Kinetics of the base catalysed hydrolysis of methyl paraben revisited: Implications for determination of the effective volume of flow-microcalorimeters used to study cell cultures

Energy dissipation in early detection of cellular responses to metabolic challenges

“…The nominal volume flow rate in the peristaltic pump was adjusted so achieve an actual flow rate of 1.0 mL·min -1 . This adjustment was regularly checked, since flow rate variations affect various calorimetric parameters, such as the calibration constant (Leskiv et al, 2009), the effective volume of the calorimetric vessel (Bento et al, 2018; Leskiv et al, 2009) and the sensitivity (Garedew et al, 2004). Growth in the calorimetric set up was verified to be equivalent to that of a control cell culture (kept in an Erlenmeyer flask, under orbital stirring, inside an incubator, at 30 °C) until the end of the exponential phase, which was the period investigated in this work.…”

“…In order to assign the power dissipated by a cell culture to a specific cell number or biomass it is necessary to know the effective volume of the calorimetric cell (O’Neill et al, 2003), which differs from its physical volume since the flow of cell culture results in transport of heat away from the detection area. The effective volume of the LKB 10700-1 flow-through cell, V eff = 0.547±0.012 mL ( n = 4), under the temperature and volume flow rate conditions of the present experiments, was determined as recommended in the literature (O’Neill et al, 2003), using the kinetics of the base catalyzed hydrolysis of methyl paraben (Bento et al, 2018). The calculations also relied on the standard molar enthalpy of that reaction at 30 °C, kJ·mol -1 , proposed as benchmark (Bento et al, 2016).…”