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.

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.

Chromatographic and Extraction Techniques for Vitamin C Assay

1965 ◽  
Vol 48 (5) ◽  
pp. 985-991
Author(s):  
Elmer De Ritter
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Thin Layer ◽  
Dehydroascorbic Acid ◽  
Reduced Form ◽  
Extraction Techniques ◽  
Total Vitamin ◽  
High Efficient ◽  
Efficient Extraction ◽  
Layer Chromatography

Abstract A review is presented of chromatographic procedures used in the assay of vitamin C. Paper, thin layer, and column chromatography have been used to advantage for separating interfering substances. Even the closely related erythorbic acid, which has no vitamin C activity, can be separated from ascorbic acid by various techniques on paper. Total vitamin C can be determined chromatographically after reduction of dehydroascorbic acid with H2S or after oxidation of the reduced form to dehydroascorbic acid. A combination of column and thin layer chromatography on silica gel of the dinitrosazone formed by reaction of dehydroascorbic acid with 2,4-dinitrophenylhydraiine is recommended as an effective method for achieving specificity in vitamin C assays of foods and feeds where the level of interference is high. Efficient extraction procedures are described for determining added ascorbic acid in feeds and mineral premixes.

Determination of Total Vitamin C by Ion Exclusion Chromatography with Electrochemical Detection

1989 ◽  
Vol 72 (4) ◽  
pp. 681-686
Author(s):  
Hie-Joon Kim
Keyword(s):  
Ascorbic Acid ◽  
Sulfuric Acid ◽  
Vitamin C ◽  
Retention Time ◽  
Acid Content ◽  
High Speed ◽  
Reference Electrode ◽  
Dehydroascorbic Acid ◽  
Total Vitamin

Abstract A rapid and sensitive liquid chromatographic method for determination of total vitamin C in foods and beverages is described. Ascorbic acid and dehydroascorbic acid are extracted with sulfuric acid solution, and the dehydroascorbic acid in the extract is reduced to ascorbic acid by dithiothreitol at pH 7. The reduction is complete in 2 min at room temperature. The resulting total ascorbic acid is separated on an anion exclusion/high speed column with 20mM sulfuric acid as eluant and detected amperometrically with a platinum electrode operating at +0.6-0.8 V vs Ag/AgCl reference electrode. Dithiothreitol (retention time, 3.2 min) does not interfere with the separation and detection of ascorbic acid (retention time, 1.3 min). The dehydroascorbic acid content can be estimated as the difference in ascorbic acid content measured with and without reduction by dithiothreitol. The completeness of the reduction was demonstrated by purposely allowing the oxidation of ascorbic acid in the food extract and determining the total vitamin C after reduction. The determinations of vitamin C content in selected foods and beverages were in good agreement with the expected values. Total analysis time for vitamin C is 10 min and the detection limit is 0.1 ng. The method is specific for vitamin C, and interference by other food constituents is minimal.

Automated Fluorometric Method for the Determination of Total Vitamin C in Food Products

1976 ◽  
Vol 59 (6) ◽  
pp. 1244-1250 ◽  
Author(s):  
Ram B Roy ◽  
Aldo Conetta ◽  
Jerry Salpeter
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Dehydroascorbic Acid ◽  
Food Products ◽  
Total Vitamin ◽  
Automated Method ◽  
Highly Sensitive ◽  
Aoac Method ◽  
Analytical System

Abstract A specific microfluorometric method for the determination of ascorbic acid, dehydroascorbic acid, and total vitamin C in food products has been automated. The procedure developed is an adaptation of the official AOAC method (secs. 43.056–43.062), except that N-bromosuccinimide is used instead of Norit to oxidize vitamin C. Ascorbic acid is selectively oxidized by N-bromosuccinimide before other interfering substances that may be present, so this method is a highly sensitive and specific technique with extensive applicability. The proposed automated method is simple, rapid, reliable, and sufficiently sensitive to analyze as little as 2 × 10−3 to 0.1 mg ascorbic acid/ml. Analytical results obtained for ascorbic acid, dehydroascorbic acid, and total vitamin C in a wide variety of food products are reported. The analytical system developed has the capability of analyzing 50 samples/hr.

Liquid Chromatography, Microfluorometry, and Dye-Titration Determination of Vitamin C in Fresh Fruit and Vegetables

1983 ◽  
Vol 66 (6) ◽  
pp. 1377-1379
Author(s):  
Ron B H Wills ◽  
Pushparany Wimalasirl ◽  
Heather Greenfield
Keyword(s):  
Ascorbic Acid ◽  
Liquid Chromatography ◽  
Vitamin C ◽  
Dehydroascorbic Acid ◽  
Fresh Fruit ◽  
Fruit And Vegetables ◽  
End Point ◽  
Liquid Chromatographic ◽  
Good Agreement

Abstract The vitamin C content of several fresh fruit and vegetables was determined by a liquid chromatographic (LC) method which gave simultaneous separate values for ascorbic acid and dehydroascorbic acid (DHA) and by the official AOAC methods of microfluorometry and dye-titration. The levels of ascorbic acid obtained by LC and dye-titration were in good agreement, except for a few colored products where it was difficult to determine the end point of the titration. The combined values for ascorbic acid and DHA obtained by LC and microfluorometry were in agreement for most produce, but for about one-third of the samples, the values obtained by microfluorometry were significantly higher.

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.

The determination of vitamin C in evaporated and fortified sterilized milks

1970 ◽  
Vol 37 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Joyce Toothill ◽  
S. Y. Thompson ◽  
W. B. Hill
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Chromatographic Separation ◽  
Dehydroascorbic Acid ◽  
Reconstituted Milk

SummaryA study has been made of the use of 2,6-dichlorophenolindophenol (DCP) and also of 2,4-dinitrophenylhydrazine (DNPH) with and without chromatography of the DNPH derivatives, for the determination of ascorbic acid (AA) and dehydroascorbic acid (DHA) in evaporated milks, and of AA in AA-fortified sterilized milks.In the DNPH method, when interfering compounds were removed by the chromatographic separation of the DNPH derivatives, absorption curves typical of the pure DHA derivative were obtained.The DCP method gave erroneously high values for the AA and DHA content, and the lower values obtained by the DNPH method with chromatography of the DNPH derivatives were judged correct. Thus for an evaporated milk, the values for vitamin C content (AA + DHA) were, in mg/100ml reconstituted milk, 0·88 (DCP method), 0·66 (DNPH method without chromatography), and 0·48 (DNPH method combined with chromatography). The AA contents (mg/100 ml) of the 2 fortified sterilized milks were 3·63 and 5·78 (DCP method); 3·01 and 4·28 (DNPH method combined with chromatography).The AA contents of the 5 different evaporated milks, determined by chromatography of the DNPH derivatives, ranged from 0·07 to 0·63 mg/100 ml reconstituted milk. The DHA content was negligible.As judged by the shape of the absorption curves after chromatography of the DNPH derivatives, it is concluded that this method is the most reliable of those studied.

Handling Practices to Control Ascorbic Acid and β-Carotene Lossess in Collards (Brassica oleracea)

2009 ◽  
Vol 15 (5) ◽  
pp. 445-452 ◽  
Author(s):  
F.M. Campos ◽  
J.B.P. Chaves ◽  
R.M.C. de Azeredo ◽  
D.S. Oliveira ◽  
H.M. Pinheiro Sant'Ana
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Waiting Time ◽  
Dehydroascorbic Acid ◽  
Nutrient Content ◽  
Time Control ◽  
Handling Practices ◽  
Reduced Time ◽  
Β Carotene

Knowledge of the alterations in the nutrient content of vegetables after harvest and during preparation is still limited although studies have been reported. The objective of this study was to select handling practices to control losses of vitamin C (ascorbic acid (AA) and dehydroascorbic acid) and β-carotene in collards during storage, sanitization, slicing, and time after preparation. Determination of carotenoids was carried out by HPLC. β-carotene retention was greater at 10°C than 23°C after 24-h storage. Sanitization for a period longer than 15 min negatively affected AA retention in the sample stored under refrigeration. Increased waiting time between frying and consumption of stir-fried collards increased AA losses both in sliced and torn collards. Storage under refrigeration, sanitization time control, and reduced time between preparation and consumption are therefore recommended.

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