title: An improved method to validate the relative humidity generation in sorption balances.
abstract: Sorption balances are instruments in which samples are weighed as they are exposed to a programmed relative humidity (RH). Such instruments are used to measure sorption isotherms and to study solid-vapour interaction. There are different methods to validate the performance of the RH generation in such instruments by charging them with saturated salt solutions and ramping/stepping the RH past the deliquescence RH of the salts. In this paper, an improved approach to perform validation is presented, where the RH is kept stepwise constant at a quasi-randomly chosen set of RH-values above and below the deliquescence RH. From the rates of change of mass as a function of RH, it is possible to calculate the RH at which deliquescence takes place. This alternative method gives similar results as the slow ramp method, but it is less sensitive to disturbances and is less time consuming.
authors.affiliation: Building Materials, Lund University, Lund, Sweden. lars.wadso@byggtek.lth.se
authors.forename: Lars
authors.initials: L
authors.lastname: Wadsö
authors.forename: Anders
authors.initials: A
authors.lastname: Anderberg
authors.forename: Ingrid
authors.initials: I
authors.lastname: Slund
authors.forename: Olle
authors.initials: O
authors.lastname: Söderman
mesh_terms: D000327:Adsorption; D002626:Chemistry, Pharmaceutical / Q000295:instrumentation* / Q000379:methods; D003460:Crystallization / Q000379:methods; D004058:Diffusion; D005740:Gases; D006813:Humidity; D015203:Reproducibility of Results; D012492:Salts / Q000737:chemistry; D012995:Solubility; D013678:Technology, Pharmaceutical / Q000295:instrumentation / Q000379:methods; D013696:Temperature; D014835:Volatilization
chemical_list: D005740:Gases; D012492:Salts