Instead of using active carbon as oxidizing agent as described in the briginal Roe-Kuether method, the present authors adapted O2 and ascorbic acid 6xida.sc to oxidize ascorbic acid. The interfering substances such as reductone and sugars are thus eliminated and the specificity of the Roe-Kuether method for ascorbic acid is, therefore, highly increased, and the time for the determination is shortened. The details of the working conditions have been worked out. The modified procedure may be briefly outlined as follows:Extraction: To x gm of sample add 4x ml of 5% metaphosphoric acid. Grind with sand, add 5x ml of water, stir and centrifuge. Take the supernatant clear layer for analysis, its pH is about 1.7 and the concentration of metaphosphoric acid is about 2%. In case of a liquid sample, both the metaphosphoric acid and water may be added directly to the [sample solution before centrifugation.Oxidation: Delivery 2.5 ml aliquot of the extract to a test tube graduated at 10 ml. Place the tube in a water bath at 37℃, and pass O2 through a capillary tube into the test solution for 15 minutes (about 9000 ml O2 for 15 minutes). Remove the tube from the warm water and adjust the pH of the extract to 6 with 2N NaOH (0.13ml). Add 0.1 ml of ascorbic acid oxidase solution and again pass O2 for another 5 minutes. Readjust the pH of the test solution to its original value (about 1.7) by adding 0.13 ml of IN HCl and finally add 6.% trichloroacetic acid to the 10 ml mark. Through this treatment, the ascorbic acid is quantitatively converted into dehydroascorbic acid and the interfering substances are completely removed.Color Comparison: To each of 2 colorimetric tubes add 4 ml aliquot of the oxidized extract and 2 drops of 10% thiourea. After thorough mixing, set one tube to serve as a blank, and to the other add 1 ml of 2% 2,4-dinitrophenylhy-drazine solution. Mix and incubate the latter tube at 37℃ for exactly 3 hours. Place both tubes in ice water and to each add slowly 5 ml of 85% H7SO4 (the addition should take 1-2 minutes). The ascorbic acid content of the unknown solution (mg/100 ml) is determined by interpolation of the optical density values on a standard curve prepared by a series of gradient ascorbic acid solutions.

Iron deficiency anemia is a world wide concerned problem especially for the populations of children and pregnant women. Using table salt as a vehiclefor iron fortification is one way of preventive measures. This observation was using iron fortified salt with the level which provided an additive 5 to 10 mg of iron supplement for preschool children daily. Basically two groups of children living in different kindergartens, one had been given the fortified salt and the other served as control for one year. The initial hemoglobin levels of both group was the same, but one year later the hemoglobin level of the experimental group had changed from 11.78 ?0.57 up to 12.72? 0.70 and was different significantly from the control (p

In this article, a rapid, simple, and dependable method is introduced to determine the content of calcium from 0.5ppm to 200ppm in some foods by AAS. It has not only accuracy but has wide range for the determination of concentration.As for low concentration of calcium, the position of the burner must be parallel to the axis of beam while delerming. For high concentration, changing of the condition of operation is unnecessary except for the burner turn 90? from the axis horizontally. So it is quite easy for operation.The SiO32-, PO43-, and A13+ may interfere in the determination of calcium seriously, but this can be eliminated effectively by adding a certain amount of Sr2+ (as a releasing agent) to the sample to be tested.In the determination of low concentration of calcium, the recovery and coefficient of variation are 95-105% and

An observation on the accuracy of the titration method for ascorbic acid with 2,6-dichlorophenolindophenol adapted by the Department of Nutrition, Chinese Academy of Medical Sciences. The photometric method of and the paper chromatographic method of Robert et al. was made. The percentage error of the determination is -3.1-1.36% (above 18?g); -3.9-6.7%; and -6.1--18.4% (above 11.1?g) and also the percentage recovered of the added amount of asorbic acid is 95-99%; 95-109% (above 31?g) and 76.5-97.5% respectively.We have modified the developing reagent used by the paper chromatographic method and rendered it more sensitive.The photometric method of et. al. is found to be more adaptable than the other two methods, therefore further observations on the colorimetric method were made.1.The reproducibility of this method is comparatively good and a considerable amount of excess of 2,6-dichlorophenolindophenol (0.15 ml.) added at the end point has no influence on the results.2.The standard curves are not identical at different times of estimation so that parallel determination of optical density of the standerds and the sample should be made.3.The stability of the colour developed is much better than that obtained with Bessey's method.

From previous investigation, it appears that vitamin C content of one variety of vegetable as found in the market may vary considerably. However data on this point are few. Present study investigated the variation of vitamin C content of a number of common vegetables available in the Shanghai market and the influence of different methods of cooking. Harris & Olliver method slightly modified was used to determine the ascorbic acid and dehy-droascorbic acid. Roe, Mills, Osterling & Dainron method was also used to determine the ascorbic acid, dehydroascorbic acid and diketogulonic acid.The results were as fellows:1.Among 26 different vegetables, the vitamin C of each variety taken at different times of the year showed a variation from less than 1 to 5 times. Generally the variation was from 2 to 3 times. Spinach, green peppers, potato, small onion, aster shoots, foreign cabbage, leeks, string beans showed variation of from 3 to 5 times. Majority of the vegetable showed vitamin C content similar to those in Peking, a few showed values twice as high as those in Peking.2.Dehydroascorbic acid was present in all but 2 of the 35 kinds of vegetable tested. The majority showed less than 10% of the total vitamin C. Eight vegetables showed a presence of 10-20%, seven vegetables 21-50%, and only one vegetable over 50%. Among 32 kinds of vegetable studied, the majority showed an absence of dikitogulonic acid, only a i'ew showed a trace of the acid.3. Four different methods of cooking were used. The loss of ascorbic acid during quick frying (used small amount of oil) was 6.2-48.7%, averaging 25.2%. Dehydroascorbic acid and ascorbic acid showed a total loss of from 7.3-46.8%, averaging 23.4%.Boiling of vegetable caused a loss of ascorbic acid of 4.6-50.6%, averaging 16.2%, while the loss of the sum of ascorbic acid and dehydroascorbic acid was 4.6-40.4%, averaging 15.3%.Steaming of vegetable on the whole caused a destruction of vitamin C more than quick frying and quick boiling. The average loss was 31.9% of ascorbic acid and 23.6% of the sum of ascorbic acid and dehydroascorbic acid.Salting of vegetable for one hour caused an average loss of 24,7% of ascorbic acid and an average loss of 18.1% of the sum total of ascorbic acid and dehydroascorbic acid.Standing for one hour after steaming caused an average loss of about 73% of ascorbic acid, while standing for one hour after quick frying caused only a loss of about 13% of ascorbic acid.

The paper was designed to consider the effect of vitamin E on metabolism of cyclic nucleotide in cold exposed male rats. The urinary excretion of cyclic nucleotide was investigated by radioimmunoassay after male rats treated with vitamin E in 4℃ exposure. The results showed that urinary excretion of cyclic nucleotide had been increasing and cAMP/cGMP ratio had been not changing in cold exposed male rats. When one week of the experiment vitmin E could increase urinary cAMP excretion more in its treated group than cold exposed group alone (P

In order to study the new function of riboflavin, the experiments of ri-boflavin on the prevention of teratogenesis were conducted. The experimental rats were divided into four groups A,B,C,D. A served as a control group, B,C,D, were given 50?g, 250ng and 1000?g of riboflavin respectively for one week intragastrically prior to the study. After pregnancy, all rats including controls were given teratogenic pesticide Dikushuang 0.75mg/kgbw for contaminaton intragastrically, riboflavin being given continually as before, to observe the effects on body weight growth and hemoglobin level of pregnant rats. The following parameters were measured: the reproduction of pregnant rats, the development of fetus and the teratogenic activity of fetus after animals were killed. The experimental results showed that the average body weight gain in the each dose groups of riboflavin were higher than the control group, but the difference was not significant. The hemoglobin levels at various experimental times were less significant among the groups.The rates of the resorption and the living fetus in 250?g and 1000?g groups were significantly lower than the control (P