Hi professor Goacher, Thank you for sharing the video. I am just wondering if in real samples, do we use calibration curve at all? Because I think most samples have complex matrix. Can you please give an example where we would use calibration curve over standard addition?
would be able to help me clear my doubts that what factors decide the type of calibration either linear or logit calibration? and also what determines number of standards required for an assay calibration?
The wording isn't always clear when something is called a control. In biological and medical experiments in particular, the control is something that doesn't have the affect-so no treatment or no drug. In that way, the control is kind of like a blank. But in analytical chemistry, the blank does not contain the analyte while control solutions contain the analyte in a known quantity. Therefore the blank provides information about the background and the control is used for checking if your method produces the right concentration of analyte. I hope that makes sense and answers your question.
Hi Anantharaj, if you expect a linear response based on the physics of the measurement (such as for Beer's law in UV-visible absorbance spectroscopy) then you should not fit to a quadratic curve. There are some measurements where quadratic curves are appropriate (such as the atomic absorbance or AA of some elements). I think it is important that you have replicate samples at each concentration before you decide to use a quadratic equation, since you do not want to over-fit noise in the data. I hope that helps.
@@AnantharajJack I am not an expert in phthalates in GC-MS but in general the GC-MS peak area should be linear with intensity. I recommend that you check that you are using peak area instead of peak height (area is better since the later-eluting peaks in chromatography become wider). Then I suggest that you check whether your data is linear if you use only lower concentrations. You might be saturating the detector at high concentrations which will lead the calibration curve to flatten out. If you can look up existing methods and literature on this particular analyte in GC-MS that can also provide guidance, but my instinct is that your results should be linear, not quadratic.
@@robyngoacher8521so, linear curve is good for quantification to get reliable concentration. I understand that. But if I use quadratic curve, will there be much deviation in the final results?!!
Jongsky Jongsky criticizes my speech habits as annoying. This user has fallen to the habit of criticizing people online who are offering help for free. It's annoying. We are both people and I would hope for more politeness.
Robyn Goacher I did say you have good content right? But dropping voice and modulating from normal to course while lowering volume is a habit of most. Sometimes the end is unintelligible. But dont get me wrong. Its not personal. Its called constructive criticism. Its not my habit to criticize. Your the first actually. Maybe the last. Hope you continue making content like this but much more better audio. Criticism is part of everyday life and it makes things improve providing its not personal. Thank you
