What is the main difference between single sweep polarography and ordinary polarography? Why can't we speed up the voltage scanning rate infinitely to improve the sensitivity?

The main difference is that the polarization rate of single sweep polarography is faster. As a quantitative basis, the peak current is proportional to the square root of the voltage scanning rate. However, the sensitivity cannot be improved by infinitely accelerating the voltage scanning rate, because when the voltage scanning rate increases, the charging current also increases.