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More method validation

Question asked by megaflorch on May 29, 2019
Latest reply on May 29, 2019 by megaflorch

I have a question related to my previous question of the last three weeks. To review, I am working on method development for analysis of solvents used in vapor degreasing. My starting solutions are all 99.9% purity. To me, this translates out to 99.9%=999000 ug/g. Before, I used 100g +/- 0.001g of each compound and combined them into one mixture. Combining them in this way caused my previous calibration method to quarter every sample, thereby not allowing a higher quantitation than 25.0%. I tried to create a calibration curve by creating each calibration level with one component per level instead of four components per level, even by entering in each area, level, and response factor in my calibration table, it would not link the like compounds into a viable curve. So, if I take instead 100g of each compound and combine them together ( resulting in a 25.0% limit), could I take less, like 100000 ug, effectively 10.0% in terms of purity, and call that 100% and create my curve based on this. Another idea I had is to weigh out exactly the amount for each component that reflects the upper limit of quantitation, e.g. weigh out 999000ug/g of component 1 to DCM 1000 ug, 999900ug/g of component 2 to DCM 100g, etc to refect the exact weight/percentage. This is a problem, however, since each sample vial is approximately 2000000ug. Perhaps if I made one reference standard for each 2 compounds, that might work.....but then I would need one curve for each standard in the mixture. Or create a four component mixture, dilute that down to 100000 ug, call that 100% and then dilute every  testing sample 1:10. Any feedback is appreciated!!

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