ATAGO 5010, Instruction Manual, Page: 20 / 27

-13-
5. Scales
ANGLE OF ROTATION
- Denoted by "
α
" and expressed in degrees ("° ")
The rotation of polarized light is observed when polarized light that is oscillating unidirectionally rotates as it
passes through a liquid. The measurement of the angle of such rotation is called the "Angle of Rotation."
The angle of rotation is the basic numeric value measured by polarimeters and are dependent on the
concentration of the liquid, the length of the observation tube, temperature, and the measurement wavelength.
The instrument measures angle of rotation equivalent to a 20mm observation tube.
Brix (%)
Brix (%) represents the weight of sucrose in 100 grams of sucrose solution as percentage by weight. When other
dissolved solids are present in the solution, Brix (%) conversion may be applied.
Brix (%) is a measure of the total dissolved solids in a solution and indicates the combined concentration of all
soluble substances, such as sugar, salt, protein, and acids.
The readings are corrected, based on the temperature of the prism, within the automatic temperature
compensation range.
PURITY
- Expressed in %
The Purity is the proportion of sucrose comprised in a soluble solid content (a sample).
Sucrose content is symbolized by "POL," and is determined by the following formula:
POL = (26.016/Mass (density) of 100mL) × International Sugar Scale
The mass (density) of 100mL is determined by the Brix (%) value that has been input into the instrument beforehand.
The purity is determined by the sucrose content and the Brix (%) value, using the following formula:
Purity = (POL/Brix) × 100
The instrument displays temperature-compensated purity, based on the angle of rotation and Brix measurements.
Purity readings are always positive, but negative values are also displayed when the angle of rotation is negative.
INTERNATIONAL SUGAR SCALE (ISS)
- Expressed in °Z
The International Sugar Scale is determined by the following formula:
International Sugar Scale = Angle of Rotation × 2.888
The measurement value of 26.000g/100cm
3
of sucrose solution in a 200mm observation tube is 100°Z.
This measurement value is commonly used in the sugar manufacturing industry and is usually
temperature-compensated to the reference temperature of 20˚C or 68˚F.
The instrument multiplies the angle of rotation readings with the 20mm observation tube by 10 (to calculate the
equivalent readings with a 200mm observation tube) to compute the °Z values.
SPECIFIC ROTATION
- Denoted by "[
α
]" and expressed in degrees ("° ")
The Specific Rotation is a numeric value unique to each substance. By definition, the specific rotation value is
equivalent to the angle of rotation obtained by a measurement using a solution of 100% concentration in a
100mm observation tube (although such a measurement is actually not practicable). The specific rotation is
determined by the following formula:
Specific Rotation = (10,000 × Angle of Rotation)/(length of observation tube [mm] × Concentration [g/100mL]
*1
)
*1
m
To measure the specific rotation, input the concentration value of the
※
1
m
sample to be measured into the instrument before taking a measurement. (
r
page 11)
CONCENTRATION
- Expressed in g/100mL
The Concentration is the density of an optically active substance dissolved in water or alcohol. The concentration
is determined by the following formula:
Concentration = (10,000 × Angle of Rotation)/(length of observation tube [mm] × Specific Rotation
*2
)
*2
m
To measure the concentration, input the specific rotation value of the
※
2
m
sample to be measured into the instrument before taking a measurement. (
r
page 11)