Test findings for Ph reading of salt.

Today i went into lab in period 1 during my free to do my PH testing. The equipment i used for the PH testing was:

1. Data logger
2. Ph Probe
3. Dropper bottle of demineralised water.
   
   Results are shown below:
   
   • Sample 1/site 1:
     PH probe started on 4.37
     PH: 6.31
     
   • Sample 2/site 2:
     PH: 6.27
   • Sample 3/site 3:
     PH: 6.53
   • Sample 4/site4:
     PH: 6.32
     
     
   • When i put the probe back in the chemical mixture it took a reading of 4.57.
     
     When i finished my first lot of soil samples i realised that i had enough time to do a second lot. But this time i thought i would joint down the PH probe reading every time to see how much is varied and to see if i contaminated it.
     PP: means the PH probe
     PH: means the PH i got.
     
     
   • Sample 1/site 1:
     PP: 4.35
     Ph:6.32
   • Sample 2/site 2:
     PP: 4.40
     Ph:6.40
   • Sample 3/site 3:
     PP:4.37
     ph: 6.58
   • sample 4/site 4:
     PP: 4.40
     Ph: 6.33
     
     The PH probe was 4.39 when i put it back into the mixture this means that i have not contaminated the mixture.