Hydroxyl-2-pyridone

Phototransformation in water

Administrative data

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-10-10 to 1994-10- 17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Study type:

direct photolysis

Test guideline

Qualifier:

according to guideline

Guideline:

other: Food and Drug Administration (FDA) Environmental Assessment Technical Assistance Handbook, Section 3.10

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Hydroxyl-2-pyridone

EC Number:

212-506-0

EC Name:

Hydroxyl-2-pyridone

Cas Number:

822-89-9

Molecular formula:

C5H5NO2

IUPAC Name:

1-hydroxy-1,2-dihydropyridin-2-one

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study reports): Oxy PYRION
- Physical state: solid (powder)
- Appearance: white speckled gold powder

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch n°: 93100020
- Analytical purity: > 96.0%
- Expiration date of the lot/batch: not reported

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: ambient
- Stability under test conditions: not reported

Study design

Radiolabelling:

no

Analytical method:

high-performance liquid chromatography

Details on sampling:

- Sampling method for processing the light exposed and dark control samples: An aliquots (1.0 mL) of sample was removed and transferred to a sub-sample vial and an aliquot (50 µL) of 0.869 M copper (II) nitrate: 0.989 M citric acid (1:1 by vol) was added.
- Sampling intervals/times for pH measurements: 0 hr, 1 hr, 6 hr, 1 day, 2 days, 5 days
- Sampling points for photodegradation: 0 hr, 1 hr, 6 hr, 1 day, 2 days, 5 days

Buffers:

- pH: 7
- Type and final molarity of buffer: 0.01 M potassium phosphate
The buffer solutions were autoclaved (121°C for 20 minutes) twice after preparation. The pH of the buffer solution was adjusted following autoclaving, where necessary, so that a pH value of exactly 7 was obtained.

Light source:

Xenon lamp

Light spectrum: wavelength in nm:

>= 290 - <= 800

Relative light intensity:

ca. 425

Details on light source:

- Emission wavelength spectrum: 290 to 800 nm
- Filters used and their purpose: UV special glass filter
- Relative light intensity based on intensity of sunlight: 425W/m2

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test apparatus/vessels: the photolysis cells were 50 mL capacity glass containers, with an outer glass jacket for circulating water and a quartz screw cap lid. Photolysis cells and associated glassware were autoclaved (121 °Cfor 20 min) before use.
- Sterilisation method: the buffer solutions and associated glassware were sterilised using a Denley BA 852 Sovereign Portable Autoclave (Denley Instruments Ltd, Billinghurst, Sussex)
- If no traps were used, type of test system: [closed/open] closed
- Indication of test material adsorbing to the walls of test apparatus: [yes: /no] no

TEST MEDIUM
- Kind and purity of water: All chemicals and reagents were of analytical grade or HPLC grade supplied by Fisons, Loughborough, Leics, or BDH chemicals, Poole, Dorset

REPLICATION
- No. of replicates (dark): 2
- No. of replicates (irradiated): 2

Duration of test at given test condition

Duration:

120 h

Temp.:

25 °C

Initial conc. measured:

0.753 mg/L

Reference substance:

no

Dark controls:

yes

Results and discussion

Spectrum of substance

Parameter:

max lambda

Value:

311 nm

Remarks:

molar absorption coefficient of 12441 (log = 4.09)

% Degradation

% Degradation 1

% Degr.:

57

Sampling time:

1 h

Remarks on result:

other: light exposed samples

% Degradation 2

% Degr.:

100

Sampling time:

6 h

Remarks on result:

other: light exposed samples

Dissipation half-life of parent compound

Key result

DT50:

ca. 1 h

Remarks on result:

other: due to the rate of photodegradation of oxypyrion, insufficient data was collected to allow determination of the photolysis rate constant (Kp) and half life (T1/2)

Transformation products:

not measured

Details on results:

In the light exposed samples the concentration of the test substance was 0.43 mg/mL at 1 hour and there was no measurable level of the test substance at 6 hours. There were also no measurable levels of the test substance in samples taken at 1, 2 and 5 days.
The test substance was rapidly photodegraded with a half-life of approximately 1 hour. However, due to insufficient data the photolysis rate constant (Kp) and the half life (t1/2) were not determined.
The test substance was shown to be hydrolytically stable at pH7 (samples incubated in the dark at 25°C).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Nominal test solution conc. for Oxypyrion was 0.5 mg/L, achieved fortification of Oxypyrion in test solutions was 0.9 mg/L. The reason for the achieved fortification being 0.9 mg/L was unknown. However it was considered to affect the validity of the study

Conclusions:

A FDA assessment (Section 3.10) has been carried out to obtain preliminary information on the photolysis of Oxypyrion at a single pH in aqueous solution at 25°C. The test substance was rapidly photodegraded with a half-life of approximately 1 hour and no Oxypyrion measurable after 6 hours. However, due to insufficient data the photolysis rate constant and half life were not determined.
The test substance was shown to be hydrolytically stable at pH 7. The results of the study can be considered reliable without restrictions.