Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Systemic alkalinising agent.
DEFINITION
Solution of a mixture of the enantiomers of sodium (2RS)-2-hydroxypropanoate in approximately equal proportions.
Content
Minimum declared content 50 per cent m/m of sodium (2RS)-2-hydroxypropanoate (C3H5NaO3; Mr 112.1); 96.0 per cent to 104.0 per cent of the content of sodium lactate stated on the label.
CHARACTERS
Appearance
Clear, colourless, slightly syrupy liquid.
Solubility
Miscible with water and with ethanol (96 per cent).
IDENTIFICATION
A. To 0.1 mL add 10 mL of water R. 5 mL of the solution gives the reaction of lactates (2.3.1).
B. It gives reaction (a) of sodium (2.3.1).
TESTS
Solution S
Dilute a quantity of the substance to be examined corresponding to 40.0 g of sodium lactate to 200 mL with distilled water R.
Appearance of solution
The substance to be examined is clear (2.2.1) and not more intensely coloured than reference solution BY7 (2.2.2, Method II).
pH (2.2.3)
6.5 to 9.0 for the substance to be examined.
Reducing sugars and sucrose
To 5 mL of the substance to be examined add 0.2 mL of copper sulfate solution R and 2 mL of dilute sodium hydroxide solution R. The solution is clear and blue and remains so on boiling. Add to the hot solution 4 mL of hydrochloric acid R. Boil for 1 min. Add 6 mL of strong sodium hydroxide solution R and heat to boiling again. The solution is clear and blue.
Methanol
Gas chromatography (2.4.24).
Limit:
— methanol: maximum 50 ppm, calculated with reference to sodium lactate, if intended for use in the manufacture of parenteral preparations, dialysis, haemodialysis or haemofiltration solutions.
Chlorides (2.4.4)
Maximum 50 ppm calculated with reference to sodium lactate. Dilute 5 mL of solution S to 15 mL with water R.
Oxalates and phosphates
To 1 mL of the substance to be examined add 15 mL of ethanol (96 per cent) R and 2 mL of calcium chloride solution R. Heat at 75 °C for 5 min. Any opalescence in the solution is not more intense than that of a standard prepared at the same time and in the same manner using a mixture of 1 mL of the substance to be examined, 15 mL of ethanol (96 per cent) R and 2 mL of water R.
Sulfates (2.4.13)
Maximum 100 ppm calculated with reference to sodium lactate.
To 7.5 mL of solution S, add 1.9 mL of hydrochloric acid R1 and dilute to 15 mL with distilled water R. The solution complies with the test for sulfates without addition of 0.5 mL of acetic acid R. Acidify the standard solution with 0.05 mL of hydrochloric acid R1 instead of 0.5 mL of acetic acid R.
Aluminium
Maximum 0.1 ppm, if intended for use in the manufacture of parenteral preparations, dialysis, haemodialysis or haemofiltration solutions.
Atomic absorption spectrometry (2.2.23, Method I). For the preparation of the solutions, use equipment that is aluminium- free or that will not release aluminium under the conditions of use (glass, polyethylene, etc).
Modifier solution Dissolve 100.0 g of ammonium nitrate R in a mixture of 4 mL of nitric acid R and 50 mL of water R and dilute to 200 mL with water R.
Blank solution Dilute 2.0 mL of the modifier solution to 25.0 mL with water R.
Test solution To 5.0 g add 2.0 mL of the modifier solution and dilute to 25.0 mL with water R.
Reference solutions Prepare the reference solutions immediately before use (0.010 ppm to 0.050 ppm of aluminium) using aluminium standard solution (200 ppm Al) R.
Source Aluminium hollow-cathode lamp.
Wavelength 309.3 nm.
Atomisation device Graphite furnace.
Carrier gas argon R.
Conditions The device is equipped with a non-specific absorption correction system. Heat the oven to 120 °C for as many seconds as there are microlitres of solution introduced into the apparatus, then heat at 1000 °C for 30 s and finally at 2700 °C for 6 s.
Iron (2.4.9)
Maximum 10 ppm calculated with reference to sodium lactate. Dilute 5 mL of solution S to 10 mL with water R.
ASSAY
Dissolve a quantity of the substance to be examined corresponding to 75.0 mg of sodium lactate in a mixture of 10 mL of glacial acetic acid R and 20 mL of acetic anhydride R. Allow to stand for 15 min. Add 1 mL of naphtholbenzein solution R and titrate with 0.1 M perchloric acid.
1 mL of 0.1 M perchloric acid is equivalent to 11.21 mg of C3H5NaO3.
LABELLING
The label states:
— where applicable, that the substance is suitable for use in the manufacture of dialysis, haemodialysis and haemofiltration solutions;
— where applicable, that the substance is suitable for use in the manufacture of parenteral preparations;
— the declared content of sodium lactate.
