USP 901 Detection of Asbestos in Pharmaceutical Talc
Particle Technology Labs (PTL) offers support to talc manufacturers through polarized light microscopy (PLM) in accordance with USP-NF General Chapter <901>, Detection of Asbestos in Pharmaceutical Talc. Asbestos is a naturally occurring potential contaminant in talc, which is known to be a carcinogen if inhaled. Properly quantifying asbestos’ presence, or lack thereof, in talc is of particular concern to PTL’s clients in the pharmaceutical and cosmetic industries for ensuring product safety.
The USP general chapter outlines criteria for identifying and imaging asbestos particles in talc samples using light microscopy. Our expert lab staff use top-of-the-line microscopy equipment to produce reliable, quality results so that industry leaders can understand whether their materials meet USP standards for asbestos detection in talc.
Sample material is evaluated under a microscope using a combination of morphological characteristics, such as pleochroism, refractive indices, birefringence, extinction angle, sign of elongation, and dispersion staining, to confirm or deny the presence of asbestos particles. Any particles present are measured, and multiple digital images of each are captured with dispersion staining/showing signs of elongation at various angles. With this technique, PTL helps manufacturers and quality control personnel identify amphibole asbestos and chrysotile (commonly called white asbestos) that might otherwise go undetected in talc, a critical step to maintain compliance and prevent production slowdowns.
Advantages
- Meets polarized light microscopy (PLM) requirement of USP <901> for asbestos detection in pharmaceutical talc
- PTL uses a verified PLM method in actual conditions
- Orthogonal confirmation – complements X-ray powder diffraction (XRD) by combining mineral identification with morphological assessment
- Reduces false positives – XRD may detect an amphibole mineral, while PLM helps determine/confirm whether the mineral is asbestos
- Visual confirmation - distinguishes true asbestos from non-asbestiform cleavage fragments or talc particles
- Asbestos family determination – can differentiate chrysotile from amphibole type asbestos
Considerations
- Must be used in conjunction with X-ray powder diffraction (XRD) to meet USP <901> requirements
- PTL does not perform XRD, only the polarized light microscopy (PLM) portion of USP <901> testing is available at our lab. PTL can provide a referral to a lab that can assist with XRD analysis
- Resolution limit – cannot reliably detect very thin fibers (less than ~1 µm)
- Not quantitative – intended only to determine the presence of asbestos rather than concentration or quantitative amount
- Sampling limitations – at very low asbestos concentrations, fibers may not be sampled in the portion analyzed
Sample Requirements
A minimum of 50 grams per sample submission is required for this technique.
If sample quantity is limited, please contact our team to share specifics and discuss options for testing.
Detection Range
USP <901> outlines a detection limit of <0.01% weight percentage or <100 ppm by weight (µg/g) for the presence of asbestos particles in talc.
The available objectives for the Nikon Lab-O-Phot microscope are 4x, 10x, and 40x. The lower limit of particle size that can be detected using this technique is approximately 1 µm.
Data Reported
The number of asbestos particles found, the length and width of individual particles, digital images of each particle, and an assessment of asbestos “detected” or “not detected” as outlined in USP <901>.
Instrumentation
Particle Technology Labs uses state of the art equipment to perform polarized light microscopy testing according to USP <901>, Detection of Asbestos in Pharmaceutical Talc.
