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 web site.

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

Navigation: Water activity
  What is water activity
  Test Introduction
Test details
  Salt solutions
  Calibration samples
    Desktop instruments
  Portable instruments
Results
  Desktop instruments
  Decagon AquaLab 3TE
  Novasina LabMASTER-aw
  Rotronic HygroLab 2
  Portable instruments
  Decagon PawKit
  Rotronic HygroPalm
  Testo 650
Summary
  Desktop instruments
  Portable instruments
 

 

AquaLab 3 TE

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

The results were obtained by run-
ning 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 subse-
quent measurements gave the same
result in the fourth figure.

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.

 


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 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
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.

 


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 A new s hours.

 
   

Rotronic HygroLab 2

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

The instrument measured aw con-
tinuously, and the results were trans-
ferred 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. 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 calibra-
tion samples 33 and 75. During calibra-
tion, 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.


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

 
           
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