A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection

This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO2 gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO2 gas into the acceptor stream changes the conductivity of the acceptor solution causing an increase of signal at the capacitively coupled contactless conductivity detection (C4D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on ‘membraneless vaporization’ (MBL-VP).The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33–99% (w/w) CaCO3). Analysis of samples by this method is direct and convenient as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision.