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5
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4. Samples
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Basics/A. Measurement/4.Samples
No.
Question
Answer
1
What is the reagent sodium
tartrate dihydrate and when is
it needed?
Sodium tartrate dihydrate (Na
2
C
4
H
4
O
6
・
2H
2
O; molecular mass:
230.082) is sodium tartrate (Na
2
C
4
H
4
O
6
) chemically bonded to
two water molecules (2H
2
O; molecular mass: 36.031). The
water separates from the sodium tartrate when heated. The
moisture content rate of sodium tartrate dihydrate is the ratio of
the molecular mass of the two water molecules, or 15.66%
(36.031/230.082). Since its moisture content is theoretically
known, it can be used as a test sample to confirm the
performance of analyzers. Samples are included with the
MS/MX/MF and are available as an option for the ML (12
pieces of 30 g).
2
Why don’t I get a result of
15.66% when I measure
sodium tartrate dihydrate?
1. Moisture bonded inside of the material as crystal water is
theoretically 15.66%. However, ambient air during usage
and storage has moisture with a relative humidity of 10% to
90%, and moisture equivalent to 0.09% of the sample mass
can adhere to the sample. Furthermore, moisture and
impurities that have adhered to the pan, along with
measurement instrument errors, can cause results to vary
between 15.0 and 16.0% in actual measurements.
2. If there is a large difference between the actual result and
15.66, the heating temperature may be too low.
When using sodium tartrate dihydrate to test the accuracy
of the MS/MX/MF/ML, set accuracy to MID and the heating
temperature to 160 ºC and then pre-heat for 8 minutes.
Next, spread approximately 5 g of the sample evenly on
the pan and then measure at 160 ºC.
3
Is sodium tartrate dihydrate
safe?
Is there any special handling
process?
1. Sodium tartrate dihydrate can be handled safely. It is used
as a flavoring in foods and is harmless at normal dosages.
(Acute toxicity: 218 g/50 kg (Median oral lethal dose for
rats.)) However, contact with skin or the mucous
membranes of the eyes and nose may cause a reaction. In
such cases, wash the affected area immediately.
2.
It can be disposed of as standard burnable waste. No
special disposal process is required.
4
Can sodium tartrate dihydrate
be reused?
No, it can be used for one test only. Once the moisture is
released from the crystals from heating, it generally cannot be
rehydrated.