Chemistry Reference
In-Depth Information
groundwatersamplesfromtheU.S.showedsucralosecanbefoundintheaquaticenvironmentat
concentrationsupto2.4μg/L,thusprovidingagoodindicationofwastewaterinputfrombeverage
sources.
9.18.8 Fluorescence Spectroscopy
Becauseofthepresenceofvariousaromaticcompoundsinsapandsyrup,intrinsicluorescence
wasusedbyClement,Lagace,andPanneton(2010)tocharacterizethephysicochemistryandtypic-
ityofmaplesyrup.Twohundredsamplesofsapandtheircorrespondingsyrupwereobtainedfrom
variousfarmsin2003and2004.Theywereanalyzedbyconventionalphysicochemicaltestsand
luorescencespectroscopy.Twomajorregionsofluorescencewerefound,whichweremostlythe
sameforsapandsyrup.Theirstregionwasat320nm,excitedat275nm,andthesecondregion
wasat460nm,excitedat360(syrup)or370(sap)nm.
Maplesyrupisproducedbytheheatevaporationofmaplesapcollectedfrommaplesugartrees
(
Acer saccharum Marsh
)duringtheearlyspringseasoninNorthAmerica.
Clement,Lagace,andPanneton(2010)determinedthepotentialofluorescencespectroscopy
to assess the major physicochemical characteristics of maple sap and syrup in a rapid and non-
destructivewayandexplorednewpossibilitiesofautomatedclassiication,includingtypicityand
themomentofsapharvest.Theyfoundthatprecisefarmlocation,ratherthanthebroadregionof
production,isthemajorfactoroftypicity.
Opticalspectroscopycombinedwithchemometricscancharacterizeandclassifyfoodproducts
(KarouiandDeBaerdemaeker2007;Kulmyrzaevetal.2007).Forinstance,near-infrared(NIR;
Ruoffetal.2007)andfront-faceluorescencespectroscopy(Ruoffetal.2005)havebeenproposed
tocharacterizethephysicochemicalpropertiesandadulterationofhoney.Dataavailableonmaple
syruphaveshownthatvariousspectroscopicmethods(NIR,Raman,andFTIR)coulddetermine
thepresenceofadulterants(Paradkar,Sivakesava,Irudayaraj2003).
Raman spectroscopy is an important tool in the quantitative analysis of complex mixtures
(Strachanetal.2007;Peica2009).Oneofitsbeneitsliesinthefactthatwaterdoesnothinderthe
analysisofliquidsamples.
Itisanondestructivetechniquethatyieldsreliableresultsforsolidandliquidmulticomponent
samples,especiallywhentheanalyteconcentrationexceeds0.5%-1%byweight.
QuantiicationofaspartameincommercialsweetenerswascarriedoutbyMazurekandSzostak
(2011).TheyreportedthetreatmentofRamandatawiththreechemometricmethods:partialleast
squares(PLS),principalcomponentregression(PCR),andcounter-propagationartiicialneuralnet-
works(CP-ANN).Fourcommercialpreparationscontainingbetween17%and36%ofaspartame
by weight were evaluated by applying the developed models. Concentrations found from Raman
dataanalysisagreeperfectlywiththeresultsoftheUV-Visreferenceanalysis.
9.18.9 atomic absorption Spectrophotometry
Anatomicabsorptionspectrometricmethodforthedeterminationofsodiumsaccharinincom-
merciallyavailablemixturesofartiicialsweetenersandpharmaceuticalsbycontinuousprecipita-
tion with silver ion in a low manifold is proposed by Yebra, Gallego, and Valcarcel (1995), and
Yebra-Biurrun(2000).
The silver saccharinate precipitate formed is retained on a ilter, washed with diluted acetic
acid,anddissolvedinammoniaforonlineatomicabsorptiondeterminationofsilver,theamount
ofwhichintheprecipitateisproportionaltosaccharininthesample.Theproposedmethodallows
thedeterminationofsodiumsaccharinintherangeof5-75μgml
−1
withaRSDof2.7%atarate
ofca.20samplesh
−1
.Themethodisveryselective;othersweetenersdonotinterfere,butchloride
mustbeabsent.
Search WWH ::
Custom Search