On the Influence of Additives and Modifiers on the Chiral HPLC Separation of the Enantiomers of Nicotine.

The influence of additives and modifiers on the chiral HPLC separation of the nicotine enantiomers using UV/Vis detection is discussed. Selected alcohols as modifiers and selected amines as additives were found to have a significant effect on the resolution and retention times of nicotine enantiomers even to the point of eliminating component elution. Systematic variations in the concentration of ethanol, methanol, and isopropanol, as modifiers, along with variations in the concentration of diethylamine, triethylamine, tributylamine, ethylenediamine, isopropylamine, as additives, revealed that the average resolution (R) of the nicotine enantiomers ranged from 2.

Tumour growth rate and invasive interval cancer characteristics in a UK breast cancer screening population.

Objectives: To estimate tumour volume doubling time (TVDT) of interval cancers (ICs).

Methods: Two radiologists retrospectively reviewed prior screening and diagnostic mammograms and measured mean diameter on "visible" ICs. Univariate analyses of clinicopathological variables (ER, HER2, grade, age at diagnosis, and breast density) were undertaken, and those with p < 0.