DELIVERY
COLUMN CHROMATOGRAPHY (Charcoal-Celite, 1:1) 1.0-g Sample 1. Elute with 7% Ethanol (300 mL) ^ ^ \ ^ g 0 B
STOCK 1
Mono- and Disaccharides DISCARD
. . . Higher Saccharides
THIN-LAYER CHROMATOGRAPHY (Silica Gel G) Elute with n-Butanol: Acetic Acid:Water (2:1:1) Detect Spots with Aniline-Diphenytamine Spray Reagent for Carbohydrates
Figure 3. Thin-layer chromatographic test for honey adulteration
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2. Elute with 50% Ethanol (100 mL)
Dissolve in Water (10 mg/mL Water)
NaCI-KCI-KBr-CaFzMgF2· BaF2· G e · Si · ZhSe-KRS-5-ZnSCsBr-Csl-LiF-SrF2· Cultured Quartz· Sapphire · Fused Silica · Irtran 2
OPTICAL
i ^ J ^ l
Evaporate (Steam, Then Vacuum Oven) Higher Saccharide Syrup
WINDOWS, LENSES & ATR PLATES
V INFRARED
ν ΐώ
in ordinary laboratories for selecting samples sufficiently suspicious to jus tify the confirmatory isotope ratio test. Recently, we developed two such methods, one using thin-layer chroma tography and the other gas-liquid chromatography. The thin-layer chromatographic method (19) has been subjected to successful collaborative testing (20) and recommended for adoption as an official method of analysis. A flow di agram of the procedure is given in Fig ure 3. This very sensitive procedure involves isolation of a fraction con taining oligo- and polysaccharides from both honey and HFCS by col umn chromatography on charcoal-Celite. After concentration, these frac tions were examined by silica gel thinlayer chromatography; consistent dif ferences between honey and HFCS fractions were revealed. Whereas pure honeys yielded only one or two bluegrey or blue-brown spots of Rf greater
than 0.35, a series of spots or blue streaks extending from the origin characterized adulterated samples. The method detects HFCS and the traditional honey adulterants, even when present as 10% or less of the total mixture. An added advantage is that this procedure should detect in honey the presence of all starch-de rived sugar syrups tested, regardless of the plant source. Figure 4 shows the differences in the chromatographic profiles of honey, HFCS, and adulter ated mixtures. This procedure is being used routinely to screen samples, not only for HFCS but also for other adul terants of honey, including conven tional corn syrup and inverted sucrose syrups. A gas-liquid chromatographic meth od (21 ) based on the determination of maltose and isomaltose has been use ful in our laboratory. However, in view of the small number of successful col laborative tests (20), it could not be
Table IV. Gas Chromatographic Determinations of Maltose and Isomaltose In Honey (80 U.S. Samples, 35 Imported Samples) and in HFCS (21 Samples} Maltose Mean < % )
Domestic honey Imported honey HFCS
1.93 2.17 0.72
SD
0.51 0.53 0.26
Isomaltose Mean ( % )
0.64 0.87 1.50
SD
0.37 0.50 0.82
Reprinted with permission from rel. 21. Copyright 1979 Association of Official Analytical Chemists.
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230 A · ANALYTICAL CHEMISTRY, VOL. 5 1 , NO. 2, FEBRUARY 1979
