OECD Test 101 – Determination of the UV-Visible Spectrum of a Substance

The OECD 101 test determines the UV-Visible absorption spectrum of a chemical substance between 290 and 800 nm, in accordance with OECD guidelines . This spectrum is obtained by measuring the absorbance of a homogeneous solution or suspension of the substance in a suitable solvent using a UV-Vis spectrophotometer.

The objective is to identify the maximum absorption wavelengths (λmax) in order to assess the molecule's sensitivity to light and its phototransformation potential . This data is crucial for environmental assessment, photodegradation , phototoxicity , or to guide other tests (e.g., OECD 102, 113, or 316) .

Measurements are performed under standardized conditions (quartz cuvette, background spectrum, concentration adapted to linear absorbance) according to Good Laboratory Practices (GLP) . In case of insolubility or instability, an adaptation of the method is proposed according to OECD recommendations.

OECD 101 Test: Frequently Asked Questions

– What substances can be analyzed with the OECD 101 test?

The OECD 101 test is primarily applicable to organic or inorganic substances soluble in UV-transparent solvents (water, ethanol, acetonitrile, etc.). In cases of low solubility or turbidity, method modifications may be recommended. It is notably used for active ingredients (plant protection products, biocides, pharmaceuticals), cosmetic ingredients, synthetic intermediates, and industrial additives.

– Is this test mandatory for a REACH or biocide dossier?

The OECD 101 test is often required in REACH registration dossiers or under the Biocidal Products Regulation (BPR) . It assesses the potential photostability of a substance and determines the need for further testing (e.g., phototransformation, phototoxicity). The absence of UV-Vis data can be considered a regulatory gap .

– What is the difference between the OECD 101 test and a simple UV spectrum?

The OECD 101 test follows a standardized methodology validated by the OECD, with strict criteria regarding concentration, solvent selection, spectral resolution, and result quality. Unlike a simple routine UV spectrum, this test provides reproducible, legally interpretable , and GLP-compliant that can be used in registration dossiers.

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