scholarly journals Investigation of Hopanoid Biomarkers in Lake Sediments by GC-MS and RP-HPLC-APCI-MS

2009 ◽  
Vol 6 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Gamze Kavran Belin
Keyword(s):  
Lake Sediments ◽  
Silica Gel ◽  
Sodium Borohydride ◽  
Periodic Acid ◽  
Swiss Alps ◽  
Anoxic Sediment ◽  
Sediment Samples ◽  
Geological Materials ◽  
Rp Hplc ◽  
Bacterial Lipid

Hopanoids are mainly derived from bacteriohopanpolyols that occur especially in bacteria, show the importance of bacterial lipid contributions in geological materials. In this work, GC-MS and RP-HPLC-APCI-MS analyses of hopanoid biomarkers in oxic and anoxic sediment samples from Lake Cadagno (Swiss Alps) and Lake Voua de la Motte (Haute Savoie, France) are presented and discussed. Samples were ultrasonically extracted, fractionated by flush chromatography on silica gel and derivatised before the analyses. Periodic acid/ sodium borohydride cleavage was used to identify highly functionalised hopanoids

Simultaneous Gas Chromatographic Determination of Dibutyltin and IHbutyltin Compounds in Biological and Sediment Samples

1986 ◽  
Vol 69 (6) ◽  
pp. 981-984
Author(s):  
Taizo Tsuda ◽  
Hiroshi Nakanishi ◽  
Takashi Morita ◽  
Junko Takebayashi
Keyword(s):  
Gas Chromatography ◽  
Ethyl Acetate ◽  
Simultaneous Determination ◽  
Electron Capture ◽  
Silica Gel ◽  
Sodium Borohydride ◽  
Biological Samples ◽  
Chromatographic Determination ◽  
Sediment Samples

Abstract A method is described for the simultaneous determination of nanogram amounts of dibutyltin and tributyltin compounds in biological and sediment samples. These compounds are converted to the corresponding chlorides with HC1, extracted with ethyl acetate-hexane (3 + 2) for biological samples and with hexane for sediment samples, and hydrogenated with sodium borohydride. The corresponding hydrides, Bu2SnH2 and Bu3SnH, are detected by electron-capture gas chromatography after cleanup by silica gel column chromatography. Detection limits are 1.0-2.0 and 0.5-1.0 ng/g, respectively, for biological and sediment samples.

Emergence of seedlings of aquatic macrophytes from lake sediments

1983 ◽  
Vol 61 (1) ◽  
pp. 148-156 ◽  
Author(s):  
Richard W. Haag
Keyword(s):  
Lake Sediments ◽  
Initial Treatment ◽  
Aquatic Macrophytes ◽  
Potamogeton Pectinatus ◽  
Sediment Texture ◽  
Substantial Variation ◽  
Initial Exposure ◽  
Sediment Samples ◽  
Thermal Effluent ◽  
Myriophyllum Exalbescens

Sediment samples were collected in May 1980 from 11 stations at five sites in Lake Wabamun. Emergence of seedlings was recorded in a greenhouse at 19 °C for 120 days. The sediments were then chilled at 4 °C for 120 days and reexposed to greenhouse conditions for a further 90 days. Total seedling densities varied from 0 to 2335 m−2. Depth and sediment texture each accounted for 20% of the variance in seedling numbers. Discharge of thermal effluent from the Wabamun generating station also caused substantial variation in seedling number; seedling numbers at the shallowest Wabamun Outlet station were over four times those at any other site. Chilling of the sediment samples in the laboratory caused further emergence of seedlings from the four sites with the highest seedling densities in the initial treatment. Total numbers were up to 50% of those for seedlings that emerged during the initial exposure to greenhouse conditions. Potamogeton pectinatus and P. pusillus were most common among the seedlings of six species. Two of the three most common macrophytes in the lake were rare as seedlings, while no seedlings were recorded for the most common angiosperm, Myriophyllum exalbescens. Reproduction by seed makes a secondary contribution to the dynamics of the vegetation of Lake Wabamun.

THE FIRST EVIDENCE OF BIOEROSION IN CHITINOUS LACUSTRINE MICROFOSSILS FROM GLACIAL LAKES (LATE PLEISTOCENE AND HOLOCENE, BOHEMIAN FOREST)

Palaios ◽  
2020 ◽  
Vol 35 (8) ◽  
pp. 317-326
Author(s):  
KATARÍNA HOLCOVÁ ◽  
VLADIMÍR SUCHÁNEK ◽  
ZUZANA HEŘMANOVÁ ◽  
DANIEL VONDRÁK
Keyword(s):  
Lake Sediments ◽  
Maximum Diameter ◽  
Glacial Lakes ◽  
Central European ◽  
Sediment Samples ◽  
Size Groups ◽  
Rapid Transport ◽  
Common Sign ◽  
Pollen Records ◽  
Profundal Zone

ABSTRACT Microbioerosion structures are a common sign of microbial activity known mainly from marine environments and calcareous substrates, or from pollen records. However, the same phenomenon has been overlooked in animal fossils preserved in lake sediments. We studied 430 fragments of chitinous microfossils from three central European glacial lakes and detected microboring structures in approximately 10%. The microfossils belong to two size groups: (1) spherical objects with lengths ranging from 50 to 300 μm that are probably microturbelarian (Turbellaria: Rhabdocoela) cocoons, and (2) larger remnants (up to 2 mm long) of caddisfly (Insecta: Trichoptera) frontoclypeal apotomes. Four microbioerosion morphotypes were distinguished: (1) small holes (< 0.6 μm) oriented perpendicular to microfossil walls, likely produced by bacteria or fungi; (2) simple meandering tunnels and; (3) asterisk-like tunnel structures produced by fungi and/or fungus-like organisms; and (4) abrasions caused by biofilms. The maximum diameter of the simple holes and both tunnel structures depended on host-microfossil size: a higher diversity of microbioerosions was found on larger chitinous fragments. We propose that the good preservation of microfossils in the studied sediment samples might be due to rapid transport to the anoxic profundal zone or by rapid burial in anoxic sediments.

scholarly journals Determination of Folic Acid in Multivitamin Preparations by Reversed Phase HPLC

2021 ◽  
Vol 11 (3) ◽  
pp. 185-192
Author(s):  
A. S. Alekseeva ◽  
M. V. Gavrilin ◽  
T. B. Shemeryankina ◽  
M. S. Smirnova ◽  
E. P. Fedorova ◽  
...  
Keyword(s):  
Folic Acid ◽  
Silica Gel ◽  
Ferrous Sulfate ◽  
Reversed Phase ◽  
Asymmetry Factor ◽  
Array Detector ◽  
Isocratic Elution ◽  
Rp Hplc ◽  
Acid Determination

A great variety of components in multivitamin preparations containing folic acid, and a variety of test methods and conditions of folic acid determination proposed by manufacturers, require alignment of test procedures for products with similar composition.The aim of the study was to compare the results of experimental verification of folic acid determination procedures which use reversed phase high-performance liquid chromatography (RP HPLC) with isocratic elution mode. Materials and methods: The Agilent 1260 Infinity II LC system with a diode array detector (280 nm), isocratic elution mode, C8- and C18-bonded silica gel chromatographic columns, model mixtures containing folic acid, cyanocobalamin, ferrous sulfate, and potassium iodide, were used in the study.Results: The lowest relative standard deviation of the folic acid peak area (RSD=0.09%), and the lowest asymmetry factor (As=1.04) for folic acid were observed for the model mixture “ferrous sulfate+folic acid+cyanocobalamin” and the following test conditions. Column: 250×4.0 mm, silica gel for chromatography, octylsilyl (C8), endcapped; mobile phase:  methanol‒phosphate buffer (12:88), pH 6.6; column temperature: 25ºС. The study demonstrated the feasibility of using these conditions for determination of pteroic acid impurity with simultaneous precipitation of interfering ferrous ions, using ethylenediaminetetraacetic acid solution, pH 9.5, as a solvent.Conclusions: RP HPLC can be recommended as an optimal aligned test procedure for determination of folic acid in combination products. It is recommended to use a solution containing folic and pteroic acids for system suitability testing.

Silica gel-assisted reduction of nitrostyrenes to 2-aryl-1-nitroalkanes with sodium borohydride

1983 ◽  
Vol 24 (3) ◽  
pp. 227-230 ◽  
Author(s):  
Achintya K. Sinhababu ◽  
Ronald T. Borchardt
Keyword(s):  
Silica Gel ◽  
Sodium Borohydride
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