Al-Cit和A-Cf是什么？

最好能将文献片段上传，不然这样很难分析！

您好！以下是部分原文

Taking Al-Cit and Al-Tf as model species for small-molecule
and large-molecule Al species, respectively, the retention behaviors
of different Al species on CHAPS modified C18 column were further
investigated by on-line ICP-MS detection, the chromatograms
were shown in Fig. 3. As could be seen, the retention times on
the modified C18 column were about 2.72 min for Al-Cit and
2.36 min for Al-Tf, which was consistent with the results obtained
by UV detection. Further studies indicated that the recoveries
for small-molecule Al-complex compounds and large-molecule