Samples Of Plant Material Research Articles

Determination of lead and cadmium by atomic absorption spectrometry coupled with slurry sampling of carbonized samples: Use of palladium-bearing activated carbon as a matrix modifier

The determination of Pb and Cd by electrothermal atomic absorption spectroscopy with the slurry sampling of carbonized samples into a graphite furnace was considered. Textural and chemical properties of new palladium-carbon modifiers based on activated carbon and carbonized nutshell were studied by high-resolution electron microscopy, x-ray photoelectron spectroscopy, and the adsorption of liquid nitrogen. Advantages of activated carbon as a modifier support were substantiated. Pyrolysis and atomization temperatures were selected for determining elements using matrix modifiers. The developed analytical procedure was tested with reference samples of plant materials. The results obtained agreed well with the certified analyte concentrations. The RSD values were no higher than 8% for lead and cadmium in the ranges 0.3–3.3 and 0.110–1.34 mg/kg, respectively.

Rapid analysis of controlled substances using desorption electrospray ionization mass spectrometry

The recently developed technique of desorption electrospray ionization (DESI) has been applied to the rapid analysis of controlled substances. Experiments have been performed using a commercial ThermoFinnigan LCQ Advantage MAX ion-trap mass spectrometer with limited modifications. Results from the ambient sampling of licit and illicit tablets demonstrate the ability of the DESI technique to detect the main active ingredient(s) or controlled substance(s), even in the presence of other higher-concentration components. Full-scan mass spectrometry data provide preliminary identification by molecular weight determination, while rapid analysis using the tandem mass spectrometry (MS/MS) mode provides fragmentation data which, when compared to the laboratory-generated ESI-MS/MS spectral library, provide structural information and final identification of the active ingredient(s). The consecutive analysis of tablets containing different active components indicates there is no cross-contamination or interference from tablet to tablet, demonstrating the reliability of the DESI technique for rapid sampling (one tablet/min or better). Active ingredients have been detected for tablets in which the active component represents less than 1% of the total tablet weight, demonstrating the sensitivity of the technique. The real-time sampling of cannabis plant material is also presented.

Tomato yellow leaf curl and Tomato mottle begomoviruses

<i>Tomato yellow leaf curl</i> and <i>Tomato mottle begomoviruses</i>

Long-term effects of short-fallow on soil phosphorus pools in Costa Rica

Many Costa Rican farmers have shortened the fallow period associated with frijol tapado, a slash/mulch bean ( Phaseolus vulgaris L.) system, from 3 or more years to only 9 months. This study determined the long-term effects of continual short-fallow (9 months) frijol tapado on soil phosphorus (P) fractions and assessed the importance of these fractions for crop nutrition. It also examined the effect fallow length had on biomass production and mulch P, when fallow included established, dispersed trees. The study was conducted on three bean sites that had been cropped using short-fallow frijol tapado for more than four decades and on a virgin forest site. Prior to seeding in 1999, one bean site was fallowed for 9 months, another for 21, and the third for 33. There were established, dispersed trees within each. Samples of surface soil (four divisions to 30 cm), mulch cover, and living vegetation were collected before slashing, after seeding, and at harvest. Plant material and soil samples were analyzed for total P; soils were subjected to sequential P extractions. Results demonstrated that, compared to the virgin forest soil, soils which had been cropped with short-fallow frijol tapado for decades were depleted in top- and subsoil stable organic P (Po) and labile inorganic P. The bean soils had not accumulated P in other fractions, indicating that substantial fractional redistribution had not occurred. Of the soil P fractions, NaOH Po made the most important contribution to plant nutrition during the cropping season in the 1- and 2-year fallow bean sites. The 1- and 2-year fallows supplied similar quantities of mulch and mulch P. The dispersed trees probably played a role in this, and lower P concentrations in the older fallows’ mulches also helped equalize total mulch P values. Additionally, mulch variability, before and after slashing, in the 2- and 3-year fallow sites obscured what differences there may have been. The exceptionally steep slope of the 3-year fallow site (92%) overwhelmed other effects and prohibited meaningful comparisons with other sites.

Polychlorobiphenyl Content in Infusions and Decoctions Prepared from Raw Medicinal Plant Materials of the Altai Region

The content of polychlorobiphenyls (PCBs) in 129 samples of raw medicinal plant materials collected in the Rubtsovsk Region of the Altai Territory was determined by methods of capillary chromatography and gas chromatography/mass spectrometry (GC/MS) using an HP 5890A gas chromatograph equipped with an HP 5972A mass-spectrometric detector and an autosampler. The content of PCBs in all samples exceeds the content of other chlorine-containing organic pesticides. In the infusions and decoctions prepared from the raw materials studied, the PCB concentration falls within 0.1 – 9.8 ng/g, which does not exceed 57.86% of the toxicant content in the initial raw materials. The maximum degree of PCB transfer from the raw materials to extracts was observed for samples with an initial toxicant content within 10.0 ng/g. The maximum PCB concentrations were found in decoctions prepared from the underground parts of the plants studied, while the maximum degrees of transfer were observed in decoctions prepared from fruits.

Preparation of Reagents for the Sensitive Spectrophotometric Determination of Carbaryl in Environmental Samples

A simple and sensitive spectrophotometric method was described for the determination of carbaryl in its formulations, fortified water, food grains, polluted water, plant material (cabbage), soil, and biological samples (blood and urine) with the prepared coupling reagents. The method was based on alkaline hydrolysis of the carbaryl pesticide, and the resultant hydrolysis product of 1‐naphthol was coupled with 2,6‐dibromo‐4‐methylaniline to give a purple product with λmax of 505 nm or coupling with 2,4,6‐tribromoaniline to produce a violet colored product with λmax 535 nm or coupling with 2,6‐dibromo‐4‐nitroaniline to form pale‐red colored product has a λmax of 492 nm. The formation of colored derivatives with the coupling agents are instantaneous and stable for 48 h, 40 h, and 36 h, respectively. The results indicate the proposed method's sensitivity, selectivity, and the recovery of the carbaryl from the fortified water, food grains, polluted water, plant material (cabbage), soil, and biological samples (blood and urine) are higher than the other methods. The authors thank Bayer (India) Ltd., Bombay, for the supply of technical grade carbaryl and the Head of the Dept. of Biotechnology, S. V. University, Tirupati for providing instrumental facility to carry out this work.

Intra- and Inter-plant Variation in Nitrogen Concentration and 15N Abundance in Cereals Fertilized with 15N

Nitrogen (N) enriched with the 15N isotope is often used in studies of the crop utilization of applied fertilizer N, and furthermore 15N-labeled plant material is frequently used in N cycling studies concerning decomposition of added organic matter. The variation in N and 15N concentrations among plant parts may be important to consider in such experiments. The intra-plant variation was examined in a pot and two field experiments with spring wheat and barley after application of 15N-labeled fertilizer. Main shoots were sampled at anthesis; the ears were dissected into anthers, ovaries, inner and outer glumes, and the straw was divided into leaves and 5-cm stem intervals. Inter-plant variation was examined in ear and straw of single wheat plants sampled at maturity from the one field experiment. Dry matter weight of the different plant parts was determined and all samples were analyzed for total N concentration and 15N abundance. The variation in N concentration among plant parts was significant. Neither was the 15N-labeling uniform, but there was less intra-plant variation in 15N abundance than in N concentration. In contrast, the inter-plant variation in 15N abundance of mature wheat plants sampled from the same plant row was significant (coefficient of variation, CV 33–39%) compared to the N concentration (CV 10–17%). It is important to take these findings on intra- and inter-plant variation into consideration in the sampling, handling and use of 15N-labeled plant material. The samples should be handled quantitatively throughout, across plants and plant parts, to obtain representative subsamples.

Simultaneous determination of chlorophyll a and chlorophyll b by derivative spectrophotometry.

Chlorophyll a (Chl a) and chlorophyll b (Chl b) plant pigments, which are important in the food industry and are beneficial as environmental pollution indicators, have been extracted with a novel solvent mixture (1:1 v/v acetone-propanol) not containing chloroform and simultaneously determined by first-derivative spectrophotometry. The results were statistically compared to those obtained by the ordinary absorption spectrophotometric reference utilizing the principle of additivity of absorbances. The testing of the developed method in synthetic mixtures of Chl a and Chl b and in real plant material samples (grass, spinach, chard, purslane, black cabbage, crisp lettuce, rocket, dill and seaweed) proved successful in that the developed extractive derivative spectrophotometric method was both rapid and precise, and was not dependent on the Chl a/b ratio in contrast to the reference method which was adversely affected by the latter parameter.

Genomic DNA methylation of juvenile and mature Acacia mangium micropropagated in vitro with reference to leaf morphology as a phase change marker.

Genomic DNA methylation was analyzed in Acacia mangium Willd. microshoots micropropagated in vitro from juvenile and mature explants, and in relation to leaf morphology of the microshoots, which is considered a phase change indicator. Based on high performance liquid chromatography (HPLC) analyses, we found more DNA methylation in microshoots exhibiting juvenile leaf morphology (22.4%) than in microshoots of the mature phyllode morphological type (20.7%), irrespective of the age of the source material. Overall, the degree of DNA methylation in A. mangium microshoots was consistent with values reported for other angiosperms. Complementary investigations based on methylation sensitive amplification polymorphism (MSAP) techniques established that, of 1204 fragments revealed by the different primer pairs used, 49 (i.e., 4.08%) were derived from C(5m)CGG methylated sites. Three of these C(5m)CGG sites were exclusive to the juvenile plant material, and three sites were exclusive to the mature source. No fragments were associated specifically with leaf morphology, rather than with plant age. Thus, although the two age classes could not be distinguished based on a quantitative HPLC measure of DNA methylation, qualitative differences existed, as demonstrated by the six age-specific markers identified by MSAP. The reliability of the MSAP data was confirmed on a larger sample of juvenile plant material, which suggested that the total of six methylation markers detected is probably an underestimation of the age-related differences in DNA methylation that may exist between juvenile and mature plant materials.

Variation within and between two saltbush species in plant composition and subsequent selection by sheep

This work examines nutritive value and preference by sheep of 2 saltbush species, river saltbush (Atriplex amnicola) and old man saltbush (Atriplex nummularia). Both species are woody perennials that are native to Australia and used in commercial grazing systems. The hypothesis for this study was that sheep will graze saltbushes with higher nutritive value and lower secondary compounds in preference to bushes with lower nutritive value and higher secondary compounds. This was expected to be found both within and between the old man and river saltbush species. To test the hypothesis, 10-month-old Merino ewes grazed a 10-ha plot containing a mixture of old man and river saltbush in approximately equal proportions. Within the plot, and prior to grazing, 20 bushes of each species were pegged for identification and samples of edible plant material collected for analysis. Each week during the grazing period the bushes were photographed for assessment of preference. Sheep preferred river saltbush to old man saltbush and also showed some preferences for specific bushes within each species. Differences in digestibility of dry matter and organic matter, crude protein, ash, oxalates, and nitrates were not clearly associated with differences in preference. Although the reasons for preferences were not demonstrated, the analysis of the plant material did indicate that the content of total ash and oxalates was at levels likely to depress voluntary feed intake.

Trace element distribution in geochemical environment of the island Krk and its influence on the local population

Samples of soil, plant material and water collected on the Croatian island Krk in northern Adriatic sea were analyzed for a number of elements (Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Pb) by using energy dispersive X-ray fluorescence (EDXRF) as an analytical tool. Some of these data have been previously used to produce geochemical map of the island.1 In addition, trace element contents of hair from children, attending elementary and secondary schools, has been investigated using the same analytical method for Mg, S, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Hg and Pb elements. Concentrations of the twelve elements and nine variables from the questionnaire, i.e., age, sex, living place, transportation, medication, hair colour, hair type, type of shampoo used and hair treatment, were considered in the statistical analysis. The observed differences for the seven island's communes have also been discussed.

Species-specific PCR primers for Pythium developed from ribosomal ITS1 region.

To develop a specific method for distinguishing and detecting Pythium species. Twenty PCR primers were designed from the sequences of the rDNA internal transcribed spacer 1 (ITS1) region from 34 Pythium species. The specificity of these forward primers paired with ITS2 or ITS4 and reverse universal primers was tested. Five species-specific primers were obtained, other primers showed different specificity to Pythium species. The specific amplifications enabled nine Pythium species to be differentiated. Specific detection of Pythium aphanidermatum from infested plants and P. dimorphum from soil was demonstrated. A method for identifying nine Pythium species using specific PCR amplification was achieved. Because of its rapidness and ease, the results of PCR amplified with different primers can be a powerful method for identifying Pythium species and detecting or monitoring the target fungus directly from plant material, soil and water samples.

Preparation of samples of plant material for chromatographic analysis.

The selection, collection, and preliminary treatment of plant material samples are discussed. Stages of sample preparation and extraction techniques presently used are described, and the most recent examples of sample preparation for chromatographic analysis are reviewed. Recent applications of gas chromatography for the assessment of emission of volatile organic compounds by plants are also described.

A highly sensitive spectrophotometric determination of platinum(IV) using leuco xylene cyanol FF.

A new, simple, highly sensitive and rapid spectrophotometric method has been described for the determination of platinum(IV). The method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by platinum(IV) in sulfuric acid medium (pH 1.0-2.5), the formed dye shows an absorption maximum at 620 nm in acetate buffer medium (pH 3.0-4.5). The method obeys Beer's law over a concentration range of 0.3 to 2.6 micro g mL(-1) platinum, having molar absorptivity and Sandell's sensitivity of 5.1x10(4) L mol(-)(1) cm(-1) and 0.0038 micro g cm(-2), respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of platinum in pharmaceutical preparations, soil, natural water, plant material, platinum-containing catalyst, and synthetic alloy samples.

Spectrophotometric determination of selenium by use of thionin.

A simple, rapid, and sensitive spectrophotometric method has been developed for the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic cosmetic and in pharmaceutical preparations. The method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine. The liberated iodine bleaches the violet color of thionin, and which is measured at 600 nm. This decrease in absorbance is directly proportional to selenium concentration and obeys Beer's law in the range 1-5 micro g selenium in a final volume of 10 mL (0.1-0.5 microg mL(-1)). The molar absorptivity and Sandell's sensitivity of the method were found to be 7.33 x 10(4) L mol(-1) cm(-1) and 0.0011 microg cm(-2), respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination is described.

Measurement of Resistant Starch by Enzymatic Digestion in Starch and Selected Plant Materials: Collaborative Study

Interlaboratory performance statistics was determined for a method developed to measure the resistant starch (RS) content of selected plant food products and a range of commercial starch samples. Food materials examined contained RS (cooked kidney beans, green banana, and corn flakes) and commercial starches, most of which naturally contain, or were processed to yield, elevated RS levels. The method evaluated was optimized to yield RS values in agreement with those reported for in vivo studies. Thirty-seven laboratories tested 8 pairs of blind duplicate starch or plant material samples with RS values between 0.6 (regular maize starch) and 64% (fresh weight basis). For matrixes excluding regular maize starch, repeatability relative standard deviation (RSDr) values ranged from 1.97 to 4.2%, and reproducibility relative standard deviation (RSDR) values ranged from 4.58 to 10.9%. The range of applicability of the test is 2-64% RS. The method is not suitable for products with <1% RS (e.g., regular maize starch; 0.6% RS). For such products, RSDr and RSDR values are unacceptably high.

137Cs and 40K soil-to-plant relationship in a seminatural grassland of the Giulia Alps, Italy

To examine the soil-to-plant transfer of 137Cs and 40K, we performed a study based on sampling of natural soil and plants from an alpine pasture site situated in the Giulia Alps, Italy, during July 1997. High 137Cs activity was present in the upper most soil layer, and decreased one order of magnitude at a depth of 10 cm. An opposite gradient was observed for 40K. Simultaneous sampling of soil and plant material was performed in order to analyse transfer factor (TF) values. In spite of homogeneous 137Cs activities in soil, grass samples showed a high variability. A negative correlation was detected between 40K- and 137Cs-activities in plants. TF values for 137Cs were highly variable, thus suggesting that this parameter would be independent of 137Cs soil activity. Lower variability was observed for 40K TFs values. Our results suggest that TFs are highly variable parameters that appear to be independent on radionuclide soil activity. Because soil and plant characteristics strongly affect TF values, caution is necessary when TF values are used as the sole parameter to predict radionuclide uptake by plants in semi-natural ecosystems.

Quantitative determination of dithiocarbamates in human plasma, serum, erythrocytes and urine: pharmacokinetics of broccoli sprout isothiocyanates in humans

Background: Humans are exposed to substantial quantities of isothiocyanates and glucosinolates from vegetables. Since dietary isothiocyanates are widely regarded as potentially important chemoprotectors against cancer, reliable methods for measuring the plasma and tissue pharmacokinetics of isothiocyanates and their dithiocarbamate metabolites are essential for defining dosing regimens. Methods: Isothiocyanates (ITC) and dithiocarbamates (DTC) react quantitatively with 1,2-benzenedithiol to produce 1,3-benzodithiole-2-thione that can be quantified spectroscopically. Although this cyclocondensation reaction has been highly useful for analyzing plant material and urine samples, the determination of DTC/ITC (the total quantity of DTC and ITC components in a sample that react in the cyclocondensation reaction) in blood and tissues has been hampered by their low levels and the high concentrations of proteins that interfere with the cyclocondensation reaction. The protein content of blood and tissues was reduced by the precipitation with polyethylene glycol (PEG) or ultrafiltration, and the sensitivity of the method was increased substantially by the solid phase extraction of the cyclocondensation product. Results: Pharmacokinetic measurements were made in four human volunteers who received single doses of about 200 μmol of broccoli sprout isothiocyanates (largely sulforaphane, with lesser amounts of iberin and erucin). Isothiocyanates were absorbed rapidly, reached peak concentrations of 0.943–2.27 μmol/l in plasma, serum and erythrocytes at 1 h after feeding and declined with first-order kinetics (half-life of 1.77±0.13 h). The cumulative excretion at 8 h was 58.3±2.8% of the dose. Clearance was 369±53 ml/min, indicating active renal tubular secretion. Conclusion: A sensitive and specific method for quantifying DTC levels in human plasma, serum, and erythrocytes has been devised. Determinations of ITC/DTC levels are important because: (i) dietary isothiocyanates are of potential value in reducing the risk of cancer, and (ii) humans are extensively exposed to DTC as fungicides, insecticides, pesticides and rubber vulcanization accelerators.

Determination of Steroidal Saponins in Tribulus terrestris by Reversed-Phase High-Performance Liquid Chromatography and Evaporative Light Scattering Detection

This paper describes the first analytical method suitable for the determination of steroidal saponins in Tribulus terrestris. A separation by high performance liquid chromatography (HPLC) was achieved by using a reversed-phase (RP-18) column, evaporative light scattering (ELS) detection, and a water/acetonitrile gradient as the mobile phase. The marker compound, protodioscin, was detected at a concentration as low as 10.0 microg/mL. Several different samples of plant material were successfully analyzed, and depending on origin and plant part used for extraction, significant differences in the composition of the saponins were observed. The analysis of market products showed considerable variations of 0.17 to 6.49% in the protodioscin content.

A facile spectrophotometric method for the determination of selenium.

A rapid and sensitive spectrophotometric method is described for the determination of trace amounts of selenium using Variamine Blue (VB) as a chromogenic reagent. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine, which oxidizes Variamine Blue to form a violet-colored species having an absorption maximum at 546 nm. Beer's law is obeyed in the range 2-20 g of selenium in a final volume of 10 ml. The molar absorptivity and Sandell's sensitivity were found to be 2.6 x 10(4) l mol-1 cm-1 and 0.003 microgram cm-2, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic samples of cosmetics and pharmaceutical preparations.