TDS meter or calibration solution wrong?

[Zoajohn]

So my HM digital handheld tds meter was showing 1 TDS out of my 4 stage RODI filter, while my in line was showing 0. I decided it has been two years and I need to calibrate the handheld. So I got the HM 342 TDS calibration solution, and the meter is showing TDS of 394 in it. This seems weird since it’s only 1 off from my RO water, and HM is pretty reliable with their products. Which do you guys think is causing the discrepancy? One thing I’ll note is my bottle leaked a little bit as the plastic packaging was a little wet, but should that matter?

This is the meter I have:
HM Digital TDS-4 Pocket Size TDS Tester Meter with 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 2% Readout Accuracy

 

[lapin]

If the bottle was not sealed, over time some water could evaporate and cause the higher reading.
Thats about 15% off I think. 2% for meter error. I dont own one of those meters so I dont know how far off they can drift.

 

[Zoajohn]

If the bottle was not sealed, over time some water could evaporate and cause the higher reading.
Thats about 15% off I think. 2% for meter error. I dont own one of those meters so I dont know how far off they can drift.

It had a seal, but some liquid must have seeped out. I don’t see how it would’ve been enough, or even made a change in the TDS since it is a solution.

 

[Zoajohn]

Strangely enough last night I tried again, and it read 360, without making any adjustments. Add in the 2% margin for error, and that comes to 353, which is still 11 TDS higher than reference