| Title: | Inter-laboratory comparison of water solubility methods applied to difficult-to-test substances |
| Author(s): | Letinski DJ; Redman AD; Birch H; Mayer P; |
| Address: | "Toxicology and Environmental Sciences Division, ExxonMobil Biomedical Sciences, Inc., 1545 US Highway 22 East, Annandale, NJ, 08801-3059, USA. daniel.j.letinski@exxonmobil.com. Toxicology and Environmental Sciences Division, ExxonMobil Biomedical Sciences, Inc., 1545 US Highway 22 East, Annandale, NJ, 08801-3059, USA. Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs, Lyngby, Denmark" |
| DOI: | 10.1186/s13065-021-00778-7 |
| ISSN/ISBN: | 2661-801X (Electronic) 2661-801X (Linking) |
| Abstract: | "Water solubility is perhaps the single most important physical-chemical property determining the environmental fate and effects of organic compounds. Its determination is particularly challenging for compounds with extremely low solubility, frequently referred to as 'difficult-to-test' substances and having solubility's generally less than 0.1 mg/L. The existing regulatory water solubility test for these compounds is the column elution method. Its applicability, however, is limited, to non-volatile solid or crystalline hydrophobic organic compounds. There currently exists no test guideline for measuring the water solubility of very hydrophobic liquid, and potentially volatile, difficult-to-test compounds. This paper describes a 'slow-stir' water solubility methodology along with results of a ring trial across five laboratories evaluating the method's performance. The slow-stir method was applied to n-hexylcyclohexane, a volatile, liquid hydrophobic hydrocarbon. In order to benchmark the inter-laboratory variability associated with the proposed slow-stir method, the five laboratories separately determined the solubility of dodecahydrotriphenylene, a hydrophobic solid compound using the existing column elution guideline. Results across the participating laboratories indicated comparable reproducibility with relative standard deviations (RSD) of 20% or less reported for each test compound - solubility method pair. The inter-laboratory RSD was 16% for n-hexylcyclohexane (mean 14 microg/L, n = 5) using the slow-stir method. For dodecahydrotriphenylene, the inter-laboratory RSD was 20% (mean 2.6 microg/L, n = 4) using the existing column elution method. This study outlines approaches that should be followed and the experimental parameters that have been deemed important for an expanded ring trial of the slow-stir water solubility method" |
| Keywords: | Difficult-to-test Generator column Hydrophobic organics Ring test Slow-stir method Volatile Water solubility; |
| Notes: | "PubMed-not-MEDLINELetinski, Daniel J Redman, Aaron D Birch, Heidi Mayer, Philipp eng Long-Range Research Initiative ECO38/European Chemical Industry Council/ Switzerland 2021/09/17 BMC Chem. 2021 Sep 15; 15(1):52. doi: 10.1186/s13065-021-00778-7" |
