K. Hejtmánková

Pesticide adsorption in relation to soil properties and soil type distribution in regional scale.

Study was focused on the evaluation of pesticide adsorption in soils, as one of the parameters, which are necessary to know when assessing possible groundwater contamination caused by pesticides commonly used in agriculture. Batch sorption tests were performed for 11 selected pesticides and 13 representative soils. The Freundlich equations were used to describe adsorption isotherms. Multiple-linear regressions were used to predict the Freundlich adsorption coefficients from measured soil properties. Resulting functions and a soil map of the Czech Republic were used to generate maps of the coefficient distribution. The multiple linear regressions showed that the K(F) coefficient depended on: (a) combination of OM (organic matter content), pH(KCl) and CEC (cation exchange capacity), or OM, SCS (sorption complex saturation) and salinity (terbuthylazine), (b) combination of OM and pH(KCl), or OM, SCS and salinity (prometryne), (c) combination of OM and pH(KCl), or OM and ρ(z) (metribuzin), (d) combination of OM, CEC and clay content, or clay content, CEC and salinity (hexazinone), (e) combination of OM and pH(KCl), or OM and SCS (metolachlor), (f) OM or combination of OM and CaCO(3) (chlorotoluron), (g) OM (azoxystrobin), (h) combination of OM and pH(KCl) (trifluralin), (i) combination of OM and clay content (fipronil), (j) combination of OM and pH(KCl), or OM, pH(KCl) and CaCO(3) (thiacloprid), (k) combination of OM, pH(KCl) and CEC, or sand content, pH(KCl) and salinity (chlormequat chloride).

Effect of peeling and three cooking methods on the content of selected phytochemicals in potato tubers with various colour of flesh

The impact of peeling and three cooking treatments (boiling, baking and microwaving) on the content of selected phytochemicals in white-, yellow-, red- and purple-fleshed potatoes was investigated. Ascorbic acid and chlorogenic acid contents were determined by HPLC-DAD, total anthocyanin content by pH-differential spectrophotometry, glycoalkaloid, α-chaconine and α-solanine contents by HPLC-ESI/MS/MS. All cooking treatments reduced ascorbic and chlorogenic acid contents, total glycoalkaloids, α-chaconine and α-solanine with the exception of total anthocyanins. The losses of ascorbic and chlorogenic acids were minimised with boiling and total anthocyanin levels retained the highest. Boiling of peeled tubers decreased contents of total glycoalkaloids (α-chaconine and α-solanine) and appeared as the most favourable among the three tested methods. Moreover, due to higher initial levels, red- and purple-fleshed cultivars retained higher amounts of antioxidants (ascorbic acid, chlorogenic acid and total anthocyanin) after boiling and may be healthier as compared with white or yellow cultivars.

Production of Benzoic Acid in Fermented Goat's and Sheep's Milk

Abstract The content of hippuric acid in raw goats and sheeps milk and the content of benzoic acid in model fermented milk drinks prepared using different cultures of bacteria of milk fermentation were determined. All fermented milk drinks contained benzoic acid in the range 5.0-78 mg kg-1. Higher quantity of benzoic acid in fermented sheeps milk drinks corresponded also to significantly higher quantity of hippuric acid in raw sheeps milk. No significant differences among used cultures of bacteria of dairy fermentation and the quantity of benzoic acid in fermented milk drinks were recorded. In addition, the quantity of benzoic acid in various commercial goats and sheeps cheeses produced directly in farms was analyzed. The contents of benzoic acid in cheeses ranged from 5.1 to 90 mg kg-1. No significant difference in the quantity of benzoic acid from goats and sheeps cheeses was found, whereas significant differences were registered in the quantity of benzoic acid in cheeses produced in individual farms.

Determination of Flavonoids in Stellaria by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

The genus Stellaria (Caryophyllaceae) presents widely distributed plants often used in traditional medicine. Flavonoids are highly active plant secondary metabolites that may be involved in some of the effects of Stellaria plants. In this study, two new high-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI-MS-MS) methods were developed for the determination of flavonoids and isoflavonoids in plant material. The separations were performed on a reverse-phase C18 column with gradient elution using methanol and water with 0.5% acetic acid as the mobile phase. Multiple reaction monitoring was used for the tandem mass spectrometry detection and the two most intensive transitions were chosen for the identification of each analyte. The limits of detection and the limits of quantification were between 0.2 and 15.0 ng/mL and 0.6 and 50.0 ng/mL. The developed methods were successfully used for the analyses of four representatives of the genus Stellaria. All the studied herbs contained luteolin and its 7-O-glycosides, naringenin, kaempferol, quercetin, its glycoside rutin, apigenin, and its 7-O-glycoside. One coumarin, scopoletin, was also found. Isoflavones were primarily represented by genistein, genistin, and ononin. Some of the analytes were detected for the first time in Stellaria sp. The findings support that these methods are suitable for analyses of plant material.