For some compounds, probe position may give a great influence to sensitivity. If the probe position is out of place, sensitivity fluctuation may become large.
When the optimum probe position largely shifts, the ESI spray state may be deteriorated. Check around the nozle.

 

«Corrective Actions»

By FIA (without column) analysis, find a best position by moving the scale left or right by 0.5 scale using the default position as a reference.
When the scale is moved in the direction of arrow, the ESI probe moves in the direction away from the DL.

As the flow rate increases, move the ESI probe farther away from the DL.

[Reference] 0.2 to 0.5ml/min: -1 to +2 mm
                   1ml/min or more +3 mm