Sample inhomogeneity:

It must be remembered that the probable contamination during dissolution and at the workplace is the most significant source of error in the analysis of trace elements and must be prevented. Contamination might come from the air, from the skin of the subject/ sample collector and additives, reagents used in the analysis, as well as parts of instrumentation involving glass or plastic wares. Biological materials of human and plant origin must be handled along with extreme care because of sample inhomogeneity especially for trace element analysis. Body fluids like as blood, viscera, urine, etc. In further required stabilization and homogenization so as to prevent occurrence of any changes in their composition, prior to actual analysis. That is also advisable to remain the total number of transfers to a minimum, and to use accessories that were made of non-wettable and inert materials.