the winery of napa valley michael mondavi family estate jeanette schandelmier
TRANSCRIPT
Laboratory Instrumentation in a Mid-
size WineryThe Winery of Napa Valley
Michael Mondavi Family EstateJeanette Schandelmier
Topics to Cover1. Which instruments were purchased for
the winery lab with a 1500 ton bond (250,000 gallons).
2. Focus on FSO2 using the Metrohm Titrino.3. Touch on how much it costs to set up and
how much reagent expense is, as well as how long the analysis takes.
4. Describe accuracy and precision, reliability and durability of the Metrohm Titrino.
Mandatory Tools in a Winery Lab Autotitrator for F/TSO2 and TA/pH. Spectrophotometer for enzymatic analysis of Residual Sugar,
Malic Acid, Acetic Acid, NOPA and Ammonia pH meter (separate from autotitrator) for preparing buffers, acid
trials, etc. Alcohol Analyzer (NIR) Turbidimeter (Hach) Oxygen meters (portable and benchtop) Pipettes for dispensing accurate volumes, stir plates, vortex Centrifuge, analytical balance, fume hood, water bath and stability
oven and refrigerator Microscope Ultrapure water for buffer preparation Vacuum pump for degassing wine samples Music source
FSO2 DETERMINATION BY METROHM TITRINOWe run at least 4500 FSO2 per year.We run pre- and post- FSO2 on each lot at
monthly topping, making sure we hit the target.Metrohm Titrino can also perform Total SO2 and
TA /pH (separate cartridge). The tests can not be run concurrently.
Manual dispensing of sample and reagents, no turntable, though they are available.
My prime directive is accurate results with a quick turnaround time.
Metrohm Titrino
Both cartridges
FSO2 DETERMINATION BY METROHM TITRINOHow:The measurement utilizes titration of an
acidified sample containing iodine to an iodometric end-point. A double Platinum sheet electrode that is polarized by applying a current is used for determining the endpoint. As long as the SO2 is in excess, the voltage remains high and constant. As soon as iodine is present in excess, the electrodes depolarize and voltage drops toward 0 mV. (aka magic)
Advantages of the Double Pt Sheet Electrode
More appropriate for low level measurements–SO2(2 to 100 ppm)
50 times more surface area than double Pt pin electrode allowing quicker response time.
Larger potential change at endpoint–Improves accuracy and reproducibility
No reference or filling solution
Greater sensitivity than Redox
Free Sulfur by Metrohm Titrino Why: FSO2 is the amount of sulfur dioxide in wine that is functional as a preservative. It is important
to make sure the correct amount of FSO2 is present to ensure protection of the wine. How: We use the Metrohm Titrino to analyze for FSO2. It utilizes titration of an acidified sample
with iodine to an iodometric end-point. The endpoint is measured with a platinum electrode. Important Procedural Steps: Once you add the KI and the H2SO4, quickly place the beaker on
the stir plate and push start. Make sure you have a stir bar in the beaker and that it is not stirring too fast. Keep the platinum electrode off to the side of the beaker so it does not get hit by the stir bar. Do not bend it and make sure the two plates are not touching.
Safety: Safety glasses should be worn. The acid can burn you so use caution and if you get any on yourself, flush with water immediately.
Procedure: If the instrument is not already programmed for SO2, put module with Platinum electrode on titrator.
Push “user method”, “enter” and scroll using the arrow keys to SO2. Push “Enter”. Using a 20 ml volumetric pipette, put 20 ml of sample into a 50 ml beaker along with a small stir
bean. Add 7 ml of 20% KI to the sample using the repipette. Add 5 ml of 25%H2SO4 to the sample using the repipette and immediately place the beaker on the
Titrino stir plate. Using extreme care, lower the electrode, temperature probe and dispensing tip down into the beaker
by squeezing the lever on the burette stand. Make sure the platinum electrode is near the side, away from the stir bean, so it does not get hit.
Push “Start” to begin titrating with 0.0156 N Iodide-Iodate solution. Make sure the stir bean is mixing the solution. If it does not stir, push the “stir” button on the main panel.
After the titration is complete, write down result, rinse probe, dispensing tip and temperature probe and leave in air.
Reagents: 1. Use premade and purchased Iodide-Iodate solution and 25% H2SO4. 2. 20%KI: Weigh out 100 grams of KI using the analytical balance and put into a 500 ml graduated
cylinder. QS to 500 ml using ultra pure water. Mix well.
Iodometric vs. Mean of PI/AO/ETS
0
5
10
15
20
25
30
35
06SB0
3A
06SB0
1A NSA
06SB0
1A OTV
N
06CS5
8PQ1
OTV
N
06CS5
9PQ
2 OTV
N
06CS5
6VQ
1 OTV
N
06CS5
7VQ2 O
TVN
06CS5
8PQ1
NTV
N
06CS5
9PQ
2 NVTN
05CS2
0Y N
TVN
05CS2
7Y N
TVN
05CS2
4BV
05CS8
5 HVY
06CS L
EES
05CS1
2A O
TVN
05CS1
3 OTV
N
05CS3
7Y O
TVN
05CS3
8Y O
TVN
05CS3
9Y O
TVN
06CS1
4Y N
TVN
05CSL
EESC
L
05CS7
5A
05CS7
5B
05CS9
0ZR2
05CS9
0ZR2
05CS7
8B
05CS9
0ZR2
I/ I vs. Mean
Level
of F
SO2
I/ I
M ean
Accuracy: +/- 2 ppm for FSO2 and +/- 5 ppm for TSO2+/- 0.2 g/L TA and +/-0.02 pH The mean of my control is based on accumulation of data (at least 30 initial data points, plus data from the reference lab) and I use 2 standard deviations from the mean as acceptable. I use quality control charts so I can quickly see if I am outside 2 SD or have a trend or shift developing.
Precision or reproducibility:+/- 1 ppm for FSO2 and +/- 4ppm for TSO2 +/- 0.2 g/L TA and +/-0.02 pH
REFERENCE LAB MMFE
FSO2 (ppm) 32 31
TSO2 (ppm) 74 75
TA (g/L) 5.8 5.71
pH 3.54 3.55
Out of control can be outside 2 std dev, 7 consecutive points in an upward or downward trend or 7 consecutive points above or below the mean.
TA/pH
TA 6.0 g/L Tartaric Acid High/// pH Control Supersaturated KHT 3.57
TA 1 2 3 4 5 6 7 8 9 # # # # # # # # # # # # # # # # # # # # #
x
6.2 x x
x x x x x
6.1 x x x x
x x x
6.0 g/L x
x
5.9 x
x
5.8
x
Time and MoneyEach sample takes 3 to 4.5 minutes including
pipetting and clean up (I use bottletop dispensers).In 2007 I paid $7,500.00 for the instrument with
SO2 and TA/pH cartridges and Pt electrode. The turntable would have doubled that price. Replacement Pt electrodes run $310.00. pH probes run $540.00.
Reagents include 20% KI ($77/500 g = ~350 tests), 25% H2SO4 ($27/L= 200 tests) and 0.156 N Iodide-Iodate ($22/L = ~200 tests) solution. So reagents run 47 cents per test to run a FSO2.
Since building the lab in 2007…There are over 65,000 results in WMDB.We have served 39 different clients.We’ve tracked ~750 lots from grape to bottle.We’ve gone through 3 Platinum electrodes
and 5 pH electrodes.Annual maintenance recommended on Titrino
and NIR.
