www.chemistry.org/education/chemmatters.html

Question From the ClassroomBy Bob Becker

Q. My mother remembers her baby teeth were used in some sort ofresearch study when she was young. What was that all about?

A. Have you ever heard the expression:“You are what you eat?” Well, there’s a lot oftruth in it.

Perhaps you’ve never thought about itbefore, but every atom in your body got therethrough something you ate. That carbonatom on the tip of your finger mighthave been in those scrambled eggsyou ate a few months back. The ironatom in that hemoglobin moleculepassing through your heart right nowmight have come from yesterday morning'sbowl of cereal.

Realizing that people are indeed whatthey eat, in the late 1950s, researchers atWashington University in St. Louis began amost unusual research project: They asked alllocal residents to send in their children’s teeth(after they had fallen out, of course!). At thetime, there were public concerns about theradiation levels caused by all the nuclearweapons tests that were being conducted.Back then, before we were fullyaware of the hazards of radioactivefallout, testing took place out in theopen (above ground). If you haveever seen video footage of a nuclearexplosion and the resulting mush-room cloud, chances are thatfootage came from one of theseaboveground tests. As it turned out,it was actually the findings of thisbaby teeth research project, along with otherevidence, that prompted the United States tosign a 1963 international treaty banningaboveground testing.

But why baby teeth? And what were theresearchers looking for in those teeth? Theanswer: strontium. More specifically: stron-tium-90 (90Sr), a radioactive isotope that isone of the dangerous byproducts of nuclearfission. But why would they find 90Sr in babyteeth? Take a quick glance at the periodic

table. Where is strontium (Sr)located? In the same group as calcium

(Ca). And being in the same group, strontiumis chemically very similar to calcium and thusgets taken in and directed to the bones andteeth. The growing bones and teeth of chil-dren require large amounts of calcium. So, if achild drinks milk from a cow that has eaten90Sr-contaminated grass, 90Sr will be found inthe child’s teeth.

While our bodiesnaturally contain somestrontium, about 300mg, only a very tinyfraction is normally90Sr. After collectingover 300,000 babyteeth, the researchersshowed, however, thatthis tiny fraction had

increased dramatically during the years thataboveground testing occurred, with radioac-tivity levels rising above 1400% between 1954and 1964. Similar studies in other parts of thecountry reported comparable findings.

And what does one do with 300,000baby teeth? Those in the St. Louis projectwere put into long-term storage and com-pletely forgotten. Forgotten, that is, until thespring of 2002, when some scientists werecleaning out an old ammunition bunker and

2 ChemMatters, DECEMBER 2003

COVER ILLUSTRATION BY MICHELLE BARBERACOVER PHOTOGRAPHY BY MIKE CIESIELSKI

Production TeamKevin McCue, EditorCornithia Harris, Art DirectorLeona Kanaskie, Copy Editor

Administrative TeamHelen Herlocker, Administrative EditorSandra Barlow, Senior Program Associate

Technical ReviewSeth Brown, University of Notre DameFrank Cardulla, Northbrook, IL

Teacher’s GuideFrank Cardulla, EditorSusan Cooper, Content Reading ConsultantDavid Olney, Puzzle Contributer

Division of Education and International ActivitiesSylvia Ware, DirectorMichael Tinnesand, Assistant Director for AcademicPrograms

Policy BoardSusan Cooper, Chair, LaBelle High School, LaBelle, FLLois Fruen, The Breck School, Minneapolis, MNDoris Kimbrough, University of Colorado–DenverRon Perkins, Educational Innovations, Inc. Norwalk, CTClaudia Vanderborght, Swanton, VT

Frank Purcell, Classroom Reviewer

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Natural Abundance of Strontium Isotopes

84Sr 0.56 %86Sr 9.86 %87Sr 7.00 %88Sr 82.6 %90Sr 0.00 %

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Vol. 21, No. 4 DECEMBER 2003

ChemMatters, DECEMBER 2003 3CMTEACHERS! FIND YOUR COMPLETE

TEACHER’S GUIDE FOR THIS ISSUE ATwww.chemistry.org/education/chemmatters.html.

found hundreds of shoe-box sized containersfilled with baby teeth, 85,000 in all. With eachtooth was a card carrying information aboutthe child who lost it. Not having any ideawhere they came from, the scientists nearlydiscarded the entire collection. Luckily,someone made the connection to the 90Srresearch project, and recognized the incredi-ble opportunity to conduct a follow-up study.

Now in their 40s, these individuals werecontacted and asked to complete a healthhistory survey to see what correlationsmight exist between their childhood 90Srlevels and their medical records. Concernexists, however, about the validity of sucha nonrandom study: After all, who would

be more likely to fillout such a survey: aperfectly healthyindividual or onewith a history ofhealth problems?

Similartooth collectionprojects are still

conducted today,not in connection with

nuclear weapons testing, butin an effort to determine whether living in nearto a nuclear power plant leads to increased90Sr in the children’s teeth.

Question From the Classroom 2My mother remembers her baby teeth were used in some sortof research study when she was young. What was that allabout?

ChemSumerVanilla! It’s Everywhere! 4Vanilla, it’s in everything from hair sprays to soda to chocolate.You might be surprised to learn that the primary flavorcompound, vanillin, can be made from rice, beets, wood pulp,and even petroleum.

Teeth Whitening 7Pastes, gels, and strips are all available for application,either in a dentist’s chair or at home, to whiten teeth. The

active ingredient in many whitening products is carbamideperoxide. What is it? How does it work?

Activity: Releasing the Power of Oxygen 10No, this isn’t an activity from a cheesy infomercial. We’ll usetwo household products to make oxygen and learn aboutcombustion.

Four Cool Chemistry Jobs 12You like chemistry, but you’re not sure whether it’s the careerfor you. Read about four exciting careers that might changeyour mind.

Hydrothermal Vents and Giant Tubeworms 14Imagine life near a deep-sea vent. It spews hot hydrogensulfide and other chemicals into the surrounding water.Photosynthesis is impossible in the dark. Food is scarce. Whatdoes a giant tubeworm have to do to get a meal around here!?

MysteryMattersScanning Electron Microscopy Solves a Mystery:The Mystery of the Pockmarked Paint Job 17

High-end sports cars are coming off an assembly line withbad paint jobs. Using a scanning electronmicroscope, a researcher discovers a clue.

The answer is “elementary”.

Chem.matters.links 20

H080

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22.990

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39.102

Rb37

85.47

Cs55

132.91

Fr87

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Mg12

24.31

Ba56

137.34

Ra88

226.05

Sc21

44.96

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88.91

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Ti22

47.90

Zr40

91.22

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178.49

V23

50.94

Nb41

92.91

Ta73

180.95

Ca20

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Sr38

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t’s almost unbelievable the num-ber of things vanilla is in. Vanillacan be produced from peanuts,grapefruit, cloves, rice bran, andeven barrels of crude oil. Origi-nally discovered in Mexican

orchids, it has spread from ataste hoarded by royalty into

the flavor in everybody’s ice cream sun-dae. Vanilla is the world’s most widelyused flavoring, a long-believed aphro-disiac, and a contributor to the manu-facture of specialty drugs.

A trip through the average hometurns up vanilla in vanilla extract, room spray, soap, body lotion andmassage oil, pudding mix, vanilla-scented candles, potpourri, and, ofcourse, vanilla ice cream—the number-one seller. A flood of recent tele-vision ads—like the one featuring the bouncing Pepsi truck—signal that

Coca-Cola and Pepsiare going head-to-head in the battlefor vanilla colasupremacy.

Almost every chocolate recipecalls for it. Tobacco and cattle foodare flavored with vanilla, and it iseven used in baby food. Where doesall this vanilla come from? TheUnited States alone consumes morethan 1000 tons of vanilla beans peryear, just for “high-end” products.The world demand for vanilla farexceeds the natural supply.

Growth and harvesting

In order to meet demand, planters once carried cuttings of thetree-climbing vines from Mexico to Madagascar and other tropicalareas, but the vines did not set pods. Vanilla planifolia (old name V. fragrans), which produces 99% of the pure vanilla sold, had been polli-nated occasionally by hummingbirds, but mainly by a strain of MexicanMelipona bees. No bees meant no seedbeds and no vanilla. To makematters even more complicated, each flower opens for one day only. In1841, growers began to hand-pollinate the orchids with a sharp bamboostick—as they still do—and V. planifolia flourished. In Tahiti, vinesmutated into a new species, V. tahitensis, the other commercial 1%.

Today, each ripening vanilla pod is so valuable that it is guardedand sometimes tattooed with its own I.D. number. Picked while green,

the large pods have no characteristic smell. First, they mustbe “killed” in hot water, “sweated” in the sun, dried in the

shade, and “conditioned” in a closed box untilthey turn brown, supple, and fragrant. Thisprocess, which promotes enzymatic action todevelop the flavor, requires 3–8 months,

www.chemistry.org/education/chemmatters.html4 ChemMatters, DECEMBER 2003

From steamy Mayan jungles to cold Norwegian pulp mills ...

from the Aztec halls of Montezumathrough Europe to Thomas

Jefferson’s plantation, one spice has been there. Chocoholics step

aside, it is vanilla that reignssupreme as the world’s most

widely used flavoring!

By Gail Kay Haines

It’s Everywhere!It’s Everywhere!

finally yielding long, skinny blackish-brown pods—each weighing about5 grams—filled with tiny black seeds. From planting to market can takefive years, making natural-grown vanilla the second most expensive flavor, after saffron.

VanillinVanillin, C8H8O3, is the major component (about

2%) of “pure vanilla”, a complex mixture of four pri-mary and nearly 300 minor chemicals. All four majorcompounds belong to the group called “aromatics”,which means they contain a benzene ring—C6H6—with various side chains substituted for hydrogen.

To protect consumers, different types of vanillahave specific legal meanings. Vanillin is only slightlysoluble in water, but it dissolves easily in ethanol(ethyl alcohol). Pure vanilla extract is made fromchopped vanilla beans, soaked for days or weeks indilute alcohol. It is the only flavoring to have a U.S.Food and Drug Administration standard of identity.Pure vanilla extract must contain “the extractivematerial from 13.35 oz. of vanilla beans per gallonand at least 35% alcohol by volume”. The extractpicks up hundreds of chemicals from the vanilla pod,giving “pure” vanilla its complex taste.

But vanillin is vanillin, what-ever the source. In the 1880s, German chemistssynthesized it as acheap substitute forvanilla. “Imitationvanilla” is mainly syn-thetic vanillin. “Nat-ural” vanilla is vanillinfrom other food sources mixedwith a little pure extract. Since

the price differences are huge, chemical testsexist to make sure each product is what the labelsays. But words do not always mean what theysuggest. For instance, “vanilla bean” ice creammay contain, not tiny seeds, but flecks of groundpods left over from the extraction process. Vanillin

ChemMatters, DECEMBER 2003 5

Legal Vanillinand Counterfeit Extract

Because synthetic vanillin is so much cheaper than natural vanillin and not subjectto the fluctuations of supply and price that affect natural foods, it offers an inex-pensive way for a food producer to impart a vanilla flavor to a food or beverage.

Substituting synthetic vanillin for natural vanilla is safe, sensible, and legal—as long as theproduct is properly labeled as containing artificial vanilla flavoring.

But passing off synthetic vanillin for vanilla extract can be lucrative. A quick trip tothe supermarket reveals that vanilla extract can sell for close to $3.50 per oz., whereasimitation vanilla sells for about $0.20 per oz. This presents a tempting situation for coun-terfeiters.

The possibility of cheating means that food chemists must devise a method to deter-mine when a product contains natural or synthetic vanillin. But vanillin is the same chemi-cal compound, whether it originates in the bean or is synthesized from lignin. Standardchemical analysis indicates the identity and quantity of a compound, but usually gives noclues about its sources. In the past few years, researchers have been able to distinguishbetween vanillin from fossil precursors, such as coal and petroleum, and vanillin of beanorigin by using isotopic ratio mass spectroscopy and nuclear magnetic resonance.

The source can be determined by inspecting the carbon atoms in the vanillin with atechnique called stable isotope ratio analysis (SIRA). SIRA is based on the fact that not allcarbon atoms have the same mass. Of the carbon atoms found in nature, 98.9% have amass number of 12, and 1.1% have a mass number of 13. Most organic compounds con-tain these percentages of carbon-12 (12C) and carbon-13 (13C) atoms. However, the ratio ofthese isotopes is slightly different for natural vanillin than for synthetic vanillin. The syn-

thetic vanillin is enriched in 13C. This happens because of differences in biochem-istry of the vanilla orchid and that of most other plants.

The vanilla orchid carries on photosynthesis by a series of reactions known asthe Crassulacean pathway. Most plants, however, including trees, use the Calvinpathway, which involves a greater number of chemical reactions. Because 13C isheavier than 12C, 13C reacts more slowly—and less 13C is incorporated during eachphotosynthesis reaction step. Most plants that will eventually become oil, coal, andlignin use the longer pathway. So synthetic vanillin from these sources has a lowerpercentage of 13C. By measuring the 13C:12C ratio with a mass spectrometer, scien-tists at the Bureau of Alcohol, Tobacco, and Firearms have been able to identifycounterfeit vanilla extract, and federal attorneys have prosecuted unscrupulous sup-pliers.

But the detective story does not end here. When counterfeiters discovered thatchemists could tell the difference between natural and synthetic vanillin by means ofisotope ratios, they searched for ways to adjust the 13C:12C ratio in the syntheticproduct to more closely match that of natural vanillin. The easiest way is to removethe –OCH3 group containing 12C and replace it with another –OCH3 group containing13C. But the government chemists were able to spot this ploy by removing the–OCH3 group and testing for the presence of 13C using mass spectrometry.

Adapted from a classic ChemMatters article by R. C. Breedlove, August 1988

Where does vanillin come from?

www.chemistry.org/education/chemmatters.html6 ChemMatters, DECEMBER 2003

probably makes up the difference. Andalthough high-fat ice creams require ahigher concentration of vanillin—because there is less air to deliver thefragrance—no-fat ice creams requirethe most. A mixture of extract and con-centrated vanillin seems to work best.

The scent in your hand lotion islikely synthetic, as is 95% of theworld’s vanilla supply. Once, most syn-thetic vanillin came from lignin—thenatural polymer removed from woodpulp in papermaking. It was a good usefor waste lignin, but the process gaveoff so much waste sulfuric acid that allsuch plants in North America haveclosed due to pollution.

Now, vanillin is more likely to be made from petro-leum or coal tar. Ethyl vanillin from crude oil—whichreplaces the methyl (CH3–) side chain in vanillin with ethyl,(C2 H5–)—has a vanilla taste that is 3 times stronger thanvanillin, but it is insoluble in butter, caramel, and choco-late. It is used in perfumes and low-fat ice cream. Eugenolfrom clove oil and guaiacol from coal tar can both beturned into vanillin. As wines and liquors age in oak bar-rels, alcohol pulls vanillin right out of the wood. Bothpeanuts and their hulls contain vanillin, which, even atparts per million (ppm) levels, adds a major flavor note.Grapefruit contains vanillin in the ppm range too, but hereit causes an “off” taste. In this case, less vanillin tastes better.

Medicinal useVanilla even has some medicinal uses. Vanillin is used in the man-

ufacture of medications for Parkinson’s disease and high blood pres-sure. Memorial Sloan-Kettering Cancer Center discovered that the

vanilla-like scent of heliotropin—a com-pound in Tahitian vanilla—produced a63% reduction in patient anxiety duringMRI scans. Vanilla is one of the threemost widely used flavoring/scents tomask the bad taste of medicine, andherbalists are reviving its popularity as afolk remedy to heal and soothe.

For hundreds of years, many peo-ple have ascribed aphrodisiac propertiesto vanilla. European physicians oncebelieved that vanilla could cure sexualailments and improve performance.Chocolate, also thought to have similarproperties was considered “cold”, whilevanilla was “hot”.

Before visiting his harem, the Aztec ruler Montezumawould consume large quantities of “chocolatl” containingvanilla extract. We’ll never know if Montezuma’s successwith the ladies was a result of the smell of chocolate on hisbreath or vanilla’s aphrodisiac qualities.

Maybe it’s not quite that “hot”, but modern researchhas shown men respond to vanilla more than to any otherscent. Today, it is appreciated for its mood-lifting, roman-tic appeal to both sexes. Unless you happen to be a bug.Vanilla scent, alone or with DEET makes a good insectrepellent, yet vanilla is used in flypaper, to attract flyingpests. Go figure.

Either way, fans of vanilla owe a huge debt of grati-tude to chemistry, for making so many sources of vanilla available.Otherwise, this “nectar of the gods”, as the Totonacs called it, mightstill be property of the royal rich.

Gail Kay Haines is a science writer and book author from Olympia, WA.

A flood of recent television ads—like the one

featuring the bouncingPepsi truck—signal thatCoca-Cola and Pepsi aregoing head-to-head in

the battle for vanilla colasupremacy.

HistoryThe Totonacs, in Mexico, first gathered seed

pods of the wild orchid for their unique fla-

vor. They traded pods as vine-grown “money”

with the Maya, who paid the beans in taxes to the

Aztecs. When Cortez invaded the New World,

around 1520, his men named the pods “vainilla”

(little sheath) and shipped them home as part of

the Aztec treasure. From Spain, vanilla spread

across Europe, sometimes as a flavoring for

chocolate. Some 250 years later, when Thomas

Jefferson was ambassador to France, he brought

vanilla back to America. The popularity of ice

cream took vanilla flavoring to the top, but chem-

istry brought it into everyone’s life.

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Scanning Electron Microscopy Solvesa Mystery!

ChemMatters, DECEMBER 2003 17

MysteryMatters

Jerry Jourdan’s day started just like most others.As a research microscopist for one of the largestchemical manufacturers in the world, his job is to

evaluate chemical samples using scanning electronmicroscopy (SEM). Although much of his analytical workis routine, frequently, some very interesting projects comeacross his desk.

As he rifled through the scheduled work for this par-ticular day, one request immediately caught his attention. Asample of red paint had arrived from one of the major

automobile manufacturers for analysis. The red paint pig-ment manufactured by his company was being used topaint a high-end sports car. The automobile manufacturerwas having a problem applying the paint.

Defects, known as craters, were appearing on someof the cars and ruining the quality of the finish. Repaintingthese cars was a costly and time-consuming repair— a billthat could cost hundreds of thousands of dollars! If hiscompany had supplied a faulty pigment, it would be liablefor the cost of the repairs.

By Tim Graham

The Mystery of The PockmarkedPaint Job

Small crater-like defects mysteriously began appearingin the paint jobs of high-end

sports cars coming off a particular line at a car factory.

Repairing the defects wasvery costly. For such a

well-established process, themanufacturer was stumped.What could be responsible?

Defective paint? Bad equipment? Sabotage?Well maybe not sabotage,

but no one really knew until amicroscopist found the

crucial clue.PHOTODISC

18 ChemMatters, DECEMBER 2003 www.chemistry.org/education/chemmatters.html

Great detectives and scientists have a lotin common. Both are armed with powers ofdeduction and equipment that helps them fer-ret out and understand clues. SherlockHolmes had a magnifying glass. Jerry Jourdanhad the SEM. He knew that for this type ofsmall-surface defect, the SEM could revealwithin minutes clues that would help himunravel the mystery.

Understanding scanning electronmicroscopy

The SEM is probably as big amystery to most of us as the paintdefect was to Jerry. Here’s how itworks.

The key behind an SEM’s success is theuse of electrons instead of light to form animage. The first modern scanning electronmicroscope was developed in the CambridgeUniversity Engineering Laboratory more than50 years ago, in 1951.

Whereas an optical microscope producesan image by using lenses to bend light waves,an SEM uses electromagnets to bend an elec-tron beam. This beam is then converted to animage on a computer screen. A beam of elec-trons is produced by heating a metal filamentcalled a tungsten hairpin gun. (Tungsten is thesame metal that is used in incandescent light

bulbs like the ones you typically use at home.)When voltage is applied, the filament heatsup. Negatively charged electrons are emittedfrom this hot filament and are acceleratedtoward a positively charged plate. These elec-trons are then directed through the micro-scope, where a series of electromagneticlenses focuses them into a fine beam thateventually strikes the sample.

This entire process must be done undera vacuum because other molecules couldabsorb electrons that would destabilize thebeam. The presence of air could also causethe electron source (tungsten filament) tooverheat and burn out.

Once this electron beam strikes the sam-ple, several interactions occur between thebeam and the specimen being analyzed. Twosuch interactions are typical: (1) secondaryelectrons accompanied by X-rays are pro-duced when electrons from the beam areabsorbed by the sample and, (2) backscat-tered electrons are formed when the electronsfrom the SEM beam collide with the specimenand are reflected with little loss of energy.The absorption and reflection of electrons aremeasured with separate detectors to provideuseful information about the specimen beingstudied.

Secondary electronsVery much like sonar (sound navigation

ranging), which bounces sound waves off theocean floor to determine the shape of the

How the SEM Works

Powder (above) and Iguanascales (right).

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seafloor, secondary electrons can be used tomap the surface features of a specimen. Thesesecondary electrons are produced when theoriginal higher-energy electron beam knockselectrons out of (ionizes) atoms on the sur-face of the sample. As the electron beamscans the entire surface of the sample, thesesecondary electrons are detected and thenconverted into an image. Areas of greater ion-ization appear brighter than areas with lowerionization. The resulting three-dimensionalimage has much higher clarity than an imageproduced by normal photographic techniques.

X-raysThe secondary electrons emitted from a

specimen usually come from one of the lowerenergy levels in the atoms. Because thisleaves a “vacancy” in one of the lower energylevels, an electron from a higher energy posi-tion in the atom will “fall” into this vacancy.This results in the release of energy, and typi-cally, this energy appears in the X-ray regionof the electromagnetic spectrum. Because X-rays have characteristic energies, unique tothe element from which they originated, theidentity of an element can be determined. Thetechnique, energy dispersive X-ray analysis(EDX), is typically used to help identify thecomposition of the contaminant particle(s).SEM/EDX can detect elements at levels as lowas 0.1 atomic percent.

Backscattered electrons

SEM produces a second groupof electrons called backscattered elec-trons. These result from the primaryelectrons from the beam striking thesurface of the sample. Measuringthese electrons provides an evenmore complete evaluation of the spec-

imen. When the primary electrons from thebeam strike the surface of the sample,backscattered electrons are reflected awayfrom the sample. Atoms with higher atomicnumber show up brighter on the computerscreen. Images produced from backscatteredelectrons provide useful information aboutthe surface of relatively smooth specimens,but more importantly, give analysts informa-tion on the atomic number, and therefore theidentity, of the element being bombarded.Scientists can combine the information pro-vided by X-rays, secondary electrons andbackscattered electrons to determine thecomposition of the contaminant. SEM/EDXproves to be a powerful tool in making suchdeterminations.

Back to the mystery …

When Jerry Jourdan firedup his SEM, analysis revealedthe presence of the contami-nants aluminum, silicon, chlo-rine, and zirconium in the redpaint samples. What on earthcould introduce these ele-ments?

Jerry knew. The answerwas “elementary”. All of theseelements can be found in a very common

household product—underarm deodorant!

The active ingredientof many antiperspirant/deodorants is aluminumzirconium chlorohydrexgly (anhydrous). Silica(SiO2) is used to providetexture. The SEM datamade Jerry suspect thatthe cratering was due tothe interaction of thedeodorant solids with thepaint during the dryingprocess. Somehow these

deodorant solids had made their way into thepaint!

Although, Jerry and an investigatingteam were certain that deodorant was the cul-prit, it would take further investigation to findthe source of the deodorant. The most likelysource of these solids was an employeeworking either in the manufacturing of thepigment or on the auto paint line. Plant offi-cials investigated the process area at thechemical plant to determine whether properprotocols were being followed. They easilydetermined that the antiperspirant particlesdid not originate in the manufacturing of thepigment.

Next, officials were dispatched to theautomobile facility to monitor the paint appli-cation area. A careful review of the data hadrevealed some additional interesting cluesabout the cratered paint samples. The dam-age only occurred on the driver-side fenderand hood of the automobile, and only on carspainted during a certain time of the day.These two areas used the same spray nozzleand were operated by a single individual.Hmmm …

When investigators monitored the oper-ations they found that the auto plantemployee who painted this section of the carwould have to swing the spray nozzle over thehood, while stretching his entire arm over the

flawed areas of thecar. Further monitor-ing revealed thatwhen the painter didthis, flakes from hissolid underarmdeodorant fell into thefreshly applied paint!

Once the sourceof the problem was

identified, new procedures were put intoplace to prevent this from happening in thefuture.

Jerry’s team had rightly interpreted theSEM/EDX data. It was simply a task of apply-ing some good detective work and logicalreasoning to find the origin of the contami-nant. In the end, his company was absolvedof all responsibility for providing flawed paintpigments.

ChemMatters, DECEMBER 2003 19

Tim Graham teaches chemistry at Roosevelt HighSchool in Wyandotte, MI. His most recent article,“Luminol—Casting a Revealing Light on Crime”,appeared in the December 2001 issue ofChemMatters.

SEM/EDX images of the paint defect indicate the presence ofZr, Al, Si, and Cl.

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Elemental essaysTest your “elemental” knowledge.

What patriotically named element isvital to the operation of smoke detec-tors? What’s the most abundant ele-ment in the universe? What elementis an aluminum can made of? No, no… wait that’s not right.

Anyway, if you likefacts and sto-ries aboutthe ele-ments,Chemical &EngineeringNews hasrecently posted89 essays on theelements on itswebsite. Don’texpect an encyclo-pedic recitation offacts. Eminent scien-tists and writerswrote many of theessays about their personal experi-ences with a particular element orelements. Read the essays to find theanswers to the two questions above.They are available as a linked periodictable. http://pubs.acs.org/cen/80th/elements.html

Submit your own SEM sampleThat’s right! You’ve read about scan-ning electron microscopy (SEM) in

this issue; now you and your classcan submit and view your own sam-ples. Professor Scott Chumbley, atIowa State University, MaterialsScience and Engineering Department,is hoping to receive requests to viewsamples from interested students and

teachers who want to operate theSEM over the Web and view sam-ples from their classroom.Submitted samples may thenappear in the image library withthe name of the sample, thename of the student (or class)and school submitting thesample, and a short descrip-tion of the sample.

What can you submit?Lots of things! Samples ofinsects, common materi-als, and even pond scumare already available for

viewing. Take special note: Not allsamples can be viewed in the SEM.Generally, the samples must be dry,nonliving, and capable of being coatedwith a material to make them electri-cally conducting.

Contact Scott Chumbley at chumbley@iastate.edu if youwish to operate the SEM from yourclassroom.

If you want to see more SEMimages or fill out a submission form,

visit http://www.mse.iastate.edu/microscopy/home.html.

Explore deep sea ventsIf you’d like to see more pictures

of hydrothermal vents, the Alvin sub-mersible, or the giant tubeworm’sneighbors, the National Oceanic andAtmospheric Administration (NOAA)has a site for you—http://oceanexplorer.noaa.gov—withlots of pictures and information.

Ocean Explorer provides currentinformation on NOAA scientific andeducational explorations and activi-ties in the marine environment. Readthe log and view pictures from a 2002NOAA expedition to look athydrothermal vents.http://oceanexplorer.noaa.gov/explorations/02galapagos/galapagos.html.

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