Variability of the essential oil from three sorts of Echinacea MOENCH genus during ontogenesis.

Variability of the essential oil from three sorts of Echinacea MOENCH genus during ontogenesis The content and quality of the essential oil in relation to the main ontogenetic stages of plants were studied in three various sorts of Echinacea genus. The comparison included Echinacea purpurea, Echinacea atrorubens, and Echinacea pallida. The differences in the content of the oil in different parts of plants and the abundance of individual oil constituents in oils from the sorts under study at the optimum stage of ripeness for harvest were evaluated as well.

[Modern HPLC in drug analysis]. / Moderná HPLC v analýze lieciv.

High performance liquid chromatography found wide-spread utilization almost in all fields of pharmaceutical analysis since the 1980s. The article summarizes the new knowledge and interesting findings about HPLC used in the analysis of drugs during the last three years with a supplement of particular applications in pharmaceutical analysis.

[Infant formulas based on dried milk and risks of its contamination with residual pesticides]. / Náhradná detská výziva na báze suseného mlieka a riziko jej kontaminácie rezíduami pesticídov.

Residues of agricultural pesticides have the potential to enter the organism of farm animals and, subsequently, they can be transferred to milk. Infant formulas are manufactured from dried hydrolyzed cow's milk. Therefore, attention should be paid to possible contamination of the raw material for the manufacture of infant formulas with pesticide residues, especially those of persistent triazine herbicides. Dried milk based formulas are often the only food of young children in their first months of life. Thus, the control of infant milk formulas for pesticide residues is an important issue.

[Qualitative characteristics of selected species of the genus Echinacea Moench]. / Stúdium kvalitatívnych vlastností vybraných druhov rodu Echinacea Moench.

The paper examined the effect of production-technological conditions in relation to the ontogenetic stage of plants in three different species of the genus Echinacea Moench., comparing the species Echinacea purpurea, Echinacea atrorubens, and Echinacea pallida. It also examined the differences in the content of essential oil in different plant organs and evaluated the representation of individual components in the essential oils of the species under study at the stage of the optimal maturity for collection.

[Determination of residual trifluralin in the herbal drug Mentha piperita L]. / Stanovenie rezíduí trifluralinu v droge Mentha piperita L.

A HPLC/UV method was worked out to determine the residues of the herbicide trifluralin in the vegetable drug of the peppermint (M. piperita L.). The yield of the method, determined in model samples, was at least 70%, the determination limit of the method being 0.07 mg.kg-1. The content of trifluralin residues in the vegetable drug of the peppermint plant after application of the preparation Treflan 48 EC (in a dose of administration of 2 kg.ha-1) for the treatment of the growth in a small-plot experiment was below the detection limit of the analytical method.

Interlaboratory study of identification and quantitation of multiresidue pyrethroids in agricultural products by gas chromatography-mass spectrometry.

This paper deals with the different GC-MS analytical conditions adopted by four laboratories in an attempt to confirm the accuracy of the GC-electron-capture detection (ECD) analytical results during the international collaborative study for the establishment of the AOAC Official Method 998. 01. What is especially noted is that two laboratories have conducted comparative analysis of the respective 12 blind samples with both methods of GC-ECD and GC-MS, and the analytical results of the two methods turn out to be basically identical. This fully demonstrates that GC-MS is not only an effective confirmation tool in the analysis of the pyrethroid residues but also of sufficient sensitivity regarding the maximum residue limit of determination prescribed by FAO/WHO. Moreover, its selectivity is better than GC-ECD.

Determination of the hop-derived phytoestrogen, 8-prenylnaringenin, in beer by gas chromatography/mass spectrometry.

A method was developed to determine 8-prenylnaringenin, a novel hop-derived phytoestrogen, in beer. Matrix purification involved solid-phase extraction on octadecyl silica followed by liquid/liquid extraction on a ChemElut 1010 column connected to a Florisil adsorption/desorption cartridge. 8-Prenylnaringenin was eluted from the tandem columns using a 1:1 mixture of diethyl ether and ethyl acetate and subsequently determined as tris(trimethylsilyl) ether by GC/MS-SIM. The recovery of 8-prenylnaringenin in beer samples was between 61.1 +/- 6.6 and 82.2 +/- 8.8% for levels of 37 and 92.5 microg L(-1), respectively, and the detection limit was approximately 5 microg L(-1). Although most beers do not contain 8-prenylnaringenin in detectable quantities, the highest concentration found was 19.8 microg L(-1). The concentration of 8-prenylnaringenin in beers and, possibly, its absence depend on the selection of particular hop varieties, the hopping rate, or the type of hop product used in brewing. The efficiency of transfer of 8-prenylnaringenin from hops to beer is between 10 and 20%.

Development of a simple method for the determination of genistein, daidzein, biochanin A, and formononetin (biochanin B) in human urine.

A simple method was developed for the determination of free and/or total isoflavones daidzein, genistein, and their respective 4'-methoxy derivatives biochanin A and formononetin (biochanin B) at low levels in human urine. A solid-phase extraction on octadecyl silica (C(18)) columns was used for the isolation of the phytoestrogens from the matrix. An extraction on a ChemElut 1010 column connected on-line to a Florisil cartridge by a Teflon stopcock was used for effective eluate purification. A mixture of dichloromethane and ethyl acetate was used for elution of the isoflavones from the columns in tandem. The isoflavones were determined as trimethylsilyl (TMS) ethers using GC/MS-SIM after separation on an HP-5MS fused silica column. TMS ethers were obtained by using BSTFA containing 1% of TMCS. For the determination of free isoflavones 6-hydroxyflavone was used as internal standard, whereas robigenin was used in the case of total isoflavone determination. Recoveries for free isoflavones under study varied from 63.5 to 89.6% at the 25 ng mL(-)(1) level and from 63.5 to 89. 2% at the 5 ng mL(-)(1) level in urine. Analytical curves were linear between 5 and 25 ng mL(-)(1). Detection limits varied from 1 ng mL(-)(1) for formononetin to 2.3 ng mL(-)(1) for daidzein. Recoveries for total isoflavone determination after enzymatic hydrolysis with glucuronidase from Helix pomatia ranged from 56.5 to 77.1% at the 25 ng mL(-1) level.

Gas chromatographic method for determination of uracil herbicides in roots of Echinacea angustifolia Moench (Asteraceae).

A GC/NPD method and a rapid screening TLC method were developed for the simultaneous determination of uracil herbicide residues (bromacil, lenacil, terbacil) in the roots of Echinacea angustifolia Moench (Asteraceae). The uracil herbicide residues were extracted into acetone. After evaporation of acetone from the acetone-water extract the residue was dissolved in water-methanol (5:1 v/v). Cyclohexane was used for removal of the non-polar co-extractives in the sample matrix. After separation of the cyclohexane phase the uracil herbicide residues were extracted into chloroform. This extract was purified on a Florisil column, and residues were eluted with dichloromethane-acetone (9:1, v/v). The cleaned up extract was analysed by the GC/NPD method on a capillary column DB-1 using atrazine as internal standard. A minimum recovery of 70% was attained for contamination levels of 0.02-0.40 mg kg(-1).

Pesticide residue analyses in plant material by chromatographic methods: clean-up procedures and selective detectors.

This paper deals with the analysis of pesticide residues by chromatographic methods in samples of plant origin. Emphasis is put on the isolation and clean-up steps of the sample preparation for GC or LC determination. The problems of the extraction solvent selection and clean-up procedures using different types of adsorption column chromatography or gel permeation chromatography are discussed. Attention is also given to alternative techniques such as supercritical fluid extraction (SFE), matrix solid-phase dispersion (extraction) (MSPD) and sweep co-distillation that are used for sample processing prior to GC and LC analysis. Currently, pesticide residue analyses are typically multi-residue procedures with highly sensitive methods. Consumption of costly and toxic solvents is being minimized and fully automated analytical procedures can be expected in the future.

The effect of herbicides on the qualitative properties of healing plants. Part 2: Content and composition of the essential oil from Salvia officinal is L. after application of Afalon 50 WP.

The aim of our work was to study the changes of the content and quality of volatile oil in Salvia officinalis L. being treated with Afalon 50 WP (the active substance linuron) in the major ontogenetic phases of the plant growth. The plants treatment with a herbicide in pre-emergence did not cause a dramatic change in the essential oil content or in the proportional representation of its individual components. During the investigation of the changes in quality of the essential oil after an application of Afalon during various plant growth phases there was found the same relationship when compared with those being untreated.

Chromatographic methods in the determination of herbicide residues in crops, food and environmental samples.

The state of the art of chromatographic methods used in the determination of herbicide residues in crops, food and environmental samples is reviewed. The main structural groups of herbicides, i.e., triazines, phenyl- and sulphonylureas, carbamates, uracils and phenoxyalkanoic and arylphenoxypropanoic acids, and important degradation products (dealkylated triazines, substituted anilines, chlorophenols) are considered. Advantages and drawbacks of gas (GC), liquid (LC) and thin-layer chromatography in this type of analysis are discussed. The characteristics of a modern chromatographic method for the determination of herbicide residues are summarized and trends in the development and combination of current GC and LC methods discussed.

Isotachophoretic determination of herbicides prometryne, desmetryne, terbutryne and hydroxy-derivatives of atrazine and simazine in extracts of milk.

A method is described for the determination of the triazine herbicides prometryne, desmetryne, terbutryne, OH-atrazine and OH-simazine in purified extracts of milk using analytical capillary isotachophoresis. The reproducibility of isotachophoretic analyses was 3.5% and the detection sensitivity reached 2 ng. Recovery of triazines from fortified samples of homogenized full milk (0.05 mg/L) was about 65%.

Determination of acrylamide in sugar by capillary GLC with alkali flame-ionization detection.

A method for the determination of acrylamide traces as a residue of anti-incrustation agents in sugar was developed. Acrylamide was extracted into ethyl acetate after derivatization by bromination to 2,3-dibromopropionamide (2,3-DBPA). The extract was cleaned up on a silica gel column and analysed by gas-liquid chromatography with an alkali flame-ionization detector (AFID). A glass capillary column with OV-1 stationary phase was used for this analysis. The recovery of the method determined in model experiments was 70.0% and 77.1% at 100 micrograms kg-1 and 20 micrograms kg-1, respectively. The limit of detection of acrylamide in sugar is 1-10 micrograms kg-1. Parameters of the described method are compared with other published methods.

Analysis of triazine herbicides residues in butter and pasteurized milk.

A method has been developed for the determination of atrazine, cyanazine, prometryn, simazine, and terbutryn residues in butter. The residues were extracted from the matrix with a mixture of petroleum ether/methanol (3 + 1), and from the separated water-methanol phase extraction was carried out with chloroform. The extract was cleaned up on an alumina column. Capillary glass liquid chromatography using a 15 m x 0.32 mm glass capillary column coated with OV-1 and an alcali flame ionization detector were employed for the analysis of the residues. The analyses were evaluated by the internal standard method, using metribuzin as the internal standard. The recovery of the method was 68.7%-79.8% for the individual herbicides under study at the fortification level of 0.1 mg.kg-1 and 79.2%-91.9% at the fortification level of 0.02 mg.kg-1. The determination limit of the method was 0.005 mg.kg-1. When centrifuging full milk, residues of triazines were partitioned between the water and fat phases, whereby 17%-82% of the residues were transferred to the milk fat. Samples of commercial butter were analysed and found to contain 0.005-0.023 mg.kg-1 atrazine.

Analysis of herbicide residues in sugar beet and sugar.

A simple quantitative TLC method for the determination of the residues of herbicide inhibiting photosynthesis was compared with capillary GLC for the analysis of atrazine, chloridazone, lenacil, phenmedipham and desmedipham in sugar beet and sugar. No significant differences in the determination limit and precision of the two methods were found. Monitoring of herbicide residue levels in commercial sugar revealed low levels of atrazine (0.003 mg.kg-1 on average) in all the samples. This contamination level does not present a health hazard consumers.

Determination of herbicide residues in agricultural crops, foods, soil and water by chronometric method.

The method described is based on the biochemical detection of herbicides on a silica gel thin layer following their chromatographic separation. The detection reagent is a mixture of a homogenate of bean leaves (Phaseolus vulgaris) and of the redox indicator 2,6-dichloroindophenol. This chronometric determination of herbicide residues is based on the observation that dark blue inhibition zones appear on a pale yellow-green background during the exposure of the sprayed chromatoplates Silufol to light. The dark blue zones disappear again after a time, their lifetime is proportional to the amount of the herbicide in the zone. Because of the high selectivity and sensitivity of the biochemical detection this method does not require a multiple clean-up procedure, nor does it require sophisticated instrumentation. It equals gas chromatography in sensitivity and precision. The determination limit lies between 0.01 and 0.001 mg X kg-1, the average recovery rate is 85 to 90%.