Use of elemental profiles determined by energy-dispersive X-ray fluorescence and multivariate analyses to detect adulteration in Ceylon cinnamon.

The price of Cinnamomum verum (Ceylon cinnamon) is around twice as high as that of the other cinnamon varieties commonly grouped under the name cassia cinnamon, making the former spice an attractive target for fraudsters. This work demonstrates that elemental profiles obtained by energy-dispersive X-ray fluorescence in combination with multivariate analyses can be used as a screening method to detect Ceylon cinnamon adulteration. Thirty-six elements were analysed in 52 commercially available cinnamon samples, 29 Ceylon, 8 cassia, and 15 for which no indication about variety was provided. Fifty-eight percent of the samples were either adulterated or did not meet international quality criteria. Four of the ground cinnamon samples labelled as Ceylon cinnamon were found to be pure cassia or a mixture with a high cassia content, and 26 samples were suspected of other types of adulteration including replacement of bark with other parts of the cinnamon tree. Headspace gas chromatography-mass spectrometry and ash determination by thermogravimetric analysis confirmed the conclusions reached by elemental analysis. Only one sample labelled as Ceylon cinnamon and that according to its volatile composition was cassia cinnamon was not flagged as suspicious by elemental analysis.

Are the elemental fingerprints of organic and conventional food different? ED-XRF as screening technique.

Research has been conducted the last years to assess whether organically grown food is chemically different from produce of conventional agriculture and which markers are appropriate to discriminate between them. Most articles focus on one single food commodity, produced under strict controlled organic farming conditions, leaving open the question whether the difference would be seen when applied to the same commodity under different growing conditions. In this work 118 organic and 151 conventional samples of commercially available paprika powder, cinnamon, coffee, tea, chocolate, rice, wheat flour, cane sugar, coconut water, honey and bovine milk were characterised for their elemental composition using energy dispersive X-ray fluorescence. Resulting profiles were analysed using univariate and multivariate statistical techniques. Organic samples of a given commodity clustered together and were separated from their conventional counterparts. Differences in the elemental composition of food, could be used to develop statistical models for verifying the agronomical production system.

Use of elemental profiles to verify geographical origin and botanical variety of Spanish honeys with a protected denomination of origin.

Honey with Protected Denomination of Origin (PDO) could be an attractive target for fraudsters. Elemental profiles by Energy Dispersive-X Ray Fluorescence were processed by multivariate methods to classify 183 PDO honeys produced in three regions of Spain (Liébana, Granada, Tenerife). Additional honey samples (18) produced in a fourth region without PDO (El Bierzo) separated well from the PDO clusters. The manganese content was a discriminant marker of Liébana PDO and El Bierzo, that could also be differentiated from each other. Within each region, distinct clusters revealed differences between dark vs light varieties, multi- vs uni-floral honey and producers of the same PDO. The developed models were validated with 131 samples produced outside the PDO regions and El Bierzo. The proposed classification approach could be implemented as a fast screening tool to support pollen analysis in honey authentication. The reduced number of observations in some light honey models affected their performance.

Use of energy-dispersive X-ray fluorescence combined with chemometric modelling to classify honey according to botanical variety and geographical origin.

Honey is one of the food commodities most frequently affected by fraud. Although addition of extraneous sugars is the most common type of fraud, analytical methods are also needed to detect origin masking and misdescription of botanical variety. In this work, multivariate analysis of the content of certain macro- and trace elements, determined by energy-dispersive X-ray fluorescence (ED-XRF) without any type of sample treatment, were used to classify honeys according to botanical variety and geographical origin. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were used to create classification models for nine different botanical varieties-orange, robinia, lavender, rosemary, thyme, lime, chestnut, eucalyptus and manuka-and seven different geographical origins-Italy, Romania, Spain, Portugal, France, Hungary and New Zealand. Although characterised by 100% sensitivity, PCA models lacked specificity. The PLS-DA models constructed for specific combinations of botanical variety-country (BV-C) allowed the successful classification of honey samples, which was verified by external validation samples. Graphical abstract.

Determination of linear and cyclic volatile methyl siloxanes in biogas and biomethane by solid-phase microextraction and gas chromatography-mass spectrometry.

A new method based on solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of seven linear (L2 - L5) and cyclic (D3 - D5) volatile methyl siloxanes (VMS) in biogas and biomethane, directly collected into Tedlar® bags (Tedlar SPME) from anaerobic digesters and wastewater treatment plants. The method was employed to monitor VMS content in biomethane produced by biogas upgrading with a pilot-plant membrane unit and provided adequate limits of quantification (< 0.05 mg m-3) to detect trace siloxane impurities. Tedlar SPME was validated against a standard procedure based on indirect sampling of gas streams with sorbent tubes followed by solvent extraction and GC-MS. Method precision (RSD) on total and individual VMS concentrations was lower than 10%, while RSD values of the standard procedure were higher than 20%. Tedlar SPME suitably revealed high VMS levels, expressed as total volatile silicon (> 1 mgSim-3), in wastewater biogas and provided a more efficient sampling of heavier VMS in comparison to the sorbent tubes method. At low values (< 0.1 mgSim-3) typical of wood waste biogas and biomethane, no statistically significant differences were observed between the two methods. Overall, Tedlar SPME simplified the analytical procedure by reducing the procedural steps, avoiding the use of solvents and demonstrated its applicability for testing the quality of biomethane as advanced biofuel.

Getting to the root of the matter: Water-soluble and volatile components in thermally-treated biosolids and biochar differentially regulate maize (Zea mays) seedling growth.

The use of thermally treated biomass, including biochar, as soil amendments can improve soil fertility by providing nutrients, stable C and improving soil water-holding capacity. However, if the degree of carbonization is low, these soil amendments can lower crop productivity as a result of high salinity or organic compounds. The overall effect of these soil amendments is mediated by complex relationships between production conditions, soil properties and environmental conditions. This study aimed to 1) characterize the physiochemical properties and organic compounds released by three soil amendments (softwood biochar or pyrogenic carbonaceous biosolids), 2) determine the effects of these amendments on maize (Zea mays) seedling productivity, and 3) relate properties of these amendments to effects on maize seedling productivity under controlled environment conditions. Physicochemical properties and mobile organic compounds (water-soluble and volatile organic compounds were determined. The amendments were tested in maize germination and greenhouse experiments. Chemical fingerprinting of volatile and water-soluble compounds revealed over 100 mobile organic species. Increasing treatment temperature from 270 to 320°C reduces phytotoxicity of pyrogenic carbonaceous biosolids soil amendments. Water-soluble components of pyrogenic carbonaceous biosolids produced at 270°C (inorganic N, Na and/or organic compounds) were associated with reduced maize seedling productivity. Volatile components of pyrogenic carbonaceous biosolids produced at 320°C were associated with improved maize seedling productivity; nitrogen uptake was increased in spite of smaller root systems as a result of increased mineralization of soil or amendment N and/or uptake of organic N compounds. These results suggest that pyrogenic carbonaceous biosolids have potential benefits to provide plant nutrients when the amount of organic and inorganic species are limited during early growth stages, under greenhouse conditions. Future studies should examine these effects under field conditions to confirm whether controlled environment results translate into effects on yield.

Determination of volatile fatty acids in digestate by solvent extraction with dimethyl carbonate and gas chromatography-mass spectrometry.

Volatile fatty acids (VFAs) are among the most important parameters in process monitoring of anaerobic digestion plants for biogas production. The concentration of single VFA species is typically determined by direct injection of the acidified aqueous phase of digestate samples into GC-FID. Analysis of dimethyl carbonate extracts was investigated as an alternative method consisting of a simple and rapid in-vial procedure of acidification and solvent extraction of the sample, followed by centrifugation and GC-MS analysis. The principal figures of merit resulting from internal standard calibration were comparable to those proposed for the direct analysis of aqueous digestate, while the analysis of real samples did not provide statistically significant differences between the two methods according to parametric and non-parametric tests. Procedural aspects including sample amount and solid removal improved with dimethyl carbonate, while GC contamination was reduced. The method was applied to seventeen samples from fully operating anaerobic digesters fed with various feedstocks and enabled the individuation of high probability of system stress through the values of total VFA, propanoic acid, longer chained VFA concentrations and the ratio between acetic and propanoic acid concentrations. The use of dimethyl carbonate allowed the detection of alicyclic and aromatic acids that could represent new molecular markers in assessing the origin of feed and process conditions.

Source and Biological Response of Biochar Organic Compounds Released into Water; Relationships with Bio-Oil Composition and Carbonization Degree.

Water-soluble organic compounds (WSOCs) were extracted from corn stalk biochar produced at increasing pyrolysis temperatures (350-650 °C) and from the corresponding vapors, collected as bio-oil. WSOCs were characterized by gas chromatography (semivolatile fraction), negative electron spray ionization high resolution mass spectrometry (hydrophilic fraction) and fluorescence spectroscopy. The pattern of semivolatile WSOCs in bio-oil was dominated by aromatic products from lignocellulose, while in biochar was featured by saturated carboxylic acids from hemi/cellulose and lipids with concentrations decreasing with decreasing H/C ratios. Hydrophilic species in poorly carbonized biochar resembled those in bio-oil, but the increasing charring intensity caused a marked reduction in the molecular complexity and degree of aromaticity. Differences in the fluorescence spectra were attributed to the predominance of fulvic acid-like structures in biochar and lignin-like moieties in bio-oil. The divergence between pyrolysis vapors and biochar in the distribution of WSOCs with increasing carbonization was explained by the hydrophobic carbonaceous matrix acting like a filter favoring the release into water of carboxylic and fulvic acid-like components. The formation of these structures was confirmed in biochar produced by pilot plant pyrolysis units. Biochar affected differently shoot and root length of cress seedlings in germination tests highlighting its complex role on plant growth.

Relationships between Chemical Characteristics and Phytotoxicity of Biochar from Poultry Litter Pyrolysis.

Three biochars were prepared by intermediate pyrolysis from poultry litter at different temperatures (400, 500, and 600 °C with decreasing residence times) and compared with biochars from corn stalk prepared under the same pyrolysis conditions. The phytotoxicity of these biochars was estimated by means of seed germination tests on cress (Lepidium sativum L.) conducted in water suspensions (at 2, 5, and 40 g/L) and on biochars wetted according to their water-holding capacity. Whereas the seeds germinated after 72 h in water suspensions with corn stalk biochar were similar to the control (water only), significant inhibition was observed with poultry litter biochars. In comparison to corn stalk, poultry litter generated biochars with higher contents of ash, ammonium, nitrogen, and volatile fatty acids (VFAs) and a similar concentration of polycyclic aromatic hydrocarbons (PAHs). Results from analytical pyrolysis (Py-GC-MS) indicated that nitrogen-containing organic compounds (NCCs) and aliphatic components were distinctive constituents of the thermally labile fraction of poultry litter biochar. The inhibition of germination due to poultry litter biochar produced at 400 °C (PL400) was suppressed after solvent extraction or treatment with active sludge. A novel method based on solid-phase microextraction (SPME) enabled the identification of mobile organic compounds in PL400 capable of being released in air and water, including VFAs and NCCs. The higher phytotoxicity of poultry litter than corn biochars was tentatively attributed to hydrophilic biodegradable substances derived from lipids or proteins removable by water leaching or microbial treatments.