Possible Error on Water Data

It appears that I have run into an issue when comparing previous data to new data. As you may remember, I had been collecting water samples from around Siena College when I stumbled upon high levels of antimony. I was getting readings over 200ppm. I may have briefly mentioned that these numbers were outrageously high and did not make any sense. Antimony levels above 30ppm would make you sick, but this water did not. Keep in mind I took samples of water all week from different areas and they all came back outrageously high. Below is from my first sample collected.

Now, I decided to check up on the same samples by running them through the machine again. Remember I said I ran THE SAME SAMPLES. The results I received were very different then previously. Below is the same first sample, but the most current reading.

I am more likely to assume these are the correct readings from the machine. The question now becomes why did the machine give off such high readings of antimony before? I proceeded to check the calibration of the machine and all of the numbers matched up. What is even stranger is that only the antimony levels appear off. I will not know for sure what numbers are correct until I get my water reference sample.