It could be due to a number of factors, including contamination of the samples, improper sample handling, or instrumentation issues. Contamination of the samples could be from a variety of sources, such as the lab environment, the sample collection and handling process, or the sample itself. Improper sample handling could include issues such as not following proper protocols for sample preparation and extraction, or not properly accounting for sample losses during the process. Lastly, instrumentation issues could include not properly calibrating or maintaining the instrument, as well as potential issues with the instrument’s calibration curve. It is important to consider all of these potential sources of error when attempting to determine the cause of the high procedural blanks.

Thank you very much Peter for your answer! Well i thought that if was a lab contamination problem, i would have had samples not lower than blanks. The insteument works well, good linearity, repeatability, no carry-over problems between injections…could be maybe due to a different matrix? Because my blanks are with no samples or with sediments >63 um in which i suppose not to find fragrances.