THE ANTIMONY TRICHLORIDE METHOD FOR THE DETERMINATION OF VITAMIN A

1944 ◽  
Vol 22b (2) ◽  
pp. 21-31 ◽  
Author(s):  
G. H. Benham
Keyword(s):  
Vitamin A ◽  
Petroleum Ether ◽  
Ethyl Ether ◽  
Soap Solution ◽  
Antimony Trichloride ◽  
Chemical Test ◽  
The Absolute

A critical description of the antimony trichloride method for the determination of vitamin A is presented. Low values for vitamin A result from:(1) Incomplete extraction from the alcoholic soap solution by using petroleum ether instead of ethyl ether,(2) Incomplete separation of the layers during extraction and washing,(3) Incomplete filtration through anhydrous sodium sulphate.If strict attention is paid to details of procedure, the method gives consistent and reproducible results. Uncertainty in regard to the exact factor for converting the E values to international units makes it impossible at this time to state accurately the absolute values. It is pointed out that this in no way detracts from the usefulness of the chemical test.

Volumetric Determination of Malathion, Using Dichlorofluorescein as Indicator

1976 ◽  
Vol 59 (1) ◽  
pp. 216-218
Author(s):  
Miguel Siquiroff ◽  
Ricardo Pollero ◽  
Rodolfo Goyena
Keyword(s):  
Standard Deviation ◽  
Petroleum Ether ◽  
Silver Nitrate ◽  
Ethyl Ether ◽  
Colorimetric Method ◽  
Florisil Column ◽  
Average Recovery ◽  
Florisil Column Chromatography ◽  
Volumetric Determination

Abstract A method has been developed which is based on alkali cleavage of malathion and volumetric determination of the resulting dimethylphosphorodithioate with silver nitrate, using dichlorofluorescein as the indicator. Pure malathion standards were analyzed by the proposed method, yielding a standard deviation of 0.27. Four typical malathion formulations containing talc, wheat flour, and anionic and nonionic emulsifiers were analyzed by both the proposed method and the former official first action colorimetric method with comparable results. Potential interferences from surfactants currently employed in liquid formulations are avoided by the use of Florisil column chromatography. Malathion is eluted from the column with petroleum ether-ethyl ether with an average recovery of 92.5%.

Determination of Vitamins D2 and D3 in Pharmaceuticals by Gas-Liquid Chromatography

1968 ◽  
Vol 51 (4) ◽  
pp. 839-840
Author(s):  
T K Murray ◽  
P Erdody ◽  
T Panalaks
Keyword(s):  
Vitamin D ◽  
Liquid Chromatography ◽  
Vitamin A ◽  
Coefficient Of Variation ◽  
Internal Standard ◽  
Antimony Trichloride ◽  
The Other ◽  
Gas Liquid Chromatography ◽  
Partition Chromatography

Abstract A method is described for determining vitamin D in multivitamin preparations; in the method, vitamins D2 and D3 are isomerized with antimony trichloride and separated by GLC. Vitamins D,2 and D3 are differentiated and measured separately and one vitamin may be used as an internal standard for the other. Vitamin A is largely removed by partition chromatography but can be tolerated in the final dilution in a ratio of 1:1 with vitamin D. When the method was used for the assay of multivitamin preparations, the coefficient of variation was 3.2%.

Simultaneous Determination of Vitamins A and D in Dosage Forms by High Pressure Liquid Chromatography

1982 ◽  
Vol 65 (3) ◽  
pp. 619-623
Author(s):  
Maria Ines ◽  
R M Santoro ◽  
João F Magalhães ◽  
Erika R M Hackmann
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Vitamin A ◽  
Petroleum Ether ◽  
High Pressure Liquid Chromatography ◽  
Mobile Phase ◽  
Dosage Forms ◽  
Reverse Phase ◽  
Solvent Residues

Abstract Vitamins A and D were determined simultaneously in oily solutions, ointments, and elixirs, but only vitamin A could be determined in capsules. Samples were saponified with KOH in isopropanol-water, using hydroquinone as antioxidant, and extracted with ether-petroleum ether (1 + 1). After evaporation of solvent, residues were dissolved in isopropanol. Vitamins in these solutions were determined by reverse phase high pressure liquid chromatography, using methanol-water as mobile phase and detection at 254 nm. The reproducibility, using external standards, was 1.6-2.5% and 1.2-3.8% for vitamins A and D, respectively.

Gas-Liquid Chromatographic Determination of Kepone Residues in Finfish, Shellfish, and Crustaceans

1978 ◽  
Vol 61 (4) ◽  
pp. 877-883
Author(s):  
Richard A Carver ◽  
Arnold P Borsetti ◽  
Laverne R Kamps
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Petroleum Ether ◽  
Ethyl Ether ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract Finfish, shellfish, and crustacean samples are extracted with isopropanol and benzene; the extract is filtered and then concentrated. The extract, dissolved in hexane, is treated with oleum and extracted with aqueous alkali. The aqueous phase is acidified and extracted with petroleum ether-ethyl ether (1+1). The Kepone residue is determined by electron capture gas-liquid chromatography (GLC). Recoveries obtained by 8 laboratories from 15 species of finfish fortified at 0.02-0.23 ppm ranged from 37 to 107% with a mean ± relative standard deviation of 79.4±14.5%. For oysters fortified at 0.01- 0.10 ppm, recoveries range from 63 to 129% with a mean of 78.2 ±20.8%. For crustaceans fortified at 0.05—0.26 ppm, recoveries ranged from 52 to 110% with a mean of 78.8±16.4%. The approximate limits of quantitation for finfish and for shellfish and crustaceans are 0.02 and 0.05 ppm, respectively, under the GLC conditions used in this study.

Rapid Spectrophotometry Method for the Determination of Sorbic Acid in Fresh Dairy Products

1972 ◽  
Vol 55 (1) ◽  
pp. 07-08
Author(s):  
J J Maxstadt ◽  
A B Karasz
Keyword(s):  
Petroleum Ether ◽  
Ethyl Ether ◽  
Dairy Products ◽  
Sorbic Acid ◽  
Dairy Product ◽  
Metaphosphoric Acid ◽  
Absorbance Maximum ◽  
Ether Mixture ◽  
Ether Solution

Abstract A rapid and accurate spectrophotometry method for sorbic acid in fresh dairy products has been developed. Sorbic acid is extracted from the dairy product with aqueous metaphosphoric acid and partitioned into an ethyl ether-petroleum ether mixture. The concentration of sorbic acid is determined from its absorbance at 250 nm and its presence is confirmed by the disappearance of this absorbance maximum after shaking the ether solution with aqueous permanganate. The procedure is very rapid; an analysis can be completed in 1 hr. Recoveries of added sorbic acid from various dairy products average 97.9%.

Screening Procedure for Organothiophosphate Pesticide Residues on Fruits and Vegetables by Microeoulometric Gas Chromatography

1966 ◽  
Vol 49 (4) ◽  
pp. 763-766 ◽  
Author(s):  
Richard C Nelson
Keyword(s):  
Gas Chromatography ◽  
Petroleum Ether ◽  
Ethyl Ether ◽  
Pesticide Residues ◽  
Fruits And Vegetables ◽  
Petroleum Ether Extract ◽  
Water Layer ◽  
Ether Extract ◽  
Ppm Level

Abstract Microeoulometric gas chromatography (sulfur detector) has been extended to include additional cleanup of the petroleum ether extract, using Florisil columns of varying lengths with eluting mixtures of ethyl ether/dioxane in petroleum ether. Preliminary results show fair-to-good recoveries of most compounds and generally satisfactory cleanup of six crops. A procedure is presented for the extraction and determination of the thiophosphates remaining in the acetonitrile-water layer after petroleum ether partitioning. Recoveries of dimethoate (0.2–2.0 ppm level) and Guthion (2.0–10.0 ppm level) were 70% or better. Studies of the method will be continued, with emphasis on cleanup procedvires.

Polarity Determination in Sphalerite and Wurtzite Structures

1990 ◽  
Vol 48 (2) ◽  
pp. 500-501
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Opposite Polarity ◽  
Single Domain ◽  
Polar Material ◽  
Electron Microscopic ◽  
Dynamical Interaction ◽  
X Ray ◽  
Polarity Determination ◽  
The Absolute ◽  
Microscopic Techniques

The determination of the absolute polarity of a polar material is often crucial to the understanding of the defects which occur in such materials. Several methods exist by which this determination may be performed. In bulk, single-domain specimens, macroscopic techniques may be used, such as the different etching behavior, using the appropriate etchant, of surfaces with opposite polarity. X-ray measurements under conditions where Friedel’s law (which means that the intensity of reflections from planes of opposite polarity are indistinguishable) breaks down can also be used to determine the absolute polarity of bulk, single-domain specimens. On the microscopic scale, and particularly where antiphase boundaries (APBs), which separate regions of opposite polarity exist, electron microscopic techniques must be employed. Two techniques are commonly practised; the first [1], involves the dynamical interaction of hoLz lines which interfere constructively or destructively with the zero order reflection, depending on the crystal polarity. The crystal polarity can therefore be directly deduced from the relative intensity of these interactions.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

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