Chromatography Forum

hi

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In regulated labs, when preparing Standards the primary standards are prepared in duplicate and compared. if the comparison is not acceptable (eg response difference > 2%) they are not used. If they compare with in the desired criteria on of these will be used to prepare the calibration.

From this data you can monitor the quality of STD production and also identify operator variations.

Having a wide variation in curve equations could be down to poor STD preps or an unstable method.

One question I have is what exactly is your variation from day to day? You said it was large but didn't give any information regarding how large. How many curves do you have and over what time span? Has any sort of pattern developed over time? Have there been any changes in your system, lab, equipment, procedure or personnel? It could be something as simple as a pipettor wearing or it could be more involved.