[Lushi]

Please can anyone recommend a good TLC system for Beauvericin?
I need visualisation method, solvent mix, Rf value. I am a poor student and  cannot afford a true reference standard.
Lushi

[barcrphd]

at least provide the structure. then we could suggest some solvent systems. first of all, you should have some idea about the nature of the compound. if it is polar you will go for polar solvent or otherwise. for understanding how to choose solvents for tlc, refer to vogels, practical organic chemistry book.

[chiralic]

Beauvericin (BEA)

Beauvericin is a mycotoxin produced by several Fusarium species and has also been isolated from Beauveria bassiana.

Extraction
Extraction of beauvericin from cereal and corn samples takes place using an acetonitrile-water mixture by blending the sample. Alternatively Shephard et al. extracted the homogenised sample with methanol and (after evaporation and re-dissolving in mobile phase) injected the extract directly into the LC-MS without any further clean up and resulting in an LOD of 8 µg/kg. Filtering is usually included in all extraction procedures. Sometimes a defatting step using an extraction with hexane in the procedure, which however results in a considerable loss of BEA, is included. In order to obtain reasonable recoveries, the defatting step should be replaced by an appropriate clean-up (Josephs et al., 1999).

Clean-up
Liquid-liquid-partitioning with dichloromethane is often combined with SPE columns. Josephs et al. (1999) reported a Mycosep #224 and Silica SPE column clean up suitable for the µg/kg range and a recovery of 96.4%. Subsequent elution was performed with chloroform/2-propanol (97:3). The use of C18 clean-up columns has also been reported.

Separation and Detection
Separation and detection were performed by Josephs et al. using an HPLC-DAD system with a reversed phase C18 column and an acetonitrile-water mixture as mobile phase. 192 nm and 209 nm were used as detection wavelengths. LC-MS (Shephard et al.) and thermo spray MS systems have been used for detection and identification, and NMR Spectroscopy was used for identification purposes. Other separation and detection systems also include normal phase HPLC systems with silica columns.

High performance thin layer chromatography (HPTLC) has also been used as a means of separation using precoated silica gel 60 plates that were spotted with methanolic extracts. Mobile phases were toluene/acetone, chloroform/2-propanol and ethyl acetate/hexane. Detection was performed at 365 and 254 nm after colouring with iodine vapours with a detection limit in the mg/kg range.

It is important to note that so far no reliable and established methods exist for the determination of trace levels (lower µg/kg range) of BEA in cereals or similar complex matrices (in particular with respect to robustness and reproducibility). LC-MS is a promising and powerful tool for the determination and identification of BEA, but still subject to ongoing research. Disadvantages of LC-MS techniques are the high costs involved and the experience that is required.

References BEA
1. Josephs, R.D., Krska, R., Schuhmacher, R., Grasserbauer, M., A Rapid Method for the Determination of the
    Fusarium Mycotoxin Beauvericin in Maize, Fresenius J. of Anal. Chem. 363, 130-131 (1999)

2. Shephard, G.S., Sewram, V., Nieuwoudt, T.W., Marasas, W.F.O., Ritieni, A., Production of the Mycotoxins
    Fusaproliferin and Beauvericin by South African Isolates in the Fusarium Section Liseola,
    J.Agric. Food Chem., 47, 5111-5115 (1999)

3. Logrieco, A., Moretti, A., Ritieni, A., Chelkowski, J., Altomare, C., Bottalico, A., Randazzo, G.,
    Natural Occurrence of Beauvericin in Preharvested Fusarium subglutinans Infected Corn Ears in Poland,
    J. Agric. Food Chem., 41, 2149-2152 (1993)

4. Ritieni, A., Moretti, A., Logrieco, A., Bottalico, A., Randazzo, G., Monti, S.M., Ferracane, R., Fogliano, V.,
    Occurrence of Fusaproliferin, Fumonisin B1 and Beauvericin in Maize from Italy,
    J. Agric. Food Chem., 45, 4011-4016 (1997)

Regards,

Chiralic from Tepui's Land!

[barcrphd]

seeing the structure, i feel 15% ethyl acetate, pet etherwill be a good solvent system to start with. seeing the movement you can adjust the polarity of the mixture accordingly. presence of phenyl rings may make it UV active. so you can use a UV lamp for visualization. the molecule may even adsorb iodine.
best of luck

[movies]

If those really are all alcohols, then you will need something a fair bit more polar that 15% EA!

[Lushi]

Big ThanX everyone !