Possibilities and limitations of steam distillation—extraction as a pre-concentration technique for trace analysis of organics by capillary gas chromatography

Abstract

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Capillary gas chromatography/Fourier transform infrared spectroscopy using an injector/trap

“…Strong to weak GC peaks associated with three of these spectra are shown in Figure 3 (arrows). The corresponding infrared spectra are shown in Figures (4)(5)(6), respectively, and have been positively identified as phenethyl acetate (peak A), tetramethylpyrazine (peak B), and trimethylpyrazine (peak C), all known to be constituents of chocolate (8). Trimethylpyrazine has an absorptivity about 3 times less than that of p-dioxane.…”

“…Commercially available chocolate chips (10.0 g) were steam distilled in 100 mL of distilled water and the distillate was simultaneously extracted with 50 mL of predistilled Freon-11 for 90 min. The 50 mL of Freon containing the chocolate volatiles after this steam distillation-extraction (SDE) (6) was reduced in volume to 0.25 mL by a gentle sweep of nitrogen. A 100-µ sample of this Freon solution was injected into trap 1 set at +25°C ; other conditions were the same as those listed above for a typical loading sequence.…”

Solvent Extraction

“…The efficiency of the process is mainly controlled by the efficiency of the steam distillation step. 56,57 The decrease of the water solubility for various organic compounds that would favor distillation can be achieved by salting out the water solution. Various theoretical models have been proposed for the calculation of SDE recoveries.…”

Técnicas de aislamiento y concentración de volátiles de aceites vegetales

“…Es un método ampliamente utilizado que fue introducido por Likens y Nickerson en 1964 (Rijks, 1983). Consiste en que la muestra diluida en agua y el disolvente destilan de forma separada y condensan en la misma zona produciéndose en ella la extracción, separándose y recirculando posteriormente las dos fases.…”