Extra Column Dispersion - Dispersion in Unions and Stainless Steel Frits > Page 36

The results obtained from the different types of union are given in Table 3.

Table 3. Dispersion in Normal and Drilled-Out Unions


Union Type Variance (ml2)
Normal 1.464
Drilled-Out 0.113


It is seen that the low dead volume union can still cause significant peak dispersion, however, by drilling out the union, so that the conduit tubes or conduit tube and microbore column can face up to each other, the dispersion is greatly reduced. This is a fairly simple modification but requires some care in the assembly of the union to ensure the conduit and column are touching.

The same authors also measured the dispersion arising from stainless steel frits and their results are shown in figure 16. They measured the dispersion that occurred in a sandwich of frits contained in a drilled out union so that the dispersion could be plotted against the number of frits.

Figure 16. Graph of Peak Variance against Number of Frits