Related Experiment Video
Updated: Aug 29, 2025
10:22
Split Point Analysis and Uncertainty Quantification of Thermal-Optical Organic/Elemental Carbon Measurements
Published on: September 7, 2019
8.3K
Quantifying residual elemental carbon by thermal-optical analysis using an extended IMPROVE_A protocol with higher
Xiaolu Zhang1, Krystyna Trzepla1, Warren White1
1Air Quality Research Center, University of California Davis, Davis, California, USA.
Journal of the Air & Waste Management Association (1995)
|September 7, 2022
Summary
Higher temperatures in thermal-optical analysis can better quantify elemental carbon (EC) in air samples. This improved method reveals significant residual EC missed by standard protocols, especially in urban areas.
Area of Science:
- Atmospheric chemistry and air quality monitoring
- Particulate matter analysis
- Carbonaceous aerosol quantification
Background:
- Thermal-optical analysis (TOA) is standard for measuring organic carbon (OC) and elemental carbon (EC) in air samples.
- The IMPROVE_A protocol, commonly used, may underestimate EC by not fully evolving it at 840°C.
- Residual EC in Chemical Speciation Network (CSN) samples suggests limitations in current TOA methods.
Purpose of the Study:
- To investigate operational conditions for evolving and quantifying residual elemental carbon (EC).
- To evaluate modifications to the IMPROVE_A protocol for enhanced EC detection.
- To assess the impact of higher temperatures on EC quantification in CSN samples.
Main Methods:
- Modified the IMPROVE_A protocol by introducing a higher temperature step (930°C) for EC evolution.
- Analyzed four heavily loaded CSN samples to evaluate protocol modifications.
- Applied the extended protocol to over 2600 CSN samples to quantify residual EC.
Main Results:
- A 930°C step evolved residual EC more effectively than extending the 840°C step duration.
- The modified protocol quantified additional EC, representing 7.6% to 25.1% of total carbon.
- Measurable residual EC was found in 6.4% of analyzed CSN samples, reaching up to 28% of total EC in highly loaded samples.
Conclusions:
- The standard IMPROVE_A protocol likely underestimates elemental carbon (EC) in CSN samples.
- Increasing the maximum heating temperature to 930°C improves EC quantification.
- This enhanced method is crucial for accurately assessing EC in areas affected by fresh urban emissions.
Related Concept Videos
01:21Atomic Absorption Spectroscopy: Lab
535
For AAS measurements, samples must be introduced as clear solutions, often requiring extensive preliminary treatment to dissolve materials like soils, animal tissues, and minerals. Common methods for sample preparation include treatment with hot mineral acids, wet ashing, combustion in closed containers, high-temperature ashing, or fusion with reagents.
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing...
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing...
535
01:29Atomic Emission Spectroscopy: Lab
230
AES is a powerful analytical technique, especially effective when used with plasma sources, producing abundant spectra in characteristic emission lines. The Inductively Coupled Plasma (ICP), in particular, yields superior quantitative analytical data due to its high stability, low noise, low background, and minimal interferences under optimal experimental conditions. However, newer air-operated microwave sources are emerging as promising alternatives that could be more cost-effective than...
230
01:20Atomic Emission Spectroscopy: Overview
2.5K
Atomic emission spectroscopy (AES) is an analytical technique used to determine the elemental composition of a sample by analyzing the light emitted from excited atoms. In AES, atoms in a sample are excited to higher energy levels by thermal energy from high-temperature sources, such as plasma, arcs, or sparks. When these excited atoms return to lower energy states, they emit light at specific wavelengths characteristic of each element. The resulting atomic emission spectrum, which consists of...
2.5K
01:27Atomic Absorption Spectroscopy: Overview
2.4K
Atomic absorption spectroscopy (AAS) is a technique used to analyze elements by measuring electromagnetic radiation (EMR) absorbed by atoms, which causes them to transition to a higher-energy orbit. The most crucial step in AAS is atomization, where the analyte is converted into gas-phase atoms, typically through a flame or furnace. Some of these atoms become thermally excited in the flame, while most remain in the ground state.
When irradiated by EMR of a particular wavelength, these...
When irradiated by EMR of a particular wavelength, these...
2.4K
01:25Atomic Absorption Spectroscopy: Atomization Methods
627
Atomic Absorption Spectroscopy (AAS) atomizes samples through flame atomization or electrothermal atomization. Flame atomization typically involves a nebulizer and spray chamber assembly to combine the sample with a fuel–oxidant mixture, creating a fine aerosol mist that enters a burner. Typically, the fuel and oxidant are combined in an approximately stoichiometric ratio. However, for atoms that are easily oxidized, a fuel-rich mixture may be more advantageous. Only about 5% of the...
627
01:10Volatilization
446
Volatilization gravimetry is an analytical technique that measures the mass lost due to the volatilization of the substance. This technique is used to estimate the amount of volatile material in a sample. To perform this method, heat a known amount of the sample to a high temperature in a crucible or other suitable vessel. The volatile substance in the sample evaporates, and the vapor is completely expelled from the crucible either by heating the sample or bubbling a stream of inert gas through...
446