Regarding the letter from Dr. Yuh-Shan Ho, submitted to Electronic Journal of Biotechnology, we would like to address the following topics:

1.      We considered that the concept of pseudo-second order kinetics is well established among researchers from this area, and we believe that it is no longer necessary to include reference(s) regarding this point. In our paper submitted at Electronic Journal of Biotechnology (http://www.ejbiotechnology.info/content/vol6/issue3/full/5/index.html), we have included some literature references, discussing kinetics of sorption by biological materials, and those papers did not mention the original Lagergren's or Ho's works, as well. We consider that, once a model is accepted by scientific community (represented by its citation and/or use in the technical literature), there is no need to keep on mentioning works previously dealing with such model. We also believe that "A research paper's contribution exists not only in its originality and creativity but also in its continuity and development for research that follows", as stated by Dr. Ho. On the other hand, we also consider that the wide acceptability of models by the scientific community is the best means of providing credibility to such models, so, there is no need to mention original references to every published papers.

2.      Dr. Ho suggests that Ho's pseudo-second order kinetic expression paper should be cited by us in the above mentioned paper. I believe that, for editorial reasons, it is impossible, in 2004, to change a paper that has already been published in 2003 at Electronic Journal of Biotechnology, to include Dr. Ho's reference.