Determination of manganese with Thiazolylblue tetrazolium bromide in some vegetable crops

A study was made on the manganese content in the crop production of 28 vegetable species. The manganese content was determined by a new extraction - spectrophotometric method with Thiazolylblue tetrazolium bromide (MTT). The ion - associate of Mn(VII) was completely extracted in a single extraction of only 5 s, and the 1,2 - dichloro-ethane layer remained constant for 20 days under the usual laboratory conditions. The molar absorptivity of the associate was (1.0 +/- 0.04)x10(4) L mol(-1) cm(-1). This indicates the high sensitivity of the given reaction. Manganese has been determined by the atomic - absorption method, in order to compare the results. The most common vegetable cultivars from the main vegetable species were involved in the study. The obtained results have shown that the manganese content varies significantly in the different vegetable species and cultivars. In various sorts of tomatoes the content of manganese was 7.50 to 22 mg/kg Mn dry mass; in sorts of peppers - 5.95 to 21.50 mg/kg Mn dry mass. In the studied onion sorts the range was still wider - 9.90 to 407.50 mg/kg Mn dry mass. The least manganese content variation was found in the sorts of early white cabbage, viz. 15 to 24.80 mg/kg Mn dry mass. The manganese content in more widely used sorts of tomatoes, peppers, head cabbage, melons, and radishes was studied in order to establish the kind of differences in respect to the level of this element in their production.