# Viability of ABO Blood Typing with ATR-FTIR Spectroscopy
## 4 Conclusions  
Incorporating infrared spectrometry and chemometrics for ABO blood typing yields improved results compared to random classification, although it still falls short of competing with traditional immunological methods. The presence of the antigen 'B' appears to impart discernible characteristics to the blood sample, which can be easily detected with FTIR. In contrast, the antigen 'A' remains largely elusive using this technique, posing challenges in its identification. It is possible that the difficulty in identifying blood type A may be attributed to the existence of subgroups, mainly A1 and A2, within this serological type. While there are also subgroups for blood type B, the difference between them is less pronounced. This fact appears to support the findings obtained in this study [13]. Although the success rate is worse than in classic biochemical blood typing methods, this methodology emerges as a promising alternative.  
Conceptualization, A.F.-G. and R.B.-L.; methodology, A.F.-G.; software, A.F.-G.; formal analysis, T.F., A.F.-G. and C.C.-T.; investigation, R.B.-L.; resources, A.J.O. and T.F.; data curation, A.F.-G.; writing--original draft preparation, A.F.-G., A.J.O. and C.C.-T.; project administration, R.B.-L.; funding acquisition, R.B.-L.; informed consent and ethical aspects: A.J.O. All authors have read and agreed to the published version of the manuscript.  
The authors gratefully acknowledge the financial support from the Ministerio de Ciencia, Innovacion y Universidades (MCIU), the Agencia Estatal de Investigacion (AEI), and the European Regional Development Fund (FEDER), project # RTI2018-099756-B-I00 (MCIU/AEI/FEDER, UE).  
Ethical review and approval were waived for this study due to the utilization of leftover samples from analytical procedures prior to their use in blood donation.  
Patient consent was waived due to the utilization of aliquots taken from analytical samples obtained from anonymous blood donors.  
Data Availability Statement: Data are available upon request to the authors.  
We would like to thank the Centro Comunitario de Sangre y Tejdos de Asturias who kindly provided us with blood samples from anonymous donors. We would also like to acknowledge the vibrational and electronic spectroscopy unit from the Scientific-Technical Services of the University of Oviedo.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**NBC Classification**} & \multicolumn{4}{c}{**Random Classification**} \\ \hline  & \multicolumn{4}{c}{**Assigned Class**} & \multicolumn{4}{c}{**Assigned Class**} \\ \hline  & & A & B & AB & 0 & & A & B & AB & 0 \\ \cline{2-10} \multirow{4}{*}{**B-C**} & A & 7\% & 3\% & 0\% & 10\% & A & 5\% & 8\% & 2\% & 4\% \\ \cline{2-10}  & B & 3\% & 31\% & 7\% & 4\% & B & 8\% & 21\% & 5\% & 10\% \\ \cline{2-10}  & AB & 1\% & 8\% & 4\% & 1\% & AB & 2\% & 5\% & 2\% & 3\% \\ \cline{2-10}  & 0 & 12\% & 2\% & 0\% & 10\% & 0 & 4\% & 10\% & 3\% & 6\% \\ \hline  & & & & T+ & & T- & & F+ & & F- \\ \hline A-type success rate & \(\downarrow\) 7.1\% & \(\uparrow\) 66.2\% & \(\downarrow\) 14.7\% & \(\searrow\) 12.1\% & \\ \hline B-type success rate & \(\searrow\) 31.3\% & \(\
earrow\) 42.9\% & \(\searrow\) 12.1\% & \(\downarrow\) 13.6\% & \\ \hline AB-type success rate & \(\downarrow\) 3.5\% & \(\uparrow\) 80.8\% & \(\uparrow\) 7.1\% & \(\uparrow\) 8.6\% & \\ \hline
0-type success rate & \(\downarrow\) 10.1\% & \(\uparrow\) 62.1\% & \(\downarrow\) 14.1\% & \(\downarrow\) 13.6\% & \\ \hline IMAC Success rate & \(\downarrow\) 13.0\% & \(\uparrow\) 63.0\% & \(\searrow\) 12.0\% & \(\searrow\) 12.0\% & \\ \hline \hline \end{tabular}
\end{table}
Table 9: IMAC blood typing confusion matrix.