Mystery peak

[domino1]

Hi all,

Another question.

We have been seeing a peak in our blank injections on many systems, columns, water, ACN etc.

The spectrum is above. Does anyone recognize what it might be?

Just thought I would throw it out there and see if anyone might recognize it. We don't have any spectral libraries here.

Thanks,

Domino

[syx]

Domino, though DAD could give us sufficient data to recognize a substance through its spectra it is still having weakness. In fact, there are substances which could give same spectra. So, we could not give any answer to your simple question.

[Bryan Evans]

Just some very general thoughts:

1. Any change to your glassware washing
procedure (i.e. new detergant, new machines, ect.)

2. Have you confirmed that your water purification system
is still operating within spec (TOC, pH, conductivity, ect.)

[HW Mueller]

Do all the ghosts you see give this same spectrum?

[domino1]

We just started to go through old data to look at previous ghost peaks. This is when we found the connection.

The problem is that some people used bottled water, some Milli-Q. We also have tried rinsing glassware just in case it was detergent, but that has not fixed it. Also, people have been using different brands of acetonitrile.

I thought maybe we were leaching something from the pH meter probes, but in one case, the probe never entered the mobile phase.

Does anyone know of a spectra database where I could search to find a matching footprint? I know it will be hard since all I have are the two maximas.

Thanks again,

Lisa.

[Basil]

Hi domino1,

UV depends on amount, mobil phase (ph, solvent) .... I thought that will not be possible to identify using spectra database, or also as syx said you could find more than one.

We would need more details on mobile phase,... salt or any acid or base to adjust pH.....

[DR]

I wouldn't waste time figuring out what it is. Figure out the source and just get rid of it.

[domino1]

Agreed. It just seems that we have changed out everything and still it appears.

It is possible that it is a reminant from something that has been run on all of the systems. Passivation may be our only hope.

Thanks again. Just wanted to know if it stood out as obvious to anyone.

Domino