Chemical structure and vitamin A activity

An in situ assessment of the specific lysis rate in continuous cultures ofMethylococcussp. (NCIB 11083) grown on methane

“…It is possible that the difference between the two techniques reflects the presence of a large percentage of dead cells which have [5] and [lID with and without correction for the specific lysis rate It is assumed that the specific lysis rate in the mixed culture is the same as in the pure culture. The maintenance coefficients were calculated from the in situ rates of methane and oxygen uptake at various dilution rates [6,8] extrapolated to zero growth rate.…”

“…Further, because the specific lysis rate increases with growth rate (Fig. 1), the extrapolated yields (calculated from the reciprocal of the slope [6] of the situ methane and oxygen uptake rates [8] against dilution rate) can be corrected for lysis rate e.g. the extrapolated yield on methane for a methane-limited, ammonia-grown mixed culture is 13.6 g mo1-1 and on oxygen is 9.6 g mo1-1 , but these decrease to 12.6 g tool -1 and 8.8 g mol -t respectively when corrected for the specific lysis rate.…”

“…This is of practical importance because in a single cell protein process the lyric products will have to be removed from the culture via added heterotrophic bacteria [5] so that the carbon is retained within the biomass and the build up of lyric products with associated foam production is avoided. It is also of theoretical importance [7] because when the specific growth rate of the viable cells is greater than the dilution rate, then estimations of the maintenance coefficient [8] via plots of in situ oxygen and methane uptake rates against dilution rate [6] rather than against the specific growth rate will be in error.…”

Insights into Analytical Precision: Understanding the Factors Influencing Accurate Vitamin A Determination in Various Samples

“…Elmer McCollum and Marguerite Davis' groundbreaking work in the early 1910s, emphasizing the vital role of vitamin A in human health, catalyzed the interest in analytical methodologies [16]. The development of analytical methods faced challenges, primarily due to the intricate nature of vitamin A's chemical structure and the existence of multiple isomers [19][20][21]. These isomers encompass various forms, such as all-trans-, 13-cis-, 11-cis-, 9-cis-, 9,13dicis-, and 11,13-dicis-retinol [22].…”

“…Initial techniques, including colorimetric assays and spectrophotometric analyses, provided a starting point, but were restricted by issues related to specificity and sensitivity [23,24]. The interference posed by other dietary The development of analytical methods faced challenges, primarily due to the intricate nature of vitamin A's chemical structure and the existence of multiple isomers [19][20][21]. These isomers encompass various forms, such as all-trans-, 13-cis-, 11-cis-, 9-cis-, 9,13dicis-, and 11,13-dicis-retinol [22].…”