Abstract: The present invention relates to a computer implemented method for controlling a fluid coupling network (170), the fluid coupling network (170) being configured to be fluidly couplable to bioreactor (110), a gas source (120), a buffer source (140), a waste port (150), a processing system (160) and a conduit reservoir (208), the fluid coupling network (170) comprising a barrier unit (220) configured to sterilely separate fluid paths within the fluid coupling network (170), the fluid coupling network (170) being controllable to sample the bioreactor (110), the method comprising obtaining (510) a fluid sample from the bioreactor (110), wherein the step of obtaining the fluid sample comprises controlling a flow of fluid from the bioreactor (110) via the conduit reservoir (208) and the fluid coupling network (170) to the waste port (150), to fill the conduit reservoir (208) with the fluid from the bioreactor (110), providing (530) the fluid sample, wherein the step of providing the fluid sample comprises to provid

Abstract: A method of preparing a liquid mixture of controlled pH including (i) one or more buffering species, (ii) an acid or alternatively a base, (iii) optionally a salt; and (iv) a solvent wherein the proportions of the different components ((I) to (iv)) of the mixture are concomitantly varied in such a way as to take into account of the interrelationship of the ionic strength and the pH of the mixture.