Low Calorie Nonnutritive Sweeteners - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 106

3. Useofretentionofonlyoneanalyteinthesolidphasethatillsthelowcell,whilethesecondana-
lyteismeasuredwhenitlowsalongtheinterstitialsolutionthroughtheparticles.
4. Use of a chemometric approach without separation of the analytes prior to the detection step
(Jiménezetal.2009).
A multianalyte low-through sensor spectrophotometric method achieved the simultaneous
determinationofASPandACS-Kintabletopsweeteners.Theprocedureisbasedonthetransient
retentionofACS-KintheionexchangerSephadexDEAEA-25placedinthelow-throughcellof
amonochannelFIAsetupusingapH2.7composedfromorthophosphoricacid/sodiumdihydrogen
phosphate buffer (0.06M) as a carrier. In these conditions, ASP is very weakly retained, which
makesitpossibletomeasuretheintrinsicUVabsorbanceofirstASPat226nmandthenACS-K
at205nmafterdesorptionbythecarrieritself.ThelinearconcentrationrangeforASPisfrom10
to100μg/mL,thedetectionlimitis5.65μg/mL,andtheRSDis3.4%(at50μg/mL).Thelinear
concentrationrangeforACS-Kisfrom40to100μg/mL,thedetectionlimitis11.9μg/mL,andthe
RSDis1.61%(at50μg/mL).Nointerferenceiscausedbyglucose,sucrose,lactose,maltose,fruc-
tose,glycine,andleucineevenwhenpresentinconcentrationshigherthanthosecommonlyfoundin
thetabletopsweetenersanalyzed.Thelevelofthesolidphaseinthelowcellshouldbethatneeded
toillituptoasuficientheight,allowingtheradiationbeamtopasscompletelythroughthesolid
layer. The height of the solid support considerably inluences the separation of both sweeteners
(Jiménezetal.2006).
Amultianalyte low-throughmethod isproposed forthesimultaneous determination of ASP,
ACS-K,andsaccharininseveralfoodandsoftdrinksamples.Theprocedureisbasedonthetran-
sientretentionofthethreesweetenersinacommercialquaternaryamineionexchangermonolithic
column, placed in its speciic holder, and allocated in a monochannel FIA setup using (pH 9.0)
composedfromTrisbuffer0.03M,NaCl0.4M,andNaClO 4 0.005Masacarrier.Inthesecondi-
tions,ASPisveryweaklyretained,whileACS-Kismorestronglyretained,makingitpossibleto
measuretheintrinsicUVabsorbanceofASPandthenACS-Kafterdesorptionbythecarrieritself.
ThelinearconcentrationrangeforASPisfrom9.5to130.0μg/mL,thedetectionlimitis2.87μg/
mL,andtheRSDis1.46%(at65μg/mL).ThelinearconcentrationrangeforACS-Kisfrom2.2to
600.0μg/mL,thedetectionlimitis1.0μg/mL,andtheRSDis0.08%(at300μg/mL).Themethodis
appliedandvalidatedsatisfactorilyforthedeterminationofASPandACS-Kinfoodsandsoftdrink
samples,comparingtheresultswithanHPLCreferencemethod(Jiménezetal.2009).
AnewmethodtodeterminemixturesofthesweetenersASPandACS-Kincommercialsweet-
enersisproposedmakinguseofchemometrics.Aclassical5 2 fullfactorialdesignforstandardsis
usedforcalibrationintheconcentrationmatrix.Salicylicacidisusedastheinternalstandardin
ordertoevaluatetheadjustmentoftherealsamplesinthePLS-2model.Thismodelisobtained
fromUVspectraldata,validatedbyinternalcross-validation,andusedtoindtheconcentration
ofanalytesinthesweetenersamples.Themeanvalueofrecoverydegreeis99.2%withstandard
deviationof3.2%.Theproposedprocedureisappliedsuccessfullytothedeterminationofmixtures
ofASPandACS-Kinbulksamples(Cantarellietal.2009).
HPLC and GC are commonly used for food sample analysis (Table 4.4). A common HPLC
method that is used nowadays as a basic procedure for sweetener determination and used as a
referencemethodforvalidationisthefollowing:ThemethodusesaUVlightdetectorbyusing
absorbance measurements at 205 nm. Seven standard solutions and ive replicates are prepared
for both ASP and ACS-K. The HPLC carrier low is 0.75 mL/min. Every sample is accurately
weightedinavolumetriclaskanddilutedtothevolumewith0.02MKH 2 PO 4 :acetonitrile(90:10
v/v). Then every sample is sonicated for 5 min in an ultrasonic water bath to extract sweeten-
ersfromthematrix.Onemilliliteroftheextractisdilutedandilteredthrougha0.22-μmnylon
membrane.TheRSD(RSD%)valuesarebetterthan0.3%forASPand0.1%forACS-K(Armenta
et al. 2004a,b). For the estimation intake of intense sweeteners from nonalcoholic beverages in