The right answers to frequently asked questions
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General Questions regarding Sample Submission, Ordering & Sample Shipment & Results can be found here:
What kind of quality control do you perform?
All ready-to-load libraries received are subject to a quality and quantity control to accurately determine the appropriate sequencing dilution and achieve optimal cluster densities.
What should I do if my sample fails the entry QC?
If the amount, concentration or quality of the ready-to-sequence library does not meet the requirements for further sample processing, we will contact you to discuss how to go on with the project. Whenever possible, Eurofins Genomics will make recommendations for optimisation of sample quality.
Do you guarantee a certain number of reads?
The actual achieved sequencing output (read length, read quality and number of reads) is directly correlated with the quality of the sequencing library used. Eurofins Genomics cannot give any guarantees for sequencing data resulting from ready-to-load libraries prepared by the customer. If unsatisfactory sequencing results are due to technical problems with the sequencing kits or machines, the sequencing will be repeated at no additional cost to the customer.
Is the sorting of the reads included?
Raw data sorting according to Illumina Index read is included. Used index type (single-indexed or dual-indexed) and corresponding index sequences have to be provided prior to project start.
Raw data sorting according to customer specific tags at read start can be offered at additional costs. We highly recommend to avoid the “in-line” barcoding strategy and use the Illumina index system instead (i.e. the barcodes are read in a separate read and do not interfere with cluster registration). It is important to ensure that the base composition of the indices is balanced to optimise the ability of the image analysis software to distinguish signals.
What steps are taken to increase sequencing quality?
Illumina cluster detection algorithms are optimized around a balanced representation of A, T, G, and C nucleotides. Any divergence from equal base distribution will negatively influence the amount and quality of sequencing data produced. To increase the library nucleotide balance a spike-in of 20% PhiX will be used for samples with low diversity or unbalanced base composition (e.g., amplicons, bisulfite converted samples). The extent to which the negative impact of the unbalanced base composition will be reduced by spiking the PhiX control depends on individual sample and sequence characteristics. For more information please refer to the Illumina website.