By Anonymous on Monday, May 24, 1999 - 11:42 am:
While I troubleshoot this, maybe someone here can save me time! I'm running a oxynaphthoic acid anilide sample on a photo-diode array Waters system. At the beginning and end of the sample peaks, the sample spectra is exhibiting negative spikes. This is the first I've seen of this. MP is 55% ACN/43% H2O/2% THF (H2O and THF are prepped as a 5% THF soln). The samples are prepped in THF. Inj vol's are usually < 5 uL. Column is Waters C18 Novapak, 3.9x150 mm. And flow is 1 mL/min. With negative spikes, there are no peak purity results or library matches. Any suggestions? TIA.
By Anonymous on Saturday, June 19, 1999 - 02:24 am:
Rerefence Waters manual 022378 - Guide to successful operation of your LC system.
I think the reason you are seeing the negative peaks is that your sample eluent is absorbing.
Try using a sample eluent which is similar to the mobile phase for the analysis. The negative peaks should disappear.
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