20.500.12556/RUL-179688 Systematic errors in isothermal titration calorimetry the role of feedback power and effects of mixing and diffusion on concentrations Using experiments based on the NaCl dilution calibration method, we examine several previously unstudied instrumental effects that can lead to systematic errors in isothermal titration calorimetry (ITC). We confirm earlier results that power feedback can affect estimated heats and find further that it can also affect cell temperature and introduce temperature “noise.” To estimate effects from loss of titrant from the syringe through diffusion, and concentration changes in the cell from mixing with the overflow volume, we conduct experiments with injections separated by time intervals Δt from 8 to 60 min, giving run durations from 6 h to over 2 days. Because the effects are small, we have developed a global least-squares fitting algorithm to analyze 20 datasets simultaneously, from which three parameters governing diffusion and mixing (“leakage”) are estimated, along with calibration parameters for heat and cell volume. Expressed as an effective volume loss from the syringe, Δv$_{dif}$ is found to be of order ∼0.03 μL per injection for NaCl into water. Its effect is predicted to be negligible in many ITC applications. The effects from leakage are more significant but their neglect is still predicted to affect both NaCl calibration and 1:1 binding results by ∼1 %, which is marginally significant for calibration but seldom so for 1:1 binding. The calibration results for the cell volume V$_0$ are particularly sensitive to temperature and to the literature source for the relative molar enthalpy function for NaCl(aq). isothermal titration calorimetry calibration diffusion and mixing NaCl dilution feedback power control global least-squares analysis izotermna titracijska kalorimetrija kalibracija difuzija in mešanje redčenje NaCl kontrola povratne moči globalna analiza z metodo najmanjših kvadratov true false true Angleški jezik Slovenski jezik Članek v reviji 2026-02-20 11:11:24 2026-02-20 11:11:26 2026-02-21 04:40:47 0000-00-00 00:00:00 2026 0 0 7 str. Vol. 709, art. 116010 Feb. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 536.6 0003-2697 10.1016/j.ab.2025.116010 263754243 RAZ_Medos_Ziga_2026.pdf RAZ_Medos_Ziga_2026.pdf 1 8232AC0D93CE90D1320B077466EF8D44 86a454dc4a8bff1b6f9367c51341032dbdc1fee4e4fd95f0dde080a41bae888e ccebbf10-0e44-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=228465 https://www.sciencedirect.com/science/article/pii/S0003269725002490 1 431d0cdb-0e44-11f1-a1ba-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=228464 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0