Identification and Quantification of Single and Multi‐Adulteration of Beeswax by FTIR‐ATR Spectroscopy

Abstract

Marketing of adulterated beeswax foundation has recently become a major economic problem for beekeepers. Paraffin contamination leads to collapse of combs, and stearic acid has a negative influence on the development of bee brood. The quality of beeswax for beekeeping has not been standardized in EU regulations. Recently, it was shown that attenuated total reflectance Fourier-transform infrared spectroscopy (FTIR-ATR) can be used to determine beeswax adulteration. Differences in the IR spectra of authentic beeswax can be identified and calculated through comparison with authentic beeswax. In this study, the method is further validated by employing a high number of samples of authentic beeswax from different origins. Low quantification and detection limits are achieved for paraffin, stearic acid, tallow, carnauba wax, and candelilla wax. Furthermore, the FTIR-ATR analytical conditions are verified by analyzing 358 samples of commercial and beekeeper-produced beeswax foundations. Multi-adulterated samples with as many as five different additives in beeswax mixtures are identified with the same accuracy as single substances. Additionally, the spectra of a further 14 different natural and synthetic waxes and hardened fats are analyzed and are compared with beeswax. Finally, a spectral library is established that can be used for further studies. Practical Applications: FTIR-ATR is a fast and cost-efficient tool in beeswax analysis for accurately monitoring a high sample volume. Analysis of 358 beeswax foundations showed an adulteration of 21.8% of the samples with paraffin, stearic acid, tallow, and combinations. Based on the results of this study, it is possible to detect beeswax adulteration of less than 3% of these adulterants and their combinations by FTIR-ATR spectroscopy. This method can be used for monitoring beeswax foundations to identify adulterated materials, exclude these materials from the recycling process, and produce high-quality beeswax, which is essential for bee health.

Adulteration of beeswax: A first nationwide survey from Belgium

“…When detecting beeswax adulteration, FTIR-ATR spectroscopy technique has the advantage to detect adulteration at a relatively low level (< 3%) for paraffin, beef tallow, stearin, stearic acid, palmitin, and carnauba wax [ 39 ], and its ability to detect mixtures of beeswax adulterants with the same accuracy as single substances [ 40 ].…”

A combined physical–chemical and microbiological approach to unveil the fabrication, provenance, and state of conservation of the Kinkarakawa-gami art

“…Thus, vibrational modes typical of proteinaceous binders (INV_15) or waxes (INV_13_9 and INV_20) were detected (Supplementary Tables 3 – 4 ), which is in agreement with the Japanese traditional use of animal glue ( nikawa ), gelatine cubes, and beeswax as binders 15 , 25 . Since IR absorption bands distinctive of proteinaceous binders or waxes are more present in the 3770–2750 cm −1 interval 30 , 31 , the partitioning of µATR-FTIR spectra of INV_15 recto in cluster 3 (average s i = 0.66), INV_13_9 and INV_20_3 in cluster 1 (Fig. 3 c, d) statistically supported these observations.…”

“…The identification of inorganic pigments highlighted the need for Japanese artisans to use binders (e.g., proteinaceous binders, vegetable oils, waxes, and lacquers) for their painting 15 . Although the type of these substances is generally determined through FTIR, the wallpapers' complexity impaired their univocal identification, since they had similar IR absorption bands and their specific vibrational modes often overlapped with each other (Supplementary Tables 1-4) 30,31 . In this regard, the clustering analysis in the 1840-719 cm −1 interval revealed that spectra featuring Indigo's IR contributions grouped in cluster 2, while cluster 1 featured the verso spectra and those where the organic pigment was absent or less present, in which overlapping vibrational modes of cellulose, lignin, silicates, carbonates, and organic binders were ubiquitous (Fig.…”

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“…Beeswax spectrum presented the typical bands around 2957 cm À1 associated with asymmetric stretching vibration of CH 3 and asymmetric and symmetric stretching vibration of CH 2 around 2922 and 2852 cm À1 , respectively. Also, CH 2 scissor deformation and rocking vibration of CH 2 groups were appreciated around 1456 and 720 cm À1 [54]. The carbonyl C = O stretching vibrations were observed around 1739 and 1172 cm À1 overlapped with the C-H bending vibrations in the band about 1172 cm À1 , characteristic of the monosaturated fatty acid esters of the beeswax [54,55].…”