Air Toxic Compounds Research Articles

Using the POD sampler for quantitative diffusive (passive) monitoring of volatile and very volatile organics in ambient air: Sampling rates and analytical performance

POD diffusive samplers loaded with Carbopack X and Carbograph 5TD were exposed to certified calibration mixtures containing a total of 110 different ozone precursor and air toxic compounds. Constant sampling rates were identified for 39 ozone precursors and 33 air toxics. As 9 of these compounds were included in both mixtures, this meant a total of 63 different volatile and very volatile compounds were sampled using the POD with overall expanded uncertainties below 30 % for the sampling rate associated with the whole range of sampling times from 2 to 24 h.Carbograph 5TD exhibited superior performance for diffusive sampling of oxygenated and halogenated compounds in the air toxics mixture, while Carbopack X showed higher sampling efficiencies for aliphatic and aromatic hydrocarbons, as well as halogenated compounds derived from benzene and C2 carbon number hydrocarbons.A model has been developed and applied to estimate sampling rates, primarily for the more volatile and weakly adsorbed compounds, as a function of the collected amount of analyte and the exposure time. For an additional 9 ozone precursors on Carbopack X, and 11 air toxics on Carbograph 5TD, the expanded uncertainties of modelled sampling rates were reduced to below 30 % and have a significantly reduced uncertainty compared to those associated with an averaged sampling rate.The paper provides Freundlich’s isotherm parameters for the estimated (modelled) sampling rates and defines a pragmatic approach to their application. It does so by identifying the best sampling time to use for the expected exposure concentrations and associated analyte masses. This allows for expansion of the sampling concentration range from hundreds ng m−3 to mg m−3, while avoiding saturation of the adsorbent.Finally, field measurement comparisons of POD samplers, pumped tube samplers and online gas chromatography (GC), for sampling periods of 3 and 7 days in a semi-rural background area, showed no significant differences between reported concentrations.

Respiratory Symptoms and Pulmonary Function of Workers in the Waste Management Industry.

Introduction: Waste handling workers are exposed to air pollutants and toxic compounds produced during waste management and processing that can cause respiratory symptoms and lung function impairment. This study aimed to evaluate the respiratory health of exposed workers in a waste management plant in Attica, Greece.Methods: 50 field workers exposed to outdoor pollutants (exposure group) and 32 office clerks with no exposure (control group) were evaluated. Upper and lower respiratory symptoms were documented and spirometry was performed.Results: There was no statistically significant difference between the exposure and the control group in forced expiratory volume in one second (FEV1)%, forced vital capacity (FVC)%, FEV1/FVC% predicted values. Workers had lower maximal mid-expiratory flow (MMEF)% predicted values compared to controls (82% vs 94%, p=0.019). No difference was observed regarding the respiratory symptoms between the two groups.Conclusion: Lower MMEF values were observed in the exposure group. Low MMEF can be indicative of small airway disease, thus smoking cessation, close follow-up, and the use of personal protective equipment are recommended.

Fuel cell and electrolyzer using plastic waste directly as fuel

The effective utilization of plastic waste, including its use as an energy or chemical resource, has attracted much attention. Nevertheless, energy recovery from plastics via incineration generates air pollutants and toxic compounds, while chemical conversion requires significant energy inputs, especially in the case of gasification. Herein, we report the electrochemical conversion of plastics into electricity or hydrogen without the use of special procedures. When a mixture of plastic solid combined with an acidic solution was fed into an electrochemical cell, the solid was found to dissolve in the solution at 100 °C or higher, followed by the release of protons from the anode to the cathode according to a multi-electron oxidation reaction. This oxidation reaction required an anode that was sufficiently porous so as to allow transport of the reactants. Taking the sponge sample as an example, the dissolved polyurethane had a molecular weight of 2000 or higher, the transport of which was facilitated using a carbon support with a pore diameter of approximately 10 nm. In addition, carbon black having an ordered porous structure exhibited better reagent transport compared to a disordered porous carbon black with similar pore diameters. As a consequence, this cell continuously provided power densities on the order of mW cm−2 in the fuel cell mode and generated hydrogen at a low cell voltage of 0.55 V in the electrolyzer mode, using plastics as fuels at an operational temperature of 200 °C.

DYNAMIC AIR TOXIC EMISSION FACTOR OF MOTORCYCLES IN BANGKOK, THAILAND

Average emission factors of air toxic compounds, emitted from motorcycles in Bangkok, Thailand were analyzed using the IVE (International Vehicle Emission) model. The model was utilized taking into account the actual fleet and characteristics of motorcycles of the study area. Four air toxic compounds (namely benzene, 1,3 butadiene, acetaldehyde and formaldehyde) and their emission rates were calculated under two main pollution abatement scenarios (the improvement of fuel quality and switching of fuel types). The results were then compared with the BAU (Business as Usual) case to illustrate the effectiveness and appropriateness of proposed measures. In the BAU scenario the average emission factors of air toxics from motorcycles were greatly reduced by the replacement of engine technology from the carburetor system with the electronically controlled fuel injection system. Improvement of fuel quality standard (from EURO II to EURO IV) resulted in a decrease in average emission factors of air toxics from motorcycles. Calculated results indicated that the average emission factors of air toxic compounds in the year 2012 when this policy began as implemented by the Thai government were approximately 93 %, 62 %, 59 % and 59 %, a decrease as compared to the BAU case in the same year for benzene, 1,3-butadiene, acetaldehyde and formaldehyde, respectively. The introduction of gasohol as alternative fuel was found to greatly influence the emission factors of acetaldehyde and formaldehyde. Calculated results in the year 2012 indicated that acetaldehyde average emission factor increased from 123mg/km (BAU case) to 2,272 mg/km (gasohol scenario) in the same year. However, the average emission factors of benzene and 1,3 butadiene that were the result of gasohol usage were less when compared with the BAU case.

Partition of the carbonyl compounds between the indoor and outdoor air at residental areas in District 5, Ho Chi Minh City

Indoor air pollution, especially for the air toxic compounds such as carbonyls, is the most common issue in large cities. Indoor and outdoor air samples were simultaneously collected at six homes to estimate the pollution levels of carbonyl compounds at some points in the residential area, Ho Chi Minh City. The gaseous carbonyls were measured in the period of August and September, 2011 corresponding to the rainy season. The results showed that formaldehyde, acetaldehyde and acetone were the most abundant carbonyls in both indoor and outdoor air, accounted 80 % of the interested compounds, followed by propionaldehyde and benzaldehyde. In the outdoor air, the mean concentrations of formaldehyde, acetaldehyde and acetone were 15.21±6.42, 13.77±7.63, 12.11±11.72 μg.m-3, respectively. Meanwhile, the indoor concentrations were 25.45±19.49, 26.21±13.03 and 22.12±18.08 μg.m-3 for formaldehyde, acetaldehyde and acetone, respectively. Formaldehyde/acetaldehyde and acetaldehyde/ propionaldehyde ratios were 2.23±1.41 and 6.09±5.00, respestively, indicating that main sources of outdoor carbonyls came from the anthropogenic source. The mean carbonyl concentrations of the present study compared with those of other countries showed that indoor carbonyls were similar to other studies, but outdoor carbonyls were much higher. In addition, most of the indoor/outdoor ratios were slightly higher than 1 and levels of benzaldehyde and tolualdehyde were a little high in the indoor air. These results indicated that the indoor carbonyls were strongly affected by the outdoor air infiltration.

Effect of Ambient Temperature on Total Organic Gas Speciation Profiles from Light-Duty Gasoline Vehicle Exhaust.

Total organic gases (TOG) emissions from motor vehicles include air toxic compounds and contribute to formation of ground-level ozone and secondary organic aerosol (SOA). These emissions are known to be affected by temperature; however previous studies have typically focused only on the temperature dependence of total emission factors and select toxic compounds. This study builds on the previous research by performing an evaluation of a comprehensive set of gas-phase organic compounds present in gasoline motor vehicle exhaust. A fleet of five vehicles using port fuel injection engine technology and running on E10 fuel was tested. Overall, three temperatures (0, 20, and 75 °F; or -18, -7, and 24 °C), two driving conditions (urban-FTP75 and aggressive driving-US06) and 161 compounds were evaluated; the emissions distributions were used to construct speciation profiles for each driving cycle and temperature. Overall, the speciation results indicated a significant increase in alkane and methane content, and decrease in alcohol, aldehyde and ketone content with decreasing temperature. These were verified using a statistical significance test. The fraction and composition of Mobile Source Air Toxics (MSATs) were significantly affected by temperature for both driving cycles. The ozone forming potentials of these profiles were evaluated using the maximum incremental reactivity (MIR) scale. Aromatic content was predicted to be a major driver behind the ozone forming potentials. Additionally, the decreasing ozone potential could be attributed to increased methane fractions with increasing temperature.

Analysis of mobile source air toxics (MSATs)—Near-road VOC and carbonyl concentrations

Exposures to mobile source air toxics (MSATs) have been associated with numerous adverse health effects. While thousands of air toxic compounds are emitted from mobile sources, members of a subset of compounds are considered high priority due to their significant contribution to cancer and noncancer health risks and the contribution of mobile sources to total exposure as evaluated by the U.S. Environmental Protection Agency (EPA) National-Scale Air Toxics Assessments (NATA). These pollutants include benzene, 1,3-butadiene, ethylbenzene, acrolein, acetaldehyde, formaldehyde, naphthalene, polycyclic organic matter, and diesel particulate matter/organic gases. This study provided year-long trends of benzene, 1,3-butadiene, acrolein, acetaldehyde, and formaldehyde in Las Vegas, NV. Results indicated that MSAT concentrations often did not exhibit trends typical of other primary emitted pollutants in this study. Instead, other mobile sources beyond the highway of interest contributed to the measured values, including a major arterial road, a large commercial airport, and a nearby parking lot. The data were compared with relevant census-tract NATA estimates, with estimated ambient 1,3-butadiene concentrations similar to the measured values. Measured benzene values were much lower relative to the NATA total ambient benzene concentrations. Measured acrolein values were much higher relative to the NATA total acrolein concentrations. Measured acetaldehyde and formaldehyde values were also higher relative to the NATA total acetaldehyde and formaldehyde concentrations for all wind conditions and downwind conditions. Some possible explanations for these differences include nearby sources influencing the measured values; meteorological influences that may not be well captured by the NATA modeling regime; chemical reactivity of measured compounds; and additional explanatory variables may be needed for certain urban areas in order to accurately disaggregate anthropogenic air toxics emissions. Implications: Comparison of air toxics concentrations measured at four long-term near-road sites in Las Vegas, NV, show generally good agreement with the EPA 2005 NATA total ambient concentrations. Measured concentrations did not compare as well with EPA 2005 NATA for the on-road mobile portion of the ambient concentrations. This highlights the complexity of air toxic emission sources and impacts in urban areas, especially around large highway facilities; NATA's inability to capture local-scale meteorology and fine-scale ambient gradients; and that additional explanatory variables may be needed for certain urban areas in order to accurately disaggregate anthropogenic air toxics emissions.

Development of Air Toxic Emission Factor and Inventory of On-road Mobile Sources

Dynamic emission factors of air toxic compounds, emitted from vehicles in Bangkok, Thailand, are developed using the IVE model. The model takes into account the actual fleet and characteristics of vehicles in the study area. It is found that the calculated emission factors are greatly influenced by vehicle emission control policy. Approximately 2000 tons of benzene emission per year is reduced by the changing of fuel quality from Euro 2 to Euro 4 standards. As for mitigation measures, introduction of gasohol and natural gas as alternative fuels, as well as encouraging the utilization of public transportation systems, are analyzed. The outcomes reveal that a combined scenario using 100% gasohol plus decreasing vehicle kilometers traveled (VKT) by 20% is the most effective in reduction of benzene emission. In addition, 1,3-butadiene, acetaldehyde and formaldehyde emissions are greatly decreased by the combined scenario of using compressed natural gas (CNG) plus decreasing VKT by 20%.

Enhanced, multi criteria based site selection to measure mobile source toxic air pollutants

A multi-criteria-based site selection process that was developed for the Las Vegas near-road study is used to select the most appropriate near-road measurement sites in the Detroit area. The study measures particulate matter with aerodynamic diameters ⩽2.5 μm and mobile source air toxic compounds, and to document the rationale for selecting or rejecting specific sites. An application of this multi-criteria decision analysis may be the recent US Environmental Protection Agency rule requiring the siting of NO 2 monitors within 50 m of major roads as well as siting for the measurement of community-wide NO 2 concentrations.

Air quality impacts of increased use of ethanol under the United States’ Energy Independence and Security Act

Abstract Increased use of ethanol in the United States fuel supply will impact emissions and ambient concentrations of greenhouse gases, “criteria” pollutants for which the U. S. EPA sets ambient air quality standards, and a variety of air toxic compounds. This paper focuses on impacts of increased ethanol use on ozone and air toxics under a potential implementation scenario resulting from mandates in the U. S. Energy Independence and Security Act (EISA) of 2007. The assessment of impacts was done for calendar year 2022, when 36 billion gallons of renewable fuels must be used. Impacts were assessed relative to a baseline which assumed ethanol volumes mandated by the first renewable fuels standard promulgated by U. S. EPA in early 2007. This assessment addresses both impacts of increased ethanol use on vehicle and other engine emissions, referred to as “downstream” emissions, and “upstream” impacts, i.e., those connected with fuel production and distribution. Air quality modeling was performed for the continental United States using the Community Multi-scale Air Quality Model (CMAQ), version 4.7. Pollutants included in the assessment were ozone, acetaldehyde, ethanol, formaldehyde, acrolein, benzene, and 1,3-butadiene. Results suggest that increased ethanol use due to EISA in 2022 will adversely increase ozone concentrations over much of the U.S., by as much as 1 ppb. However, EISA is projected to improve ozone air quality in a few highly-populated areas that currently have poor air quality. Most of the ozone improvements are due to our assumption of increases in nitrogen oxides (NOx) in volatile organic compound (VOC)-limited areas. While there are some localized impacts, the EISA renewable fuel standards have relatively little impact on national average ambient concentrations of most air toxics, although ethanol concentrations increase substantially. Significant uncertainties are associated with all results, due to limitations in available data. These uncertainties are discussed in detail.

Source Characterization of Volatile Organic Compounds Affecting the Air Quality in a Coastal Urban Area of South Texas

Selected Volatile Organic Compounds (VOC) emitted from various anthropogenic sources including industries and motor vehicles act as primary precursors of ozone, while some VOC are classified as air toxic compounds. Significantly large VOC emission sources impact the air quality in Corpus Christi, Texas. This urban area is located in a semi-arid region of South Texas and is home to several large petrochemical refineries and industrial facilities along a busy ship-channel. The Texas Commission on Environmental Quality has setup two continuous ambient monitoring stations (CAMS 633 and 634) along the ship channel to monitor VOC concentrations in the urban atmosphere. The hourly concentrations of 46 VOC compounds were acquired from TCEQ for a comprehensive source apportionment study. The primary objective of this study was to identify and quantify the sources affecting the ambient air quality within this urban airshed. Principal Component Analysis/Absolute Principal Component Scores (PCA/APCS) was applied to the dataset. PCA identified five possible sources accounting for 69% of the total variance affecting the VOC levels measured at CAMS 633 and six possible sources affecting CAMS 634 accounting for 75% of the total variance. APCS identified natural gas emissions to be the major source contributor at CAMS 633 and it accounted for 70% of the measured VOC concentrations. The other major sources identified at CAMS 633 included flare emissions (12%), fugitive gasoline emissions (9%), refinery operations (7%), and vehicle exhaust (2%). At CAMS 634, natural gas sources were identified as the major source category contributing to 31% of the observed VOC. The other sources affecting this site included: refinery operations (24%), flare emissions (22%), secondary industrial processes (12%), fugitive gasoline emissions (8%) and vehicle exhaust (3%).

Verification results of jet resonance-enhanced multiphoton ionization as a real-time PCDD/F emission monitor

A jet resonance-enhanced multiphoton ionization (REMPI) monitor was tested on a hazardous-waste-fired boiler for its ability to determine concentrations of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/Fs). Jet REMPI is a real-time instrument capable of highly selective and sensitive (from parts per billion to parts per trillion) detection of a broad range of aromatic compounds, including a number of air toxic compounds. The PCDD/F toxic equivalency (TEQ) value was derived from a predetermined correlation (R2 = 0.74) with monochlorobenzene (MClBz). This relationship was applied to nine subsequent jet REMPI on-line measurements of MClBz and parallel, standard extractive sampling for PCDD/F TEQ. For high waste-firing rates, with a range of PCDD/F TEQ values between 3.9 and 6.0 ng TEQ/m3, the TEQ values predicted by jet REMPI had a relative difference of 26% with the standard EPA Method 23 results. At low waste-firing rates (0.9–1.6 ng TEQ/m3), the relative difference increased to 219%. This limited testing shows that jet REMPI has promise as an on-line diagnostic monitor, providing feedback on the effects on PCDD/F emissions of operating parameter changes such as fuel feed interruptions or air pollution control failures.

A comparison of PAMS and air toxics measurements

One of the requirements of the 1990 Clean Air Act Amendments (CAA) is that 1-h ozone nonattainment areas that are classified severe or higher category are required to operate a network of photochemical assessment monitors (PAMS) to provide hourly measurements of volatile organic compounds (VOCs) comprising of Carbon number <12 (C2–C12), along with carbonyl measurements at 3-h intervals during the summer ozone season. Often collocated with PAMS are 24-h-integrated canister and cartridge-based measurements of selected air toxic compounds, thereby providing an opportunity for inter-comparison and validation of both sets of data. In this study, we report such a comparison and estimates of trend for benzene, m-, p- and o-xylene, toluene, ethylbenzene, 1,2,4-trimethylbenzene, formaldehyde and acetaldehyde at Bronx, NY. The analysis shows that hourly PAMS and 24-h-integrated air toxics are in good agreement with each other exhibiting similar trends and that the PAMS with the higher temporal resolution offers information on excursions of the toxic compounds that would be quite useful in assessment of acute health effects. These findings were also found to be applicable to other locations such as South De Kalb, GA; Gary, IN and Lynn, MA.

Criteria and Air-Toxic Emissions from In-Use Automobiles in the National Low-Emission Vehicle Program

The U.S. Environmental Protection Agency (EPA) implemented a program to identify tailpipe emissions of criteria and air-toxic contaminants from in-use, light-duty low-emission vehicles (LEVs). EPA recruited 25 LEVs in 2002 and measured emissions on a chassis dynamometer using the cold-start urban dynamometer driving schedule of the Federal Test Procedure. The emissions measured included regulated pollutants, particulate matter, speciated hydrocarbon compounds, and carbonyl compounds. The results provided a comparison of emissions from real-world LEVs with emission standards for criteria and air-toxic compounds. Emission measurements indicated that a portion of the in-use fleet tested exceeded standards for the criteria gases. Real-time regulated and speciated hydrocarbon measurements demonstrated that the majority of emissions occurred during the initial phases of the cold-start portion of the urban dynamometer driving schedule. Overall, the study provided updated emission factor data for real-world, in-use operation of LEVs for improved emissions modeling and mobile source inventory development.

Summer and Winter Nonmethane Hydrocarbon Emissions from On-Road Motor Vehicles in the Midwestern United States

On-road vehicle emission rates of nonmethane hydrocarbons (NMHCs) were measured in two tunnels in Milwaukee, WI, in summer 2000 and winter 2001. Seasonal ambient temperatures in the Midwestern United States vary more widely than in locations where most studies of NMHC emissions from vehicle fleets have been conducted. Ethanol is the added fuel oxygenate in the area, and, thus, emissions measured here are of interest as other regions phase out methyl tertiary butyl ether and increase the use of ethanol. Total emissions of NMHCs in three types of tunnel tests averaged 4560 ± 800 mg L−1 fuel burned (average ± standard error). To investigate the impact of cold start on vehicle emissions, samples were collected as vehicles exited a parking structure in subzero temperatures. NMHC emissions in the subzero cold-start test were 8830 ± 190 mg L−1 fuel–nearly double the tunnel emissions. Comparison of ambient data for the Milwaukee area with tunnel emissions showed the impact of seasonal differences in fuels and emissions on the urban atmosphere. Composition of fuel samples collected from area gas stations in both seasons was correlated with vehicle emissions; the predominant difference was increased winter emissions of lighter hydrocarbons present in winter gasoline. A chemical mass balance model was used to determine the contributions of whole gasoline and gasoline headspace vapors to vehicle emissions in the tunnel and cold-start tests, which were found to vary with season. Results of the mass balance model also indicate that partially combusted components of gasoline are a major contributor to emissions of aromatic compounds and air toxic compounds, including benzene, toluene, xylenes, napthalene, and 1,3-butadiene, whereas air toxics hexane and 2,2,4-trimethylpentane are largely attributed to gasoline and headspace vapors.

MOBILE6.2 Modeling of Exhaust Air Toxic Emission Factors

The newly released MOBILE6.2 has incorporated both air toxic and particulate matter emission factor modeling functions. A series of test runs were performed to gain a better understanding of the air toxic modeling function and overall model behavior. These test runs and scenarios evaluated the changes in emission factors of all six built-in air toxic compounds as affected by vehicle activities, fuel physical properties, fuel chemical compositions, oxygenated fuel additives, and environmental conditions. Results obtained indicate that exhaust emission factors for acrolein, acetaldehyde, benzene, 1,3-butadiene, formaldehyde, and methyl tertiary butyl ether are inversely proportional to freeway and arterial vehicle speeds. This phenomenon follows the trend of total organic gas emission factors. Effects from roadway facility differences indicated that the higher the percentage of vehicle miles traveled on a freeway, the lower the air toxic emission factors on a per vehicle mile traveled basis. Exhaust air toxic emission factors increase when fuel Reid vapor pressure value and sulfur content increase. Diesel sulfur content has no effect on the six toxic compound emission factors. Effects from fuel chemical compositions on all emission factors varied. However, chemical compositions do have significant effects on all air toxic compound emission factors. On the same note, both minimum and maximum temperatures affect all air toxic emissions significantly. The time series evaluation indicates that all six tested air toxic compound emissions decrease linearly from the year 2002 to 2020.

MOBILE6.2 Modeling of Exhaust Air Toxic Emission Factors: Trend and Sensitivity Analysis

The newly released MOBILE6.2 has incorporated both air toxic and particulate matter emission factor modeling functions. A series of test runs were performed to gain a better understanding of the air toxic modeling function and overall model behavior. These test runs and scenarios evaluated the changes in emission factors of all six built-in air toxic compounds as affected by vehicle activities, fuel physical properties, fuel chemical compositions, oxygenated fuel additives, and environmental conditions. Results obtained indicate that exhaust emission factors for acrolein, acetaldehyde, benzene, 1,3-butadiene, formaldehyde, and methyl tertiary butyl ether are inversely proportional to freeway and arterial vehicle speeds. This phenomenon follows the trend of total organic gas emission factors. Effects from roadway facility differences indicated that the higher the percentage of vehicle miles traveled on a freeway, the lower the air toxic emission factors on a per vehicle mile traveled basis. Exhaust air toxic emission factors increase when fuel Reid vapor pressure value and sulfur content increase. Diesel sulfur content has no effect on the six toxic compound emission factors. Effects from fuel chemical compositions on all emission factors varied. However, chemical compositions do have significant effects on all air toxic compound emission factors. On the same note, both minimum and maximum temperatures affect all air toxic emissions significantly. The time series evaluation indicates that all six tested air toxic compound emissions decrease linearly from the year 2002 to 2020.

Using Genetic Algorithm to Identify Completely Unknown System in FTIR Spectra Analysis

The article mainly focuses on how to identify completely unknown systems in FTIR spectra analysis by Genetic Algorithm (GA). The technique of multiplespot crossover combined with quantitative and adaptive mutation is used and the whole process is controlled by the fitness value and probability of selection in GA. A standard pure FTIR spectra database containing 101 air toxic organic compounds is set up. Six unknown samples are identified and quantitatively analyzed. The results indicate that GA can successfully identify even a perplexing sample containing 18 components. The concentration of each component in the samples can be determined at the same time. The maximal relative error is no more than 10%. It means that GA has the capability of simultaneous identification and prediction, especially for those completely unknown mixed spectra in FTIR.

Simultaneous determination and spectra correction of air toxic organic compounds using pls and ann in ftir spectroscopy

In this paper, the residual spectra library search was used to correct the spectrum containing one interferent. Two groups of which each sample contained no or one interferent were supplied to amplify the above method. PLS was used to identify the interferents and correct the spectra, the corrected spectra information was sent into the PLS(Partial Least Squares) and ANN(Artificial Neural Network) prediction step. The concentration of each component in the unknown mixtures was determined using two different prediction method. The RSD%(mean relative standard deviation) for the two groups was calculated respectively. The prediction results of PLS and ANN was compared to illustrate which one is better in solving this problem.

Simultaneous Determination of Multicomponents in Air Toxic Organic Compounds Using Artificial Neural Networks in Ftir Spectroscopy

The application of Artificial Neural Networks (ANNs) for nonlinear multivariate calibration using simulated FTIR data was demonstrated in this paper. Neural networks consisting of three layers of nodes were trained by using the back-propagation learning rule. Since parameters affect the performance of the network greatly, simulated data were used to train the network in order to get a satisfactory combination of all parameters. The mixtures of four air toxic organic compounds whose FTIR spectra are overlapped were chosen to evaluate the calibration and prediction ability of the network. The relative standard error (RSD%), the percent standard error of prediction samples (%SEP) and the percent standard error of calibration samples (%SEC) are used for evaluating the ability of the neural network.