The best approach to conducting spectral interference checks is to have single-element standards for every element that you reasonably expect to be in your samples. You then prepare solutions that contain only one element at a relatively high concentration in your analytical matrix, and monitor emission lines for all the other elements of interest. Once you’ve characterized potential interferences using these single-element solutions, you can start to mix elements together to mimic real-world samples, and repeat the process all over again. It’s a great approach, but time-consuming. Our recommendation would be to first analyze the 2007ICS solutions separately at dilution factors of 50 – 100x to provide an initial characterization of the spectral interferences, and then combine the three solutions at 50 – 100x dilutions to evaluate if more spectrally complex solutions (i.e., ‘real-world’) affect the interference assessment. We’d suggest starting with 2007ICS-4, as it contains five ‘major’ elements, which are ones considered to be present at relatively high concentrations in many different samples. At a 50x dilution this standard will mimic the matrix of many samples such as natural/treated waters, sewage sludge, rocks and minerals, etc. Once you have characterized potential interferences from the five elements in 2007ICS-4, we’d recommend spiking in lower concentrations of the elements in 2007ICS-1 and 2007ICS-3 (separately at first) to compare what you know is present with what you observe. What you’ll notice is that absolute concentrations are less important than the ratio of the interfering element to the element of interest.