Doxorubicin (DOX) is a widely used anthracycline that has been effective in treatments of leukemia and breast cancer in humans (A. B. Anderson, C. M. Ciriaks, K. M. Fuller, and E. A. Ariaga, Anal. Chem., 2003, 75,8). Unfortunately, side effects, such as liver toxicity and drug resistance, have been reported. In a recent study, Anderson et al. used laser-induced fluorescence (LIF) as a detection mode for CE to investigate metabolites of DOX in single cells and subcellular fractions. The following are results similar to those obtained by Anderson et al. for quantifying doxorubicin by LIF. The CE peak areas were measured as a function of the DOX concentration to construct a calibration curve.
(a) Find the equation for the calibration curve and the standard deviations of the slope and intercept. Find the R2 value.
(b) Rearrange the equation found in part (a) to express concentration in terms of the measured area.
(c) The limit of detection (LOD) for DOX was found to be 3 X 10-11 M. If the injection volume was 100 pL, what was the LOD in moles?
(d) Two samples of unknown DOX concentration were injected and peak areas of 11.3 and 6.97 obtained. What were the concentrations and their standard deviations?
(e) Under certain conditions, the DOX peak required 300 s to reach the LIF detector. What time would be required if the applied voltage were doubled? What time would be required if the capillary length were doubled at the same applied voltage?
(f) The capillary used in part (e) under normal conditions had a plate count of 100,000. What would N be if the capillary length were doubled at the same applied voltage? What would N be if the applied voltage were doubled at the original capillary length?
(g) For a 40.6-cm-long capillary of inside diameter 50 μm, what would the plate height be for a capillary with N = 100,000?
(h) For the same capillary as in part (g), what is the variance σ2 of a typical peak?