Chemistry Reference
In-Depth Information
3,4-dimethoxyphenylsulfamateshavebeenexamined.WhentheASVsforthesearecombinedwith
thosefor15aliphatic,aromatic,andalicyclicsulfamatesfromapreviousstudy,manyofthevalues
are seen to fall into the region that was previously identiied as the “sweet area,” i.e., the ASVs
laybetween0.0.5and0.0.7(afewsweetcompoundsfallbelowthisrange,anditissuggestedthat
itcouldbeextendedslightlytoaccommodatethese).Interestingly,theanilinomethanesulfonates,
ArNHCH
2
SO
3
Na(Ar=C
6
H
5
-,3-MeC
6
H
4
-and3-ClC
6
H
4
-)lieclearlyinthesweetregion,butonly
oneofthemshowsslightsweetness,showingthemolecularstructuralchangemade(comparedwith
theparentsulfamate-
NHSO
−
)cannotbeaccommodatedatthereceptorsite.
9.19.2 electronic Nose, electronic tongue, and array-Based Sensing
Detectionofchemicallydiverseanalytesisdonebyproducingspeciicitynotfromanysingle
sensorbutasauniquecompositeresponseforeachanalyte.Suchcross-reactivesensorarraysmimic
themammalianolfactoryandgustatorysystemsandareawidelyusedapproachinelectronicnose
(GardnerandBartlett1999)andtongue(Anandetal.2007;Toko2000)technologies.
Adisposable,low-costcolorimetricsensorarrayhasbeendescribedbyMusto,Lim,andSuslick
(2009)andcreatedbypin-printingontoahydrophilicmembrane16chemicallyresponsivenanopo-
rouspigmentsthatcomprisedindicatorsimmobilizedinanorganicallymodiiedsilane(ormosil).
The array has been used to detect and identify 14 different natural and artiicial sweeteners at
millimolar concentrations, as well as commonly used individual-serving sweetener packets. The
arrayhasshownexcellentreproducibilityandlongshelflifeandhasbeenoptimizedtoworkinthe
biologicalpHregime.
Suslicketal.(2007)havedevelopedanalternativeoptoelectronicapproachusingsimplecolo-
rimetric sensor arrays for the detection and identiication of a wide range of analytes (Suslick et
al.2007;Zhang,Bailey,andSuslick2006;ZhangandSuslick2007).Theyhaverecentlyreported
the use of nanoporous pigment arrays for the discrimination of several carbohydrates (Lim et al.
2008).
9.20 MULtIVarIate aNaLYSIS/CheMOMetrICS
Honey can be adulterated with sweeteners, such as cane sugar, beet sugar, and corn syrup.
Different analytical techniques have been employed to detect the adulteration of honey, such as
isotopic (Padovan et al. 2003; Cabañero, Recio, and Rupérez 2006), chromatographic (Cordella
etal.2003b,2005;Morales,Corzo,andSanz2008),andthermalanalysisofDSC(Cordellaetal.
2003a) and NMR (Cotte et al. 2007; Doner and Philips 1981). HFCS has been detected in apple
juiceby
13
C/
12
Cisotopicratio.However,thesemethodsaretimeconsuming,destructive,and,some-
times,expensive.Moreover,vibrationalspectroscopicmethodssuchasmiddle-infrared(Gallardo-
Velazquezetal.2009;Kelly,Petisco,andDowney2006a,2006b;SivakesavaandIrudayaraj2002;
Irudayaraj,Xu,andTewari2003;Bertellietal.2007)andNIRspectroscopy(Kelly,Petisco,and
Downey2006a;Toher,Downey,andMurphy2007)havepreviouslybeenappliedtoauthenticate
honey.
Zhu et al. (2010) used NIR spectroscopy combined with chemometric methods to detect the
adulterationofhoneysamples.Thesamplesetcontained135spectraofauthentic(
n
=68)andadul-
terated(
n
=67)honeysamples.Spectraldatawerecompressedusingwavelettransformation(WT)
andPCA,respectively.Theyreportediveclassiicationmodelingmethods,includingleastsquare
supportvectormachine(LS-SVM),supportvectormachine(SVM),backpropagationartiicialneu-
ralnetwork(BP-ANN),lineardiscriminantanalysis(LDA),andK-nearestneighbors(KNN),which
wereadoptedtocorrectlyclassifypureandadulteratedhoneysamples.WTprovedmoreeffective
Search WWH ::
Custom Search