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Improved Detection Sensitivity for Asbestiform Minerals in Talc Using FTIR and Multivariate Analysis

Abstract No:

1717

Abstract Type:

Professional Poster

Authors:

S Yang¹

Institutions:

¹NIOSH, Pittsburgh, PA

Presenter:

Sena Yang
NIOSH

Description:

This study presents an integrated workflow to improve detection of asbestiform amphiboles (anthophyllite and tremolite) in asbestos contaminated talc by combining sodium polytungstate (SPT) heavy liquid separation (HLS) to separate dense mineral fractions, diffuse reflectance Fourier Transform Infrared (FTIR) Spectroscopy (DRIFT) to measure spectral features, and partial least squares-discriminant analysis (PLS-DA) to classify mineral type. This approach reduces the impact of spectral overlap in talc-dominant mixtures and supports more reliable identification for exposure prevention.

Situation / Problem:

Talc is widely used in consumer products, but certain talc deposits have historically contained asbestiform minerals. Reliable identification is critical because asbestos exposure is linked to serious respiratory outcomes and because trace contamination in talc-based products may contribute to consumer and worker exposure. Although FTIR is rapid, sensitive, and non-destructive, distinguishing asbestiform minerals from talc is challenging due to overlapping infrared features especially when talc signals dominate mixture spectra. This work evaluates whether pairing heavy liquid separation with targeted FTIR regions and multivariate classification can improve detection performance.

Methods:

"• Sample preparation: Laboratory-generated mixtures of talc/anthophyllite and talc/tremolite mixtures with 2.0, 1.0, 0.5, 0.1 wt% were prepared across multiple concentrations.
• Heavy liquid separation: Mixtures were processed using sodium polytungstate heavy liquid separation followed by centrifugation, settling over 8 hours and extraction of bottom fraction.
• Spectral analysis: FTIR spectra were collected for pure talc, anthophyllite, tremolite, and extracted samples from 4000-400 cm-1, 4cm-1 resolution, 16 scans with KBr background using Diffuse Reflectance Infrared Fourier Transform (DRIFT).
• Multivariate classification: Mineral type was predicted using partial least squares-discriminant analysis (PLS-DA) trained on two spectral regions, 3640-3700 cm-1 (OH stretching) and 700-779 cm-1 (symmetric Si-O-Si stretching) that exhibited asbestiform mineral-specific spectral features."

Results / Conclusions:

"FTIR spectra of talc/asbestos mixtures were dominated by talc features and PLS-DA classified all mixtures as talc across various concentrations without heavy liquid separation. However, the PLS-DA model successfully identified anthophyllite and tremolite in most separated samples following heavy liquid separation processing. It indicates that the separation + FTIR + multivariate workflow can support improved detection in talc mixtures. Misclassifications occurred in a subset of samples where asbestiform minerals were predicted as talc or unassigned. A second heavy liquid separation step was applied to these cases and it improved overall classification reliability. Anthophyllite identification accuracy increased from 72 % to 95 % after second separation, and from 88 % to 98 % for tremolite.
An integrated workflow combining heavy liquid separation, FTIR, and PLS-DA improved identification of anthophyllite and tremolite in talc. This approach offers a practical pathway to enhance detection of asbestiform minerals in talc-containing products, supporting improved hazard characterization and risk mitigation for workers and consumers."

Core Competencies:

Chemical Sampling and Instrumental Analysis

Keywords

Choose at least one (1), and up to five, (5) keywords from the following list. These selections will optimize your presentation's search results for attendees.

Asbestos, lead, and dust

Peer Review Group Selection

Based on the selected primary competency area of your proposal, select one group below that would be best suited to serve as a subject matter expert for peer review: (Select one)

Sampling and Laboratory Analysis Committee

Targeted Audience (IH/OH Practice Level)

Based on the information that will be presented during your proposed session, please indicate the targeted audience practice level: (select one)

Professional: Professional is a job title given to persons who have obtained a baccalaureate or graduate degree in IH/OH, public health, safety, environmental sciences, biology, chemistry, physics, or engineering or who have a degree in another area that meets the standards set forth in the next section, Knowledge and Skill Sets of IH/OH Practice Levels, and has had 4 or more years of practice. One significant way of demonstrating professional competence is to achieve certification by a 3rd party whose certification scheme is recognized by the International Occupational Hygiene Association (IOHA) such as the Board of Global EHS Credentialing (BGC).

Volunteer Groups

Was this session organized by an AIHA Technical Committee, Special Interest Group, Working Group, Advisory Group or other AIHA project Team?

Worker Exposure Data and/ or Results

Are worker exposure data and/or results of worker exposure data analysis presented?

Practical Application

How will this help advance the science of IH/OH?

This study advances industrial hygiene and occupational environmental health and safety by improving analytical capability to detect and classify asbestiform minerals in talc materials where traditional FTIR interpretation is limited by spectral overlap. By integrating heavy liquid separation with FTIR and multivariate data analysis (PLS-DA), it strengthens sensitivity and decision confidence for hazard identification which is foundational to exposure assessment and prevention.

Content Level

What level would you consider your presentation content geared towards?

Advanced: Specific topic within a subject in great detail. May cover current issues, involve complex calculations, analysis and synthesis, or evaluations/assessments of real-life scenarios Participant must have ten (10) or more years of experience in industrial hygiene or OEHS. Prerequisites required: working knowledge of the specific topic before the course.