The forms of cobalt in some Scottish soils as determined by extraction and isotopic exchange

The results of fractionation and correlation studies provided evidence that cobalt in soils is associated predominantly with the soil oxide fraction, particularly the manganese oxides. Only a small proportion of the total cobalt present in soils was extracted by acetic acid, EDTA, pyrophosphate or hydroxylamine. Cobalt extracted with these reagents was considered to be derived principally from easily reducible manganese oxides, although the origin of the cobalt extracted by acetic acid in particular was not well defined. The bulk of the cobalt present in soils appeared to be occluded by more highly crystalline oxide materials or was present in the structures of primary and secondary minerals. Labile cobalt in soil was assessed by extraction with acetic acid and EDTA and by determination of isotopically exchangeable cobalt. The amounts of cobalt extracted by both EDTA and acetic acid were highly dependent on the length of extraction period and on the temperature of extraction. Neither of these reagents appeared likely to give good estimates of the quantity or intensity factors of soil cobalt supply to plants as defined by the isotopic exchange determinations.     

Analysis of both cobalt and selenium in feed‐stuffs and in biological tissue by chelation‐extraction and graphite furnace atomic absorption spectroscopy

Abstract

A procedure for measuring cobalt in feedstuffs and biological tissues using ammonium pyrrolidine dithiocarbamate (APDC) and methyl isobutyl ketone (MIBK) chelation‐extraction and graphite furnace atomic absorption spectroscopy is described. This procedure, except for the graphite furnace and spectrophotometer programs, is identical to another method for analysis of selenium in the same types of sample materials. Therefore, only one chelation‐extraction is now required to measure both cobalt and selenium in the same sample. No evidence was seen of interference from other metals in the sample materials used in this study.     

Continuous sorbent preconcentration for the electrothermal atomic absorption spectrometric determination of ultratrace amounts of cobalt in milled wheat fractions

A method for the rapid determination of cobalt at ultratrace levels was applied in flour and flour byproducts (shorts and bran) obtained from various types of wheat that includes on-line preconcentration and electrothermal atomic absorption spectrometry is proposed. Solutions in 0.1 mol/L HNO(3) of milled wheat fractions subjected to wet ashing are preconcentrated in a straightforward flow-injection system by sorption on a RP-C(18) column following chelation. The eluent, ethanol, is carried by an air stream, and the chelate is eluted and collected in a 500 microL PTFE autosampler cup. The determination of cobalt features a precision (RSD) of 6% for a concentration of 0.2 ng/mL and a sensitivity (slope of the calibration graph) of 0.38 +/- 0.03 A s x ng/mL. The cobalt content in each type of wheat was found to be influenced by its geographical origin and texture. Also, it was found to depend on the amount of bran present in the milled wheat fraction. On the other hand, it is not significantly affected by the technological processes involved in wheat milling at a flour-producing factory.     

Determination of Major and Trace Elements in Plant Samples by Inductively Coupled Plasma–Mass Spectrometry

The determination of several trace elements [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), and lead (Pb)] in plant samples using inductively coupled plasma–mass spectrometry (ICP‐MS) was evaluated. It was established experimentally that moderate amounts (0.2–2%) of dissolved solids decreased the analyte signals significantly. Internal standardization with Rh was efficiently used to compensate for these matrix effects. The accuracy of the method was verified using reference materials digested according to two different procedures: dry ashing and microwave digestion. No significant differences were observed between measured concentrations and certified values. The investigation was next extended for the determination of major elements [aluminum (Al), boron (B), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), and zinc (Zn)] on the same reference materials. The ICP‐MS values agree well with the values supplied. However, it appeared that Sc was the most useful internal standard for major elements.     

Determination of copper, cobalt, nickel, and manganese in baby food slurries using electrothermal atomic absorption spectrometry

The analytical conditions for the electrothermal atomic absorption spectrometric determination of copper, manganese, nickel, and cobalt in different types of baby foods using slurried samples are presented. Suspensions were prepared in a medium containing 0.1% w/v Triton X-100, 30% v/v concentrated hydrogen peroxide, 1% v/v concentrated nitric acid, 1% w/v ammonium dihydrogenphosphate (only for copper atomization), and one drop of silicon antifoam.The slurries were homogenized by using a potter and were introduced directly into the furnace. The amount of analyte extracted to the liquid phase was investigated. The graphite furnace conditions were optimized for each element. No matrix effect was observed, and calibration could be carried out using aqueous standard solutions. The detection limits were 3.4, 2.1, 5.4, and 3.7 pg for copper, manganese, nickel, and cobalt, respectively. The reliability of the procedures was checked by statistically comparing the results obtained with those found by using a previous microwave-oven mineralization stage and by analyzing several certified reference materials.     

DETERMINATION OF ORGANIC CARBON IN SOIL

The organic carbon contents of a range of soils and of various organic materials (mostly of plant origin) were determined by the titrimetric methods of Tinsley and Walkley and Black, and the results compared with those obtained by Shaw's wet combustion method. Tinsley's method gave more reliable results with soils than Walkley and Black's method, but neither is satisfactory for precise work. Both give high results with organic materials less oxidized than elemental carbon and low results with organic materials more oxidized, although this effect is masked with materials which do not react completely under Walkley and Black conditions. Quantitative results were obtained on a range of whole plant materials with both Tinsley's and Walkley and Black's methods. The latter thus provides a very rapid method for the determination of carbon in plants. The carbon contents, determined by Tinsley's method, of a range of pure organic compounds agreed with the predicted values. Tinsley's method does not give quantitative results with certain soils, partly because of the oxidation level of the organic matter in these soils and partly because oxidation is incomplete.     

Determination of folacin in foods and other biological materials

The objective of most methods for determination of folates in foods and other biological materials is to estimate the total folacin content of the sample. Because folacin comprises a diverse group of related compounds exhibiting similar biological activity, the analytical method must be capable of measuring all of the folates. Methods have been developed for separation of folates in their monoglutamyl form by using anion-exchange, paired-ion reverse phase, or conventional reverse phase liquid chromatography (LC). The application of these separations to determination of folates in foods and other biological materials has been limited largely by the need for development of adequate preparative methods and sufficiently sensitive and specific detection procedures. Although LC with ultraviolet absorption detection has been successful in certain limited applications, the development of fluorometric detection methods has permitted LC determination of folates in a wide range of materials. Tetrahydrofolic acid and its substituted derivatives are detected by monitoring their native fluorescence in an acid mobile phase, while folic acid and certain other folates are measured by using an oxidative post-column fluorogenic derivatization system. Methods also have been developed for determination of the polyglutamyl chain length distribution of folates in biological materials. In total, these procedures permit a direct determination and characterization of folacin compounds.     

Improved cleanup for gas chromatographic determination of propiconazole residues in soil, wheat grain, straw, and leaves

A simple and sensitive method is described for determination of propiconazole, a new type of broad-spectrum systemic fungicide, in soil, wheat grain, straw, and leaves. Pesticide residues in or on grain and green plant materials are extracted with methanol (or a mixture of methanol and water (4 + 1), for soil), partitioned into methylene chloride, and cleaned up on an alumina column for grain and soil or an activated charcoal column for green plant materials. The amount of residue is quantitatively measured by gas chromatography using an alkali flame ionization detector in the nitrogen-sensitive mode. Recoveries from soil, grain, and green plant materials fortified at 0.1-5 mg/kg are better than 80%. The practical detection limits of this method are 0.01 mg/kg in grain and soil and 0.02 mg/kg in green plant materials.     

ICP-AES法测定土壤及肥料中的硼含量

采用岛津 ICP- 10 0 0 型真空单道扫描发射光谱仪测定了土壤及肥料中的硼含量 ,方法经标准土壤样品验证 ,并与肥料测定的国家标准方法相比较 ,结果均十分符合。同时给出方法的精密度、检出限等参数 ,说明该方法准确度、灵敏度高 ,操作简便快速     

Quantitative analysis of cystine, methionine, lysine, and nine other amino acids by a single oxidation--4 hour hydrolysis method

The sulfur-containing amino acids cystine and methionine play important roles in animal, especially avian, nutrition. Because these sulfur-containing amino acids are destroyed to varying extents by 6N HCl hydrolysis, oxidation and hydrolysis of cystine to cysteic acid and methionine to methionine sulfone have been widely used for determination of cystine and methionine. Lysine is considered the next limiting amino acid after the sulfur amino acids in poultry nutrition; therefore, determination of the amino acid content of rations focuses first on these 3 amino acids. The objective of this investigation was to establish whether lysine and other amino acids could be accurately determined in proteinaceous materials which had undergone performic acid oxidation. To perform this evaluation, lysine was determined in a variety of protein-containing materials both with and without performic acid oxidation. Performic acid oxidation followed by 6N HCl hydrolysis at 145 degrees C for 4 h allows accurate measurement of 3 amino acids especially important to poultry nutrition, cystine, methionine, and lysine, in a single preoxidized hydrolysate; this method can be extended to another 9 protein amino acids.     

High-throughput analysis of total nitrogen content that replaces the classic Kjeldahl method

A high-throughput method for determination of total nitrogen content has been developed. The method involves decomposition of samples, followed by trapping and quantitative colorimetric determination of the resulting ammonia. The present method is rapid, facile, and economical. Thus, it can replace the classic Kjeldahl method through its higher efficiency for determining multiple samples. Compared to the classic method, the present method is economical and environmentally friendly. Based on the present method, a novel reactor was constructed to realize routine high-throughput analyses of multiple samples such as those found for pharmaceutical materials, foods, and/or excrements.     

The determination of boron in soil extracts,plant materials,composts, manures,water and nutrient solutions

Abstract

A rapid colorimetric method for the determination of boron in soil extracts, plant materials, composts, manures, water and nutrient solution is proposed. The method is rapid, reliable and carried out in aqueous solution. A marked advantage is that boron can be determined in the same soil extract or plant material digest used for determination of other elements.     

Rapid, economical method for determination of aflatoxin and ochratoxin in animal feedstuffs

A quantitative procedure widely used in European Economic Community (EEC) countries has been successfully scaled down to produce a rapid method for determination of aflatoxin B1 (and other aflatoxins) in animal feeds. Without modification, the method may be used for simultaneous ochratoxin A determination in simple feeds, but a slightly different extraction procedure is required for compound feeds. Validity of the method has been demonstrated by comparison with the full EEC procedure for aflatoxin B1 and the Nesheim method for ochratoxin A. Analyses may be completed within 2 h and there is a considerable savings in materials over the 2 reference methods. The procedure is also less hazardous because volumes of toxic extract are small, and the operator is exposed to minimum solvent vapor.     

钴对冬小麦生理生化性状和产量影响的初步研究

在潮土上采用大田小区进行了钴元素肥效试验。试验结果如下:施用适量的钴可以显著提高旗叶的叶绿素含量、硝酸还原酶活性以及小麦的根系活力;各施钴处理较对照增产7 4%～20 3%,施钴量在0 75kg/hm2以内,随着施钴量的增加,增产效应提高,当施钴量超过0 75kg/hm2时,随着施钴量的增加,冬小麦的产量增加,但增产效应下降。经回归分析,小麦产量与施钴量呈抛物线型,回归方程为y=-1263 9x2 2083 4x 4371 7,相关系数r=0 8910,达到5%显著水平。     

Determination of diclofenac sodium and related compounds in raw materials and formulations

A liquid chromatographic method has been developed for determination of drug and related compounds in diclofenac sodium raw material, slow-release, and enteric coated tablets. The method specifies a 5 microns octadecylsilane bonded phase column, a mobile phase of tetrahydrofuran-acetonitrile-buffer, pH 5 (1 + 4 + 8.3), and detection at 229 nm. The method resolves 10 known related compounds with limits of quantitation of 0.2% or less. Seventeen drug raw material samples were evaluated. Total impurity levels ranged from 0.1 to 0.9%. The method has also been used for determination of drug content in raw materials and formulations. Mean assay levels in drug raw materials ranged between 98.3% and 101.8%.     

Determination of cobalamin in nutritive supplements and chlorella foods by capillary electrophoresis-inductively coupled plasma mass spectrometry

A capillary electrophoresis-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for the determination of cobalamin is described. Samples of cobalt-containing compounds were subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100) of ICP-MS. The Co-containing compounds studied include cyanocobalamin (CN-Cbl, vitamin B12), hydroxocobalamin (OH-Cbl), and Co(II). The species studied were well separated using a 70 cm lengthx75 microm i.d. fused silica capillary with the applied voltage set at +20 kV. A 25 mM Tris buffer (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS) was used as the electrophoretic buffer. The CE-ICP-MS detection limits were 0.3, 0.2, and 1.7 ng of Co mL(-1) for CN-Cbl, OH-Cbl, and Co(II), respectively. The concentrations of cobalamin compounds were determined in selected nutritive supplements and chlorella samples. A microwave-assisted extraction method was used for the extraction of these compounds. Over 92% of the total cobalt species was extracted using a 5% v/v HNO3 solution in a focused microwave field within a period of 10 min; spike recovery was in the range of 94-105% for various species. The major cobalt species in nutritive supplements and chlorella samples was cyanocobalamin.     

Total content and extractable fraction of cadmium,cobalt, copper,nickel, lead,and zinc in calcareous orchard soils

Abstract

The levels and availability of six heavy metals cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in calcareous orchard soils were measured in an investigation of a method for the determination of total content and extractable fraction of these metals by atomic absorption spectrometry. The digestion step was performed comparatively using two different types of heating. Cadmium, Cu, Ni, Pb, and Zn were determined by flame atomic absorption spectrometry (F‐AAS) and Cd was determined by electrothermal or graphite furnace atomic absorption spectrometry (GF‐AAS) using the method of standard addition. The detection limits, precision values, and accuracy (recovery assays) show the reliability of the method. The conditions for the determination of the extractable fraction of the metals were also optimized. Extraction time for Cd and Zn was studied, and the application of two hours of shaking was selected. The tested method was applied to real samples corresponding to highly calcareous orchard soils characteristic of the Mediterranean area. Only Zn, Cu and Pb showed high levels in their extractable forms, whereas Cd and Co had highest levels in their total contents. An important bio‐availability was observed in all the studied metals, but mainly for Cd and Pb.     

Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography

The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.     

施钴对冬小麦产量和蛋白质含量及土壤有效钴含量的影响

采用盆栽试验的方法,研究了石灰性褐土上不同钴施用量对冬小麦产量、蛋白质含量及土壤有效钴含量的影响。试验结果表明:施用适量的钴可以显著提高冬小麦的产量和蛋白质的含量。各施钴处理较对照增产0.98-13.73%, 生物产量增加2.01-18.47%,其中以处理Co3增产最高。在施钴量4mg kg-1以内,随着施钴量的增加,增产效应提高,但当施钴量超过4mg kg-1时,冬小麦的籽粒产量和生物产量增加,但增产效应下降。处理Co1、处理Co2的蛋白质含量分别比对照增加2.14和1.1个百分点,但处理Co3、处理Co4的蛋白质含量分别比对照减少0.07和0.21个百分点。各处理的蛋白质产量比对照增加0.06%-20.02%,其中以处理Co1增加最大,处理Co2次之。土壤有效钴含量与施钴量呈极显著正相关,小麦籽粒中钴含量与施钴量呈显著正相关。     

Determination op fluoride in plant samples by a potentiometric method and near‐infrared reflectance spectroscopy

Abstract

The determination of fluoride in plant materials was studied using a specific ion electrode following extraction using either deionized water or 0.1 M perchloric acid.

When the extracting agent was water, the amount of fluoride determined was generally 37% less than that obtained using perchloric acid. However, a close relationship was observed between the amounts extracted by either procedure. When perchloric acid is used, the method was found to be precise (variation coefficient 0.74%), accurate (average recovery 98.67%) and sensitive enough to be used in the routine analysis of plant materials.

The determination of fluoride by near‐infrared reflectance analysis (NIRA) was also used which gave generally acceptable results.