Acquity FLR wavelength optimization and sensitivity

<p>We have a new FLR installed and are experiencing some start up issues.</p><p></p><p>Our analyte is an alkylated naphtalane.</p><p></p><p>I was wondering what the typical concentration is used to run a spectrum analysis? For this analyte we filled the standard flow cell of the FLR with a 0.1µg/l solution in acetonitrile. We were able to get a nice 3D spectrum using the lambda-lambda mode (see attachment). Analyses of a blank acetonitrile afterwards however showed a very similar spectrum. Is this due to an overload of the sample cell of the FLR, which is still not cleaned after being flushed withs several ml's acetonitrile?</p><p></p><p>My second question is about the "Spectrum scanning". In Empower we were unable to find how to perform a Spectrum scanning. Only 2D channel, 3D and the lambda-lambda mode are shown (see attachment).</p><p></p><p>My last question for now is: What typical sensitivity can I expect from UPLC-FLR analyses using a highly sensitive compound such as this alkylated naphtalene?</p><p></p><p>Thanks in advance for your answer.</p><p></p><p>Martien</p>


  • In addition to my question. I think it is not possible to perform the lambda-lambda scan without using the optional cuvette holder. The obtained FLR spectra (see attachment original message) contains emission wavelengths exactly 2x the excitation wavelengths. So this probably has to do with another fluorescence phenomena.

    What we did now is using a UV-Vis spectrophotometer to obtain the UV spectrum (ie excitation spectrum) and using the observed maxima we ran a 3D scan during a chromatographic method. From this we did obtain a fine emission wavelength spectrum, so now we are able to do 2D channel analyses.

    Yet, I am still curious what the answers to my other questions are.

    And what workflow is recommended to find the appropriate excitation and emission wavelengths of an "unknown"?