Q.1 THP 1 cell is a suspension cell and recommended seeding density for 6 well plate is 5×105 cells/ml. So, If I add 2ml/well the overall cell number will increase by double (2 times of 5×105 cells/ml)?
Am I right? Please Correct me if I am wrong?
Q.2 If a compounds (X) concentration is recommended 20 μM, and I add 1 ml of media containing 20 μM of the ‘X’ / well the conc. is 20 μM only, but if I add 2 mL with 20 μM conc. of ‘X’, the overall conc will increase. Isn’t it?
Dear Dr. Moumita Saha
Q.1 THP 1 cell is a suspension cell and recommended seeding density for 6 well plate is 5×105 cells/ml. So, If I add 2ml/well the overall cell number will increase by double (2 times of 5×105 cells/ml)?
Yes, you are right. The cell number will be doubled (1 x 10^6).
Q.2 If a compounds (X) concentration is recommended 20 μM, and I add 1 ml of media containing 20 μM of the ‘X’ / well the conc. is 20 μM only, but if I add 2 mL with 20 μM conc. of ‘X’, the overall conc will increase. Isn’t it?
No, you are incorrect. This calculation is different from the above question.
2ml of media containing 20μM of 'X' will be diluted to half. So the concentration of compound 'X' in 2ml will be 10μM. Therefore, 1ml of media containing 20μM conc. of ‘X’ will be more concentrated than 2ml of media containing 20μM conc. of ‘X’.
The addition of more media, will reduce the overall concentration as the moles of solute (compound ‘X’) remain unchanged.
The concentration of the solute is determined as the number of moles of solute dissolved in the media. So, if the solute solubility in the media is more, more amount of solute will be dissolved in the same amount of media, and as a result, the concentration will increase. In this particular case, you are adding more media with the number of moles of the solute remaining the same. So naturally the concentration of compound ‘X’ will decrease and not increase.
Regards,
Malcolm Nobre
