Ergot alkaloids assay

Schnitzius, J. M., Hill, N. S., Thompson, C. S. and Craig, A. M. 2001. Semi-quantitative determination of ergot alkaloids in seed, straw, and digested samples using a competitive enzyme-linked immunosorbent assay. Journal of Veterinary Diagnostic Investigation, 13 230-237. 

Foster, MacDonald and Jones applied the principle of paper chromatography to the separation of ergot alkaloids and developed an approximate assay for ergometrine based on the fluorescence of developed chromatograms, compared visually with a series of standard spots prepared at the same time as the sample under test. 

A number of EA exhibit a strong fluorescence upon irradiation. This feature is extensively used for the detection of EA after their separation by HPLC or TLC. Without any preceding separation, the fluorescence of ergot derivatives can also be used for the development of some fluorimetric assays (Gyenes and Bayer, 1961 Hooper et al., 1974). The limitation of all direct methods of EA determination including colorimetry, spectrophotometry or fluorimetry is the lack of specificity regarding related alkaloids or their own degradation products. Consequently, the majority of these methods has now been abandoned, but the specific features or reactions of EA are further employed for their detection by more sophisticated HPLC and TLC methods. 

The assay of ergot has concerned analysts for many years and the continuous steady stream of papers devoted to the subject indicate that a confident solution to the problem has not yet been found. However, little ergot is now used other than for extraction of the alkaloids by manufacturers. 

Ergot, B.P. C., is standardised to contain total alkaloids, minimum OT 9 per cent calculated as ergotamine, of which not less than 15-0 per cent consists of water-soluble alkaloids calculated as ergometrine. Prepared ergot, B.P.C., deprived of fat and standardised to contain total alkaloids 0-18 to 0-20 per cent calculated as ergotamine, of which not less than 15-0 per cent consists of water-soluble alkaloids calculated as ergometrine. It must be noted that these standards for water-soluble alkaloids are dependent on the method of assay and lower figures must be expected if the N,F, method described below is used. 

Assay for ergometrine. Pipette 20 ml of the concentrated solution of total alkaloids, representing 4 g of ergot, into a 250-ml separator, add 30 ml of water and make slightly alkaline to phenolphthalein with strong... 

Alexander and Banes have published a new procedure for the assay of ergot. The extraction and preparation of total alkaloids closely follows that of the N.F. given above and water-soluble alkaloids are separated by column chromatography. The total and water-soluble alkaloids are then determined colorimetrically with />-dimethylaminobenzaldehyde. 

The acid maleate of an alkaloid obtained from ergot. It is officially assayed by the colorimetric method, given under Ergot, against a standard solution of ergometrine maleate. It can also be determined by the U,S,P. method. 

The tartrate of an alkaloid obtainable from certain species of ergot. It is assayed colorimetrically by the dimethylaminobenzaldehyde method given under Ergot after solution in 1 per cent tartaric acid against a standard ergometrine maleate solution. 1 mg of ergometrine maleate = 1 488 mg of ergotamine tartrate. 

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