Development of an online citrate/Ca2+ sensing system for dialysis
Yang Y, Szamosfalvi B, Yee J, Frinak S, Anslyn EV. Development of an online citrate/Ca2+ sensing system for dialysis. Analyst 2011; 136(2):317-320.
An online citrate and Ca2+ sensing system based on sequential injection analysis (SIA) is developed as a safety module for hemodialysis. Host 1 displays high affinity towards citrate, and was selected for this study owing to its unique structural features. The o-aminomethylphenylboronic moiety can effectively interact with the α-hydroxycarboxylate moiety of citrate and the remaining two guanidiniums may further stabilize the complex via hydrogen bonds. Fura-2 chelates to Ca2+ with a high selectivity and affinity and was utilized in this study for Ca2+ measurements. The citrate sensing chemistry via an indicator displacement assay is orthogonal to the Ca2+ sensing chemistry, and the use of sophisticated chemometrics is not required for data analysis. The citrate and Ca2+ concentrations in dialysate samples are measured with the developed SIA system. The obtained citrate concentrations were verified via a commercially available enzymatic assay and an NMR method, respectively, while the Ca2+ concentrations were verified via atomic absorption.