Anal. Chem. 1981, 53, 1 R-13R
Air Pollution Donald L. Fox” and Harvey E. Jeffries Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 275 14
This review covers the literature from late 1978 to October 1980. A major source of information was Chemical Abstracts Selects: Pollution Monitoring. In addition, journals in the air pollution and analytical chemistry fields were surveyed. The authors also selected several key proceedings and books for inclusion. Many contract reports and articles not readily available were not included. The organization consists of two major divisions: gaseous methods, which have single letter designations after reference numbers, and aerosol and particulate methods, which have two letter designations after the reference numbers. Within these two categories, reviews were first organized by compound and then by technique. It was not possible to have subdivisions for every compound and only the most important species were discussed by techniques used for their analysis. This somewhat arbitrary division was not mutually exclusive; therefore, material on sulfur, for example, a pears in several sections in GASES, in Sulfur Speciation, a n f i n several of the technique sections in AEROSOLS. The major divisions discussed above are followed by Table I which contains some of the recent reports from the Quality Assurance Division/Environmental Monitoring and Surveillance Laboratory of the Environmental Protection Agency. The complete EPA requirements associated with the provisions of the Clean Air Act may be found in the Code of Federal Regulations (CFR) under Title 40 Protection of the Environment. Chapter 1is on the Environmental Protection Agency. This chapter has several divisions entitled “Parts”. Parts 50-59 contain information about standards, state implementation plans, ambient air monitoring, reference and equivalent methods, and ambient air quality surveillance. Parts 60-80 are concerned with stationary sources and parts 85-87, mobile sources. Extensive additions were promulated on May 10,1979 creating a new Part 58-Ambient Air Quality Surveillance, which delineates criteria for quality assurance, monitoring methods, siting and operating schedules for reporting ambient air quality data, and information. Title 40 is undated as of Jul 1 of each year by the U S . Government Printing Office a n l e a c h annual issue contains all new information published in the Federal Register during the previous 12-month eriod in addition to the existing permanent rules of the EPW.
P
GASES Books and Reviews. Criteria documents for ozone (03), nitrogen dioxide (NO,), and sulfur dioxide (SOz) have been revised by the U.S. Environmental Protection Agency. The ozone document has been issued (1A)and the NO2 document and the SO2 and particulate matter document are currently in draft form and are expected to be finalized within the next year. These documents include chapters on analytical methodology. Books also included information on air pollution analytical methodology (2A-5A). Proceedings of several symposia included information on monitoring including NO2 (6A),effects of vegetation (7A),and background monitoring @A). Reviews included general reviews (9A-I1 A), nitrogen dioxide methods (12A-I4A), organic and carcinogenic materials methods (15A-17A), and remote sensing and monitoring (MA, 19A).
Calibration Methods. An evaluation of the stability of sub-ppm concentrations of SOz,.NOz, and NO in A1 and stainless steel compressed gas cylinders ( I B )showed that a reasonable de ee of stability could be obtained for short term use (2 monthx All of the samples, however, were considered unstable over periods greater than 3 months. The use of permeation tubes to calibrate flame photometric detectors was described by Lewis et al. (2B). The generation 0003-270018 110353-1R$01.2510
of SO NO,, H2S,HCN, and NH3 from buffer solutions was descri%ed as having precision and accuracy equal to permeation tubes with concentration variations less than 3% (3B). A number of generation techniques for more than 230 compounds including gases, va ors, fumes, and aerosols in the range 0.05-2000 ppm were &scribed by Anderson et al. (4B). A special dilution system was used to produce several concentrations levels simultaneously. A high volume, automatic, zero-air preparation method using catalytic oxidation and urification methods was described by Barsocci and Knobe (5B). Economic factors were considered in optimizing the design, and the modular system was described as expandable. A concentric pipe system with purge gas was used to perform routine on-line zero and span determinations for an in situ continuous emissions monitor for NO, C02, and opacity (6B). Quality Assurance and Collaborative Tests. The EnvironmentalProtection Agency (EPA) has establisheda policy requiring participation in an Agency-wide quality assurance program. Included are any monitoring and measurement efforts supported through contracts, cooperative agreements, or grants (IC). State and local air monitoring quality assurance programs are also included through new regulations (2C). The program includes development of reference and standard methods, certification of equivalent methods, performance of on-site system surveys, conduction of quality assurance audits for both ambient air monitorin and source sampling, development of standards materials, an8 publication of quality assurance guideline documents and handbooks. A three-volume, loose-leaf handbook for quality assurance for air pollution measurements is available from EPA (3C). Comparison studies of calibration methods for O3 showed that the methods used by Japan, EPA, and Los Angeles did not agree when the same O3 concentration was determined (4C). On the other hand, performance tests ctf opacity, SO2, NO,, and O3 monitors showed that the calibration error, zero drift, calibration drift, response time, and relative accuracy were within limits specified by EPA (5C). Ozone. In February 1979 the USEPA revised the National Ambient Air Quality Standard (NAAQS) for photochemical oxidants by: (a) changing the chemical designation of the standard from “photochemical oxidant” to “ozone”, (b) raising the primary and secondary standards to 0.12 ppm, (c) changmg to a standard with a statistical rather than deterministic form, and (d) replacing the original neutral buffer potassium iodide calibration procedure with one based on ultraviolet photometry (ID).The use of an improved boric acid potassium iodide procedure and suitable qualified and certified O3 transfer standards as a means of calibrating O3 reference methods was also described. Two methods for the determination of absolute ozone were based on pressure changes at constant volume. In the first ( 2 0 ) ,the pressure decrease that occurred when Os, a t approximately 1% , was formed by electrical discharge in a small volume of oxygen (Le., 3oz 203) was measured by a constant volume manometer. After the pressure measurement, the O3 was diluted into a lar e volume for instrument calibration. In the second rnethoj (30), the procedure was essentially reversed and the pressure rise that occurred due to the thermal decomposition of O3 (Le., 203 302)was used to determine the O3 concentration at levels near 0.02 vol. % . An improved neutral buffered potassium iodide method for O3in air added thiosulfate to the absorption solution. Excess iodine was added before determination. The method was compared with gas-phase 03-NO titration in an interlaboratory test and resulted in a 0.96:l agreement (40). A gas-olid phase chemiluminescent O3 monitoring system using gallic
-
@ 1981 American Chemical Society
-
1R
AIR POLLUTION
acid and Rhodamine B on glass disks was described (50). Huntzicker and Johnson (6D)described a large positive ozone interference when using an ultraviolet absorption ozone monitor in airborne monitoring studies. The interference occurred when traversing a plume from burning forest slash. Laboratory experiments showed that the effect arose from UV absorbing gases in the plume. They concluded that instrument may not be suitable for plume studies in which transient concentrations of 254-nm absorbing species might be present. A method for measuring the photolysis rate of O3at ground level was described by Bahe et al. (70). Nitrogen Oxides and Acids. A review of US.EPA nitrogen dioxide (NO,) monitoring methodology requirements by Purdue and Hauser has been published (IE). To eliminate the need for conversion of NOz to nitric oxide (NO),Fontijn et al. (2E) developed a monitorin method based on the chemiluminescencereaction of both N 8 and NO2 with H atoms. The feasibility study was the measurement of motor vehicle emissions in the range of 6-4000 ppm NO,. A sensitive and selective thin-film semiconductor sensor based on NO, chemisorption on the sensor surface was described (3E). Two methods based on triethanolamine tubes were compared in determinations of NO2from diesel equipment in salt mines (4E). Both methods were found suitable. Ozone interference in the manual Saltman method for NOz was again investigated (5E). Ozone and NO, mixtures were sampled with two different samplers. In one, there was no interference. In the other a negative interference occurred but an earlier report that the interference level depended upon the ratio of 0 2 to NOz could not be confirmed. Chemiluminescent NO analyzers gave 5-11 % low readings when used to determine NO in stack gases. The error occurred when the effect of sample background gas composition (C02,H20,and oxygen) variations were neglected (6E). The nitrate radical (NO3) was measured in the ambient air of Riverside and Claremont California at levels 355 parts per trillion using 0.75 to -1 km path length differential optical absorption spectroscopy (7E). The concentration-time profiies of the NO3 and other species were difficult to explain. Differential optical absorption was also used to detect 10.8 pb of nitrous acid (HNOZ)in moderately polluted air of JueEch, West Germany (8E). Nitric acid (HN03)concentrations of 5 ppb in rural air were measured by a fast chemiluminscent NO, monitor after HN03was converted to NO2 in a packed quartz tube at 350 “C (9E). Ammonia. A continuous, chemiluminescencemethod for the monitoring of ammonia (NH,) (0-10 ppb) used thermal conversion of NH3 to NO and an acidic scrubber for alternate removal of NH3 from the sample stream (IF). The hightem erature converter also converts NO2 to NO. In a second metfod (2F), ambient gaseous NH3 (0.5-25 ppb v/v) was first collected by ulling sample air through a tube packed with The NH3 was thermally desorbed a t 100 OC Chromosorb using purified air to flush the sample into a chemiluminescent or other detector. The integral of the detector response was linearly proportional to the total amount of NH3 collected. Tube loadin s were limited to 60 ng and sample times to 40 min to avoif “breakthrough”. The precision was approximately f 3 ng. Minimal interference of NH4+in the determination of NH, was achieved by drawing the air trough a vertical glass tube internally coated with oxalic acid which absorbed NH3 (3F). Analysis was performed by dissolving the oxalic acid in NaOH and determining the NH, concentration with an ion-selective electrode. The detection limit was 0.5 nmol of NH3/m3air sampled during 24 h. An automatic method for measurement of NH3 was described by Bos (4F). Nitroso and Other Nitrogen Compounds. Eight sorbents were evaluated for their ability to retain nitrosamines and for artifactual formation of nitrosamines in the presence of added precursor amines and air containing NO, (IG). The sorbents tested were activated charcoal, activated Al2O3, silica gel, Florisil, Tenax, ThermoSorb/N, impinger traps containing 1 N KOH, and impinger traps containing pH 4.5 phosphate-citrate buffer/20 mM ascorbic acid. ThermoSorb/N was the only sorbent which was both free of artifact formation and capable of retaining 100% of the nitrosamines. A method for N-nitrosamines using trapping with XAD-2, extraction with methylene chloride and analysis by gas
b.
2R
ANALYTICAL CHEMISTRY, VOL. 53, NO. 5, APRIL 1981
chromatography with flame ionization and mass fragmentography-computer quantitation was able to detect 0.2 ppb of 1-methyl-4-nitrosopiperazine (2G). Langvardt et al. (3G) describe a rocedure for personnel or area monitoring of mono-, di- ancftripropanolamine. The method had a typical detection limit of 100 ppb for 35 L of air sampled. Aliphatic amines in the exhaust of 17 cars were determined by a spectrophotometric method (4G). The concentrations were so low that only upper limits could be reported (
