Amendment to the Ordinance for Enforcement of the Food Sanitation Act  and the 
Specifications and Standards for Food s, Food Additives , Etc . 
 
The government of Japan will designate dipotassium L-tartrate  as an authorized 
food additive  and establish compositional specifications  and use standards  for this 
additive . 
 
Background  
Japan prohibits the sale of food additives that are not designated by the Minister of 
Health, Labour and Welfare (hereinafter referred to as “the Minister”) under Article 
12 of the Food Sanitation Act (Act No. 233 of 1947; hereinafter referred to as “the 
Act”). In addition, when specifications or stand ards for food additives are stipulated 
in the Specifications and Standards for Foods , Food Additives , Etc. (Public Notice of 
the Ministry of Health and Welfare No. 370, 1959) , Japan prohibits the sale  of those 
additives unless they meet the specifications or the standards  pursuant to Article 1 3 
of th e Act . 
 
In response to a request from the Minister, the Committee on Food Additives of the 
Food Sanitation Council under the Pharmaceutical Affairs and Foo d Sanitation 
Council (hereinafter referred to as “the Committee”)  has discussed the adequacy of 
the designation of dipotassium L-tartrate  as a food additive. The conclusion of the 
Committee  is outlined below.  
 
Outline of conclusion  
The Minister  should designate dipotassium L-tartrate  as a food additive unlikely to 
cause harm to human health pursuant to Article 1 2 of the Act and should establish 
compositional specificatio ns and use standards for this additive pursuant to  Article 
13 of the Act (see Attachment  for the details ). 
  Dipotassium L-Tartrate  
Ｌ-酒石酸カリウム  
 
 
Standards for Use (draft)  
Permitted for use in grape juice used for wine production and grape wine only . 
 
Compositional Specifications (draft)  
Substance Name  Dipotassium L-Tartrate  
Structural Formula  
 
 
 
 
Molecular Formula  C4H4K2O6 •1/2H 2O 
Molecular Weight  235.28  
Chemical Name  [CAS number]  
Dipotassium (2 R,3R)-2,3-dihydroxybutanedioate hemihydrate [6100 -19-2] 
Content   Dipotassium L-Tartrate , when dried, contains not less than 99.0% of 
dipotassium L-tartrate  (C4H4K2O6 = 226.27 ). 
Description   Dipotassium  L-Tartrate  occurs as colorless to white crystals or fine 
granular powder.  
Identification  
(1) A solution of Dipotassium L-Tartrate  (1 in 10) i s dextrorotatory.  
(2) Dipotassium L-Tartrate  responds to  test (1) for Calcium Salt and to all tests for 
Tartrate in the Qualitative Tests.  
Specific Rotation  [α]D20: +27.2 to +29.7   (5 g, water, 50 mL, on the dried basis).  
pH  7.0–9.0  (0.5 g, water 50 mL).  
Purity  Attachment  (1) Lead   Not more than 2 μg/g as Pb ( 2.0 g, Method 3, Control Solution: Lead  
Standard Solution 4.0 mL, Flame Method).  
(2) Arsenic   Not more than 3 μg/g as As (0.50 g, Method 1, Standard Color: Arsenic 
Standard Solution 3.0 mL, Apparatus B).  
(3) Oxalate   Not more than 100 μg/g as C 2H2O4. 
Test Solution  Weigh 0.100 g  of Dipotassium L-Tartrate , previously dried, and add 
sulfuric acid TS ( 0.01 mol/L) to dissolve it and to make exactly 20 mL.  
Control Solution  Weigh 140 mg  of oxalic acid dihydrate, and add sulfuric acid TS  
(0.01 mol/L) to dissolve it and to make exactly 1000 m L. To exactly 1 mL of this solution, 
add sulfuric acid TS (0.01 mol/L) to make exactly 200 mL.  
Procedure  Analyze 10 -μL potions of the test solution a nd the control  solution by 
liquid chromatography using the operating conditions given below. Measure the peak 
area of oxalic acid for each of the test and control solutions by the automatic integration 
method. The peak area of oxalic acid for the test solu tion is not larger than that for the 
control solution.  
Operating Conditions  
Detector: Ultraviolet spectrophotometer (wavelength: 210 nm).  
Column: A stainless steel tube (6 –8 mm internal diameter and 30 cm length). If 
necessary, two connected columns may be used.  
Column packing material: 8 -μm H -form cation -exchange resin for liquid 
chromatography.  
Guard column: Use a column with the same internal diameter that is packed with 
the same packing material as for the column above.  
Column temperature: 50°C.  
Eluent: Sulfuric acid TS (0.01 mol/L).  
Flow rate: 0.6 mL/min.  
Loss on Drying   Not more than 4.0% (150 C, 4 hours).  
Assay  Weigh accurately ab out 0.2 g of Dipotassium L-Tartrate , previously dried, add 3 
mL of formic acid, and dissolve it by warming. Add 50 mL of acetic acid f or nonaqueous 
titration, and titrate with 0.1 mol/L perchloric acid. Usually , a potentiometer is used to 
confirm the endpo int. When crystal violet –acetic acid TS (1 mL) is used as the indicator, 
the endpoint is when the color of the solution changes from purple through blue to green. 
Separately, perform a blank test to make any necessary correction.  
Each mL of 0.1 mol/L perch loric acid =11.31 mg of C4H4K2O6 
 Reagents, Solutions, and Other Reference Materials  
Sulfuric Acid TS (0.01 mol/L)  Add water to 10 mL of sulfuric acid TS (1 mol/L) to make 
1000 mL.