Water activity
instrument tests

Details for
desktop instruments
 
         

EminTech 

  
    Desktop instrument details

The instruments were kindly provided by the suppliers.
The suppliers knew that the instruments were going to be
tested and that the tests would be published at this site.

The measurements were run at room temperature, about 22 °C.
The tests were run during the first weeks of November, 2005. 		     
   
 
  
   

AquaLab 3 TE

AquaLab 3TE was set to operate at 22,5 °C.

The results were obtained by running
AquaLab in continuous mode and using
software AquaLink v. 3.0 that logged
the results in a PC.

The instrument was set to maximum
temperature stability before measure-
ments were started, i.e. 0,5 °C.
As room temperature varied around 22 °C, measurements started immediately.

One single measurement took 3-4
minutes, after which a signal sounded.

Normally 3-5 measuring cycles were
required to obtain reliable results. The
stability criterion was that two subsequent measurements gave the same result
in the fourth figure.


AquaLab 3 TE experimental data from
Decagon calibration samples (Dec .....) and
Salt solutions (X ...... with X=1,3,4,5,7,8)
 
Solution
aw
DecCal1
SatSalt2
SatSalt3
 
7 LiCl sat
0.113
0.1049
0.1046
 
Novasina 11
0.113
 
 
Dec LiCl 13.41m
0.2475
0.2482
 
 
 
5 MgCl2 sat
0.3295
0.3188
0.3183
 
Novasina 33
0.3295
 
 
3 K2CO3 sat
0.432
0.4266
0.4262
 
Dec LiCl 8.57m
0.498
0.4976
 
 
Novasina 53
0.5365
 
 
1 NaCl sat
0.754
0.7541
0.7531
 
Novasina 75
0.754
 
 
Dec NaCl 6.0m
0.760
0.,7592
 
 
Novasina 90
0.903
 
 
6 K2SO4 sat
0.9745
0.9789
0.9783
 
Novasina 97
0.9745
 
 
Dec KCl 0.5m
0.984
0.9867
 
 
8 Isotonic NaCl
0.996
0.9958
  
 
4 Water
1.00
1.0003
  

 
    Novasina calibration samples were not tested using AquaLab. The size of the samples was
too large to fit in AquaLab's sample holder.

SatSalt 3
The measurement series SatSalt3 was run 11 days after SatSalt2.		  
         
   

Novasina LabMASTER-aw

LabMASTER-aw was set to operate
at 22,5 °C.

The results were shown on the display
of the instrument. It was added manually
into a measurement result protocol.

One measurement using LabMASTER
took about 15-25 minutes, after which a
signal sounded.

The stability criterion was set to that the
result should vary less than 0.001 aw
within 5 minutes.

Series DecCal1, Satsalt2, NovCal1
Repeating the measurement, without
opening the instrument lid, took about
5 minutes and normally showed the
same result.
A single measurement was therefore
judged enough to obtain reproducible
results from this instrument.

When analyzing sample "4 Water" no
result was shown within 1 hour.

SatSalt3

Novasina LabMASTER-aw experimental data from
Decagon calibration samples (Dec .....) and
Salt solutions (X ...... with X=1,3,4,5,7,8)
Novasina calibration samples (Novasina YY with YY=11, 33, 53, 75, 90, 97)
 
Solution
aw
DecCal1
SatSalt2
NovCal1
SatSalt3
 
7 LiCl sat
0.113
0.116
0.118
 
Novasina 11
0.113
0.116
 
Dec LiCl 13.41m
0.2475
0.254
 
 
 
5 MgCl2 sat
0.3295
0.327
0.333
 
Novasina 33
0.3295
0.328
 
3 K2CO3 sat
0.432
0.437
0.440
 
Dec LiCl 8.57m
0.498
0.503
 
Novasina 53
0.5365
0.535
 
1 NaCl sat
0.754
0.756
0.758
 
Novasina 75
0.754
0.755
 
Dec NaCl 6.0m
0.760
0.758
 
Novasina 90
0.903
0.905
 
6 K2SO4 sat
0.9745
0.980
0.985
 
Novasina 97
0.9745
0.983
 
Dec KCl 0.5m
0.984
0.987
 
8 Isotonic NaCl
0.996
0.997
 
 
4 Water
1.00
-
 

Additional measurements
Novasina calibration sample 11 (with aw = 0.113 at 25 °C),
run for 3 hours at 25 °C, gave result 0.112.

A new sample of "4 Water" did not give any result after 3.5 hours.
 
 
    The measurement series SatSalt3 was run 11 days after SatSalt2. During this series, the second identical
result was used. The second result was most often identical to the first result given by the instrument.

Calibration
Calibration of the instrument was done at 25 °C using Novasina calibration samples.
During calibration, thermal equilibration time was longer than 1 hour before the calibration run was started.		  
         
   

Rotronic HygroLab 2

The analysis temperature when using
HygroLab was around 22 °C.

The instrument measured aw continuously,
and the results were transferred to a PC
using software HW3.

The log file created by the PC program
was pasted into a Microsoft Excel sheet
that draw aw versus time automatically.

Series DecCal1, NovCal1, SatSalt2
One measurement took about one hour.

The stability criterion was set to that the
result should vary less than 0.0001 aw
within 1 minute.

Series SatSalt3
The measurement series SatSalt3 was
run 11 days after SatSalt2.

Rotronic HygroLab 2 experimental data from
Decagon calibration samples (Dec .....) and
Salt solutions (X ...... with X=1,3,4,5,7,8)
Novasina calibration samples (Novasina YY with YY=11, 33, 53, 75, 90, 97)
 
Solution
aw
DecCal1
NovCal1
SatSalt2
SatSalt3
 
7 LiCl sat
0.113
0.1029
0.1034
 
Novasina 11
0.113
0.1060
 
Dec LiCl 13.41m
0.2475
0.2621
 
 
 
5 MgCl2 sat
0.3295
0.3330
0.3354
 
Novasina 33
0.3295
0.3349
 
3 K2CO3 sat
0.432
0.4384
0.4341
 
Dec LiCl 8.57m
0.498
0.5086
 
Novasina 53
0.5365
0.5375
 
1 NaCl sat
0.754
0.7553
0.7482
 
Novasina 75
0.754
0.7562
 
Dec NaCl 6.0m
0.760
0.7571
 
Novasina 90
0.903
0.8959
 
6 K2SO4 sat
0.9745
0.9546
0.9575
 
Novasina 97
0.9745
0.9640
 
Dec KCl 0.5m
0.984
0.9730
 
8 Isotonic NaCl
0.996
0.9855
0.9898
 
4 Water
1.00
0.9865
0.9898
 
  
    The results were obtained using calculation method AwQuick, run for 30 minutes.

Calibration
Calibration of the instrument was done at about 22 °C using Novasina calibration samples 33 and 75.
During calibration, thermal equilibration was longer than 1 hour before the calibration run was started.
The calibration results were obtained by running the samples for about 3 hours.		  
             
    Test of AquaLab        
    Test of HygroLab 2 aw instrument test introduction
EminTech Start Page
  
    Test of LabMASTER