, and ICP Analysis of Biomass Liquefaction Oils

Five biomass liquefaction oils (BLOs)
comprising four
different
lignocellulosic fast pyrolysis bio-oils (FPBO) and one algae-derived
hydrothermal liquefaction (HTL) biocrude were subject to an interlaboratory
study (ILS). Participating laboratories were asked to analyze all
BLOs after gentle sample mixing and again but with vigorous mixing.
Blind duplicates were included to improve the statistical power. Requested
analysis included CHN, water, trace nitrogen, and sulfur (using solvent-miscible
solvents) and ICP by an independently developed method. Blind duplicates
applied in this study indicated that representative sampling was achieved
to the extent required for bulk composition analysis. More vigorous
sample mixing did not yield benefits for precision or reproducibility
for composition analysis; however, the importance of consistent and
precise sample mixing is underscored. Results of CHN and water showed
performance similar to those of previous studies. However, adapted
trace nitrogen methods consistently report 25–50% lower nitrogen
content compared to ASTM D5291 and highlight the need for reconciliation.
Poor performance of ICP across eight participant laboratories further
underscores the need for standardization. ICP sample preparation by
dissolution is generally ineffective for the recovery of more recalcitrant
multivalent analytes. Digestion is recommended as the sample preparation
of choice for ICP analysis of BLOs.