Polarimetry and the International Sugar Scale – Official

Specification and Standard SPS-1 (2026)

1 Warnings

Warning and Safety Precautions
Persons using this ICUMSA^® standard should be familiar with normal laboratory practice. This standard does not address all the safety issues, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.

Disclaimer
The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the International Commission for Uniform Methods of Sugar Analysis (ICUMSA^®) in preference to others of a similar nature that are not mentioned.

General advice
ICUMSA^® standards are updated from time to time following scientific and technical development. Please check on https://www.icumsa.org, whether the standard in hand is the current version.
This standard edition cancels and replaces the previous (ICUMSA^® Specification and Standard SPS-1 (2017)), which has been technically revised and rewritten.

2 Scope and field of application

2.1 Scope
This standard describes the basis of the polarimetric determination of the sucrose content of sucrose-containing products [1–4].

2.2 Field of application
The standard is used in statutory analyses, trade analyses and for factory control. It is applicable to raw materials, intermediate and final products of the sugar industry.

3 Normative references

Normative references are not required for the application of this standard.

4 Terms and definitions

ICUMSA^® maintains a terminological database (under development) for use in standardisation at https://www.icumsa.org.
For the purposes of this document, the following terms and definitions drawn from the database apply:

4.1 Polarimetric sucrose content. Sucrose content of any material determined by a polarimetric method and expressed in degrees Z (°Z) [5].

NOTE 1: The unit °Z (instead of the equal SI unit g/100 g) indicates the determination by polarimetry and distinguishes from the former unit °S, which it replaced in 1988 [3].

NOTE 2: The symbol for the quantity polarimetric sucrose content is w_S,pol, it is a mass fraction.

NOTE 3: The polarimetric sucrose content has often been wrongly called “polarisation” or “pol” in the past. These expressions should be replaced wherever they appear.

4.2 The “normal sucrose solution”. The “normal sucrose solution” is defined as 26.0160 g of pure sucrose weighed in vacuo and dissolved in water at 20.00 °C to a final (vacuo-)mass of 109.7639 g. This corresponds to 26.0000 g weighed in air under normal conditions (1013 mbar, 20 °C, 50% relative humidity) and dissolved in water to a final apparent mass of 109.6604 g [6].

NOTE 4: The fourth decimal of the mass is required in order to fulfil the precision of the following calculations. This detail was discussed in reference [6] but not explicitly stated in the final Recommendation.

Alternatively, ICUMSA^® proposes the following superseded volumetric method to achieve the same results with lesser precision: The “normal sucrose solution” is defined as 26.0160 g of pure sucrose weighed in vacuo and dissolved in water at 20.00 °C to a final volume of 100.000 cm³. This corresponds to 26.0000 g weighed in air under normal conditions (1013 mbar, 20 °C, 50% relative humidity) and dissolved in water to a final volume of 100.000 cm³ [7].

NOTE 5: Volumes are given in the SI unit cm³ here. For practical purposes this can be regarded as equal to the unit mL.

4.3 Reference value (100 °Z) for polarimetric sucrose content measurement. The Reference value (100 °Z) for polarimetric sucrose content (4.1) measurement [3, 8] is the optical rotation of the oscillation plane of polarised light caused by the normal sucrose solution (4.2) at the wavelength of the green line of the mercury isotope ¹⁹⁸Hg (546.2271 nm in vacuo) at 20.00 °C in a 200.000 mm tube. For other wavelengths, the formula for the rotatory dispersion of sucrose solutions [4] is valid.

4.4 Effective wavelengths. For quartz wedge instruments the effective wavelength has been fixed at 587.0000 and/or 882.600 nm [3, 4, 9]. For the double line of yellow sodium light, the mean effective wavelength has been fixed at 589.4400 nm [3, 10].

5 Principle

The application of polarimetry in sugar analysis is based on the fact that the optical rotation caused by sucrose solutions is a nearly exact linear function of their sucrose content. That is, Biot’s Law is obeyed, see eq. 1.

\displaystyle \alpha _{\lambda }^{t}=\left[ \alpha \right]_{\lambda }^{t}\cdot \beta \cdot l     (1)

For the International Sugar Scale, the temperature, the length of the polarimeter tube and the mass concentration of the sucrose solution have been fixed by convention (4.3).
t = 20.00 °C
l = 2.00000 dm = 200.000 mm

β = 0.260160 g/cm³ = 26.0160 g/100.000 cm³ (in vacuo)

The optical rotation has been established under these conditions by precision measurements [1, 2].
Under the assumption that the specific rotation for a given temperature and a given wavelength is independent of the concentration, the polarimetric sucrose content of a sample is immediately obtained from the rotational value caused by the sample, under the conditions defined above, as a percentage of the rotation caused by pure sucrose under the same conditions.
This is strictly valid only in the theoretical case where sucrose is the only optically active constituent of the sample under investigation and where the sample contains no substances influencing the optical rotation of the sucrose. In practice, all products of sugar manufacturing fail to fulfil this precondition. The advantage of polarimetry in sugar analysis is its simple and quick practicability and its reproducibility, which is superior to most of the other possible methods. In recognition of these conditions the result of the polarimetric sugar analysis is not expressed as percentage sucrose but as “polarimetric sucrose content” (see 4.1). To avoid the calculations according to eq. 1, the analysis is standardised by the conventions specified in Section 4. The scale defined by these conventions is called the “International Sugar Scale” and the unit is °Z.
At the ICUMSA^® Session in Berlin (1998) it has been agreed to extend the valid wavelength range from (546 to 633) nm to (546 to 900) nm [4].

6 Numerical values

The calculations which follow have been made using eight significant figures. For practical applications, however, ICUMSA^® recommends values rounded to ±0.001° according to the precision of the basic measurements (see Section 7). The rounded values must not be used as starting values for calculations, e.g. to other wavelengths. For such calculations unrounded values with eight significant figures should be used.
In the following the wavelength values in vacuum are given. The temperatures are based, if not otherwise indicated, on the International Temperature Scale of 1990 [11, 12, 13].
The density of pure sucrose defined herein is ρ_S = 1587.0 kg/m³ according to Emmerich 1991 [2].

6.1 Dependence of the optical rotation on concentration and temperature. This dependence is fixed for the mass fraction w = (0 to 65) g/100 g of sucrose in solution and the temperature t = (18 to 30) °C by eq. 2, which was derived from precision measurements [1, 2, 8].

\displaystyle {{\alpha }_{{546}}}={{\alpha }_{{0,1}}}\cdot w+{{\alpha }_{{0,2}}}\cdot {{w}^{2}}+{{\alpha }_{{0,3}}}\cdot {{w}^{3}}+{{\alpha }_{{0,4}}}\cdot {{w}^{4}}+{{\alpha }_{{0,5}}}\cdot {{w}^{5}}+\left( {{{\alpha }_{{1,1}}}\cdot w+{{\alpha }_{{1,2}}}\cdot {{w}^{2}}+{{\alpha }_{{1,3}}}\cdot {{w}^{3}}} \right)\cdot \left( {t-20} \right)
(2)

The coefficients are:
α_0,1 =   1.563547156
α_0,2 =   6.1649313 · 10^–3
α_0,3 =   1.8207098 · 10^–5
α_0,4 =   7.1668107 · 10^–8
α_0,5 = –1.3233339 · 10^–9
α_1,1 = –5.6904146 · 10^–4
α_1,2 = –1.2240926 · 10^–5
α_1,3 =   7.7957582 · 10^–8

NOTE 6: The use of mass fraction, w in g/100 g, instead of mass concentration, β in g/cm³, is advantageous because the mass concentration, β, depends upon the temperature of the solution because of its thermal expansion, whereas w is independent.

Eq. 2 is valid for the International Temperature Scale of 1990. To conform with the International Temperature Scale of 1990 (IST-90) [11, 12] the rotation value required in (4.2) for the wavelength λ = 546.2271 nm had to be verified. This was performed by carrying out the calculation using t = 20.005 °C, because 20.005 °C (1968) = 20.000 °C (1990).
In addition, the density value of 1990 [13, 14] which amounts to 1097.6393 kg/m³, resulting in w = 23.701775 g/100 g for the normal sucrose solution (4.2) was applied.
The optical rotation, α₅₄₆, calculated using eq. 2, taking into account the temperature scale of 1990 as described in the previous paragraph, is valid for the standard wavelength λ = 546.2271 nm (4.3).

6.2 Dependence of the optical rotation on wavelength. Using experimental data by Bünnagel and Oehring [10, 15], Emmerich et al. [16] and the study reported by Keitel et al. [4], the relative rotatory dispersion of sucrose solution in the wavelength range (546 to 900) nm was derived and is shown in eq. 3. The original equation was reassessed in 2025 to ensure the units were consistent with current practice [4, 17].

\displaystyle \frac{{{{\alpha }_{\lambda }}}}{{{{\alpha }_{{546}}}}}=\frac{1}{{a+b\cdot {{\lambda }^{2}}+c\cdot {{\lambda }^{4}}+d\cdot {{\lambda }^{6}}}}     (3)

The coefficients are:
a = –7.504765900000 · 10^–2
b =   3.588221904585 · 10^–6
c =   5.194617830000 · 10^–14
d = –6.515194377000 · 10^–21

Within the uncertainty of the measurements, the rotatory dispersion is independent of solution content and temperature.

6.3 Linearity between the optical rotation and the concentration. The linear dependence according to Biot’s Law (eq. 1) cannot be immediately checked by eq. 2. For this purpose, the mass concentration, β, must be recalculated to the mass fraction, w, (by dividing the former by density in g/cm³). The result of this calculation was that the maximum deviation between 0 °Z and 100 °Z is less than 0.01 °Z [2].

6.4 The 100 °Z point of the International Sugar Scale at visible wavelengths. For the standard conditions (see 4.3), the 100 °Z point obtained from eq. 2 is:

\displaystyle \begin{array}{l}\alpha _{{\text{546}\text{.2271 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{40}\text{.7773}\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{\text{546}\text{.2271 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{0}\text{.71170}\pm \text{0}\text{.00002 rad}\end{array}

NOTE 7: The conversion of angular degrees to radians (S.I. unit) is based on 360° = 2π radians

The 100 °Z point at the wavelengths of other light sources used in sugar polarimetry are calculated using a combination of eq. 2 with eq. 3 [8].
These two equations are the basis for the calculation of the 100 °Z point of the International Sugar Scale.

Light of quartz wedge instruments:

\displaystyle \begin{array}{l}\alpha _{{\text{587}\text{.0000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{34}\text{.9347}\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{\text{587}\text{.0000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{0}\text{.60973}\pm \text{0}\text{.00002 rad}\end{array}

Yellow sodium light:

\displaystyle \begin{array}{l}\alpha _{{\text{589}\text{.4400 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{34}\text{.6263}\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{\text{589}\text{.4400 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{0}\text{.60435}\pm \text{0}\text{.00002 rad}\end{array}

Helium-neon laser:

\displaystyle \begin{array}{l}\alpha _{{632.9914\text{ nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=29.7515\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{632.9914\text{ nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=0.51926\pm \text{0}\text{.00002 rad}\end{array}

Near-infrared wavelength [18, 19]:

\displaystyle \begin{array}{l}\alpha _{{\text{880}\text{.0000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{14}\text{.9269}\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{\text{880}\text{.0000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{0}\text{.260525}\pm \text{0}\text{.00002 rad}\end{array}

Near-infrared wavelength:

\displaystyle \begin{array}{l}\alpha _{{\text{882}\text{.6000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{14}\text{.8359}\pm \text{0}\text{.001 }\!\!{}^\circ\!\!\text{ }\\\,\\\alpha _{{\text{882}\text{.6000 nm}}}^{{\text{20}\text{.00 }\!\!{}^\circ\!\!\text{ C}}}=\text{0}\text{.258936}\pm \text{0}\text{.00002 rad}\end{array}

6.5 The 100 °Z point for polarimeters using light sources other than spectral line emitting sources including the NIR wavelengths. Since the wavelengths of the light sources for instruments operating at near infrared wavelengths are not rigorously established like those of spectral lamps, the applicable wavelength needs to be determined accurately and the optical rotation corresponding to the 100 °Z point can then be calculated using eq. 3. The determination of the wavelength is preferably done using the reading of a well-known quartz plate together with eq. 4 in Section 8.6.

7 Precision

The uncertainty of ±0.001° given in the Recommendations of ICUMSA^® is the rounded value obtained from the standard deviation of the mean of the measurements in the immediate neighbourhood of those obtained for the normal solution [2].

8 Apparatus

8.1 General. Specifications have been developed by ICUMSA^® for polarimeters, polarimeter tubes, cover glasses for polarimeter tubes and quartz control plates for the standardisation of polarimeters. These specifications are laid down in detail in OIML Recommendation No. 14 “Polarimetric Saccharimeters”.

NOTE 8: OIML (Organisation Internationale de Métrologie Légale). The OIML Recommendation No. 14, 1995 [20], includes the new Official ICUMSA^® definitions of 1986 [3], set in force on July 1, 1988.

Many of these specifications are mainly of interest for the manufacture of instruments and accessories and for the control and standardisation of quartz control plates by specialised laboratories, e.g. the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig, Germany). They are given here in summary form to enable users to operate their equipment properly. For details the OIML document may be consulted.
The specifications given below must be observed to guarantee the rotation values of quartz control plates within the limits of ±0.001° specified by ICUMSA^®, as well as the accuracy of polarimeters and tubes including cover glasses.

8.2 Polarimeter, preferably with International Sugar Scale. The specifications apply to visual and photoelectric polarimeters [20]. Visual polarimeters shall be of the half-shadow type. If the angle of the half-shadow is fixed, it shall be between 5° and 10°, if variable, adjustable between 0° and 10°.
Instruments with a rotating analyser or polariser, the angle of which is measured, shall be illuminated with a monochromatic light of wavelength between 540 nm and 900 nm. Instruments with quartz wedge compensation may be illuminated by a monochromatic light source or by an incandescent lamp filtered to produce light with an effective wavelength of 587 nm (see 4.4).

NOTE 9: In all polarimeters the scale depends upon the wavelength of the light being used. The knowledge of the wavelength of the instrument is, therefore, indispensable for the user to apply the correct “sucrose value” of the quartz control plates (see 8.5), with reference to the certified values for these wavelengths.

The scale of polarimeters must be linear within their class of accuracy. Polarimeters equipped with the International Sugar Scale in °Z are called “polarimetric saccharimeters”. Results of polarimeters with other scales, e.g. circular scales (360° for the full circle) can be transformed into °Z using a quartz control plate (see 8.5).
According to the precision required, polarimeters have three classes of accuracy:
Class 0.2      maximum error over the scale ± 0.2 °Z
Class 0.1      maximum error over the scale ± 0.1 °Z
Class 0.05    maximum error over the scale ± 0.05 °Z

NOTE 10: Most automatic polarimeters used for sugar analysis fulfil the demands of Class 0.05.

After the first half hour of operation the systematic error of automatic polarimeters for sugar analysis due to “drift” should not exceed 0.05 °Z over 24 h. The definitive indication shall be obtained within a maximum of 30 s, whatever the value of this indication, on automatic polarimeters for sugar analysis. This is important because the temperature of the cell compartment is distinctly higher than the room temperature. Therefore, when using tubes without thermostatic temperature control, the reading should be taken within 1 min of placing the tube in the instrument, i.e. before the temperature of the solution begins to rise.

8.3 Polarimeter tubes. Simple cells, flow-through cells, or side-filling cells (with or without jacketing) may be used according to the application [21]. It must be possible to fill them without leaving any air bubbles likely to affect the path of the light. In flow-through cells the entry and exit points of the solution must be as near as possible to the ends.
The ends of the tubes must extend from (0.2 to 1) mm beyond the supporting collars centring the tube. The internal tube diameter shall not exceed 10mm. All precautions should be taken to reduce internal reflections, particularly in long, small diameter tubes.

NOTE 11: Where automatic temperature-correcting tubes are employed, the incorporated temperature sensor must be accurate to ±0.2 °C.

The end faces shall be flat, perpendicular to the tube axis and parallel to each other within the limits given in Table 1.
The tubes and their mountings shall be such that, in the corresponding polarimeter, they do not cause disturbance of the light and that the tube axis coincides with the optical axis of the polarimeter to within 0.5°.

Table 1: Tolerances for the end faces of polarimeter tubes

NOTE 12: An angular minute is one 60^th of an angular degree.

The tube length, measured at 20 °C, shall not differ from its nominal length, according to the following classes of accuracy: class A ± 0.01%, class B ± 0.2%. If the difference between the measured and the nominal length is less than 0.01%, such a tube need not bear an indication of its measured length.
If the difference exceeds the permissible deviation of class A (while remaining less than that of class B), this tube shall bear an indication of its measured length, given to the accuracy of class A. For such a tube the quotient of its nominal to its measured length is used as a correction factor for precision measurements.

8.4 Cover glasses. The faces of cover glasses shall have a good optical finish [21]. The thickness shall be between 1 mm and 2 mm. They shall be flat to within 0.01% of the length of the shortest tube with which they are to be used. The parallelism of the two faces shall be such that their angle is less than 5 angular minutes.
The glass shall be free from internal strain so that the polarimeter indication does not vary by more than 0.01 °Z when one glass of an empty tube is rotated in relation to the other, or when the two glasses are rotated simultaneously between 0° and 180°.

8.5 Quartz control plates. To meet the requirements of statutory authorities or the trade for absolute measurements, polarimeters need to be calibrated. This is basically possible with normal sucrose solutions which can, if necessary, be diluted stepwise to check the whole measuring range.
However, sucrose solutions are not stable measuring standards. Their rotation value can possibly change through evaporation, chemical or microbiological decomposition. Therefore, quartz control plates, viz. plates of crystalline quartz cut vertically to the crystal axis, are Officially prescribed for the standardisation of all polarimetric sugar analyses of an Official character. Their manufacture and fixing in suitable mounts are subject to regulations [20]. Compliance with these regulations is checked by specialised laboratories, such as for example, the PTB (Physikalisch-Technische Bundesanstalt, Braunschweig, Germany), and recorded on a certificate together with the optical rotation and sugar value.
A quartz control plate is called “normal” when it produces at 20 °C the same optical rotation as the normal sucrose solution (see 4.2) under standard conditions. Such a plate has a sucrose value of 100.00 °Z for measurements under standard conditions [3]. For a wavelength other than the standard wavelength of 546.2271 nm, a quartz plate has a sucrose value of 100.00 °Z if its optical rotation is equal to that of the normal sucrose solution at that wavelength [3].
Materials and construction have been specified [22]. A quartz plate, including the area covered by the mounting, should be completely free from non-homogeneities such as striae, twinning and inclusions. No defects should be visible on the surface when examined interferometrically.
Quartz plates with values less than 24 °Z (approx. 10° angular at 546 nm) shall consist of a dextrorotatory and a laevorotatory plate. The thickness of each plate shall not be smaller than 0.4 mm; the thickness of both plates together shall not exceed 1.6 mm.
The overall diameter of the plate shall be between 15 mm and 17 mm, and at least 4 mm greater than the diameter of the viewing aperture. The thickness of the plate shall not vary by more than 0.15 mm over the whole area of the plate. Each surface shall lie between two imaginary parallel planes 0.5 mm apart. The angle between the optical axis and that normal to the faces shall be less than 10 angular minutes.
The mounting of the plate shall be constructed so that the diameter of the viewing aperture is at least 10 mm. Squareness of the plate to the axis of the mounting tube shall be within 10 angular minutes. The axial play of the plate in its mounting shall be between 5 mm and 30 mm and the play in direction of the plane shall be less than 0.2 mm. Measurement results obtained using the quartz plate in its final mount shall not vary by more than 0.005 °Z during its full revolution of 360° along its longitudinal axis. Conformity of the plate in its final mount to these specifications has to be certified by the manufacturer.

8.6 Corrections for quartz measurements at temperatures other than 20 °C. These are to be made using the following equations [4]:

α_t / α₂₀ (589.44 nm) = 1.0 + 0.000144(t – 20) (4)
α_t / α₂₀ (882.60 nm) = 1.0 + 0.000139(t – 20) (5)

α_t         Optical rotation at temperature t in °C
α₂₀       Optical rotation at 20 °C
t           Temperature in °C

NOTE 13: Where automatic temperature-correcting quartz plates are used, the temperature sensor must be accurate to ±0.2 °C.

8.7 Use of quartz control plates in polarimeters with different wavelengths. As outlined in Section 8.5, a quartz control plate has a sucrose value of 100 °Z for a particular wavelength, if its rotation is equal to that of the normal sucrose solution at the same wavelength. The numerical values for the wavelengths used in practice are given in 6.4. They are calculated from the value at the basic wavelength of 546.2271 nm using eq. 3 for the rotatory dispersion of sucrose solutions. In addition, the rotation values of a quartz plate must be known for those wavelengths which are needed for its calibration. Using experimental data by Bünnagel and Oehring [10, 23] and reports of the 22^nd and 34^th Sessions [4, 17] the specific rotatory dispersion of quartz for a wavelength in the range (546 to 900) nm is given by eq. 6. In determining the appropriate quartz plate value for a polarimeter operated at a near infrared wavelength, the wavelength of the particular light source employed needs to be known.

\displaystyle \left[ \alpha \right]{{}_{\lambda }}=a+\frac{b}{{{{\lambda }^{2}}}}+\frac{c}{{{{\lambda }^{4}}}}+\frac{d}{{{{\lambda }^{6}}}}     (6)

The coefficients are:
a =   –1.963657 · 10^–1
b =     7.262667 · 10⁶
c =      1.171867 · 10¹¹
d =     1.955400 · 10¹⁵

Using eq. 6 the following rotation values were calculated. The calculations were made using eight significant figures, but only the values rounded to three decimal places reported.

NOTE 14: As outlined in Section 6.1 the 100 °Z point values had to be recalculated considering the density values and the temperature scale, both of 1990. Consequently, two rounded values adopted in 1986 by ICUMSA^® changed by one unit of the last decimal place. They are indicated below with a *, and they were ratified at the 21^st Session in 1994.

A quartz plate showing 100 °Z in an instrument using green Hg-light (λ = 546.2271 nm) for which the 100 °Z point is

\displaystyle \alpha _{{546.2271\,\text{nm}}}^{{100\,{}^\circ \text{Z}}}\text{= 40}\text{.777 }\!\!{}^\circ\!\!\text{ }

has rotation values, α_λ, for light sources of the following wavelengths, λ:

α_546.2271 = 40.777°
α_589.4400 = 34.692°*
α_632.9914 = 29.846°
α_880.0000 = 14.982°
α_882.6000 = 14.890°

A quartz plate showing 100 °Z in an instrument using quartz wedge compensation (λ = 587.0000 nm) for which the 100 °Z point is

\displaystyle \alpha _{{587.000\,\text{nm}}}^{{100\,{}^\circ \text{Z}}}\text{= 34}\text{.935 }\!\!{}^\circ\!\!\text{ }

has rotation values, α_λ, for light sources of the following wavelengths, λ:

[α_587.0000 = 34.935°]
α_546.2271 = 40.704°*
α_589.4400 = 34.629°
α_632.9914 = 29.792°
α_880.0000 = 14.955°
α_882.6000 = 14.863°

NOTE 15: The rotation values for 587 nm are put in brackets since there are no exact measurements carried out at this wavelength. The figures are needed for the calculation of the rotation values of the 100 °Z plate for quartz wedge instruments at the wavelengths used to calibrate the plates for such instruments.

A quartz plate showing 100 °Z in an instrument using yellow Na-light (λ = 589.4400 nm) for which the 100 °Z point is

\displaystyle \alpha _{{\text{589}\text{.4400}\,\text{nm}}}^{{100\,{}^\circ \text{Z}}}\text{= 34}\text{.6263 }\!\!{}^\circ\!\!\text{ }

has rotation values, α_λ, for light sources of the following wavelengths, λ:

α_589.4400 = 34.626°
α_546.2271 = 40.700°
α_632.9914 = 29.789°
α_880.0000 = 14.953°
α_882.6000 = 14.862°

NOTE 16: The values are from the 2017 version of SPS-1. They are still valid for use.

A quartz plate showing 100 °Z in an instrument using He-Ne-laser (λ = 632.9914 nm) for which the 100 °Z point is

\displaystyle \alpha _{{\text{632}\text{.9914}\,\text{nm}}}^{{100\,{}^\circ \text{Z}}}\text{= 29}\text{.752 }\!\!{}^\circ\!\!\text{ }

has rotation values, α_λ, for light sources of the following wavelengths, λ:

α_632.9914 = 29.752°
α_546.2271 = 40.648°
α_589.4400 = 34.582°
α_880.0000 = 14.934°
α_882.6000 = 14.843°

The fact that different wavelengths may be used in sugar polarimeters results in different sucrose values for a given quartz plate. Depending on the wavelength used in the instrument the following values will be obtained with a plate having a sucrose value of 100.00 °Z in green Hg-light.

8.8 Use of quartz control plates in polarimeters with different tube lengths. The standard tube length for polarimeters used in sugar analysis is 200.000 mm. Instruments with another, in most cases shorter, tube length can also be calibrated with quartz control plates. In these cases, the sucrose value of the plate which is always given for 200 mm by the control laboratories must be multiplied by a factor 200/l where l is the tube length (in mm) used in the instrument.

9 Bibliography

1. Emmerich A., Zander K. (1988): Polarimetry and the International Sugar Scale, Sugar Technol. Rev. 14, 275–330
2. Emmerich A. (1991): Basic measurements for the definition of the new ICUMSA^® International Sugar Scale, Zuckerind. 116, 110–120; 245–260
3. Emmerich A. (1986): Referee’s Report on Subject 5, Polarimetry, ICUMSA^® Proceedings 19^th Session, Cannes, 55–69
4. Keitel J. (1998): Referee’s Report on Subject 4, Polarimetry and Quartz Plates, ICUMSA^® Proceedings 22^nd Session, Berlin, 207–212
5. Puke H. (2023): Referee’s Report on Subject 2, Method Format, Collaborative Testing and Statistical Treatment of Data, ICUMSA^® Proceedings 33^rd Session, Vienna, Verlag Dr. Albert Bartens KG, Berlin, 173–194
6. Kuchejda M. (2016): Referee’s Report on Subject 4, Physical Methods, ICUMSA^® Proceedings 30^th Session, Warsaw, Verlag Dr. Albert Bartens KG, Berlin, 212–217
7. Schneider F. (1962): Referee’s Report on Subject 20, 100 °S Point of Sugar Scale and Automatic Polarimetry, ICUMSA^® Proceedings 13^th Session, Hamburg, 68–72
8. Schneider F. (1974): Referee’s Report on Subject 5, 100 °S Point of the sugar scale, ICUMSA^® Proceedings 16^th Session, Ankara, 52–74
9. Bünnagel R. (1972): Effektive Wellenlänge des Standard-Quarzkeil-Saccharimeters und Drehungswerte der Standard-Quarzplatte, Zucker 25, 554–559
10. Bünnagel R. (1966): Referee’s Report on Subject 6, Quartz Control Plates, ICUMSA^® Proceedings 14^th Session, Copenhagen, 27–44
11. Blanke W. (1989): Eine neue Temperaturskala – Die Internationale TemperaturskaIa von 1990 (ITS-90), PTB-Mitteilungen, 411–413
12. Preston-Thomas H. (1990): The International Temperature Scale of 1990 (ITS-90), Metrologia 27, 3–10
13. Bettin H., Spieweck F. (1990): Die Dichte des Wassers als Funktion der Temperatur nach Einführung der Internationalen Temperaturskala von 1990, PTB-Mitteilungen, 195–196
14. Spieweck F. (1990): Referee’s Report on Subject 11, Density, ICUMSA^® Proceedings 20^th Session, Colorado Springs, 265–270
15. Schneider F. (1966): Referee’s Report on Subject 5, 100 °S Point of sugar scale, ICUMSA^® Proceedings 14^th Session, Copenhagen, 16–27
16. Emmerich A., Keitel J., Mösche M., Seiler W. (1998): Rotationsdispersion von Saccharoselösungen und Quarz im nahen Infrarot, PTB-Mitteilungen 4, 293–302
17. Kuchejda M., Keiner R. (2025): Referee’s Report on Subject 4, Physical Methods, ICUMSA^® Proceedings 34^th Session, Delhi, in press
18. Kuchejda M. (2004): Referee’s Report on Subject 4, Density, Optical Rotation and Refractive Index, ICUMSA^® Proceedings 24^th Session, Atlanta, Verlag Dr. Albert Bartens KG, Berlin, 205–210
19. Kuchejda M. (2006): Referee’s Report on Subject 4, Density, Optical Rotation and Refractive Index, ICUMSA^® Proceedings 25^th Session, Aguas de São Pedro, Verlag Dr. Albert Bartens KG, Berlin, 141
20. OIML (1995): Polarimetric saccharimeters graduated in accordance with the ICUMSA^® International Sugar Scale, OIML
21. Wilson R.A.M. (1970): Referee’s Report on Subject 11, Polarisation of Raw Sugars, ICUMSA^® Proceedings 15^th Session, London, 91–106
22. Einsporn E. (1958): Referee’s Report on Subject 3, Standardisation of Quartz Control Plates, ICUMSA^® Proceedings 12^th Session, Washington, 27–32
23. Bünnagel R., Oehring, H.A. (1966): Messung der Rotationsdispersion an einem Quarz für die polarimetrische Bestimmung optischer Schwerpunkte., Z. angew. Phys 20, 419
24. Zander K. (1986): Referee’s Report on Subject 6, Quartz Control Plates, ICUMSA^® Proceedings 19^th Session, Cannes, 70–76

10 Historical

SPS-1 was first published in the 1994 Methods Book. It was subsequently revised in the 1998, 2003 and 2005 Supplements and rewritten in the 2007 Supplement. Further amendments were made following the decisions of the 30^th Session of ICUMSA^® in 2016. This latest revision was proposed to and accepted by the 34^th Session of ICUMSA^® in 2025. Subsequent to the 34^th Session, additional format and content changes were agreed and implemented to ensure the format and calculated values quoted aligned to the ICUMSA^® format for Standards and references used to define the contents of SPS-1. The agreed revision was published as SPS-1 (2026).