Chlorpyrifos

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7840 (Water Solubility)

Deviations:

no

GLP compliance:

yes

Type of method:

column elution method

Specific details on test material used for the study:

Substance ID: TSN100227
Purity: 99.8%

Key result

Water solubility:

0.001 g/L

Temp.:

20 °C

pH:

>= 6.7 - <= 6.9

Details on results:

The solubility of the test substance at the approximately 25 mL/hr collection rate was 1.176 (± 0.030) x 10-3 g/L, and the approximately 12.5 mL/hr was 0.924 (± 0.062) x 10-3 g/L. The relative difference between each replicate solubility value at each flow rate was less than 30% for both collection flow rates, confirming the solubility values reflected equilibrium of saturated solutions. Also, since the average solubility of the test substance in water at the 25 mL/hr and 12.5 mL/hr collection rates was within 30% of the overall mean, no flow rate solubility bias was observed.

Conclusions:

Water solubility (20°C): 1.05E-3 g/L

Executive summary:

The water solubility of the test substance in unbuffered water was determined at 20 ± 0.5 °C using the elution column method according to the guidelines OECD 105 and EPA OPPTS 830.7840. Saturated aqueous samples were developed by pumping water at approximately 25 mL/hr and 12.5 mL/hr over the test substance adsorbed onto an inert support. Replicate samples were assayed and an average concentration was determined for each flow rate. The two solubility values were averaged, and the solubility value for each flow rate was within 30% of the average.

The initial pH of the unbuffered water was 6.9 and 7.0 for the two sample collection flow rates. Consecutive fractions were collected and assayed at each flow rate, and the pH of the fractions immediately bracketing the consecutive fractions was determined at each flow rate (pH 6.8 ± 0.1). An external calibration curve was prepared by analyzing standard solutions of test substance, and the concentrations of the samples were determined from the calibration curve. The initial pH of the unbuffered water was pH 6.9 and pH 6.8 for the two sample collection flow rates. The solubility of the test substance at the approximately 25 mL/hr collection rate was 1.176 (± 0.030) x 10-3 g/L, and the approximately 12.5 mL/hr was 0.924 (± 0.062) x 10-3 g/L. The average solubility of the test substance in unbuffered water at 20°C was determined to be 1.050 x 10-3 (± 0.140 X 10-3) g/L.

Description of key information

OECD 105; EPA OPPTS 830.7840

Key value for chemical safety assessment

Water solubility:

0.001 g/L

at the temperature of:

20 °C