Artificial photosynthesis uses photocatalytic reactions for water splitting and carbon dioxide reduction to create hydrogen, oxygen, carbon monoxide, and formic acid. Of these reaction products, hydrogen, oxygen, and carbon monoxide escape from the sample solution as gases. However, formic acid remains in the sample together with added components, such as electron donors, and byproducts, such as formaldehyde. To measure the amount of formic acid created, it is necessary to separate it from these components. This Data Sheet highlights the pH-buffered electroconductivity method offered by the Shimadzu Organic Acid Analysis System to analyze formic acid, together with a refractive index detector for the simultaneous analysis of formaldehyde.