The sequence quality in a raw sequence file can be determined using FastQC.
Run FastQC (on macOS) or the "run_fastqc" script in the FastQC folder (on Windows).
Open a sequence file (for instance the "rnaseq-test1.fq.gz" file).
Command: File > Open...
Results: The "Overexpressed Sequences" pane shows sequences that are likely to be adapter sequences from the sequencing reactions.
Comments: matthias.wilm@ucd.ie
.