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DL-LACTONE CAS N°:79-50-5 - page 29 / 113

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OECD SIDS 2. PHYSICO-CHEMICAL DATA

DL-LACTONE

ID: 79-50-5 DATE: 18.01.2006

Value:

ca. .102 hPa at 20 degree C

Method:

Year: GLP: Test substance:

other (calculated): extrapolated from measured values at 60, 100 and 260 °C 2004 no as prescribed by 1.1 - 1.4

Method:

The three measured values were entered into a SigmaPlot spreadsheet, based on which a log-log graph of temperature (K) vs pressure (hPa) was drawn. The SigmaPlot regression line has the equation: f(x) = x*b[1] - b[0], where

b[0] = b[1] =

  • -

    40.2665002287

15.9193396988, with

Result:

r ² = 0 . 9 9 9 7 1 1 3 0 9 1 Based on the equation parameters described in Methods, a vapour pressure of approximately 0.102 hPa was extrapolated .

Reliability:

for (2)

a temperature of 20 °C. valid with restrictions

Rational but uncertainty.

coarse

extrapolation,

fraught

with

some

19-AUG-2004

2.5 Partition Coefficient

Partition Coeff.: octanol-water

log Pow: PH prec:

= -.69 at 21 degree C = 6.3 - 6.5

Method:

Year: GLP:

OECD Guide-line 107 Flask-shaking Method" 1999 yes

"Partition Coefficient (n-octanol/water),

Method:

Based on a preliminary calculation of the n-octanol/water

partition coefficient by the Rekker method, which resulted in a logKow of -0.02, the flask-shaking method OECD 107 was selected for the experimental determination of the logKow. The (acidic) pKa for dl-lactone was modelled by NOTOX to be 13.2, hence the water phase was not buffered for the test. According to the OECD 107 method, a stock solution was prepared by dissolving 64.6 mg dl-lactone in 25.0 ml double-distilled water that had been saturated with n-octanol (99% HPLC Grade, Sigma-Aldrich, USA). In order to dissolve the test substance, the solution was sonicated for for 5 min. Three tests were carried out at 21±0.5°C using different volumes of n-octanol and double-distilled water (mutually saturated). The volumetric ratios of water and octanol were 1:2, 1:1 and 2:1, respectively. For each test, duplicate vessels containing the required, accurately measured amounts of the two solvents and the stock solution were prepared and shaken by hand during 5 min. Phase separation was achieved by centrifugation for 5 min at 3500 g and 20°C. The pH of each aqueous phase was determined. For the preparation of a blank, a vessel containing equal amounts of octanol saturated with water and water saturated with octanolwas shaken, centrifuged and analysed similar to the test substance vessels.

UNEP PUBLICATIONS

29

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