I understand that my Internal Standard gets added to all samples/calibration standards/blanks. Does my surrogate also get added to ALL samples/calibration standards/blanks or just to samples?

Standard Methods for the Examination of Water and Wastewater 22nd edition, suggests using a surrogate and internal standard size of 10ng/L each, but on the surrogate it says higher concentrations can be used.

It has been suggested to us in the past that the Internal Standard be at a higher level also to make it easier to find.

My calibration standards of Geosmin/MIB are 5ng/L, 10ng/L, 20ng/L, 50ng/L, 100ng/L, and 200ng/L.

I know my LFM and LFB are going to be 50ng/L, should I make my Internal
Standard (IBMP) and Surrogate (IPMP) around 50ng/L or 100ng/L or between the two at 75ng/L?

Advice and suggestions welcome.

I also have a question regarding how accurate my calibration curve standards are going to be...following the directions in Standard Methods, going from my stock solution to my working solution for each standard is easy by diluting the 1ml of stock standard with 9ml methanol in a volumetric flask, which creates a 1:10 working standard solution, and then also going from the working standard solution to the calibration standard solution, I would dilute 45 microliters of my working standard solution with methanol, bringing it up to volume again in a volumetric flask, which makes my calibration standard solutions.

However, after that, to make my calibration curve standards, it says to add various volumes of my calibration standard solution to 45ml of DI water...well obviously, there isn't a 45ml volumetric flask available, so approximately how accurate can I expect my calibration curve standards to be when doing the dilutions in a graduated cylinder?