蜂蜜中C13同位素比检测方案(同位素质谱仪)

Applications Note： 014IsoprimeApplication of 13C EA-IRMS to the detection of adulteration of honey Applications Note： 014 Honey is a natural product that has beenused since ancient times. It is a rathercomplex product with a relatively highmarket price. As such， this makes it a prime target forfraudulent adulteration. One of the mainsources of adulteration of honeys is theaddition of High Fructose Corn Syrup(HFCS) which can be difficult to detectwith conventional techniques (Hernandez1998). The analysis of 13C/12C isotoperatios provides a very effective tool toquantify small isotopic variations that occurin natural compounds from differentorigins. The isotopic technique for thedetection of adulterated honey is based onthe fact that there is a natural difference inisotopic ratios between plants presentingC3 and C4 photosynthetic pathways(Kruger and Reesman 1982). Generally，C4 plants， for example corn， have d13Cranging between -8 to -20%o， whereas C3plants， generally nectarbearing plants，present values between -22 and -35。.The experiment described here illustratesthe ability of the 13C analyses by IsoprimeLtd EA IRMS to detect different levels ofadulterations of a pure honey. Experimental Analyses were performed on a lsoPrimeIsotope Ratio Mass Spectrometer connectedto an Elemental Analyser via the IsoprimeContinuous Flow (CF) interface. Six different samples were analysed includingan authentic honey sample， a sample ofsucrose and 4 samples with different levels ofadulteration of the pure honey with sucrose. Sample Details Weight 813C Mean St.dev (mg) (vs P.D.B.) 1 23 Cane_1 Cane_2 Cane 3 3.278 3.448 3.362 -11.06 -11.02 -10.96 -11.01 0.05 45 6 Sucrose_1 Sucrose_2 Sucrose 3 3.37 4.38 3.92 -10.63 -10.55 -10.6 -10.59 0.04 7 8 9 5 1 52 5_3 3.6 3.09 3.76 -23.29 -23.37 -23.3 -23.32 0.04 1011 12 1_1 1_2 13 5.05 3.2 3.34 -22.57 -22.79 -22.78 -22.71 0.12 1314 15 31 3_2 33 3.6 4.5 3.5 -20.22 -20.14 -20.27 -20.21 0.06 1617 41 4_2 3.3 4 -20.82 -20.96 -20.89 0.1 1819 20 2_1 2_2 2_3 3 3.6 3.8 -21.56 -21.52 -21.53 -21.54 0.02 212223 Sucrose_4Sucrose_5 Sucrose 6 3.8 3.3 3.25 -10.8 -10.83 -10.66 -10.76 0.09 Results The complete set of results is shown in Table 1. The cane sample is aworking standard used at Isoprime， and it has been calibrated againstinternational references. Samples were analysed in triplicate except forsample 4. This table shows the quality of the 13C analyses performed with theIsoprime system with external precision generally below 0.1%o， whichenables the detection of small variations in d13C values The very good agreement between the actual levels of adulteration of thepure honey with sucrose and the calculated levels of adulteration from thed13C values is illustrated in figure 1. Adulteration of honey -10--12- y=0.1275x-23.377 Sucrose-R14-2=0.9998 -16--18- Pure honey-20--22- -24- -26+ 0 20 40 60 80 100 %sugar added Figure 1 Correlation between the 813CpDB and the degree of adulteration. Conclusions References We have shown with this experiment thatcontinuous flow EA-IRMS for d13C is a verypowerful tool for the detection of honeysadulterated with sugar. H W Krueger， R H Reesman， (1982)Mass Spectrometry Rev.， 1， 205 Helena Hernandez， (1998)VAM Bulletin， Spring 98， 12-14 Acknowledgements AOAC Official Method 978.17： Corn andCane sugar products in honey. The authors are grateful to Dr Casado fromthe Laboratorio Agroalimentario deExtremadura who supplied the honeysamples. AOAC Official Method of Analysis， Chapter44， Page 27 (1995)USA lsoprime A stable future for stable isotop es Telephone：+44 (0) 161 488 3660Email：info@isoprime.co.ukWeb：www.isoprime.co.uk Isoprime Ltd.Isoprime HouseEarl Road， Cheadle HulmeSK PT -UK