Honey analytical techniques

EU legislation (Council Directive 2001/110/EC) requires that the geographical origin of honey be presented on the packaging. Honeys from specified botanical sources will often command a premium price due to their organoleptic or pharmacoactive properties. To prevent the fraudulent marketing of honey, analytical techniques are required to confirm its origin. 

TABLE 3.1 Usual chemical compositions as markers and analytical techniques for discriminating geographical or botanical origins of honeys... 

A variety of analytical techniques are used to measure PCP, including gas chromatography-mass spectrometry (GC-MS), which has a detection limit of 7.6 pg/kg honey (Muino and Taiza.no 1991), liquid chromatography with fluorescence detection (de Ruiter et al. 1990), and liquid chromatography-electrochemistry (LC-ED) procedures (Butler and Pont 1992). At present, GC-MS is the most accurate, but LC-ED is used most frequently (Butler and Pont 1992). 

By C 2/Cl3 analyses many apple products purchased from Boston and New York supermarkets were shown to be adulterated with com syrup or cane sugar. This sophisticated analytical technique has proven very useful for detecting adulteration of honey with corn syrup and cane sugar. It cannot be used, however, for detecting addition of beet sugar or sugars derived from other plants that utilize the Calvin pathway for CO2 fixation (3, U ). 

Pyrrolizidine alkaloids poison animals grazing on toxic wild plants and those fed contaminated feed, causing economic losses. They poison humans through deliberate consumption of certain foods and herbal medicines and through consumption of food contaminated by wild plants, such as via transport of the toxins by bees into honey. Analytical methods are required for different purposes - to detect the presence of pyrrolizidine alkaloids, to quantify the total level of the toxins, or to measure the quantity of individual compounds. The task is made more challenging by the variety of PAs, their widespread nature and their different forms. Analytical methods are based on color reactions, enzyme linked immunosorbent assays (ELlSAs), spectroscopy, and the full range of chromatographic techniques. A lack of reference standards and... 

Caroli S, Forte G, Iamiceu AL, Galoppi B 1999) Determination of essential and potentially toxic trace elements in honey by inductively coupled plasma-based techniques. Talanta 50 327-336. Chiswell B, Johnson D (1994) Manganese. In Seiler HG, Sigel A, Sigel H, eds. Handbook on metals in clinical and analytical chemistry. Dekker, New York. 

The popularity of this extraction method ebbs and flows as the years go by. SFE is typically used to extract nonpolar to moderately polar analytes from solid samples, especially in the environmental, food safety, and polymer sciences. The sample is placed in a special vessel and a supercritical gas such as CO2 is passed through the sample. The extracted analyte is then collected in solvent or on a sorbent. The advantages of this technique include better diffusivity and low viscosity of supercritical fluids, which allow more selective extractions. One recent application of SFE is the extraction of pesticide residues from honey [27]. In this research, liquid-liquid extraction with hexane/acetone was termed the conventional method. Honey was lyophilized and then mixed with acetone and acetonitrile in the SFE cell. Parameters such as temperature, pressure, and extraction time were optimized. The researchers found that SFE resulted in better precision (less than 6% RSD), less solvent consumption, less sample handling, and a faster extraction than the liquid-liquid method [27]. 

Analysis of drug residues in foods is a challenging task and numerous methods have been developed for the direct screening of meat, milk, eggs, and honey. The analyst has a wide range of extraction, enrichment, and instrumental techniques to choose from. There is no best method, and the analyst s choice will depend on the nature of the sample matrix, whether it is solid or liquid, fatty or nonfatty, and the expected range and levels of the analytes. The instruments available for the confirmation and quantification of the individual residues will also influence the choice of enrichment and quantification method. 

Multidimensional techniques are regularly used in analytical assessments of measurement data relating to the levels of chemical elements in the quality control of animal and plant food products. Chemometric interpretations have been obtained for the following animal products meat and meat products [316-318], fish [319-321], seafood [25, 322-328], milk and dairy products [329-332] and honey [333-339]. Similar interpretations have been obtained for the following plant products rice [143], cereals [340], vegetables [140, 341-346], fruit and fruit preserves [347], tea [155, 348-350], coffee [13, 155, 351, 352], mushrooms [26], fruit juices [141], confectionery [21, 353], nuts [354], wine [355-358], beer [66, 359] and other alcoholic beverages [159, 360, 361]. 

Several extraction techniques have been reported in the literature for the analysis of sulfonamides. Because of their polar nature, sulfonamides are readily extracted by organic solvents ° ° the most commonly used are acetonitrile.Other organic solvents used for analyte extraction and protein precipitation include dichloromethane, " acetone, ethanol, chloroform, and ethyl acetate, " which are often used either alone or in conjunction with one another. Other techniques used for protein precipitation include the use of acids such as perchloric or formic and the use of basic buffers such as potassium hydrogen phosphate and ammonium sulfate. In the case of honey, the use of acids such as trichloroacetic, " " hydrochloric, and phosphoric is necessary for hydrolysis, releasing carbohydrate-bound sulfonamide residues. Other extraction techniques reported in the literature include the use of pressurized liquid extractions, " matrix solid-phase dispersion, and magnetic molec-ularly imprinted polymers. Of additional note, several authors have observed that analyte recoveries were largely... 

A CRM for vitamins in honey does not exist at present and it is unlikely that one could prepare a RM due to the known instability of analytes. Therefore, to evaluate the bias, one must analyse the material by independent methods (Leon-Ruiz et al. 2011) or, more commonly, evaluate the recovery of known amounts of analytes spiked to honey. The first method is based on the fact that there is a negligible statistical probability that two independent methods may provide data affected by same bias, whereas in the spiking/recovery technique, recovery values statistically indistinguishable from 100% e.g. for a two-tailed t-test) indicate the absence of a bias. Table 13.5 shows recovery values of between 85 and 108.7%. Although a number of these recoveries different from 100% probably indicate some bias, it has been previously observed (AOAC 1998) that for low concentration levels recoveries can normally differ from 100%. AOAC guidelines (AOAC 1998) consider recovery levels between 80%... 

Wutz et al. (2011) developed for the first time a multianalyte immunoassay based on an automated flow-through CL microarray technique for identification and quantification of antibiotic derivatives in honey samples using regenerable antigen microarrays, an indirect competitive immunoassay format using horseradish peroxidase (HRP)-labeled antibodies and CL read-out with a CCD camera. The method allows the analysis of four analytes (enrofloxacin, sulfadiazine, sulfamethazine, and streptomycin) simultaneously in 8 min with adequate recoveries and without purification or extraction. Due to the regenerability of the microarray each chip could be individually calibrated before the analysis and allowed more than 40 assays, which reduces the costs per analysis and permits an automated work flow in routine laboratories. 

---