Notizen: Improved 2,4-Dinitrophenylhydrazine, Thin Layer Chromatography Methods for the Determination of Micro- and Macroamounts of Ascorbic Acid

1974 ◽  
Vol 29 (11-12) ◽  
pp. 777-780 ◽  
Author(s):  
A. Navon ◽  
H. Z. Levinson
Keyword(s):  
Acetic Acid ◽  
Vitamin C ◽  
Thin Layer ◽  
Condensation Reaction ◽  
Dehydroascorbic Acid ◽  
Previous Method ◽  
Aqueous Acetic Acid ◽  
Tlc Plates ◽  
Layer Chromatography

Microamounts of vitamin C could be readily determined in 20 μl-samples using the 2,4-dinitrophenylhydrazine method together with separation by thin layer chromato­graphy. The condensation reaction was carried out for 5 min at 100 °C on a glass fibre disc. Purification of vitamin C hydrazones was accomplished by repeated separation on TLC plates. An aqueous solution of 65% acetic acid was em­ployed to dissolve the vitamin C hydrazones, providing maxi­mal absorbance at 500 nm. The minimum amount detectable by this method is 0.4 μg of dehydroascorbic acid. The macrodetermination of vitamin C was improved by simpli­fying a previous method and employing 65% aqueous acetic acid as a solvent for the hydrazones.

Assay of L( + )-Ascorbic Acid in Buttermilk by Densitometric Transmittance Measurement of the Dehydroascorbic Acid Osazone

1974 ◽  
Vol 57 (1) ◽  
pp. 65-69
Author(s):  
Paul R Beljaars ◽  
Wouter Van Steenbergen Horrocks ◽  
Theo M M Rondags
Keyword(s):  
Ascorbic Acid ◽  
Acetic Acid ◽  
Quantitative Analysis ◽  
Thin Layer ◽  
Coefficient Of Variation ◽  
Dehydroascorbic Acid ◽  
Tlc Plates ◽  
The Relationship ◽  
Layer Chromatography ◽  
Flying Spot

Abstract A study is presented for the quantitative analysis of ascorbic acid in buttermilk samples, using densitometric transmittance measurements. The procedure is based on oxidation of ascorbic acid to dehydroascorbic acid, followed by reaction with 2,4-dinitrophenylhydrazine to form the dinitrosazone. The osazone is separated from interfering substances in the sample by thin layer chromatography (TLC) on silica gel G plates developed with chloroform-ethyl acetate-acetic acid (60+35+5) . The TLC plates are scanned with a flying-spot densitometer. The relationship between integrated signal and concentration is linear for 0.08—1.00 fig ascorbic acid (coefficient of variation 3—4%). Deviations from Beer's law start to appear at levels higher than 1.00 fig ascorbic acid. A mean coefficient of variation of 3.5±1.1% (P = 95%) was established for standard spot measurements (3 spots averaged) on 15 chromatoplates. Recovery of ascorbic acid added to buttermik was 98% (coefficient of variation 7.2%). Results of this study are compared with those reported for spectrophotometric, titrimetric, and potentiometric procedures. The proposed method is less accurate because of interferences and the subsequent variables which arise as a result of taking transmittance measurements through an opaque medium.

Observations on the use of 2,4-dinitrophenylhydrazine and of 2,6-dichlorophenolindophenol for the determination of vitamin C in raw and in heat-treated milk

1970 ◽  
Vol 37 (1) ◽  
pp. 29-45 ◽  
Author(s):  
Joyce Toothill ◽  
S. Y. Thompson ◽  
J. Edwards-Webb
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Ascorbic Acid ◽  
Vitamin C ◽  
Thin Layer ◽  
Dehydroascorbic Acid ◽  
Heat Treated ◽  
Sterilized Milk ◽  
Layer Chromatography

SummaryA study has been made of methods using 2,4-dinitrophenylhydrazine (DNPH) or 2,6-dichlorophenolindophenol (DCP) for the determination of vitamin C (ascorbic acid+dehydroascorbic acid) in raw, UHT processed, evaporated and sterilized milk.Interfering substances were not detected in milk that had received a heat treatment no more severe than 145°C for 4 s (UHT process), so that either reagent could be used.With more drastic heat treatment, interfering substances were formed and only the DNPH method with column and thin layer chromatography of the DNPH derivatives was specific for vitamin C. With in-bottle sterilized milk, the values for ascorbic acid were (in mg/100 ml) 1·16 (DCP method with H2S reduction); 0·58 (DCP method with Escherichia coli reduction); 0·64 (DNPH method); 0·33 (DNPH method combined with chromatography).In our experience the DNPH method combined with chromatography of the derivatives is highly specific for vitamin C and should be used to check the results obtained by other and simpler methods.

Thin Layer Chromatographic Determination of Citrinin

1979 ◽  
Vol 62 (1) ◽  
pp. 201-202 ◽  
Author(s):  
Robert D Stubblefield
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Linear Relationship ◽  
Silica Gel ◽  
Coefficient Of Variation ◽  
Ethylenediaminetetraacetic Acid ◽  
Limit Of Detection ◽  
Chromatographic Determination ◽  
Tlc Plates

Abstract Clearly defined zones of citrinin can be obtained on thin layer chromatographic (TLC) plates and measured by fluorodensitometry. Silica gel plates were prepared as a slurry with aqueous 0.05M Na2EDTA (ethylenediaminetetraacetic acid), spread at 0.5 mm wet thickness, and activated at 105°C for 1 hr. Plates were developed in acetic acid-benzene (5+95). The limit of detection was 10 ng citrinin/zone. Densitometric analysis (365 nm excitation, 505 nm emission) revealed that a linear relationship exists for levels of 10 ng to at least 100 ng/zone wtih a coefficient of variation of ±5%.

Determination of Citrinin in Corn and Barley on Thin Layer Chromatographic Plates Impregnated with Glycolic Acid

1984 ◽  
Vol 67 (1) ◽  
pp. 194-196
Author(s):  
Alberto Gimeno
Keyword(s):  
Thin Layer ◽  
Glycolic Acid ◽  
Detection Method ◽  
Minimum Detectable Concentration ◽  
Extraction Solvent ◽  
Detectable Concentration ◽  
Tlc Plates ◽  
Limit Detection ◽  
Layer Chromatography

Abstract A method is described for the determination of citrinin in corn and barley. The mycotoxin is extracted with a mixture of acetonitrile-10% glycolic acid in water, defatted with isooctane, and transferred to chloroform according to published methods. The mycotoxin is separated by thin layer chromatography (TLC) on plates previously impregnated with 10% glycolic acid solution in ethanol; identity is confirmed by chemical tests. Citrinin is then quantitated by the limit detection method. Recoveries of citrinin from corn and barley samples spiked at levels of 50, 80, 150, 300, 500, and 1000 μg/kg were in the range 91-98%. The minimum detectable concentration is 15-20 μg/ kg. Recoveries obtained with and without glycolic acid in the extraction solvent were compared. Sensitivities on TLC plates (limits of detection, μg/spot) impregnated with glycolic acid were compared with those on plates impregnated with oxalic acid.

scholarly journals Determination of New Antidepressants in Pharmaceuticals by Thin-Layer Chromatography with Densitometry

2010 ◽  
Vol 93 (3) ◽  
pp. 778-782 ◽  
Author(s):  
Tatána Gondová ◽  
Iveta Petríková
Keyword(s):  
Thin Layer ◽  
Stationary Phase ◽  
Thin Layer Chromatography ◽  
Mobile Phase ◽  
Pharmaceutical Formulations ◽  
Simultaneous Separation ◽  
Tlc Plates ◽  
Precision And Accuracy ◽  
Layer Chromatography

Abstract A new and simple TLC-densitometry method has been developed for the simultaneous separation of the two noradrenergic and specific serotonergic antidepressants mirtazapine and mianserine and validated for their determination in commercially available tablets. The method used TLC plates precoated with silica gel 60F254 as the stationary phase, and the mobile phase consisted of hexaneisopropanol25 ammonia (70 + 25 + 5, v/v/v). Densitometric analysis was carried out in the absorbance mode at 280 nm. The method was validated in accordance with International Conference on Harmonization guidelines in terms of linearity, LOD, LOQ, precision, and accuracy. Calibration curves were linear (R2 > 0.9970) with respect to peak area in the concentration range of 5002500 and 5005000 ng/spot for mirtazapine and mianserine, respectively. The LODs were 20 and 35 ng/spot for mirtazapine and mianserine, respectively. The described method was successfully applied to the determination of mirtazapine and mianserine in their pharmaceutical formulations with recovery ranging from 99.83 to 101.20 of the labeled amount of the compounds. The proposed method can be used in routine QC of these drugs in pharmaceutical formulations.

3'-O-Formyl-(N-acyl)-2'-deoxyribonucleosides as building units in the synthesis of oligodeoxyribonucleotides

1982 ◽  
Vol 47 (8) ◽  
pp. 2157-2169 ◽  
Author(s):  
Jiří Smrt
Keyword(s):  
Acetic Acid ◽  
Acetic Anhydride ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Silica Gel ◽  
Subsequent Treatment ◽  
Aqueous Acetic Acid ◽  
Formyl Group ◽  
Layer Chromatography ◽  
Methanolic Ammonia

5'-O-Dimethoxytrityl-(N-acyl)-2'-deoxyribonucleosides afford 3'-O-formyl-(N-acyl)-2'-deoxyribonucleosides Ia-Id by the action of formic acetic anhydride followed by the action of 80% aqueous acetic acid. The formyl group is removed from Ia-Id by treatment with 1 mol l-1 triethylamine 3'-O-Formyl-2'-deoxythymidine (Ia) gives 3'-O-dimethoxytrityl-2'-deoxythymidine (V) by subsequent treatment with acetic anhydride, triethylamine, dimethoxytrityl chloride and methanolic ammonia. The use of compounds I for the synthesis of d-GGAGG (XIX) and d-T16 (XXXII) is described. Systems for thin-layer chromatography of 5'-O-dimethyltrityl-oligodeoxyribonucleotides on silica gel are described.

Susceptibility of Strawberries, Blackberries, and Cherries to Aspergillus Mold Growth and Aflatoxin Production

1982 ◽  
Vol 65 (3) ◽  
pp. 659-664 ◽  
Author(s):  
Gerald C Llewellyn ◽  
Thomas Eadie ◽  
William V Dashek
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Mycelial Growth ◽  
Methylene Chloride ◽  
Aflatoxin Production ◽  
Solvent System ◽  
Mold Growth ◽  
Tlc Plates ◽  
Layer Chromatography

Abstract The susceptibility of blackberries, cherries, and strawberries to Aspergillus growth and aflatoxin production has been examined. Three aflatoxigenic isolates of Aspergillus, A. flavus ATCC 15548 and NRRL 3251 as well as A. parasiticus NRRL 2999, were cultured on homogenates of the fruits for 14 days at 28 ± 2°C. Percent mycelial growth and spore infestation were determined each day with a calibrated grid. At day 14 each culture was frozen at –5°C until aflatoxins were extracted with methylene chloride and water. Aflatoxins were separated by thin layer chromatography (TLC) with benzene-methanol-acetic acid (90 + 5 + 5). This extraction and solvent system provided satisfactory separations of the aflatoxins and was free of background interference on the TLC plates. Although all fruits served as substrates for both Aspergillus growth and aflatoxin production, cherries appeared to be a more favorable substrate than did blackberries, and the latter was more favorable than strawberries. Whereas A. flavus produced both B1 and G1 on all substrates, it yielded B2 and G2 only on cherries. Although A. parasiticus NRRL 2999 synthesized B1, B2, G1, and G2 on both blackberries and cherries, no aflatoxins were detected on strawberries. In contrast, A. flavus NRRL 3251 failed to produce detectable levels of aflatoxin on any substrate. All substrates supported both mycelial growth and subsequent sporulation with cherries > blackberries > strawberries.

Simplified Qualitative Analysis of Glycerides Derived from Coconut Oil Using Thin Layer Chromatography

2012 ◽  
Vol 506 ◽  
pp. 182-185 ◽  
Author(s):  
Sirikarn Pengon ◽  
Chutima Limmatvapirat ◽  
Sontaya Limmatvapirat
Keyword(s):  
Acetic Acid ◽  
Qualitative Analysis ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Cocos Nucifera ◽  
Coconut Oil ◽  
Solvent System ◽  
Tlc Plates ◽  
Solvent Systems ◽  
Layer Chromatography

Coconut (Cocos nucifera L.) oil is composed predominately of medium-chain triglycerides which have been reported to be beneficial to human health. It also contains free fatty acids (FFAs) which can combine with glycerol to form monoglycerides, diglycerides, and triglycerides. The analysis of FFAs and their glycerides has been proposed to assess the quality of coconut oil used as raw materials in various industrial fields. The aim of this study was to develop the qualitative method for investigation of FFA and their glycerides in coconut oil using thin layer chromatography (TLC). Coconut oil and standards of FFA and their glycerides were chromatographed separately on Silica gel 60 F254 TLC plates using hexane: ether: acetic acid (60:40:1) and hexane: ethyl acetate: acetic acid (60:40:0.5) as solvent systems A and B, respectively. The spots on developing TLC plates were detected and compared using 254-nm UV light and iodine vapor. The results showed that the resolution of solvent system A was better than that of solvent system B. However, both solvent systems were used to confirm the results. The retention factor (Rf) values of the components were in good agreement with their polarity. This method should provide a guideline for qualitative analysis of coconut oil.

scholarly journals Simultaneous Identification and Quantitative Determination of Selected Aminoglycoside Antibiotics by Thin-Layer Chromatography and Densitometry

2009 ◽  
Vol 92 (4) ◽  
pp. 1068-1075 ◽  
Author(s):  
Urszula Hubicka ◽  
Jan Krzek ◽  
Hanna Woltyska ◽  
Boóena Stachacz
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Mobile Phase ◽  
High Sensitivity ◽  
Good Separation ◽  
Fluorescent Indicator ◽  
Tlc Plates ◽  
Simultaneous Identification ◽  
Layer Chromatography

Abstract A TLCdensitometric method has been developed for simultaneous identification and quantitative determination of amikacin, gentamicin, kanamycin, neomycin, netilmicin, and tobramycin. This separation of antibiotics was achieved on silica gel TLC plates without a fluorescent indicator and with methanol25 ammoniachloroform (3 + 2 + 1, v/v/v) as the mobile phase. The densitometric measurements were made at 500 nm after detection with a 0.2 ninhydrin solution in ethanol. Under these conditions, good separation of the chosen aminoglycosides was obtained. The method is distinguished by high sensitivity, with the LOD from 0.25 g for amikacin to 1.00 g for gentamicin and the LOQ from 0.5 g for amikacin to 1.65 g for gentamicin, and a wide linearity range 0.756.25 g/spot for amikacin and netilmicin and 1.512.50 g/spot for other antibiotics. The precision of the determination was very good; RSD varied in the range 0.30.6.

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