The separation of aliphatic amines in dilute aqueous solution by gas chromatography and application of this technique to the quantitative analysis of tri‐ and dimethylamine in fish

Abstract

Gas chromatography on an alkaline Dowfax 9N9 column has been found to be suitable for the qualitative and quantitative analysis of alkylamines in dilute aqueous solution. The method has been applied to the analysis of trimethylamine (TMA) and dimethylamine (DMA) in fish and has been used to throw further light on uncertainties concerning the use of the "picrate" procedure for TMA determination. IntroductionAs a first step in dealing systematically with the analysis of flavour extracts from fish the extracts can be separated into neutral, basic and acidic fractions; such a preliminary separation will facilitate the execution and interpretation of the subsequent detailed analysis. For the analysis of volatile compounds within one of these groups their low concentration and the probable complexity of the mixtures indicate gas chromatography (g.c.) as the method of choice. In the case of the basic and acidic fractions, however, the polar nature of the solutes together with the desirability of analysing them in dilute aqueous solution make gas-liquid chromatography (g.1.c.) analysis difficult. Numerous workers have reported severe peak "tailing" and the appearance of "ghost" or "memory" peaks when attempting to chromatograph such solutions.In accordance with the general strategy outlined above it was necessary to find a g.1.c. column system which was capable of separating and quantifying mixtures of aliphatic amines in dilute aqueous solution; these compounds can form an important part of the basic fraction of flavour extracts from fish. A literature search indicated that a number of column packing materials were useful, to varying degrees, for this purpose and were experimented with.It was found that the Dowfax 9N9-NaOH column reported by O'Donnell and Mann' met our requirements to a high degree. The original system has been modified slightly by us and under these conditions direct quantitative analysis of amine hydrochlorides is possible, the free bases being liberated in situ on the column. This quantitative procedure has been exploited for the analysis of trimethylamine (TMA) and dimethylamine (DMA) in fish and results compared with those obtained by purely chemical techniques.

Studies on the Proximate Composition, Quality and Heavy Metal Concentration of two Sun-Dried Marine Fish (Sun-Dried Silver Pomfret and Sun-Dried Perch) of Cox’s Bazar District of Bangladesh

“…Selection of appropriate method for accurate determination of TVB-N is important. Literature suggests that a number of methods for TVB-N determination have been proposed by many researchers (Miller et al, 1972;Keay and Hardy, 1972;Murray and Gibson, 1972;Gruger, 1972;Ritskes, 1975;Ruiter and Weseman, 1976;Ward et al, 1979;Parris, 1984;Bhotta et al, 1984).…”

An investigation of the method of determining trimethylamine in fish muscle extracts by the formation of its picrate salt — Part II

“…There was no loss of amine at the vacuum drying stage as standard solutions in 0.6 N HC1 showed 100% recoveries. The results for the standard solutions (Keay & Hardy, 1972), indicate higher recoveries of TMA and of DMA when K O H is used as alkali compared to Ii,CO,. Table 3 shows the results found with extracts from iced fish.…”

The quantitative determination of trimethylamine in egg

“…A variety of different column preparations exists in the literature, many of which require treatment of the liquid phase with alkali. Much of the development work in this paper was carried out using a flame ionization detector and the Dowfax DN9/KOH on Silocell C22 column described by ODonnell & Mann (1964) and modified by Keay & Hardy (1972) but it proved unreliable at the low levels of trimethylamine involved in this problem. (The Dowfax DN9 phase has now been discontinued and Triton X-100 suggested as a replacement (Phase Separations Ltd.) but we have not investigated this phase.)…”