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ANALYSIS OF LEAD IN CANDLE PARTICULATE EMISSIONS BY XRF USING UNIQUANT 4
Citation:
Wasson*, S AND Z Guo*. ANALYSIS OF LEAD IN CANDLE PARTICULATE EMISSIONS BY XRF USING UNIQUANT 4. ADVANCES IN X-RAY ANALYSIS 45:539-543, (2002).
Description:
As part of an extensive program to study the small combustion sources of indoor fine particulate matter (PM), candles with lead-core wicks were burned in a 46-L glass flow- through chamber. The particulate emissions with aerodynamic diameters <10 micrometers (PM10) were captured on quartz filters and analyzed under vacuum in a Philips PW 2404 wavelength-dispersive X-Ray Fluorescence (WDXRF) Spectrometer. UniQuant 4 software was used to calculate the filter lead concentrations. Particulate filter loading masses ranged from 0.18 to 52.1 mg. The lead concentrations ranged from 0.2 to 80% by weight, with carbon comprising the remainder of the matrix. The method was validated by analyzing 87 filters, first by XRF and then by EPA Method 12 atomic absorption spectroscopy (AAS). For 84 filters, the average particle mass recovery after XRF analysis was 99 +/- 6%. For 84 filters analyzed for lead by both methods, the average recovery of lead by XRF compared to the AAS analysis was 108 +/- 9%. Modeling of candle emissions using typical room ventilation scenarios showed that even low-emitting candles can produce a lead concentration above the EPA National Ambient Air Quality Standard (NAAQS) of 1.5 micrograms/cubic meter (quarterly average). Burning more than one heavily emitting candle in a poorly ventilated space can produce concentrations exceeding the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) concentration of 50 micrograms/cubic meter (8-hour time-weighted average).