firstyearpostgrad

Thank you CharonY. I am using UV as my detection system. So as my internal standard I would use a homologue of salicylic acid or can it be anything that elutes from the column at a different time and can be distinguished from the salicylic acid. Then whatever does elute off at the expected time of salicylic acid and has the correct properties is how much has been produced by the plant due to the infection (I get this by using my caliberation curve made from known standards)? Your explanation is so clear and pretty sure I understand now. Thank you!

Hi, I am trying to quantify SA in infected leaf tissue. However, as I am new to this type of work I am a little confused as to the use of an internal standard. I am spiking all my samples with a known amount of pure SA so that I can eliminate variations between injected samples. So, I have two questions: 1) How do I calculate the percentage recovery of my SA from my samples to test how efficient my extraction procedure is? 2) If all my samples (plant extracts) are spiked with pure SA, how is this showing how much SA is produced by the plant following infection - Am I not just measuring the SA that was spiked in? If anyone can help that would be great as I am very confused! Thanks in advance.