Lithium nickel potassium oxide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption

Justification for type of information:

Analytical Limitations for the Determination of Adsorption-Desorption Potential of KDLNO in Soils (Please see the attached justification).

The test substance lithium nickel potassium oxide (KDLNO) has a maximum content of 0.8% lithium, 5.5% potassium, and 66% nickel, the remainder is oxygen and water.

Nickel was chosen as the target analyte for a recent water solubility study, due to its relatively high concentration in KDLNO and analytical sensitivity compared with lithium and potassium. A limit of detection (LOD) for nickel of 1 ppb was achieved using an inductively coupled mass spectrometry (ICP-MS) method. This LOD is approaching the technical sensitivity limit for ICP-MS and is more than sufficient for physical/chemical properties testing. The water solubility of KDLNO was determined, according to EC Method A.6 and OECD Guideline 105, to be less than 1.7 ppb based on a lack of detector response for nickel at the LOD of 1 ppb for a sample containing 59% nickel.

Due to their lower concentrations in the KDLNO test sample, LODs for lithium and potassium would have to be 0.009 ppb and 0.08 ppb, respectively, to quantify total KDLNO at the same level of sensitivity. LODs this low are typically impracticable to achieve using even the most sophisticated analytical equipment available.

The concentration of each constituent released into water (e.g., lithium, nickel, or potassium ions) must be less than the overall water solubility of KDLNO (i.e., less than 1.7 ppb) and is expected to be proportional to the constituent’s weight percent in the KDLNO product. Estimates for the concentrations of metal ion constituents possibly released into water from KDLNO are provided below.


The shake-flask and screening methods to determine the partition coefficient of a substance in accordance with EC Method A.8 and OECD Guidelines 107 and 117 were not considered appropriate for KDLNO.1 Estimation of the partition coefficient of KDLNO by calculation of the ratio of solubilities in n-octanol and water was not feasible as the solubility in both n-octanol and water was below the established limits of detection.

Based on its physical chemical properties, KDLNO is expected to have a low potential for adsorption in soil—it will neither partition to the soil phase nor aqueous phase, but simply remain a solid metal oxide in the undissolved compartment. Determination of the adsorption and desorption behavior of KDLNO in soils using a batch equilibrium method (OECD Guideline 106) or an alternative estimation method (OECD Guideline 121 or Quantitative Structure Activity Relationship (QSAR)), is technically infeasible due to the extremely low water solubility of this inorganic substance (less than 1.7 ppb) and the lack of test methods capable of measuring transportation, adsorption or desorption of KDLNO in the test system.

References:

1. Covance CRS Research Limited. (2019) Lithium nickel potassium oxide (KDLNO): Determination of General Physico-Chemical Properties. Unpublished report. Issue Date 29 October 2019.
2. [Weight percent in KDLNO] ÷ [100%] × [1.7 ppb] = [Concentration in water]

Key value for chemical safety assessment

Koc at 20 °C:

4