# Why is chloride measurment 0 [closed]

In class we did an experiment to measure chloride in different water sources, including a lake. We used Ion-selective electrode of Ag/AgCl technique. We did the calibration curve and all steps and measurments in different sources of water are consistent, for example drinking water was a bit below 250ppm. But when measuring lake water we get a measurment of 0, why could this be happening? I can't find a reason

• Are you sure that the procedure was followed correctly? Apr 14 at 4:07
• Why can't this be true? Apr 14 at 6:48
• Assuming you have followed correctly the experimental procedure, the concentration in lake water may be lower then the sensibility of your electrode. Apr 14 at 11:42
• @IvanNeretin Unless they found a first lake of freshly distilled water in the world, that's impossible. They either did something wrong or there was interference from other stuff in water. Apr 14 at 13:04
• Measuring a concentration with an $\ce{Ag/AgCl}$ electrode cannot give zero, it can give a concentration "lower than $\pu{0.00xxx}$" but it cannot be zero, if a concentration is equal to zero, applying Nernst's law gives you a potential equal to ± infinite, which does not make sense. Apr 14 at 19:22