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SummaryIn an 8 year prospective study (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985) on breast cancer, blood was taken from 5,086 women resident in Guernsey, and the serum stored at -20°C. During With the availability of a series of some 5,000 serum samples from a new prospective breast cancer study on women resident on the island of Guernsey, it seemed appropriate to re-investigate the problem using a newly developed high performance liquid chromatography (HPLC) method which included butylated hydroxytoluene (BHT) as an antioxidant (Russell et al., 1986). In addition, serum retinol binding protein (RPB), which is a good indicator of nutritional status (Gofferje, 1978;Tyler et al., 1984) Serum retinol and a-tocopherol were measured by HPLC (Russell et al., 1986). Several workers (Chow et al., 1983;Driskell et al., 1985) have shown that the addition of antioxidant at the extraction stage of the analysis prevents the loss of vitamin A, even in frozen stored serum samples. We have also found that with the addition of BHT, both vitamins A and E are stable, in that there is no significant correlation between time in storage and titre (Russell et al., 1986).The RBP was assayed by the Behring LC-Partigen Immunodiffusion Plate method from Hoechst Pharmaceuticals Ltd., Hounslow, UK. After addition of the serum to each well on the assay plates, they were left for 48 h at room temperature before measurement of the diffusion area. ResultsThe statistical analyses of the results were by the two-tailed Student's t test and also by use of a non-parametric ranking test on a case-control basis (Cuzick, 1985). There were no significant differences between the plasma concentrations of vitamin A, RBP and vitamin

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SummaryAn HPLC method utilizing a UV and a fluorimetricdetector linked in series is described. By use of a simple integrator-controlled time-switched relay, analysis of serum vitamins A and E is accomplished on the same chromatogram and at optimum sensitivity for each detector. A single internal standard (retinyl acetate) monitored only by the UV detector permits measurement of both vitamins over a wide linear range. Precision of the assays is satisfactory, both on a within-day and on a day-to-day basis. Recoveries of both vitamins are virtually 1000/0 whilst sensitivity is 2 pg/L (retinol) and 0.05 mg/L (a-tocopherol).

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