THE DETERMINATION OF SULPHUR IN WOOL

1937 ◽  
Vol 15b (2) ◽  
pp. 65-74 ◽  
Author(s):  
P. Larose ◽  
A. S. Tweedie
Keyword(s):  
Hydrochloric Acid ◽  
Organic Compounds ◽  
Dilute Hydrochloric Acid ◽  
Dry Weight ◽  
New Method ◽  
Macro Scale ◽  
Wool Wax

A modification of Pregl's micromethod for the determination of sulphur in organic compounds has been found to be satisfactory and convenient when applied on a macro scale to wool.The investigation of various methods of cleaning the samples shows that the best results are obtained when the wool wax is extracted with a solvent before washing with water. It is shown that a treatment with dilute hydrochloric acid is not necessary in preparing the sample.Three different procedures have been followed in determining the dry weight of the sample and the differences in the results are discussed. Results obtained by the new method are compared with those obtained by other recognized methods, and the agreement with the results of the Benedict-Denis-Barritt method is shown to be very good.

A new method for the determination of sulphur in organic compounds containing nitrogen.

1953 ◽  
Vol 41 (1-2) ◽  
pp. 51-57 ◽  
Author(s):  
R. Belcher ◽  
A. J. Nutten ◽  
W. I. Stephen
Keyword(s):  
Organic Compounds ◽  
New Method

scholarly journals In vitro determination of potentially bioavailable fluoride in diet and toothpaste after ingestion

2021 ◽  
Vol 20 ◽  
pp. e210971
Author(s):  
Cristiane Brandão Santos Almeida ◽  
José Augusto Rodrigues ◽  
Valéria Souza Freitas ◽  
Ynara Bosco de Oliveira Lima-Arsati
Keyword(s):  
Hydrochloric Acid ◽  
Gastric Juice ◽  
Day Care ◽  
New Method ◽  
Care Centre ◽  
Specific Amount ◽  
Day Care Centre

Aim: To propose a new method to determine in vitro potentially bioavailable fluoride (F) in diet and toothpaste after ingestion. Methods: Diet samples (D) were obtained from 15 portions of a meal served to children in a day care centre. To simulate the ingestion of toothpaste during brushing after meals, a specific amount of toothpaste was added to the diet samples (D + T). F was determined in D and D + T after incubation in a solution that simulated “gastric juice” (0.01 M hydrochloric acid) at 37oC for 30, 60 and 120 min. Microdiffusion facilitated by HMDS was used to determine the total F concentrations in samples D and D + T. The analyses were performed using an ion specific electrode. Results: For D samples, incubation in “gastric juice” for 30, 60 and 120 min resulted in F concentrations (μg F/mL) of 0.75 ± 0.06c, 0.77 ± 0.07c and 0.91 ± 0.09b, corresponding to 75.3, 77.3 and 90.7% of the total F (1.02 ± 0.12a), respectively (p = 0.0001; ANOVA + Tukey). For D + T samples, these values of F concentrations (μg F/mL) were 2.55 ± 0.46b, 2.83 ± 0.44ab and 3.15 ± 0.37a, corresponding to 86.9, 94.8 and 106.7% of the total F (2.99 ± 0.34a), respectively (p = 0.0023; ANOVA + Tukey). Conclusion: Then, it can be concluded that the proposed method of “gastric juice” is a promising protocol for determining potentially bioavailable fluoride in the diet and toothpaste after ingestion. However, additional studies are desirable.

New Colorimetric Method for the Determination of the Nitrate and Nitrite Content of Baby Foods

1965 ◽  
Vol 48 (5) ◽  
pp. 892-897 ◽  
Author(s):  
Len Kamm ◽  
G G Mckeown ◽  
D Morison Smith
Keyword(s):  
Hydrochloric Acid ◽  
Nitrate Nitrogen ◽  
Colorimetric Method ◽  
New Method ◽  
Green Beans ◽  
Baby Foods ◽  
Nitrate And Nitrite ◽  
Nitrite Content

Abstract A new method for the determination of nitrite and nitrate in foods will accurately determine concentrations as low as 1 ppm. 1-Naphthylamine is diazotized by nitrite and coupled with excess amine to give 4-(lnaphthylazo)-l-naphthylamine. The compound is extracted into CHCI3, the extract is acidified with methanol-hydrochloric acid, and absorbance is measured at 555 mµ. Nitrate is quantitatively reduced by passage through a cadmium column and determined as nitrite; nitrite passes through the column unaltered. Therefore, in samples containing both forms of nitrogen, nitrate is determined by difference. The method was applied to 194 samples of baby foods. Spinach, beets, wax beans, squash, “garden vegetables,” green beans, carrots, and “mixed vegetables” were found to contain, on the average, more than 20 ppm nitrate nitrogen.

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