Chemistry Reference
In-Depth Information
9.18.7 high-performance Liquid Chromatography
HPLCincombinationwithUVdetectionhasveryoftenbecomethemethodofchoiceforthe
determination of individual artiicial sweeteners such as saccharin, aspartame, acesulfame, and
NHDC(Montijanoetal.1997).
SaccharinisdeterminedinfoodstuffsbyHPLC,asdescribedbyAOAC(2000)andSjobergand
Alanko(1987a).
Thelackofanychromophoreinsucralosemakesasensitiveandspeciicdetectionbydirect
UVabsorptiondificult.Asaresult,currentanalyticalmethodsforitsdeterminationinfood-
stuffsinvolveeitherrefractiveindex(RI)detection(Kobayashietal.2001)orUVabsorbance
atawavelengthof200nm,whichlacksspeciicity(LawrenceandCharbonneau1988).Further
methodsthathavebeensuccessfullyappliedareHPTLC(Spangenbergetal.2003),high-per-
formanceanionexchangechromatographywithpulsedamperometricdetection(Dionex2004),
andCEwithindirectUVabsorption(McCourt,Stroka,andAnklam2005;Stroka,Dossi,and
Anklam 2003). Moreover, cyclamate does not absorb in the usable UV/visible range. This
shortcoming has been solved by using indirect UV photometry (Thompson, Trenerry, and
Kemmery 1995; Choi, Hsu, and Wong 2000), postcolumn ion-pair extraction (Lawrence and
Charbonneau1988),precolumnderivatization(Casalsetal.1996),andconductivitydetection
(Chenet al. 1997).
AHPLCmethodwithevaporativelightscatteringdetection(HPLC-ELSD)hasbeendeveloped
byWasik,McCourt,andBuchgraber(2007)forthesimultaneousdeterminationofmultiplesweet-
eners,i.e.,acesulfameK,alitame,aspartame,cyclamicacid,dulcin,neotame,NHDC,saccharin,
andsucraloseincarbonatedandnoncarbonatedsoftdrinks,cannedorbottledfruits,andyogurt.
Theprocedureinvolvesanextractionoftheninesweetenerswithabuffersolution,samplecleanup
usingSPEcartridges,followedbyanHPLC-ELSDanalysis.
The trueness of the method was satisfactory, with recoveries ranging from 93% to 109% for
concentrationlevelsaroundthemaximumusabledosagesforauthorizedsweetenersandfrom100%
to112%forunauthorizedcompoundsatconcentrationlevelsclosetotheLOQ.Precisionmeasures
showedmeanrepeatabilityvaluesof<4%(expressedasRSD)forhighlyconcentratedsamplesand
<5%atconcentrationlevelsclosetotheLOQ.
Ion-pairHPLChasbeenusedbyVerzella,Bagnasco,andMangia(1985)todetermineaspar-
tameininishedbulkanddosageformsatlevelsdownto0.1%.
Moreover, a reversed-phase HPLC method was developed by Di Pietra et al. (1990) for the
quality control of pharmaceutical and dietary formulations containing the synthetic sweeteners
aspartameandsaccharin.ArtiicialsweetenerswereanalyzedbyHPLCelectrospraytandemmass
spectrometry(HPLC-ESI-MS/MS)afterSPEaccordingtoarecentlypublishedmethod(Scheurer,
Brauch,andLange2009).Becauseartiicialsweetenerswereincompletelyremovedinwastewater
treatmentplants,someofthesecompoundsendupinreceivingsurfacewaters,whichareusedfor
drinkingwaterproduction.Thesumoftheremovaleficiencyofsingle-treatmentstepsinmulti-
barrier treatment systems affects the concentrations of these compounds in the provided drink-
ingwater.Thisistheirstsystematicstudyrevealingtheeffectivenessofsingle-treatmentstepsin
laboratoryexperimentsandinwaterworks(Scheureretal.2010).Sixfull-scalewaterworksusing
surfacewater-inluencedrawwaterweresampledupto10timestostudythefateofacesulfame,
saccharin,cyclamate,andsucralose.Saccharinandcyclamateprovedtoplayaminorrolefordrink-
ingwatertreatmentplants,astheywereeliminatedbynearly100%inallwaterworkswithbiologi-
callyactivetreatmentunits,suchasriverbankiltration(RBF)orartiicialgroundwaterrecharge.
Acesulfame and sucralose were not biodegraded during RBF, and their suitability as wastewater
tracersunderaerobicconditionswasconirmed.Sucraloseprovedtobepersistentagainstozone,
and its transformation was <20% in laboratory and ield investigations. Remaining traces were
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