However, during data collection, the apparatus must remain stationary, a feat straightforward to accomplish with tape. The cell phone should not be moved once positioned and the ambient light in the room should remain constant during the course of the measurement, as changes in lighting conditions can introduce systematic error. In contrast, due to its smaller pore diameter (5.7-6 Å), AlF shows negligible methylene blue dye adsorption (Figure ). Students can use these experiments to directly measure the consequences of pore size on guest adsorption in MOFs. Optionally, students can also measure the adsorption of iodine species by AlF; although iodine exists in Lugol's solution as a complex mixture of species, predominant species (I -, I2, and I3 -) are small enough to be adsorbed by this MOF (Figure ). We note that HKUST-1 degrades in Lugol's solution; a comparison of adsorption capacity of the two MOFs can be achieved by the CO2 gas adsorption experiment described below. To quantify dye adsorption, Microsoft Excel © is used to construct a calibration curve, record data, calculate concentration changes, and plot results.