A method for the measurement of vitamin B₁₂concentration in sea water

Abstract

The vitamin B12 concentration in sea water is so very low that only the most sensitive microbiological assay techniques are likely to be capable of measuring it, but the salt concentration is so high as to be inhibitory to most of the organisms conventionally used for the microbiological assay of the vitamin. Nevertheless, the consideration that vitamin B12 concentration may have an influence on the amounts and types of life present in sea areas has persuaded several investigators to attempt its measurement.The methods so far employed have each their own advantages and dis-advantages (Droop, 1954, 1955; Lewin, 1954; Sweeney, 1954; Cowey, 1956; Adair & Vishniac, 1958). The method to be described here offers advantages in sensitivity, permitting direct measurement of the vitamin in small quantities of oceanic waters after further dilution; samples to be measured pass through comparatively few different containers and thus there is less risk of their accumulating adventitious vitamin; simple and easily cleaned apparatus is used, and much less bench-work is involved than when methods other than dilution are used for lowering the salt concentration.

Bioassay and Distribution of Thiamine in the Sea1

“…The standard error of estimate of one standard curve is plotted in Fig. 3 to provide an indication Ryther and Guillard (1962) and Daisley (1958). The reduced recovery of the internal standards also may indicate the presence of inhibitors to the yeast.…”

Vertical distribution of vitamin B12in the sea

“…The water was collected in a Nansen Pettersson bottle and in Nansen reversing bottles, then filtered through Whatman No. 3 filter-paper, preserved and assayed by the Euglena method as already described (Daisley, 1958). The 1956 samples were assayed twice each and the mean values are given in Table i; the 1957 samples were assayed once only.…”

Microbiological Assay for Organic Compounds in Seawater

“…Summaries of these studies have been published by Provasoli (1960Provasoli ( , 1963 and Belser (1963). Most of the cited work, however, has involved extraction (Cowey, 1956), desalting (Provasoli and Pintner, 1953), dilution (Daisley, 1958), and algal assays (Provasoli 1963), which required long incubation periods.…”