Spectral Transmission Test for Colored Glass Containers | Test for Colored Glass Containers | USP 660 Glass Containers |
Glass may be colored to provide protection from light by the addition of small amounts of metal oxides and is tested as described in Spectral Transmission for Colored Class Container. A clear and colorless container that is made light resistant by means of an opaque enclosure is exempt from the requirements for spectral transmission.
Apparatus:
A UV-Vis spectrophotometer, equipped with either a photodiode detector or a photomultiplier tube coupled with an integrating sphere.
Sample Preparation:
Break the glass container or cut it with a circular saw fitted with a wet abrasive wheel, such as a carborundum or a bonded diamond wheel. Select sections representative of the wall thickness, and trim them as suitable for mounting in a spectrophotometer. Atter cutting, wash and dry each specimen, taking care to avoid scratching the surfaces. If the specimen is too small to cover the opening in the specimen holder, mask the uncovered portion of the opening with opaque paper or tape, provided that the length of the specimen is greater than that of the slit. Before placing in the holder, wash, dry, and wipe the specimen with lens tissue. Mount the specimen with the aid of wax, or by other convenient means, taking care to avoid leaving fingerprints or other marks.
Method:
Place the specimen in the spectrophotometer with its cylindrical axis parallel to the slit and in such a way that the light beam is perpendicular the surface the surface of the section and the losses due to reflection are at a minimum. Measure the transmission of the specimen with reference to air in the spectral region of 290-450 nm, continuously or at intervals of 20 nm.
Limits:
The observed spectral transmission for colored glass containers for products for nonparenteral use does not exceed 10% at any wavelength in the range of 290-450 nm, irrespective of the type and capacity of the glass container. The observed spectral transmission in colored glass containers for parenteral products does not exceed the limits given in below Table.
Limits of Spectral Transmission for Colored Glass Containers for Parenteral Products
| Nominal Volume (mL) | Maximum Percentage of Spectral Transmission at Any Wavelength between 290 nm and 450 nm | |
| Flame-Sealed Containers | Containers with Closures | |
| NMT 1 | 50 | 25 |
| 1 – 2 | 45 | 20 |
| 2 – 5 | 40 | 15 |
| 5 – 10 | 35 | 13 |
| 10 – 20 | 30 | 12 |
| NLT 20 | 25 | 10 |
Also read : USP General Chapter 660 Containers – Glass