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					                                    ECAMA
                              Specifications for
                    Trisodium Citrate Dihydrate (E 331 iii)

                                 INTRODUCTION

These specifications have been prepared by the Applications and Technology
Working Group of ECAMA (the European Citric Acid Manufacturers Association).

The ECAMA specifications have been ratified by all ECAMA members and have
attempted to harmonise universal Food Additive and Pharmaceutical compendial
requirements.

Where the European Pharmacopoeia, Food Chemicals Codex or the United States
Pharmacopoeia did not offer a Quantitative Method of Analysis ECAMA have
substituted alternative or modified procedures to produce Quantitative analytical data.

The ONLY exception has been for the determination of Sulphate which still relies on
the Qualitative Barium Chloride precipitation procedure. In the test the only
Quantitative result is when Sulphate is shown to be absent. ECAMA members have
recommended a variety of Quantitative instrumental methods for the Determination of
Sulphate at the specification recommendation of 150ppm (mg/kg) which might not be
routinely available to the end user of these products.
                             ECAMA SPECIFICATIONS

                         TRISODIUM CITRATE DIHYDRATE


       DETERMINAND                 PROPOSED LIMIT             QUANTITATIVE METHOD

Appearance                   Translucent to white crystals.   EP 3rd Edition
                             Free from visible foreign        FCC 4th Edition *
                             matters and odours*
Identification               Citrates                         EP 3rd Edition
Colour of Solution           98% min.                         Spectrophotometric 1 cm Cell
                             Transmission 420 nm              40% w/v solution.
Clarity of Solution          4 NTU max.                       Turbidity
                                                              40% w/v solution
Assay                        99% min.                         EP 3rd Edition
Iron                         5 mg/kg max.                     Spectrophotometric 1 cm Cell
                                                              40% w/v solution 360 nm
                                                              85% min Transmission.
Heavy Metals as Pb           5 mg/kg max.                     FCC 4th Edition

Lead                         1 mg/kg max.                     FCC 4th Edition

Arsenic                      1 mg/kg                          FCC 4th Edition

* Mercury                    1 mg/kg max.                     Atomic absorbtion/graphite
                                                              furnace
pH 5% w/v aqueous solution   7.5 to 9                         Use freshly boiled water
                                                              cooled to ambient in air tight
                                                              flasks.
* Sulphate                   150 mg/kg max.                   40 % w/v solution. Turbidity
                                                              with BaCl2
* Chloride                   50 mg/kg max.                    Silver nitrate titration
Oxalate as Oxalic Acid       100 mg/kg max.                   EP 3rd Edition
Dihydrate                                                     Spectrophotometric 1 cm Cell
                                                              Measured at 520 nm
Loss on Drying               12 ± 1%                          2g, 2 hours at 180°C E 331 iii
Sulphuric Acid Test          80% min.                         Spectrophotometric 1 cm Cell
(Carbonisables)              Transmission 470 nm              1 g sample 1 hour 90 ± 1°C
                                                              10 ml 98% min H2SO4
                                         APPENDIX 1


                                      ECAMA / CEFIC

                       HARMONISED METHODS OF ANALYSIS


                                        CITRIC ACID



1)    COLOUR OF SOLUTION

      The presence of Particulate Turbidity will interfere with the results of this Test Procedure.
      It is recommended that in the presence of Particulate Turbidity (Greater than 1.0 NTU)
      the test solution should be membrane filtered (0.2 micron porosity) and the particulate
      contamination examined under a microscope.


2)    IRON

i)    Principle

      Colourimetric reaction between Iron and a mixed ferro-ferri cyanide reagent measured
      quantitatively at 670 nm in a 1 cm Cell against a water reference cell using Iron
      Calibration Standards (0 to 10 ppm) prepared in Iron-Free 40% w/v Citric Acid Solutions.

ii)   Reagents

      Solution A
      Dissolve 13 g of Sodium Ferrocyanide (Na4 [Fe(CN)6] • 10H2O) in a 200ml volumetric
      flask with distilled/deionised water and make up to volume.

      Solution B
      Dissolve 7.5 g of Potassium Ferricyanide (K3 [Fe(CN)6] • H2O) in a 200ml volumetric
      flask with distilled/deionised water and make up to volume.

      Combine solutions A & B and mix well.
iii)   Analytical Procedures

       Using a 150 ml beaker prepare 100 ± 1 ml of 40% w/v Citric Acid test solution. Add 5 ±
       0.2 ml of the Combined Reagent mix well and allow to stand for 10 ± 2 minutes to permit
       Colour Development. Measure the Absorbance at 670 nm against a distilled/deionised
       water reference using 1cm cells. Calculate the Iron concentration by comparing with a
       Calibration Curve (0 to 10 ppm) or a known Standard (5 ppm) prepared in 40% w/v Iron-
       Free Citric Acid Solution and analysed at the same time as the Test Samples.

iv)    Analytical Procedure

       Detection Limit              0.2 ppm (mg/kg)
       Analytical Tolerance ± 0.3 at 5 ppm (mg/kg)


3)     CALCIUM

i)     Principle

       Atomic Absorption Spectroscopy (AAS) utilising a 10% w/v Citric Acid Solution
       measured against a Calibration Curve prepared with 10% w/v Calcium-Free Citric Acid
       Solutions.

ii)    Analytical Procedures

       Prepare duplicate Test Solutions by adding the following aliquots to 100 ml volumetric
       flasks:-

       A) 30 ± 0.2ml of 1M Hydrochloric Acid (Calcium Free)
       B) 10 ± 0.1g of Citric Acid Sample

       Finally make up to volume with distilled/deionised water and mix well.

       Calibrate the AAS Instrument with the following solutions made up in Calcium-free 10%
       w/v Citric Acid Solution:-

       Blank, 2.0, 5.0 and 10.0 ppm Calcium (mg/kg)

       and analyse the duplicate Test Solutions against the above Calibration Curve.
iii)   Calculation

       The Calcium content of the Citric Acid Sample is equivalent to:-

       Test Solution ppm x 10


iv)    Analytical Performance

       Detection Limit              2 ppm (mg/kg)
       Analytical Tolerance ± 3 at 75 ppm (mg/kg)


4)     SULPHATE

       ECAMA members have demonstrated that the Barium Chloride Precipitation Procedure
       used in the European Pharmacopoeia and many other compendial specifications can only
       be used as a Qualitative assessment of the Sulphate content of Citric Acid and the
       Citrates. Typically at 150 ppm a variance of ± 50 ppm was not uncommon. Only when
       this type of Test Procedure demonstrates an absence of Sulphate can the result be treated
       as Quantitative. This would indicate levels of Less than 10 ppm (mg/kg)

       ECAMA members would recommend the use of the following analytical procedures
       where there is a need to measure the Quantitative level of Sulphate in Citric Acid or the
       Citrates.

              Inductively Coupled Plasma Emission Spectroscopy
              X-ray Fluorescence
              Ion Chromatography
              Elemental Analysis by Combustion


5)     OXALATE as OXALIC ACID DIHYDRATE

i)     Principle

       Oxalate is determined using the European Pharmacopoeia 3rd Edition Colourimetric
       Procedure using Phenlyhydrazine hydrochloride. The Calibration Curve (0 to 150 ppm) is
       prepared from Oxalate-Free Citric Acid and Oxalic Acid Dihydrate with absorption
       measured at 520 nm in a 1 cm cell against a water reference.
ii)    Reagents

       See European Pharmacopoeia 3rd Edition.

iii)   Analytical Procedure

       See European Pharmacopoeia 3rd Edition. Following the 30 ± 5 minutes Colour
       Development period measure the Absorption at 520nm in a 1 cm cell. The Oxalate
       concentration is calculated from the Calibration Curve or from the Absorption of a known
       Standard (100ppm) prepared from Oxalate-Free Citric Acid and analysed at the same time
       as the Test Samples.

iv)    Analytical Performance

       Detection Limit              20 ppm (mg/kg)


6)     SULPHURIC ACID TEST (CARBONISABLES)

       ECAMA members have demonstrated that the Colour Standard, Fluid K used in the
       various Compendial Specification Tests for Carbonisables has a Colour Intensity which
       varies with ambient temperature. Fluid K colour increases with temperature.
       Consequently ECAMA recommend a Test Procedure which monitors the Test Sample
       against Fixed Wavelength Absorbance/Transmission of Fluid K at 25°C. Thus the
       compliance limits for any Test Solution are at 470 nm in a 1 cm Cell.

       Absorbance must not exceed 0.52
       Transmission must be equal to or exceed 30%

       Please note the colour of the Sulphuric Acid Test Solutions are NOT Temperature
       sensitive.

i)     Principle

       When Citric Acid is heated at 90°C with concentrated Sulphuric Acid a yellowish-brown
       colour develops especially in the presence of non-Citric based organic impurities or
       Nitrates. Compliance is demonstrated by comparison with a Standard Colour Solution
       Fluid K (Aqueous Solution of Cobalt and Iron Chlorides).
ii)    Reagents

       Sulphuric Acid         98% minimum Reagent Grade Sulphuric Acid
                              (low Nitrate less than 1 ppm max)

       Fluid K                Prepare as per European Pharmacopoeia
                              3rd Edition.

iii)   Analytical Procedure

       Carefully add 10 ± 0.1 ml of 98% minimum Sulphuric Acid to 1.00± 0.01 g of Citric
       Acid in a test tube (18 mm o.d, 150 mm length). These must be pre-cleaned with 98%
       minimum Sulphuric Acid at 90°C before use or previously reserved for Carbonisable
       Tests. Place the test tube in a water bath maintained at 90 ± 1°C for 1 hour. Occasionally
       remove and CAREFULLY shake the tube to ensure that the Citric Acid is dissolved and
       gaseous decomposition products are allowed to escape to atmosphere. After 1 hour cool
       to Ambient Temperature, shake to ensure all dissolved gases are removed and measure
       the Absorbance/Transmission at 470 nm in a 1 cm Cell.

iv)    Analytical Performance

       Product meets the ECAMA Specification if the Colour generated in the Sulphuric Acid
       meets the following criteria at 470 nm in a 1 cm Cell:-

       Absorbance does not exceed 0.52
       Transmission is equal to or exceeds 30%
                                       APPENDIX 2


                                     ECAMA / CEFIC

                      HARMONISED METHODS OF ANALYSIS


                    TRIPOTASSIUM CITRATE MONOHYDRATE



1.   COLOUR OF SOLUTION

     See Appendix 1 CITRIC ACID Section 1.


2.   IRON

     There is a colourimetric reaction between Tripotassium Citrate and Iron which gives rise
     to an Absorption at 360 nm. Typically for a 40%w/v solution 5 ppm of Iron in the Citrate
     will give at least 80% Transmission at 360 nm in a 1 cm Cell. Transmissions less than
     80% indicate an Iron Concentration in excess of 5 ppm.

     Please note that turbidity in the Test Solution will effect the result (See Appendix 1
     CITRIC ACID, Section 1).


3.   OXALATE

     See Appendix 1 CITRIC ACID Section 5.


4.   SULPHURIC ACID TEST (CARBONISABLES)

     For the Analytical Procedure see Appendix 1 CITRIC ACID Section 6 taking 1.00 ± 0.01
     g sample of Tripotassium Citrate Dihydrate where by compliance is demonstrated if
     Transmission at 470 nm in a 1 cm Cell is equal to or exceeds 80%.
                                       APPENDIX 3


                                     ECAMA / CEFIC

                      HARMONISED METHODS OF ANALYSIS


                         TRISODIUM CITRATE DIHYDRATE




1)   COLOUR OF SOLUTION

     See Appendix 1 CITRIC ACID Section 1.


2)   IRON

     There is a colourimetric reaction between Trisodium Citrate and Iron, which gives rise to
     an Absorption at 360 nm. Typically for a 40% w/v Solution 5ppm of Iron in the Citrate
     will give at least 85% Transmission at 360 nm in a 1 cm Cell. Transmissions less than
     85% indicate an Iron concentration in excess of 5 ppm.

     Please note that turbidity in the Test Solution will affect the results. (See Appendix 1
     CITRIC ACID Section 1).


3)   OXALATE

     See Appendix 1 CITRIC ACID Section 5.


4)   LOSS ON DRYING

i)   Principle

     Heating approximately 2g ± 1mg of Trisodium Citrate Dihydrate at 180 ± 5°C for 2
     hours.

     Please note ECAMA members have demonstrated that 180° for 2 hours is sufficient to
     dehydrate 2g of Trisoium Citrate Dihydrate to constant weight as opposed to 4 hours
     recommended in 96/77/EC of December 1996 for E331 (iii).
ii)   Analytical Procedure

      As per E331 (iii) from 96/77/EC with heating restricted to 2 hours only.


5)    SULPHURIC ACID TEST (CARBONISABLES)

      For the Analytical Procedure see Appendix 1 CITRIC ACID Section 6 taking a 1.00 ±
      0.01 g sample of Trisodium Citrate Dihydrate whereby compliance is demonstrated if
      Transmission at 470 nm in a 1 cm Cell is equal to or exceeds 80%.

				
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