An improved colorimetric procedure for the analysis of vitamin A

1976 ◽  
Vol 54 (11) ◽  
pp. 1757-1764 ◽  
Author(s):  
J. A. Blake ◽  
J. J. Moran
Keyword(s):  
Reaction Mechanism ◽  
Vitamin A ◽  
Antimony Trichloride ◽  
Factors Affecting ◽  
Related Compounds ◽  
Colour Complex ◽  
Colorimetric Procedure

Factors affecting the reaction between antimony trichloride and 2,3-dichloropropanol (2,3-DP) with retinol and related compounds were examined. It is shown that purified 2,3-DP with the addition of antimony trichloride produces a stable colour complex with retinol absorbing at 555 nm. A tentative scheme for the reaction mechanism and the possible structure of the complex are also presented.

scholarly journals The effects of maternal and infant vitamin A supplementation on vitamin A status: a randomised trial in Kenya

2007 ◽  
Vol 98 (2) ◽  
pp. 422-430 ◽  
Author(s):  
R. A. Ayah ◽  
D. L. Mwaniki ◽  
P. Magnussen ◽  
A. E. Tedstone ◽  
T. Marshall ◽  
...  
Keyword(s):  
Vitamin A ◽  
Controlled Trial ◽  
Randomised Trial ◽  
Maternal Serum ◽  
High Dose ◽  
Serum Retinol ◽  
Double Blind ◽  
Vitamin A Supplementation ◽  
Factors Affecting ◽  
Vitamin A Status

Postpartum vitamin A supplementation of mothers and infants is recommended, but the efficacy has been questioned. In this double-blind, placebo-controlled trial, Kenyan mother–infant pairs were randomised to maternal vitamin A (400 000 IU) or placebo < 24 h postpartum, and infant vitamin A (100 000 IU) or placebo at 14 weeks. Milk retinol was determined at weeks 4, 14 and 26, and maternal and infant serum retinol at weeks 14 and 26. Infant retinol stores were assessed at week 26, using a modified relative dose response (MRDR) test. Among 564 women, serum retinol at 36 weeks gestation was 0·81 (sd 0·21) μmol/l, and 33·3 % were < 0·7 μmol/l. Maternal serum retinol was not different between groups, but milk retinol was higher in the vitamin A group: (0·67 v. 0·60 μmol/l; 0·52 v. 0·44 μmol/l; 0·50 v. 0·44 μmol/l at 4, 14 and 26 weeks, respectively). When expressed per gram fat, milk retinol was higher in the vitamin A group only at 4 weeks. Infant serum retinol was not different between groups. However, although most infants had deficient vitamin A stores (MRDR>0·06 %) at 26 weeks, vitamin A to infants, but not mothers, resulted in a lower proportion of infants with deficient vitamin A stores (69 v. 78 %). High-dose postpartum vitamin A supplementation failed to increase serum retinol and infant stores, despite modest effects on milk retinol. Infant supplementation, however, increased stores. There is a need for a better understanding of factors affecting absorption and metabolism of vitamin A.

scholarly journals The interpretation of the colour match in the antimony trichloride test for vitamin A

1932 ◽  
Vol 26 (2) ◽  
pp. 377-380 ◽  
Author(s):  
Ronald Sydney Morgan
Keyword(s):  
Vitamin A ◽  
Antimony Trichloride ◽  
Colour Match

scholarly journals Some Factors Affecting the Respiratory Response of Azotobacter to 2,4-D and Related Compounds

1956 ◽  
Vol 4 (3) ◽  
pp. 109-113 ◽  
Author(s):  
Mary K. Johnson ◽  
Lyman A. Magee ◽  
Arthur R. Colmer
Keyword(s):  
Respiratory Response ◽  
Factors Affecting ◽  
Related Compounds

scholarly journals PENGEMBANGAN BAHAN AJAR KIMIA RINTISAN SMA BERTARAF INTERNASIONAL KELAS XI MATERI LAJU REAKSI

2012 ◽  
Vol 13 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Inova Putri Carera ◽  
I Wayan Dasna
Keyword(s):  
High School ◽  
High School Students ◽  
Reaction Mechanism ◽  
Reaction Rate ◽  
Reaction Order ◽  
Average Score ◽  
School Students ◽  
Factors Affecting ◽  
Rate Law

This study was aimed to develop teaching materials about chemical reaction rate which covered materials adapted to A-Level High School students of grade XI in Pioneer International Standard High School (RSMA-BI). The developmental research was adopting the instructional development model 4D which include four stages of development, namely define, design, develop, and disseminate. Instructional materials were written in English consist of seven topics titled: Reaction Rate Concept, The Exchange's Expressions, Rate Law and Reaction Order, Experimental Determination of a Rate Law, Reaction Mechanism, Theories of Reaction Rate, Factors Affecting Reaction Rate. Results of content validation from content experts obtained the average score of 3. 56 of 14 range of scores which means valid / good / decent. Test limited to high school students of RSBI obtained an average score of 3.35 (valid / good / decent). The results of the use of teaching materials obtained a score of 77.8 which is above the minimal passing grade (75). Therefore it can be concluded that the materials were feasible to be used in the classroom.Penelitian ini bertujuan untuk mengembangkan bahan ajar laju reaksi dengan cakupan materi yang disesuaikan dengan A-Level untuk siswa kelas XI Rintisan Sekolah Menengah Atas Bertaraf Internasional (RSMA-BI. Rancangan penelitian pengembangan mengadaptasi model pengembangan bahan ajar Model 4D yang meliputi empat tahap pengembangan, yaitu define, design, develop dan disseminate. Produk pengembangan adalah bahan ajar kimia RSMA-BI kelas XI materi laju reaksi yang ditulis dalam bahasa Inggris menggunakan pendekatan kontekstual. Bahan ajar terdiri atas empat bagian utama yaitu pendahuluan, materi, evaluasi dan penutup. Materi tersusun atas tujuh sub materi yaitu Reaction Rate Concept, The Rates Expressions, Rate Law and Reaction Order, Experimental Determination of a Rate Law, Reaction Mechanism, Theories of Reaction Rate, Factors Affecting Reaction Rate. Hasil validasi isi dari ahli materi diperoleh nilai rata-rata 3,56 dari rentang skor 1-4 dengan kriteria valid/baik/layak. Hasil uji terbatas pada siswa SMA RSBI diperoleh nilai rata-rata 3,35 dari rentang skor 1-4 dengan kriteria valid/baik/layak. Hasil uji penggunaan bahan ajar diperoleh skor sebesar 77,8. Skor ini diatas SKM (Skor Kelulusan Minimal) yaitu 75 sehingga dapat disimpulkan bahwa bahan ajar telah layak dan dapat digunakan dalam pembelajaran di kelas.

scholarly journals Study on Designing Sulfur Containing Bifunctional Building Block with Improved Refractive Index

2009 ◽  
Vol 6 (2) ◽  
pp. 399-411 ◽  
Author(s):  
G. S. Jha ◽  
P. Chhabra ◽  
G. Suri ◽  
M. Tyagi ◽  
P. Arora ◽  
...  
Keyword(s):  
Refractive Index ◽  
Reaction Mechanism ◽  
Reaction Time ◽  
Acid Number ◽  
Effect Of Temperature ◽  
Control Parameters ◽  
Reaction Parameters ◽  
Factors Affecting ◽  
Temperature Rate ◽  
Sulfur Containing

Sulfur and chlorine containing bifunctional diols with C-S bond has been prepared starting from chloroepoxy alkane and thioalcohol. The studies of FTIR, TLC, HPLC and NMR have been used to understand the reaction mechanism, as well as for optimization of the reaction parameters. The reaction is highly exothermic and the effect of temperature, rate of addition of reagents and reaction time are important factors affecting the formation of diol. Viscosity studies, HPLC, FTIR, NMR and acid number studies have shown that, these parameters could be used as process control parameters for the synthesis of diol. Refractive index of the synthesized diol is found to be higher than that of the reactants used.

scholarly journals Factors affecting low coverage of the vitamin A supplementation program among young children admitted in an urban diarrheal treatment facility in Bangladesh

2019 ◽  
Vol 12 (1) ◽  
pp. 1588513 ◽  
Author(s):  
Ishita Mostafa ◽  
Shamin Fatema Islam ◽  
Prasenjit Mondal ◽  
A.S.G. Faruque ◽  
Tahmeed Ahmed ◽  
...  
Keyword(s):  
Young Children ◽  
Vitamin A ◽  
Treatment Facility ◽  
Vitamin A Supplementation ◽  
Factors Affecting ◽  
Low Coverage

Factors affecting the reliability and precision of the spectroscopic determination of vitamin A

1946 ◽  
Vol 23 (3) ◽  
pp. 83-87 ◽  
Author(s):  
H. W. Rawlings ◽  
G. H. Wait
Keyword(s):  
Vitamin A ◽  
Spectroscopic Determination ◽  
Factors Affecting

FACTORS AFFECTING THE PETT VISUAL TEST FOR VITAMIN A DEFICIENCY

1941 ◽  
Vol 19b (4) ◽  
pp. 99-108
Author(s):  
L. B. Pett ◽  
Marian K. Lipkind
Keyword(s):  
Vitamin A ◽  
Diurnal Rhythm ◽  
Standard Error ◽  
Learning Effect ◽  
Vitamin A Deficiency ◽  
Bright Light ◽  
Visual Test ◽  
Factors Affecting ◽  
Test Room ◽  
The Mean

Under the conditions prescribed for the Pett test, which is described, it has been found that: (i) antecedent light does not affect the median of the three tests usually performed; (ii) no error results from the wearing or not wearing of glasses; (ii) the use of pilocarpine to contract the pupils is not advisable; (iv) some light may be admitted into the test room; (v) the time of exposure to the bright light (30 sec.) is suitable; (vi) repeated tests cause a 'learning' effect so rarely as to be of little concern; (vii) the standard error of the mean is ±1.4 and of the median is ±2.4 sec. Some results are presented suggesting that a diurnal rhythm in the vitamin A content of the blood exists.

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