The exception is for detection around the minimum detection limit MDL where noise may interfere with a peak. If you cannot get the data system to integrate automatically correctly then change either the method, or the data system Adjusting the automatic detection parameters in a method to ensure good integration is an essential part of method development and is not considered manual integration. Parameter adjustments for individual chromatograms may be necessary when you are using the full dynamic range of the chromatograph as peaks at either end of the dynamic range may require different parameters for correct detection of the start and stop of a peak.
The important thing to remember is that in any analysis, the analyst, manager, and lab, as a whole, are responsible for the results. That means that the integration has to be performed properly, and the lab needs to be prepared to defend it to the powers that be quality assurance, client, regulatory agent, etc.
The reason I say this is that I've seen labs that insist on using autointegration because it's more reproducible, even though the conditions are not always set to give suitable integration. My personal viewpoint is: The risk is that people carrying out manual integration choosing peaks manually in individual samples will be biased perhaps unconsciously by their expectations and may influence peak areas up or down in samples they expect to be higher or lower.
Document number Document name For module Language Revision Vanquish Pumps. Vanquish Autosamplers. Vanquish Detectors. Vanquish Column Compartments. Vanquish Fraction Collector. Vanquish Charger. Related resources. Learning center subtopics Liquid Chromatography Information. Alternatively, the vertical distance from the baseline is measured for each segment.
When a certain number of points in a row, for example, 5 or 10, show an increasing trend, the peak measurement is started. Figure 1. The top of the peak is determined by taking the first derivative of the peak height for each successive segment.
When this value goes to zero, it is an indication that the sequence of measurements, or the slope, is going from an increasing series to a decreasing one as the top of the peak is crossed.
The retention time is determined at this point, and the peak height is assigned to the segment with the largest height. As a side note, the retention time, or highest point in the peak, usually is ahead of the centre of mass of the peak, because most HPLC peaks tend to tail a bit. Well there are some complications. One is shown at the right, where a drifting baseline is observed. Integration has to be consistent and defensible. If it is covered by your SOPs, follow them.
If you suspect that there are abuses via manual integration and there is no SOP covering this, maybe it's time to suggest one. Thanks, DR. Certainly, in bioanalysis peak for FDA submission reintegration is permitted. However a full written justification is required in each case and the result has to be signed off by the lab manager.
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