HPLC Products

Autosampler Problems - Run time errors

You have to put your hand up for these! If the autosampler is sending the start signals and therefore effectively controlling the system, it must have a longer run time than you give the data system or the gradient controller etc. Otherwise it will make an injection before other devices are ready, and if they are not looking for a start signal, the sample will be injected but nothing will take any notice. Vial 1 will be processed correctly, vial 2 will be injected but ignored, vial 3 will be injected but processed as vial 2 etc.

If the system is controlled totally from a PC, which looks for a ready signal from all devices before giving the green light for an injection, then this does not apply. But otherwise, allow a longer run time on the autosampler. Remember for a gradient run, the gradient time will be much longer than the data system run time, because it must allow for returning to the starting conditions and re-equilibrating. The autosampler must wait till this is complete. Injection before the system is re-equilibrated will give variable retention times, and hence dodgy peak identification and quantitation.

Vial range errors arise if the samples are not placed in the vial range which is programmed into the autosampler. Its an easy mistake, but it fools the autosampler. If an autosampler reaches a blank space with no vial it will usually stop and report an error. If the cap is not fiited (I know its crazy, but people do!) sometimes the autosampler will notice this and stop anyway, reporting a vial error.