Over the years, sample preservation has been used to maintain sample integrity by reducing the rate of microbiological growth, which can cause sample contamination or degradation. Acid preservation has become the method of choice for Total Organic Carbon (TOC) analysis for many official methods. The addition of inorganic acid to the sample stops the action of metabolizing the organics for food by the microrganisms present in the sample. The decreased pH of the sample also retards the growth of slime molds that are present as spores in the atmosphere. However, a debate has occurred over which acid is best to use to preserve the sample without interfering with the sample analysis. Comparison data is examined defining the pros and cons of acid preservation on two widely used TOC technologies, persulfate and combustion. Includes 15 references, tables, figure.