 Next, samples are filtered to remove any suspended sediments and preserved with chloroform to prevent growth of microorganisms, while the others are acidified with hydrochloric acid added to keep dissolved ions from precipitating out of solution.Then, various chemical tests were applied to determine the concentration of each solute.For example, the concentrations of sodium and potassium ions can be determined by flame photometry, while the calcium and magnesium ion concentrations can be determined by atomic absorption spectrophotometry.