Any planning of analytical procedures should be based on the goals and scope of the study. The following critical steps in an analytical process can be listed: problem definition and formulation of analytical objectives; set­up of an analytical plan; sampling; sample transport and storage; sample pretreatment; analytical determination; data calculation; evaluation of re­sults to see if the objectives are achieved.

It is apparently clear from this list that the actual analytical determina­tion is just one step among the others and sometimes could not even be the crucial one. Moreover, preparation of the samples, pretreatment and evaluation of data could be more demanding or at least time-consuming. Since in catalytic transformation of lignocellulosic biomass often wood or various streams from pulping are used as raw materials, a special atten­tion should be devoted to sampling. Inappropriate sampling could under­mine the value of the whole study, therefore it should be carefully planned. Sampling and sample storage is important since samples may be altered or destroyed due to temperature, light, presence of oxygen, humidity, en­zymes or microbes (bacteria, fungi, etc.). For instance, enzymatic and mi­crobiological attack can happen for samples of fresh wood, wet pulp and paper, sludge, process waters and effluents, while polyunsaturated extrac­tives like abietic acid could be subjected to oxidation.