Technology
EPA priority pollutant rules taking shape Current efforts by EPA are on analytical methodologies, screening, and verification of 129 compounds for which EPA must establish guidelines
ACS ^ \ £ Miami Beach With the Environmental Protection Agency about halfway along on its pro gram aimed at eventual promulgation of effluent standards for what are known as priority pollutants, some information about initial analytical findings is begin ning to trickle out. The most recent con duit was provided by a Division of Envi ronmental Chemistry symposium on methods and results for EPA's priority pollutants. EPA is reluctant to be specific at this point in reporting the findings of its projects to screen and verify the priority pollutants in industrial discharges. Some of the generalities are: • Qualitation seems good, but quanti tation at this point is iffy, according to EPA branch chief William A. Telliard. Telliard also "feels better" about results on treated effluent than those on raw discharges. • Among the organic compounds being seen in discharges across all industrial categories are phthalate compounds, toluene, benzene, chloroform, polynuclear aromatics, phenol, and pentachlorophenol. • Many compounds in the list of 129 priority pollutant substances are not being found at all. • EPA expects to have within the next six months determinations on the preci sion and accuracy of analytical meth odologies for raw and treated discharge in all industries. EPA's efforts at the moment are con centrating on analytical methodologies, screening, and verification for the pollu tants. As Telliard notes, "You can't reg ulate something you cannot measure." The ultimate aim of the program, however, is regulation. It is a five-year program expected to cost $128 million. And it is a program, Telliard says, with a possible $40 billion to $60 billion impact on the U.S. economy. The EPA efforts on priority pollutants
stem from a lawsuit brought against EPA by the National Resources Defense Council and the Environmental Defense Fund %to push EPA into setting effluent limits as specified in the 1972 Clean Water Act. In 1976 the suit ended in the "Flannery decision," generally referred to as the consent decree. In 1977 the consent decree was embodied into law in amend ments to the Clean Water Act passed by Congress. Under the consent decree, EPA is committed to establishing effluent guidelines for 21 major industries covering 65 toxic chemical groups. The decree re quires EPA to promulgate best-avail able-technology regulations by July 1, 1980. Since the consent decree, EPA has expanded the 65 chemical groups into 129 specific substances, of which there are 114 organics (including 17 pesticides and seven polychlorinated biphenyls), 13 metals, cyanides, and asbestos. And it has added a 22nd group to the industries— publicly owned treatment works. The 21 industries fall into four groups, depending on when the effluent guide lines are to be promulgated. Group 1 in cludes timber products, steam electric power plants, leather tanning and fin ishing, iron and steel manufacturing, and petroleum refining. Group 2 includes nonferrous metals manufacturing, paving and roofing materials (tars and asphalt), paint and ink formulation and printing,
ore mining and dressing, and coal min ing. The industries in Group 3 are organic chemicals manufacturing, inorganic chemicals manufacturing, textile mills, plastics and synthetic materials manu facturing, pulp and paperboard products, and rubber processing. Group 4 includes soap and detergent manufacturing, auto and other laundries (industrial laundries), miscellaneous chemicals (such as pesti cides, photographic products, gums and wood, pharmaceuticals, explosives, and adhesives and sealants), machinery and mechanical products manufacturing (such as batteries, plastics, foundries, coil coating, porcelain and enameling, alumi num, copper, electronics, shipbuilding, and mechanical products), and electro plating. When the effluent guidelines are pro mulgated, they will be worked into the mechanism for issuance of National Pol lutant Discharge Elimination System permits. This permit system, established by the Clean Water Act, is a system to be administered by the states and meeting federal standards. Following promulga tion of the guidelines, companies are to have until July 1, 1984, to install equip ment needed to comply. Adding a level of complexity to its toxic pollutants program, EPA is proceeding with studies in three areas: technology; economics; and toxicology (primarily
These 49 compounds haven't been found in wastewaters Benzidine 1,2,4-Trichiorobenzene Hexachlorobenzene Bis(chioromethyl) ether 2-Chloroethyl vinyl ether (mixed) 1,3-Dichlorobenzene 3,3-Dichlorobenzidine 2,4-Dinitrotoluene 2,6-Dinitrotoluene 1,2-Dipheny (hydrazine 4-Chlorophenyl phenyl ether 4-Bromophenyl phenyl ether Bis(2-chloroisopropyl) ether Bis( 2-chloroethoxy ) methane
Isophorone Nitrobenzene N-Nitrosodimethylamine N-Nitrosodiphenylamine N-Nitrosodi-n-propylamine Diethyl phthalate Dimethyl phthalate Vinyl chloride (chloroethylene) Acrolein Acrylonitrile 2-Cloronaphthalene 1,12-Benzoperylene 1,2:5,6-Dibenzanthracene Methyl bromide (bromomethane) Trichlorofluoromethane Dichlorodifluoromethane Hexachlorocyclopentadiene
Aldrin Dieldrin 4,4-DDD (p.p-TDE) β-Endosulfan Endrin Endrin aldehyde Toxaphene 2,3,7,Q-Tetrachlorodibenzop-dioxin Parachlorometa cresol 2-Chlorophenol 2,4-Dichlorophenol 2,4-Dinitrophenol 4,6-Dinitro-o-cresol PCB-1242(Arochlor 1242) PCB-1221 (Arochlor 1221) PCB-1232 (Arochlor 1232) PCB-1248 (Arochlor 1248) PCB-1260 (Arochlor 1260)
Not·: For timber, pesticide, gum and wood, printing and publishing, and organic chemicals industries.
Sept. 25, 1978 C&EN
41
New instrument designed for organics in water As the Environmental Protection Agency focuses more and more attention on industrial wastewater pollutants—as in its priority pollutants program—more and more analyses will have to be performed. One instrument company eyeing this potential market is Finnigan Instruments. The company made the first public showing of its new OWA-20 and OWA-30 organics-in-water analysis systems at the Chemical Exposition held in conjunction with the Miami Beach ACS meeting. The OWA instruments are gas chromatograph/mass spectrometer systems designed specifically for analysis of organics in water. They combine a Perkin-Elmer Sigma 3 microprocessorcontrolled gas chromatograph, a Finnigan 3000 Series electron impact ion source along with the company's quadrupole analyzer, and a Data General minicomputer (the NOVA 3/4 with the OWA-20 and the NOVA 3/12 with the OWA-30). An entire top-of-the-line OWA package is priced at less than $100,000. The instrument, Finnigan says, has been designed to maximize reliability; it uses a turbomolecular pump, for example, rather than a diffusion pump to create the necessary vacuum. And it has been designed to be run by an operator with minimal expertise. Every function of the system is under computer control,
gleaned from the literature). These studies are being carried out by different divisions within EPA and will be brought together for the final guidelines. Telliard notes that EPA's mandate is to develop guidelines based on "best available technology economically achievable." Thus, economics, he says, will play an important role in the final 42
C&EN Sept. 25, 1978
directly or through microprocessors. An inexperienced operator, the company points out, is guided through each step of operation through a graphics display terminal. Each system includes an automated Bellar-Lichtenberg liquid sample concentrator for analysis of volatile components. The device was developed by EPA chemists Thomas Bellar and James Lichtenberg at the agency's Cincinnati laboratory. It strips organics from a water sample for concentration in a polymer collector, then reverse flushes the concentrated sample into the gas chromatograph. Each system comes with a 10megabyte disk drive with dual 5-megabyte platters. In addition, the OWA-30 includes a 101/2-inch, nine-track magnetic tape drive. Included in the 5-megabyte magnetic disk cartridge, Finnigan explains, is a general spectrum library and a special "priority pollutants library," subdivided into volatile, acid extractable, base and neutral extractable, and pesticide categories. An automatic processing routine enables the system to make a fast library search to identify an unknown compound and to quantitate the selected components using an internal standard method. Compounds on the priority pollutant list are confirmed by a reverse library search program.
guidelines. He says that the three studies will lead to recommended technologies probably at three levels: low, intermediate, and high cost. EPA is carrying out its technology program in three phases. In Phase I, screening, samples have been taken from a small number of plants in each industry. These are being analyzed by a number of
laboratories under EPA contract. In Phase II, verification, more sites have been added in each industry. Both phases are under way now. The analytical protocol set forth by EPA calls for qualitative and semiquantitative analysis. For example, the Phase I protocol specifies gas chromatography mass spectrometry for organics analysis, electron microscopy for asbestos, and atomic absorption for elemental analysis. The protocol has remained the same for Phase II. Phase III, monitoring and enforcement, will begin when the effluent guidelines are promulgated. The analytical protocols for this phase haven't been specified as yet, but Telliard says EPA's intent, when it comes to permits, is to have some other methods in addition to GC/MS, an expensive procedure. Management of the analyses is being handled by a number of EPA's labs. For example, volatile organics analysis is centered at the Cincinnati lab, extractables and pesticides at Athens, Ga., and metals at Chicago. An example of where some of the analytical studies are leading comes from Stuart A. Whitlock of Environmental Science & Engineering, Gainesville, Fla., one of the EPA contractors. ES&E has been carrying out studies in, among other areas, the timber, pesticide, gum and wood, and printing and publishing industries. In the timber industry, the company has analyzed 200 samples for the 129 pollutants, yielding some 26,000 data points. It found 35 compounds. The more prevalent were volatile organics such as chloroform and methylene chloride, solvents such as benzene and toluene, phthalates, polynuclear aromatics, and phenols. In general, pollutants were found in a range from the detection limit up to 10 times the detection limit. But for 79.4% of the 26,000 data points, nothing was detected. For the gum and wood industry, the company found roughly the same pollutants as for timber. The range was from the detection limit to 100 times the detection limit. But for the 10,000 data points from 75 samples, nothing was detected in 83.9%. The printing and publishing industry is a bit different; it is characterized by discharges of low volume but high concentration. The major constituent is metals. But, Whitlock points out, metals are naturally occurring, so that what is being found analytically doesn't necessarily have environmental significance. For organics in printing and publishing, the company is finding generally the same as in the other industries—volatile organics, solvents, phthalates, and polynuclear aromatics, with nothing found in 83.7% of the data points. Those substances found fell between the detection limit and 100 times the detection limit. Telliard points out that methylene chloride is being found across the board, but its significance is questionable since the substance is used in the lab for
cleaning bottles. The assumption now is that the methylene chloride is due to lab contamination. The same may be true of phthalates, although phthalates present an easier lab cleanup problem. In the tanning industry, according to C. J. Haile of Midwest Research Institute, another EPA contractor, analytical studies are finding methylene chloride, chloroform, benzene, ethylbenzene, toluene, dichlorobenzenes, phenanthrene, anthracene, naphthalene, phenol, 2,4,6trichlorophenol, and pentachlorophenol. Volatile organics and solvents are being found mostly at less than 10 ppb, with a few points at 10 to 100 ppb. Total phenols
are falling mostly in the range of 100 ppb to 1 ppm. Telliard stresses that what hasn't been found is as significant as what has been. For example, for all the industries it has studied so far, ES&E has not found 49 of the 129 substances in the 600 samples it has analyzed. Of the hundreds of thousands of data points, nothing has been detected for 81.5%. EPA is now starting to compile a list of what hasn't been seen—influent, effluent, or ambient. Perhaps, Telliard says, these should be dropped from the list of 129. Any modification of the list is probably a couple of years off, however. D
Dow details new coal liquefaction process ACS Miami Beach Several advances in coal liquefaction technology mark a new process recently announced by Dow Chemical to produce low-sulfur fuel oil and chemical feedstocks (C&EN, Sept. 11, page 22). Details of the process were provided by Dow researchers at a Division of Petroleum Chemistry poster session. Five years of research have gone into the process, Dow says. The company now
has successfully operated a 200 lb-per-day miniplant for more than 6000 hours. According to Dow corporate vice president and director of research M. E. Pruitt, the process is ready to move to large-scale process development. Dow researchers Norman G. Moll, George J. Quarderer, and Bruce C. Peters point out that the process has several distinguishing features: • It uses a patented catalyst system based on emulsion technology. The technology employed generates extremely small, highly active catalyst particles, making an expendable catalyst economically attractive. • It gives an improved product com-
position that yields more higher-valued products than do other coal liquefaction processes. • It uses hydroclones to provide partial solids removal from slurry makeup oil and to provide partial recycling of the catalyst to the reactor. • It uses a liquid-liquid extractor to produce an essentially solids-free, lowsulfur product oil and a high-solids concentrate that can be used as a gasifier feedstock. Dow claims that the low-cost catalyst, process simplicity, and ease of operation promise much more favorable economics than existing processes. In the process, run-of-mine coal is first prepared by crushing, drying, pulverizing, and classifying. The resultant material is mixed with a coal-derived oil to make a 40%-by-weight coal slurry. Catalyst solution, emulsified in oil, is added continuously to the slurry. The slurry is pumped to a preheater, where it is combined with hydrogen and heated to about 350° C. At this temperature, the coal softens and becomes plastic before entering the reactor. During preheating and reaction, the catalyst emulsion disappears and the dissolved catalyst is converted to very fine, insoluble particles. The Dow researchers point out that preheating of the slurry is critical to the hydrogénation process. Heat flux must be controlled carefully to prevent thermal decomposition of the coal and slurry oil.
Dow process employs emulsion catalysis, hydroclones ->
r Recycle gas cleanup Recycle hydrogen
Vent gas
Ammonia
Gas-liquid separation
Sulfur
Fuel gas
Τ Liquefied ' — petroleum gas
Light oil Naphtha
Reactor
Sour water
Catalyst Coal Coal & ilurry prep
Distillate fuel
Hydroclone
Feed preheat
Deasphaltedoil Recycle oil
Carbon dioxide Makeup hydrogen
Gas cleanup CO-Η, shift
Deasphalter
Gasifier
Sulfur Ammonia Water
Heavy fuel
Product separations
Residue Water
^
| X^ Oxygen Ash
Sept. 25, 1978 C&EN 43
Otherwise, cokelike material would form, fouling and plugging the preheater and downstream equipment. Some hydrogénation of coal takes place in the preheater, but the major reactions occur in the reactor. Conversion of coal to asphaltenes and a low yield of oil and gases, the researchers explain, is simple and fast and occurs at modest temperatures and pressures. It can be carried out noncatalytically. On the other hand, conversion of asphaltenes and nonresidual heavy oil is a good bit slower and kinetically more difficult. Higher temperatures and pressures and a catalyst are required. Thus the reactor is operated at about 450° C. And a long enough residence time is provided in the presence of the catalyst to allow the more kinetically difficult reactions to take place. Gas, liquid, and solid product flows from the reactor to a high-pressure separator. Here, unreacted hydrogen and light gases are removed overhead. Underflow moves to a second separator where pressure is reduced and liquefied petroleum gases, water vapor, and light oil are taken overhead. Underflow from this second separator contains all of the ash, unreacted coal, asphaltenes, most of the distillable (150° C+) oil, and the catalyst. The underflow goes to an initial solids separation, which is carried out with a hydroclone. The split is adjusted so that the hydroclone overflow makes up 75% of the recycle oil. Ash level is reduced, but the hydroclone overflow contains catalyst at a concentration about the same as that in the reactor. This catalyst recycle, the Dow researchers say, results in reactor catalyst concentrations two and a half times the catalyst added to the feed. Underflow from the hydroclone goes to a solvent deasphalter, where some of the more polar asphaltenes form a second liquid phase that effectively agglomerates the solids in the oil feed. Agglomerated solids settle to the bottom of the column and are removed continuously as a viscous liquid. The solids-free overhead stream is flashed to recover solvent and yields a premium low-sulfur product oil. Some of this oil is diverted to make up the remaining 25% of the recycle oil. The rest is net product. Bottoms from the deasphalter containing ash, unconverted coal, and asphaltenes are fed to a gasifier. They are contacted with oxygen and steam to convert the residual fuel to carbon monoxide and hydrogen. Offgas, cleaned to remove acid gases and particulates, is shift converted by reacting water with the carbon monoxide to form carbon dioxide and hydrogen. Carbon dioxide is removed, and hydrogen is compressed for recycle to the preheater. The process provides 70.2 lb of lowsulfur fuel and 21.8 lb of residue per 100 lb of coal, according to the Dow group. Of the fuel, 6.2 lb is methane, 13.1 lb is LPG, 13.0 lb is naphtha (C 6 to 400° F), 33.6 lb is distillate (400° to 975° F), and 4.3 lb is fuel oil (975° F+). D 44
C&EN Sept. 25, 1978
New mass analysis method uses ionization
ACS
^ V Miami Beach Mass-analyzed ion kinetic energy spectrometry—MIKES for short—represents a major innovation in methodologies for analyzing complex mixtures, according to Dr. R. Graham Cooks of Purdue University. With the new technique, molecules are converted to ions and separated by electromagnetic means, rather than separated as neutral molecules by chromatography. Cooks summarized the method for the Division of Analytical Chemistry: All the components in a mixture are first ionized, then separated by mass analysis. The separated ion of interest then is identified by ion kinetic energy spectrometry; specifically, by internally exciting the ion in a collision, causing fragmentation, and then obtaining the mass spectrum of the fragment ions. Thus, Cooks notes, MIKES bears the same relationship to conventional mass spectrometry that fluorescence spectrometry bears to conventional absorption spectrometry. The mass spectrometry/mass spectrometry technique also elicits comparison with gas chromatography/mass spectrometry, currently the ascendant method for separating and identifying the components of complex mixtures. MIKES has certain advantages, Cooks says. For example, separation of the ion of interest is accomplished almost instantly, so cycle times are greatly shortened. The technique eliminates the "chemical noise" and sample degradation that arise in the
chromatograph. Also, it's possible to analyze nonvolatile compounds that would require derivatization to be amenable to gas chromatography. The Purdue instrument developed and used by Cooks and his coworkers is essentially a reversed-sector mass spectrometer designed for high-resolution energy spectrometry but modified for analytical applications. Even though the equipment hasn't been fully "optimized" for such work, Cooks says, it nevertheless achieves detection limits in the picogram range for several classes of compounds. The first step in an analysis is ionization of the sample, usually by chemical ionization (CI). Electron ionization or field ionization can also be employed, and might be desirable for some applications. But CI has an advantage, Cooks says, in that it transforms a set of neutral molecules into a set of ions that retain the structural integrity of their precursor molecules. Also, selectivity for particular functional groups can be obtained by appropriate choice of the CI reagent gas. After ionization, the sample then enters the first (magnetic) analyzer, which is adjusted to pass only the ion species of interest. Before the ions enter the second (electric) analyzer, they go through a dissociation step. This is achieved in the region between the two sectors, through which the ions are moving at high velocity. Typically, a trace of nitrogen gas is introduced into a collision chamber in that region, and the ions are excited and dissociated in high-energy collisions. The ensemble of fragment ions is analyzed, with the result constituting the MIKES spectrum of the selected ion. Cooks points out that the detector actually determines the kinetic energies of the fragments. But the ions are moving at a constant velocity, so their kinetic energies are proportional to their masses; consequently, a mass spectrum is easily obtained.
Dr. R. Graham Cooke with his mass-analysis ion kinetic energy spectrometer
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At the Miami Beach meeting, Cooks focused on recent studies showing that pure steroids can be protonated to give ions with characteristic MIKES spectra. Isomeric steroids—for example, testosterone and dehydroepiandrosterone— give strikingly different MIKES spectra, he says; therefore, molecular weight and functional group information is accessible. It's possible to detect steroids in whole urine, without preconcentration or prior separation. In one instance, high levels (about 5 X 10~ 9 gram per microliter) of dehydroepiandrosterone were detected in a patient with an ovarian tumor, using only 2 microliters of urine. The sample was simply placed on the probe tip and introduced into the spectrometer. Also, studies of organic acids in urine show good matches between the MIKES spectra of the urinary constituents and the pure acids, Cooks says. In this case the data are obtained by using negative rather than positive ions. Analyzing negative ions requires no greater change in procedure than reversing potential on the instrument, Cooks points out. The ion formed by proton abstraction from the molecule (M-H)~ is appropriate for such an analysis; the carboxylic acid functional group is easily characterized by the presence of an intense peak associated with the reaction in which (M-H)~ loses carbon dioxide. The MIKES procedure is specific for carboxylic acids of selected molecular weights, Cooks says. Thus, for example, homovanillic acid and its isomer m-hydroxyphenylhydracrylic acid can be determined in urine at the microgram-permilliliter level. MIKES is particularly compatible with pyrolysis procedures, Cooks observes. For example, in a study involving the controlled pyrolysis of intact native DNA from salmon sperm, the pyrolysis products were injected directly into the chemical ionization source. The Purdue workers were able to identify a previously unknown DNA constituent, the modified base 1-methyladenine. Polychlorinated and polybrominated biphenyls (PCB's and PBB's) can also be characterized by the MIKES spectra of both positively and negatively charged molecular ions, Cooks says, adding that at least in some cases isomeric compounds can be distinguished. He notes that the Purdue team is now working with a Wright State University group headed by Dr. Thomas O. Tiernan, using MIKES for PBB analysis in environmental samples. Initial results for tetrabromobiphenyls show MIKES to be as sensitive and specific as traditional methods, Cooks asserts, and to possess the advantage that virtually all sample pretreatment can be avoided. Other studies on biological systems also involved examination of crude mixtures. One dealt with the analysis of polyamines in bacterial cultures; in that work, the entire culture and growth medium were sampled. Similarly, the technique has been used for the detection, structural elucidation, and quantitation of alkaloids in whole plant material. A typical result, 46
C&EN Sept. 25, 1978
Cooks notes, was the identification of the minor alkaloid cinnamoylcocaine in coca leaves. In these studies, samples of as little as 1 microgram of leaf material are introduced directly into the instrument. MIKES is still in its early stages of development, Cooks says, but it's developing rapidly. Most of the work to date has been qualitative or semiquantitative. Now, increased effort is being devoted to quantitation, through the use of calibration curves or internal standards. Approximately linear calibration curves can be obtained down to sample sizes of 1 ng, Cooks says. But, just as with GC/MS, he adds, quantitation is best done using isotopically labeled compounds as internal standards. Also, most of the earlier work has involved the monitoring of single reactions. Currently under way are multiple reaction monitoring studies yielding complete MIKES spectra. In general, Cooks notes,
these analyses are accomplished by keeping the magnetic field constant and changing the acceleration voltage to select different, mass-analyzed ions. The electric sector voltage is changed simultaneously to transmit the desired collision-induced fragment ion. Results of these experiments will be published soon. Cooks points out that others are pursuing similar lines of research, including groups headed by Dr. Fred W. McLafferty at Cornell, Dr. Michael Anbar at SUNY Buffalo, and Dr. Karsten Levsen at Bonn, West Germany. Also, Dr. Christie G. Enke at Michigan State is developing a double-quadrupole instrument for exploration of low-energy collision-induced dissociations. Prominent in the work at Purdue have been Dr. Terry L. Kruger of Ball State, former graduate students James F. Litton and Richard W. Kondrat, and former postdoctoral associate Gary A. McClusky. D
Analytical Chemistry celebrates its 50th anniversary
Dr. Lawrence T. Hallett Analytical Chemistry, one of C&EN's sister publications, is celebrating its Golden Jubilee this year. A highlight of the Miami Beach ACS national meeting was a session sponsored by the Division of Analytical Chemistry, "50th Anniversary Symposium, the journal and the science," at which several noted speakers recalled the founding and subsequent evolution of that highly successful periodical. The symposium also honored a former editor of Analytical Chemistry, Dr. Lawrence T. Hallett. Actually, there was an earlier Journal of Analytical Chemistry, begun in 1887 by Dr. Edward Hart of Lafayette College, Easton, Pa. But in 1883, when Hart was named editor of the Journal of the American Chemical Society, he merged his own journal with the society's. From 1893 until 1929, U.S. analytical chemists had no journal they could call their own. Papers or more fundamental
subjects were published in JACS. Papers dealing with more immediate analytical applications were generally published in the Journal of Industrial and Engineering Chemistry, which ACS had established in 1909. In 1929, Dr. Harrison E. Howe (who had become editor of JI&EC in 1921) started a new and separate "Analytical Edition" of JI&EC. The new addition thrived, despite the depression; at first a quarterly publication, it became a bimonthly in 1933 and a monthly in 1935. When Howe died in 1942, Dr. Walter J. Murphy succeeded him as editor. Although Murphy had a chemistry background, publishing was his primary interest. He was quick to appoint Hallett associate editor. According to one speaker, Murphy, with his organizational and business talents, and Hallett, with his strong scientific background, "constituted a powerful editorial team." The Analytical Edition continued to grow. Both men recognized that wartime analytical developments would revolutionize the field. They decided to emphasize instrumentation, and to sever the Analytical Edition's ties to JI&EC. In 1948 the name of the journal was changed to Analytical Chemistry. Hallett continued to serve as associate editor until 1953, as science editor from 1953 to 1956, when he became editor. He was succeeded in 1966 by the present editor, Dr. Herbert A. Laitinen. In addition to its scholarly papers, Analytical Chemistry also contains a magazine section, the " A pages," in which news and technical articles are interwoven with advertising. Since 1961, a team of professional chemists has worked in the Washington office, contributing and soliciting material for the magazine section and also assisting in peer review procedures for the journal section.
Source of geosmin in beets still a mystery
ACS Miami Beach Geosmin—1,10-irans-dimethyl-irans(9)-decalol—is important to food chemists, says Dr. Lucia D. Tyler, a food chemist at Cornell University's Agricultural Experimental Station. It's important, she explained to the Division of Agricultural & Food Chemistry, because it has an extremely potent earthy odor. The odor threshold for geosmin in water is about 20 ppt. So it's not surprising, Tyler says, that geosmin has been identified as an odor contaminant of fish, dry beans, and water. Geosmin also helps a beet taste like a beet. It's a major volatile of beet essence, Tyler notes, occurring in quantities up to 4 ng per gram of fresh beet juice. That's also important to food chemists. Beet pigment is a candidate to replace artificial food colors that have been outlawed by the Food & Drug Administration. But the makers of, say, strawberry soft drinks certainly don't want their product to taste like beets. The question arises, Tyler says, "Is geosmin a natural metabolite of the beet itself, or is it a contaminant?" In an attempt to find the answer, she and her associates conducted experiments in which beets were grown from seed in sterile sand, using a liquid nutrient medium to nourish them. "If we found geosmin in these beets, we would conclude that geosmin was produced by the beet itself." The specially grown beets, analyzed by gas chromatography, were indeed found to contain about 0.3 ng of geosmin per gram of beet pulp. But these results turned out to be ambiguous. At the Vermont Agricultural Experimental Station, Dr. B. F. Lutman had in the meantime discovered that filaments of actinomycetes microorganisms, many of which produce geosmin, grew in the intercellular spaces of beets right up into the flower stalks. ' O u r beet seeds may have contained spores of actinomycetes from the time they were formed," Tyler says. Next, an indirect approach was pursued. Geosmin was quantified in beet samples at various times throughout their growth and storage. That study showed that geosmin content steadily increased during the growing season. However, the concentration decreased as the beet matured. A possible reason for the decreasing concentration, Tyler says, is the concurrent decrease in the surface-to-volume ratio of the beet. That hypothesis was supported by another experiment in which beets were divided into cores, peels, and main portions, and the various parts analyzed for geosmin. The concentration
of geosmin was about 2.5 times higher in the peel than in the rest of the beet. However, the interior concentration was fairly uniform. "Therefore," Tyler says, "a bland-odored beet pulp for use as a natural pigment will not be achieved merely by peeling the beets." In yet another experiment, eight beet cultivars were examined. The geosmin content of all the red table beet cultivars fell within a fairly narrow range, 0.8 to 1.7 ng per gram. In contrast, the geosmin content of sugar beets and Swiss chard was about twice as high—3.1 to 3.4 ng per gram. There are two possible explanations for the variation, Tyler says. It could be that the greater genetic difference between the white and red roots was reflected in a greater variation in geosmin content. Or, the difference could be due to the fact that the white cultivars, which have more secondary roots, have more surface area. "In view of our previous experiments, the latter explanation seems more likely," Tyler says. The experiments have shown that a large portion (26%) of the geosmin in beets is present in the outer 2 mm of surface, but haven't explained whether the geosmin is produced by microorganisms growing into the beet, or by the beet itself. However, other experiments have eliminated the soil as a passive source of geosmin. Conceivably, Tyler says, geosmin could enter the beet by diffusing from the soil, rather than being produced by microbial metabolism or beet metabolism at the beet's surface. Geosmin and geosmincontaining spores are both present in the soil, she notes. Could spores of geosminproducing microorganisms and geosmin itself accumulate in the soil over several seasons, and thus increase the geosmin content of beets grown in that soil? To find out, Tyler analyzed beets grown in fields that were identical except that one field had a history of beet cultivation, the other didn't. No differences were found. That result, together with the fact that geosmin has never been identified in other root crops, such as carrots—even when specifically looked for—tended to eliminate the soil as a source of geosmin in beets. Also, Tyler notes, if the soil were the source of geosmin, one would expect to see a gradient in concentration from the surface of the beet to its core; instead, there is a sharp dropoff in concentration from the surface to the interior. According to Tyler, the studies also have answered another old question (old to food chemists, at least): "If geosmin is an important flavor produced by microorganisms, then why doesn't a carrot taste like a beet?" The unique mixture of chemicals that form the beet's flavor is the result either of the beet's metabolism alone, or of the symbiotic relationship between the beet's metabolism and microbial metabolism, she concludes. "In like manner, the unique metabolic chemistry of each root crop produces its individual flavor, virtually unaffected by flavors present in the common environment." G
Sufficient capital for energy growth foreseen
ACS Miami Beach Depending on how close one is to the energy business, the future capital requirements appear to be more or less frightening. The more pessimistic forecasts are fearful that there will not be enough capital to do the job. However, Herbert W. Krupp, vice president and energy economist at Bankers Trust Co., New York City, doesn't share the gloomy outlook and, at least as far ahead as 1982, he believes that domestic capital sources will be more than adequate. This forecast, presented at a Division of Fuel Chemistry symposium on U.S. energy policy situation—1978, may have more than the usual importance since it comes from a lender and not a borrower. In making a capital forecast for U.S. energy through 1982, Bankers Trust assumed many things. Probably the most important are that the growth in the gross national product, excluding inflationary effects, will be 3.8% per year, that the inflation rate will average 6% per year, and that price increases in oil will follow the inflation rate at 6% per year. Krupp expects that the demand for energy will increase at a reduced growth rate with home and commercial energy requirements reflecting a sharply increased use of electricity. But even here, the demand may be modified by higher costs. Electricity consumption in homes and commercial establishments is expected to rise from the 4.1 quadrillion Btu (quads) of 1976 to about 5.5 quads in 1982. Natural gas probably will show no growth in these markets after 1979. Petroleum consumption for the home and commercial market is expected to drop slightly from 6.4 quads in 1976 to 6.2 quads in 1982. Other forms of energy will show no significant changes before 1982. In the industrial sector, natural gas consumption likely will slump from the 8.4 quads of 1976 to 5.9 quads in 1978 and then rise again to 6.9 quads by 1982. This behavior is attributed by Bankers Trust to the availability of gas being diverted from electricity generation. Oil demand likely will be up 50% between 1976 and 1978, and thereafter stabilize and possibly show a small decline, from 1978's peak of 9.6 quads to 9.0 quads in 1982. Coal will begin to make its presence felt because of higher prices for other fuels. Coal consumption of 3.8 quads in 1976 is expected to rise to 5.0 quads in 1982 and to maintain a steady growth thereafter. Electricity consumption will grow rapidly in the industrial sector, according to the Bankers Trust forecast. The 1976 consumption of 2.8 quads could reach 3.9 quads by 1982. Sept. 25, 1978 C&EN
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