Optimisation of the retention step comprised type, concentration
and pH value of buffers used as reaction media. Buffer solutions of citrate,
oxalate, phthalate and acetate at different concentrations and
pHs were tested, leading to 12 conditions. For the elution step four eluents
namely, HCl, citric acid, L-cysteine and tartaric acid were tested
leading to four conditions. Both variables (reaction media and eluent)
were studied simultaneously and Table 2 summarises the conditions
for each variable. Full combination of the variables led to 48 cases.