Thiochrome Method Research Articles

PASTURE STUDIES. XXI.: AN IMPROVED THIOCHROME METHOD FOR THE ESTIMATION OF VITAMIN B1

The thiochrome method as applied to foodstuffs by Pyke (10) has been modified to permit the use of the fluorimeter described by Froman and McFarlane (3). Interfering pigments are destroyed by adding hydrogen peroxide to the "blank" and test solutions before extracting with isobutanol. Hydrogen peroxide does not oxidize thiamine to thiochrome nor does it destroy the latter. The procedure described is based on a reinvestigation of the various methods proposed for extracting thiamine from tissues and also of the optimum amount of each reagent used in the thiochrome test.

THE THIOCHROME METHOD OF ESTIMATING THIAMIN (VITAMIN B1) IN URINE, MILK AND CEREAL PRODUCTS

THE THIOCHROME METHOD OF ESTIMATING THIAMIN (VITAMIN B 1 ) IN URINE, MILK AND CEREAL PRODUCTS

The determination of aneurin and aneurinphosphates in yeast

AbstractMany difficulties are encountered in the determination of aneurin and its phosphoric acid esters in yeast. Most of them arise from the presence, especially in top yeasts, of a powerful phosphatase, converting aneurinphosphates into aneurin, when no precautions are taken to inhibit its action. Moreover, aneurinpyrophosphate appeared to be converted into aneurinorthophosphate already by boiling for some minutes with 0.1 n hydrochloric acid. Besides that a yeast was found, to which it was impossible to apply the thiochrome method A (in which the thiochromephosphates are determined by measuring the fluorescence of the water‐layer), as it contains a substance with a strong blue fluorescence in alkaline solution, non‐extractable with isobutanol and very sensitive to oxidation with potassiumferricyanide. This sensitivity is so great that this substance cannot be a thiochromephosphate.Generally applicable procedures, avoiding the errors, originating from these difficulties, were worked out for the determination of free aneurin (thiochrome method), total aneurin (thiochrome method), aneurinpyrophosphate (manometric method) and the sum of aneurinpyrophosphate and aneurinorthophosphate (thiochrome method).All yeasts investigated appeared to contain free aneurin. With the exception of one yeast, which had been dried on a hot rotating drum, they all contained amounts of aneurinpyrophosphate, exceeding the amounts of free aneurin.No indications were obtained that yeast, whether fresh or dried, ever contains aneurinorthophosphate. Hence we believe that for routine analyses aneurinpyrophosphate determinations by the manometric method may be omitted and the sum of the aneurinphosphates found by the thiochrome method may be equalised to the amount of aneurinpyrophosphate present.The fact that free aneurin is found and no aneurinorthophosphate proves that the aneurin is orginally present in the yeast and is not formed from aneurinpyrophosphate during drying and extraction.

食品のビタミンB<sub>1</sub>定量法に關する研究

食品のビタミンB<sub>1</sub>定量法に關する研究

CLINICAL APPLICATION OF THE THIOCHROME REACTION IN THE STUDY OF THIAMIN (VITAMIN B^1) DEFICIENCY

Article1 July 1940CLINICAL APPLICATION OF THE THIOCHROME REACTION IN THE STUDY OF THIAMIN (VITAMIN B1) DEFICIENCYHARRY J. BORSOX, M.D.HARRY J. BORSOX, M.D.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-14-1-1 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptA Chemical method for the estimation of thiamin (vitamin B1), should have the advantages, as compared to biological assay, of speed, accuracy, cheapness, and ease of performance. The great advantage of biological assay is definite specificity. However, under well controlled conditions the uncertainties of chemical assay may become negligible.Of the several methods proposed for the chemical estimation of thiamin, the thiochrome method of Jansen1has received the most attention. Recently, the method of Prebluda and McCollum2as modified by Melnick and Field3has been shown to possess a high degree of specificity and accuracy, but the technic as described...

Presence of a Hitherto Unrecognized Nicotinic Acid Derivative in Human Urine.

In the course of some studies on the excretion of thiamin in urine by means of the thiochrome method, using the procedure of Hennessy and Cereeedo,1 it was noted that treatment of the KC1 eluate of urine with alkali, even in the absence of ferricyanide, yielded a small amount of a substance soluble in butyl alcohol which gave a bluish fluorescence with ultraviolet light. This fluorescence could be distinguished from that given by thiochrome even with the naked eye, being a whitish blue without any tinge of violet. Specimens of urine from a large series of normal individuals of various ages were found to exhibit such fluorescence in slight degree. A patient receiving nicotinic acid therapy, however, was found to excrete it in large amount, suggesting that nicotinic acid was the precursor of this substance. Following this observation the effect of taking nicotinic acid was studied in normal individuals, and it was found that a dose of 50 mg of nicotinic acid, given to an adult, produced a prompt increase in...

On the determination of aneurin in urine by the thiochrome method

AbstractThe thiochrome method and its application to urine, as it is now carried out in our laboratory after three years experience, is discussed. A comparison is made of our method with a modification, in which adsorption of aneurin on franconite, previous to oxidation, is dispensed with.

Quantitative Enzymic Conversion of Cocarboxylase (Vitamin B2-Pyrophosphate) to Free Thiamin

Recently Lohmann and Schuster reported that thiamin (vitamin B1) may exist in nature as a pyrophosphoric acid ester to constitute cocarboxylase, the coenzyme of carboxylase. Thiamin itself cannot function as the coenzyme, although the action of pure cocarboxylase in vitro is strongly stimulated by the addition of the pure vitamin. However, pigeon curative tests have shown that cocarboxylase is practically as equally effective as free thiamin. A number of workers have subsequently reported that in the thiochrome method for determining thiamin the cocarboxylase forms a thiochrome but this is not extracted by isobutanol and hence cannot be estimated. For this reason analyses by this method of preparations rich in cocarboxylase (such as yeast), give values decidedly less than those obtained by biological assay. Cocarboxylase may be hydrolyzed to the monophosphoric acid ester of thiamin by 1 N HCl solution, but the latter ester is resistant to acid hydrolysis. Alkaline hydrolysis will completely remove the second phosphoric acid grouping but inasmuch as there is a concomitant destruction of the end-product (thiamin) such a procedure is impractical for analytical purposes. Levine has observed that, when aqueous yeast extracts are allowed to stand at room temperature exposed to the atmosphere for a period of 48 hours with no preservative added, there is a conversion of the cocarboxylase present to free thiamin. He attributed this change to the activity of a yeast phosphatase. Kidney phosphatase has been used as means for hydrolyzing the coenzyme to the free vitamin. However, with such a preparation the conversion does not appear to be quantitative. In the present study an extension of our chemical method for the estimation of thiamin in biological materials has been applied to an investigation of the conversion of cocarboxylase to thiamin. We have found that both cocarboxylase and the monophosphoric acid ester of thiamin react with diazotized p-amino acetophenone to yield colored solutions but that these pigments are not extracted by xylene. This is comparable to the findings recorded with the thiochrome method for determining thiamin.

Quantitative Measurement of Vitamin B1 by the Thiochrome Reaction

IT has been known to us for more than a year that there is a large discrepancy between the results of biological vitamin B1 assay and of determination of aneurin by the original method of Jansen1, when both methods are applied to animal tissues. We did not like to report on these observations before having succeeded in determining vitamin B1 quantitatively by the thiochrome method. Immediately after the publication of a paper by M. A. Pyke2, however, it was clear to us that he had estimated only a very small part of the total amount of vitamin B1 actually present in the animal tissues investigated. Dr. Pyke's letter in NATURE of June 25, p. 1141, prompts us to make the following remarks.

Determination of Aneurin (= Vitamin B1) in Urine by the Thiochrome Method

WE have now worked out Jansen's method1 for the determination of aneurin for the estimation of this vitamin in urine. Most difficulties were overcome by diluting the urine by about three times its volume of water, by working entirely in a nitrogen atmosphere and by substracting the fluorescence of a franconite eluate to which no potassium ferricyanide had been added from the fluorescences of some eluates which had been treated with different amounts of this oxidizing agent.