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A simple, rapid, precise and accurate method for determining the fluorescent whitening agents commonly used in detergents is described. The method is based on simple extraction from the detergent by methanol and on direct injection of the extract, without further purification. The extracted whitening agents were separated using a reversed-phase column (RP-18) and by ion-pair formation. The mobile phase was methanol -water (43 + 57) containing 0.005 M triethylammonium chloride, 0.002 5 M sodium acetate and 0.002 5 M acetic acid. Depending on the type of whitening agent present, the determination can be simplified by using methanolwater (1 + 1 ) as the mobile phase. Fluorimetric detection makes the method highly sensitive and specific.

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SummaryTocopherol analysis in margarine is usually carried 01 by HPLC after saponification of the sample and extraction of the vitamin compounds; these steps consume both time and solvents. In this paper we propose an on-line HPLC-HRGC coupling method, which allows us to simplify the preparation of the analytical sample. The sample of margarine is solubilized in hexane in an ultrasonic bath in the dark; the filtered solution is then injected into the liquid chromatograph using a normal phase microbore column eluted with hexane-isopropanol99.8:0.2. The a-tocopherol, which is eluted with some wax esters, is transferred on-line to the gas chromatograph, using a loop-type interface with the concurrent eluent evaporation and solvent vapor exit, thus it is separated from interfering compounds and determined using an Alltech RSL 300 column (22 m x 0.25 km i.d., 0.2 pm film thickness). The p, y, and 6-tocopherols are determined in the same LC run, using fluorimetric detection. The analysis was carried out in 50 min.