Sodium lactate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Type:

log Pow

Partition coefficient:

< -1.52

Temp.:

20 °C

pH:

7

Remarks on result:

other: based on sodium (mean)

Type:

log Pow

Partition coefficient:

< -2.13

Temp.:

20 °C

pH:

7

Remarks on result:

other: based on lactate (mean)

Type:

log Pow

Partition coefficient:

-4.77

Remarks on result:

other: calculated result (QSAR)

Details on results:

see box "Any other information on results incl. tables".

Table 1: Sodium analysis - sample compositions & results

Sample No	Volume of		Initial amount of	Actual amount after equilibrium in		Recovery in both phases
	Buffer (ml)	n-octanol (ml)	Sodium (mg)	Buffer (mg)	n-octanol (mg)	In % of used amount
1A	10	10	2.12	2.15	<0.068	101.3
1B	10	10	2.32	2.32	<0.068	100.3
2A	10	20	2.12	2.14	<0.136	101.1
2B	10	20	2.32	2.33	<0.136	100.5
3A	20	10	4.24	4.25	<0.068	100.3
3B	20	10	4.64	4.61	<0.068	99.6

 

Table 2: Sodium analysis - concentrations in the phases and partition coefficients

Sample No	Actual concentration of Na in		Pow	log Pow	pH of the aqueous phase in equilibrium
	n-octanol (mg/l)	Buffer (mg/l)
1A	<6.8	215	<0.032	<-1.50	7
1B	<6.8	232	<0.029	<-1.54	6.9
2A	<6.8	214	<0.032	<-1.50	7
2B	<6.8	233	<0.029	<-1.53	7
3A	<6.8	213	<0.032	<-1.50	7
3B	<6.8	231	<0.029	<-1.53	7

Table 3: Lactate analysis - sample compositions & results

Sample No	Volume of		Initial amount of	Actual amount after equilibrium in		Recovery in both phases
	Buffer (ml)	n-octanol (ml)	Lactate (mg)	Buffer (mg)	n-octanol (mg)	In % of used amount
1A	10	10	8.21	12.86	<0.1	157.9
1B	10	10	8.97	14.00	<0.1	157.2
2A	10	20	8.21	12.86	<0.1	159.1
2B	10	20	8.97	13.98	<0.1	158.1
3A	20	10	16.42	25.74	<0.2	157.4
3B	20	10	17.94	28.00	<0.2	156.6

Table 4: Lactate analysis - concentrations in the phases and partition coefficients

Sample No	Actual concentration of lactate in		Pow	log Pow	pH of the aqueous phase in equilibrium
	n-octanol (mg/l)	Buffer (mg/l)
1A	<10	1286	<0.0078	<-2.11	7
1B	<10	1400	<0.0071	<-2.15	6.9
2A	<10	1286	<0.0078	<-2.11	7
2B	<10	1398	<0.0072	<-2.15	7
3A	<10	1287	<0.0078	<-2.11	7
3B	<10	1400	<0.0071	<-2.15	7

The log Pow of <-1.52 of sodium was taken as most appropriate to represent the log Pow of Sodium (S)-lactate.

Conclusions:

The log Pow of Sodium (S)-lactate is < –1.52.

Executive summary:

In a GLP study conducted according to OECD 107, the shake flask method was applied to determine the octanol/water partition coefficient of Sodium (S)-lactate. The test substance is a salt - therefore the partition coefficient of the test item was determined from cations and anions, i.e., the analysis of the sodium content and the lactate content in both liquid phases. Based on sodium, the partition coefficient was determined as log Pow < -1.52 (key value). Based on lactate, the partition coefficient was determined as log Pow < -2.13.

 

This information is used in a read-across approach in the assessment of the target substance. For justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reference 2

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2022-11-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

Please refer to QPRF/QMRF documentation for detailed information on model suitability.

Qualifier:

according to guideline

Guideline:

other: Guidance on information requirements and chemical safety assessment Chapter R.6: QSARs and grouping of chemicals

Version / remarks:

May 2008

Principles of method if other than guideline:

QSAR prediction using KOWWIN v1.68 of EpiSuite v4.1. QSAR calculation is based on the fragment constant methodology.

GLP compliance:

no

Type of method:

other: QSAR calculation.

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

Smiles:
Canonical: CC(C(=O)[O-])O.[Na+]
Stereoisomers do exist. The input of the respective canonical SMILES for Sodium (S)-lactate and Sodium (R)-lactate all result in identical QSAR predictions. Stereochemistry is not expected to influence vapour pressure predictions for the different lactates.

Key result

Type:

log Pow

Partition coefficient:

-4.77

Temp.:

20 °C

Remarks on result:

other: pH not available in QSAR prediction.

Details on results:

See QPRF/QMRF.

Conclusions:

The estimated log Pow of –4.77 for Sodium lactate is very low and suggests hydrophilic properties associated with a minor potential for adsorption and bioaccumulation.

Executive summary:

In general, KOWWIN makes log P estimates that are “corrected for ionization”, i.e., KOWWIN estimates apply to compounds that are predominantly in a non-ionized form. However, KOWWIN is also capable to give log P estimates for “ion pair” compounds such as Sodium lactate. For this, KOWWIN considers Sodium lactate an “ion pair” compound and gives a corresponding estimate; effectively, the estimate for Sodium lactate is an estimate for ionized lactic acid with an additional fragment contributing factor for the sodium counter ion. This approach is considered reasonable. The model result for Sodium lactate with a log P_ow value of -4.77 matches the general behaviour for ionic compounds in a polar (water) and non-polar (octanol) environment and suggests hydrophilic properties associated with a minor potential for adsorption and bioaccumulation. Sodium lactate is within the applicability domain of the model and the result is considered adequate for a regulatory purpose.

Description of key information

All available evidence indicates that the octanol-water partition coefficient of Sodium lactate is significantly below 0. In a worst-case approach, and supported by weight of evidence the highest value of log P_ow= -1.52 is selected.

Key value for chemical safety assessment

Log Kow (Log Pow):

-1.52

at the temperature of:

20 °C

Additional information

In a weight-of-evidence approach the partition coefficient of Sodium lactate is assessed to range between -4.77 and -1.52.

In a GLP study conducted according to OECD 107, the shake flask method was applied to determine the octanol/water partition coefficient of the suitable read-across partner Sodium (S)-lactate. The log Pow was determined to be < -1.52 at 20 °C.

This value is further supported by a recent QSAR calculation using the software KOWWIN (EpiSuite). In general, KOWWIN makes log P estimates that are “corrected for ionization”, i.e., KOWWIN estimates apply to compounds that are predominantly in a non-ionized form. However, KOWWIN is also capable to give log P estimates for “ion pair” compounds such as Sodium lactate. For this, KOWWIN considers Sodium lactate an “ion pair” compound and gives a corresponding estimate; effectively, the estimate for Sodium lactate is an estimate for ionized lactic acid with an additional fragment contributing factor for the sodium counter ion. This approach is considered reasonable. The model result for Sodium lactate with a log Pow value of –4.77 matches the general behavior for ionic compounds in a polar (water) and non-polar (octanol) environment and suggests hydrophilic properties associated with a minor potential for adsorption and bioaccumulation. Sodium lactate is inside the applicability domain of the model and the result is considered adequate for a regulatory purpose.

In conclusion, adopting a worst-case approach the highest reported partition coefficient of log Pow= -1.52 is selected as the key value for chemical safety assessment. The weight of evidence indicates that this value is fully appropriate for risk assessment.