1H,5H-Pyrazolo(1,2-a)pyrazol-1-one, 2,3-diamino-6,7-dihydro-, dimethanesulfonate

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 september to 26 September 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliant to GLP and testing guideline; adequate coherence between data, comments and conclusions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

- Name of test material (as cited in study report): R0054002C, synonym IMEXINE OBH
- Physical state: yellow powder
- Purity: 99.8%
- Impurities (identity and concentrations): not indicated
- Purity test date: 22 October 2007
- Lot/batch No.: R0054002C 013 L 001, synonym 0604070001
- Expiration date of the lot/batch: 01 February 2008
- Stability under test conditions: not indicated
- Storage condition of test material: at +4°C, protected from light, humidity and under nitrogen gas

Study design

Test temperature:

Test 1: 23.7°C ± 0.5°C (non-ionized form) pH 7.2
Test 2: 23.9°C ± 0.5°C (ionized form) pH 2.9

HPLC method

Details on study design: HPLC method:

EQUIPMENT
- Type, material and dimension of analytical (guard) column: Zorbax CN (Interchim) ; particle size = 5µm ; length = 150 mm ; inner diameter = 4.6 mm
- Detection system: 2487 (Waters)


MOBILE PHASES
- Type:
Test 1 (non-ionized form):

methanol: 55%
buffer (ammonium acetate (3.08 g) was dissolved in 1800 mL of water in a beaker and the pH of the solution was adjusted to 7.5 with ammonia solution. The resulting solution was transferred into a 2000-mL volumetric flask and made up to volume with more water ): 45%

- Experiments with additives carried out on separate columns: no
- pH: 7.20

Test 2 (ionized form)

methanol: 55%
buffer (potassium dihydrogenophosphate (2.72g) was dissolved in 1800 mL of water in a beaker and the pH of the solution was adjusted to 2 with phosphoric acid. The resulting solution was transferred into a 2000-mL volumetric flask and made up to volume with more water ): 45%

- Experiments with additives carried out on separate columns: no
- pH: 2.90

DETERMINATION OF DEAD TIME
- Method: Injection of a solution of formamide was performed in duplicate.


REFERENCE SUBSTANCES
- Identity:
• acetanilide
• methylbenzoate
• naphthalene
• 1,2,3-trichlorobenzene
• pyrazophos
• phenanthrene

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column:
Injected amounts: test 1: 498 ng and Test 2: 503 ng

- Quantity of reference substances:
• formamide; Test 1: 2040 ng and Test 2: 2080 ng
• acetanilide; Test 1: 198 ng and Test 2: 206 ng
• methylbenzoate; Test 1: 509 ng and Test 2: 504 ng
• naphthalene; Test 1: 39.8 ng and Test 2: 40.4 ng
• 1,2,3-trichlorobenzene; Test 1: 198 ng and Test 2: 201 ng
• pyrazophos; Test 1: 2010 ng and Test 2: 1980 ng
• phenanthrene; Test 1: 299 ng and Test 2: 294 ng


- Intervals of calibration: Calibration injections were carried out before and after injections of the test item to confirm retention time and column performance. All injections were carried out on the same day.


REPETITIONS
- Number of determinations: 2


EVALUATION

The capacity factor k' was calculated from the dead time t0 and retention times according to the equation:
k' = (tr-t0)/ t0
t0: HPLC dead time (min)
tr: HPLC retention time of test and reference items (min).

The log k' data of the reference items were then plotted against their log Koc values from batch equilibrium. Using this plot, the Koc values determined for the reference items were within  0.5 log units of the values determined by the batch equilibrium method in the OECD guideline and the log k' value of the test item was then used to determine its log Koc value. The values of the Koc taken from the duplicate analyses were within the range of 0.25 log units.

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

Koc

Value:

< 17.8

Adsorption coefficient 2

Type:

log Koc

Value:

< 1.25

Results: HPLC method

Details on results (HPLC method):

As the test item is ionizable (predicted pKa = 4.99), two tests at two different pH values were performed.

Test 1 (non-ionized form, pH = 7.2)
As the retention time of test item is below the retention time of acetanilide (log Koc = 1.25) and close to the dead volume, the absorption coefficient was estimated by extrapolation.

Table 1: Retention times and measured log Koc values for reference items and IMEXINE OBH (non-ionized form)

item Mean

retention time k' log k' log Koc measured log Koc expected bias
formamide 1.88
acetanilide 2.72 0.452 -0.345 1.12 1.25 -0.1
methylbenzoate 3.62 0.928 -0.0323 1.90 1.80 0.1
naphthalene 6.29 2.35 0.371 2.91 2.75 0.2
1,2,3-trichlorobenzene 7.41 2.95 0.469 3.15 3.16 0.0
pyrazophos 11.4 5.09 0.706 3.75 3.65 0.1
phenanthrene 12.5 5.68 0.754 3.87 4.09 -0.2

Test item
replicate retention time k' log k' log Koc measured
IMEXINE OBH 1 2.07 0.10 -0.997 -0.51
2 2.07 0.10 -0.997 -0.51
Mean 2.07 0.10 -0.997 -0.51

Test 2 (ionized form, pH = 2.9)
As the retention time of test item is below the retention time of acetanilide (log Koc = 1.25) and close to the dead volume, the absorption coefficient was estimated by extrapolation.

Table 2: Retention times and measured log Koc values for reference items and IMEXINE OBH (ionized form)

item Mean

retention time k' log k' log Koc measured logKoc expected bias
formamide 1.90
acetanilide 2.80 0.472 -0.326 1.13 1.25 -0.1
methylbenzoate 3.74 0.968 -0.0140 1.90 1.80 0.1
naphthalene 6.61 2.48 0.394 2.90 2.75 0.2
1,2,3-trichlorobenzene 7.85 3.13 0.495 3.15 3.16 0.0
pyrazophos 12.4 5.52 0.742 3.76 3.65 0.1
phenanthrene 13.4 6.05 0.782 3.86 4.09 -0.2

Test item

replicate retention time k' log k' log Koc measured
IMEXINE OBH 1 2.38 0.25 -0.604 0.44
2 2.38 0.25 -0.601 0.45
Mean 2.38 0.25 -0.602 0.44

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

For test 1 and 2, as the retention time was close to the dead volume and below the retention time of acetanilide (log Koc = 1.25), the adsorption coefficient was estimated by extrapolation.

The adsorption coefficients of the test item on soil were:

Koc < 17.8 and logKoc < 1.25