Hanna Instruments HI 83749 - Manual (Page 18)

18
BENTOCHECK (PROTEIN STABILITY TEST)
• Turn the instrument ON by pressing ON/OFF.
When the LCD displays “----”, the instrument
is ready.
Note: On the secondary LCD the current time
appears, if selected in Setup menu.
• Select the AVG mode by pressing the AVG
key. The AVG icon will appear on the display.
• Fill a clean, dry cuvet with 10 mL of wine up to
the mark, taking care to handle the cuvet by
the top. Replace the cap and wipe the cuvet
thoroughly with a lint-free cloth (see General
Tips for an accurate measurements, page 10).
• Place the cuvet into the instrument and close
the lid.
• Press READ and “----” will blink on the
display. After a few seconds the instrument
displays the first reading. The meter continues
updating the readings until the “Lamp and Read
Status” indicator turns off. The final displayed
value is the averaged reading.
• At the end of the measurement, the instrument
directly displays turbidity in NTU.
This is T1. Record the value.
• Use the 1000 µL automatic pipette to add
exactly 1 mL of HI 83749-0 Bentocheck
reagent to the cuvet. For a correct use of the
automatic pipette please follow the related
Instruction Sheet.
e.g.
T1
23
• The final displayed value is the averaged
reading of turbidity in NTU.
This is T2. Record the value.
• Repeat the reading procedure for all samples
(#2, #3, #4) and record all T1 and T2
values.
e.g.
Sample #1
T2
• For each sample verify if “T2<T1+2”: if so, the wine can be considered stabilized. Compare
the results. It is recommanded to choose the lowest dosage of bentonite necessary to stabilize the
wine.
• To define the g/hL of bentonite to be added to the wine tank, just multiply by 100 the mL of 2,5%
bentonite suspension that was added to the HANNA vial (0.25 mL for vial #1, 0.50 mL for #2,
0.75 mL for #3 and 1.00 mL for #4):
Bentonite requirement in g/hL = mL of bentonite added with syringe x 100
For this example, 0.75 mL is the lowest bentonite dosage necessary to stabilize the
wine sample. Now just multiply the mL for 100 (0.75 x 100 = 75 g/hL) to obtain
the bentonite requirement.
#1 #2 #3 #4
(0.25 mL) (0.50 mL) (0.75 mL) (1.00 mL)
T1 6.95 6.05 5.62 5.10
T2 10.4 8.60 7.50 6.40
T2<T1+2 no no yes yes
For example:
COMPARATIVE MODE
An alternative mode of measurement is Comparative Mode. It is possible to set a reference value (T1)
and let the instrument automatically compare turbidity values.
See SETUP section, page 29-30.