This project aims to find if there are contaminants in the tap water at the University of Texas at Austin. We will focus on two methods for testing water quality. The first is the Environmental Protection Agency’s (EPA) method, which accounts for interferences by using interference equations. The second is the International Organization for Standardization’s (ISO) approach, which removes interferences using collision reaction cell technology. We will test for contaminating metals appearing in both the ISO and EPA methods. The limits for drinking water contaminants, measured in parts per billion (ppb), are as follows:

Sources: “National Primary Drinking Water Regulations | USA EPA” 

We will test for contaminants by using inductively coupled plasma mass spectrometry, also known as ICP-MS. ICP-MS is a mass spectrometer technology that uses plasma to ionize the sample. The drinking water samples will be input as liquid solutions alongside stability solutions, and data analysis will be performed according to the qualifications listed above. We expect the levels of the elements we test for not to exceed the regulatory standards. Independent verification from our lab will ensure that the results fall below the limits. We also expect the two methods to show results that do not have statistically significant differences. 

With ICP-MS technology, there are two distinct methods for testing drinking water: EPA Method 200.8 and collision reaction cells (CRC). Method 200.8 is a widely used method that uses the typical ICP-MS setup to measure elements in water samples with interference equations; the equations take the natural abundances of elements into account to calculate the actual levels of existing elements in the sample. On the other hand, collision reaction cells use kinetic energy discrimination to reduce interferences, allowing for precise testing of trace elements. While many drinking water analyses use Method 200.8, collision reaction cells more efficiently remove interferences without using interference equations, ensuring more accurate and reliable results for drinking water analysis. 

The International Organization for Standardization (ISO) offers guidance on testing for over 60 elements in water (“ISO 17294-2:2023 Water quality – Application of ICP-MS– Part 2: Determination of selected elements including uranium isotopes”). Unlike EPA 200.8, the ISO uses collision reaction cell technology to test drinking water standards.  

This project is relevant for two reasons. First, this project is of interest to UT students and faculty because it concerns their health and safety. With our ICP-MS analysis, we aim to verify the purity of the drinking water on campus to ensure the water quality is up to standard and safe for consumption. Second, a comparison of collision reaction cell and interference equation methods is of interest to agencies monitoring water quality. If the results exceed the maximum limits, then we will contact the relevant agencies to identify and amend the source of the issue. If the data falls below the maximum limit, then the results will verify the methods used to test and purify drinking water for our consumption.