Miseq A base intensity signal is decreasing after 100cycles

[d00b]

After 100 cycles, A base intensity is drastically decreasing than other bases.
Is this chemistry issue? or optic issue? Miseq V2 500 cycles kit.
cluster denstiy 850-950 K/mm2.. PF is good.. Q30 is over 80%

This is same graph as above.


This is normal running.. intensity is not decreasing even after 200 cycles.. and higher intensity.


This is PhiX running.

[Bukowski]

There is a current chemistry alert out for Illumina MiSeq 500 and 600 cycle kits, however this doesn't look like the same presentation (alert just mentions reduced %Q30 in Read1 and Read2).

I'd contact [email protected] with the batch numbers of your reagents to see if they are impacted.

[pmiguel]

Doesn't look like anything to worry about to me. Final signal is higher than initial signal.

--
Phillip

[d00b]

Thank you so much. We just received another miseq new machine and we have a plan to compare two machines. After the lower Q30 with newer lot of V2 kit, every things are being skeptical.