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Medicine Show Many

pharmaceutical chemicals when

properly prepared can evoke

marvelous images of diverse patterns

and colouration when cross-

polarized under the microscope. In

this article I will describe techniques

for preparation of pharmaceuticals,

photomicrographic techniques and a

gallery of finished images.

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Birefringence

Somecrystalsexhibitapropertycalledbirefringence

or“doublerefraction.”When lightpasses through

birefringent crystals the light rays are split into

two different polarizations.When these crystals

are viewed using unpolarized light or singularly

polarized light, their appearance is unremarkable.

However, when crystals are viewed through

crossed-polarizers, the difference between the

polarizations created by the crystals is revealed

as dynamic shapes, textures and colours.When

fine crystals such as pharmaceutical chemicals

are viewed through a microscope under cross-

polarization,oneentersafascinatingnewworld.

Specimen preparation

Notallpharmaceuticalcrystalsarebirefringent. In

fact,somepharmaceuticals(insulin,forexample)do

notcrystallizeatall.

Therefore,onehas to relyon trial anderror. For

thisarticle,IwillonlydescribethemethodsImyself

useforspecimenpreparation.

The first step is to dissolve the chemical in hot

water. Since my purpose is fine art photography

andnotresearch,hottapwaterratherthandistilled

waterwilldonicely.

Iuse50mlofwater foreachpillorcapsule.The

drugmaydissolve quicklyor, in the caseof time-

releasemedications,itmaytakeanhourormore.

Since the inactive ingredients may remain in

suspensioninthesolution,Ithenfilterthesolution

through coffee filter paper. If the solution is still

cloudy,Imaycentrifugethesolutionforfiveminutes

tosettleanyparticulatematter.ThenIcandrawoff

the clear solution from the top of the centrifuge

tubewithapipettesoastonotdisturbthepelletat

thebottomofthetube.

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Thespecimenisthendriedbyevaporation.When

I first started preparing chemicals for cross-

polarization,Iforcedriedthembyplacingtheslides

onanaluminumplateonacoffee-cupwarmer.Iwas

dissatisfiedwiththeresultantcrystalsandsuspected

thatinthecaseofsomecompounds,themolecules

of trace chemicals didn’t have time to“find” one

another to form distinct crystals of their own. I

thenwent to a slowerevaporation techniqueby

placingtheslidesonablackpieceofcardboardon

asunnywindowsill.Ipreparethreeslidesatatime

withthreeseparatedropsoneachslide,givingme

ninespecimens.

Some chemicals lend themselves to the “melt”

technique of slide preparation. A “pinch” of the

chemical isputonaslideandacoverglass isput

over it.Theslide is thenheldoveranopenflame

(alcohollamporbutanelighter)withforcepsuntil

thechemicalstartstobubbleasitmelts.Suddenly

itwillflattenoutintoathinsheetofthechemical

between the slide and the cover glass, at which

point theflame isremoved.Notallchemicalswill

melt,soonceagainitisamatteroftrialanderror

astowhatwillorwillnotmelt.Ihavehadsuccess

meltingAscorbicAcid,ResorcinolandPhenidone.

Besuretohavegenerousventilationandbecareful

nottolettheslidecatchonfire.

Cross-polarized photomicroscopy

Specialized microscopes such as petrographic

microscopes may already be set up for cross-

polarization. However, it is very easy to set up a

“hybrid” cross-polarization microscope. My setup

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isbasedonastandardtrinocularlightmicroscope

usingphotographicpolarizingfilters.

Incross-polarization,thepolarizerislocatedatthe

lightsourcebelowthestage.Theanalyzerislocated

anywhere in the light path above the objective.

Linearorcircularpolarizersmaybeused,butIhave

foundthatthetypesshouldagree–eitheralllinear

orallcircular. Ihavealso foundthat thedirection

that the light passes through the polarizersmust

also agree.This adjustment is easily addressed by

flipping the polarizer at the light source so that

thepolarizer/analyzer interfaceprovides themost

efficientpolarization.

Onmysetup,thepolarizerrestsonthemicroscopes

baseilluminator,soitcanbeeasilymanipulated

Thereisapolarizerontheeyepiecethatiskeptin

placesothatwhilesurveyingtheslide,Icanrotate

the polarizer on the light source to observe the

birefringence.

There is another analyzer in the photo (camera)

tube that rests on the photo eyepiece below the

camera, inthiscaseanOlympusNFK2.5Xphoto

eyepiece.Thisprojectstheimagedirectlyontothe

sensorofanOlympusE-330withouttheuseofa

relaylens.TheOlympusE-330hasLiveView,soIcan

rotatethepolarizeratthelightsourceandvisually

assess the polarized image being received by the

camera.

Exposureisdeterminedbytesting,sincethedegree

of birefringence of the chemical has a profound

effect on how much light passes through the

crossed-polarizers.The numerical aperture of the

objectivebeingusedandtheapertureopeningon

the substage condenser also come into playwith

regardtoexposuretime.

With some specimens, more coverage may be

required to artistically express the chemical. In

such cases I can shoot several shots to create a

panoramaoraphotomosaic inthecomputer.The

positionof the specimen is shiftedon the x, y or

x/y axeswithenoughoverlaptoenablethestitching

software tocombine the images. Iusea freeware

calledMicrosoftImageCompositeEditor(Microsoft

ICE) tostitch images together intopanoramasor

mosaics.

Michael Reese Much FRMS

Michael Reese Much FRMS is an amateur

microscopist recently retired from 40+ years

in the photographic industries, which included

positions with Kodak andOlympus in technical

capacities.

Hehasexhibitedhisphotographyinsoloandgroup

installations, and has lectured on photography

and developed an adult education course in

photographywhichhetaughtforseveralyears.He

is a frequent contributor to theUK-basedweb

magazineMicscape,forwhichhewritesarticleson

microscopy technique and restoration of classic

microscopes.

HehasplacedtwiceintheRMSScientificImaging

Competition, and his winning image of cross-

polarizedAscorbicAcidwasfeaturedonthecover

ofinfocusinDecember2010.Hehasalsohadan

image featuredon theRMS calendar every year

from2012-2015.

HeandhiswifeKathyliveonawoodedmountain

inBethlehem,Pennsylvania,USA.

e-mailAmoeba1@rcn.com

RMS Medal Series Nominations OpenWeareacceptingnominationsforthe2017RMSMedalSeries• RMSPresident’sMedal• Vice-Presidents’Medal• AlanAgarMedalforElectronMicroscopy• LightMicroscopy• LifeSciences• MedalforInnovationinAppliedMicroscopyfor MaterialsScience• ScanningProbeMicroscopy• ThePearsePrize

NominationsshouldbemadetoAllisonWinton,allison@rms.org.ukbefore30April2016.

Findoutmoreatwww.rms.org.uk/medal-series