## 3 Results
### FFF Spectral Profiles of Honey of Different Botanic Origin
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Honey Sample Label** & \(\lambda_{\rm max}\) **(nm) at \(\lambda_{\rm ex}\) = 280 nm** & \(\lambda_{\rm max}\) **(nm) at \(\lambda_{\rm ex}\) = 340 nm** & \(\lambda_{\rm max}\) **(nm) at \(\lambda_{\rm ex}\) = 420 nm** \\ \hline AC1 & 345 (440 *) & 420 & 483 \\ SU1 & 420 (490 *) & 435 & 495 \\ CL1 & 340 (320 **) & 430 & 502 \\ CL2 & 335 (320 **), 440 & 433 & 500 \\ CL3 & 340 (320 **) & 430 & 502 \\ MA1 & 345 (450 **) & 415 & 487 \\ MA2 & 345 (450 **) & 427 & 485 \\ MA3 & 340 (450 **) & 435 (400 **) & 487 \\ L1 & 360 & 440 & 503 (475 **) \\ AR1 & 470 (340 *) & 445 (385 **, 502 **) & 491 \\ IN1 & 373 (470 *) & 443 (362 **, 385 **, 503 **) & 500 (475 **) \\ FH1 & 410 *** & 405 (362 **, 385 *) & 483 \\ AA1 & 470 (361 **, 385 **) & 407 (362 **, 385 *, 470 **) & 497 \\ C1 & 385 (403 **, 463 **) & 385 (362 **, 400 **) & 487 \\ H1 & 410 (500 **) & 413 & 500 \\ S1 & 355 (420 *) & 430 (530 **) & 515 (475 *) \\ \hline \hline \end{tabular}
* * Secondary, less intense, emission band; ** broad emission shoulder; *** very broad band with relatively low intensity.  
\end{table} 
Table 4: Wavelength of the maximum emission bands observed by fixing the excitation wavelength, \(\lambda_{\rm ex}\), equal to 280, 340, and 420 nm. In the parentheses, the wavelengths relative to secondary maxima emission bands as well as to emission shoulders are also reported for each honey sample. Synchronous spectra of honey are often used to discriminate among botanic and geographic origin in combination with multivariate statistical analysis [25; 35; 36; 37; 38; 39; 40; 41], mostly due to the high sensitivity of this spectrometric technique and the possibility of identifying the emission bands specific to each sample. Moreover, synchronous spectra are used to support the identification of single fluorophore's contributions to the emission spectra [30]. By observing the synchronous spectra of the twelve honey samples reported in Figure 3, several general considerations can be drawn. In almost all honey samples, synchronous spectra are characterized by two well-defined and intense bands:  
* the first intense band (**I**) has a maximum at \(\lambda_{\rm ex}\) = 280-290 nm, mostly due to amino acids (mainly tryptophan), proteins, and some phenolic acids;
* the second intense band (**II**) has a maximum at \(\lambda_{\rm ex}\) = 340-350 nm, mostly due to other phenolic acids, flavonoids, and vitamins, such as vitamin B6 (see in particular, chestnut, marruca, heather, and sunflower honeys). Additionally, some honey samples present a third band (**III**), with maximum at \(\lambda_{\rm ex}\) = 410-420 nm due to the presence of other fluorophores, such as pigments and vitamin B9 (see, for instance,  
Figure 3: FFF synchronous spectra of honey samples in the bulk obtained with fixed wavelength interval, \(\Delta\lambda\), of 20 nm. Synchronous spectra of twelve honey samples of different botanic origin are here reported as indicated in the legend on the right. The intensity of the synchronous spectra is normalized (a.u.). Note that the spectrum of the chestnut honey sample (C1) is cut due to the very high intensity of the signal centered at 350 nm. Note that the sharp oscillations in the range between 420 and 480 are due to the xenon lamp. chestnut, marruca, sunflower, and forest honeydew). Almost all honey samples have broad emission bands around 500-550 and only sunflower honey has a defined forth band (**IV**), with a maximum at \(\lambda_{\text{ex}}\) = 520-530 nm, probably due to vitamin B2 and other pigments. A fifth band (**V**) centered around \(\lambda_{\text{ex}}\) = 640-650 nm, due to chlorophylls and their derivatives, is present in almost all honey samples, with the exception of chestnut and marruca honeys and forest honeydew.