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

Rawlings, H. W.; Wait, G. H.

doi:10.1007/bf02544153

Cited by 12 publications

(3 citation statements)

References 11 publications

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“…Battery terminals and clips should be cleaned and checked frequently. Rawlings and Wait (20) reported that the first sign of failure of the B batteries was an erratic response which results in a fivefold increase in replicate standard deviation.…”

Section: Dark Currentmentioning

confidence: 99%

“…Any irreversible arisen concerning the accuracy expected from a given instrument. It is reported that, under certain conditions, the Beckman quartz spectrophotometer is capable of yielding transmittance readings with a precision of 0.1% (6,8), ±0.07% (20), or 0.02% (3) transmittance. Ewdng and Parsons (10) reported that although individual Beckman spectrophotometers may give highly consistent results, there is a spread of several per cent between the analytical results obtained from a series of different instruments.…”

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Variability in Beckman Spectrophotometer

Caster¹

1951

Anal. Chem.

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Section: Dark Currentmentioning

confidence: 99%

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confidence: 99%

Variability in Beckman Spectrophotometer

Caster¹

1951

Anal. Chem.

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“…This compares with 0.4343, the optimum density calculated by Twyman and Allsopp (9) for use with photoelectric instruments. Rawlings and Wait (6) working with vitamin A on the Beckman model DU spectrophotometer obtained the best reproducibility by working between 0.3 and 0.8 density unit.…”

Section: Reactionmentioning

confidence: 99%

Determination of Vitamin A in Fish Liver Oils with Activated Glycerol Dichlorohydrin

Sobel¹,

Werbin²

1947

Anal. Chem.

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The alkali refining of oils containing vitamin A

Hawtman¹

1950

J. Chem. Technol. Biotechnol.

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PG 80 PG 150 PG 250 11-67 x los 8.46 x los 4'41 x 1 0 s 7'87 x 1 0 s PG 350 5.69 x loL 1'97 x 1 0 5 1.04 x 10' ppg 4.g PG 900 0.33 X lo5 ConclusionI. An investigation was made of the changes, produced by dry grinding, in the position and slope of the straight line relating to the gel strength of weak gels and the square of the pectin concentration.2. Grinding produced (a) a marked increase in the amount of material estimated as calcium pectate but not contributing to gel formation and (b) a decrease in the rate at which the strength increases with increasing pectin concentration, i.e. a decrease in the slope of the line.3. The logarithm of the slope of the line is a linear function of the limiting viscosity of the corresponding pectin determined from data for the aqueous solution of the pectin itself and for the nitro-ester in acetone solution. The slope of the line is a function of the values of Young'smodulus for the material constituting the fibrils of the gels as calculated from the formula Contrary to thc previous opinion that alkali refining reduces considcrably the vitamin A potency of fish liver oils, it has been found that under usual refining conditions the neutralization with alkalis results in increased potency. The inncasc is approximately orooortioml to the free fattv acid content of the original oil. The IO,OOO blue units er gram the loss was over so"/u.Brocklesby conckdes in his book8 : " It thus appears probable that the pigments and vitamin A are preferentially adsorbed, and due regard to this phenomenon should be taken when treating oils containing vitamin A with alkaline solutions."

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

Cited by 12 publications

References 11 publications

Variability in Beckman Spectrophotometer

Variability in Beckman Spectrophotometer

Determination of Vitamin A in Fish Liver Oils with Activated Glycerol Dichlorohydrin

The alkali refining of oils containing vitamin A

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