No abstract

A study on voltammetric analysis of blood serum diluted in a phosphate buffer is presented using advanced square-wave voltammetry at an edge plane pyrolytic graphite electrode. The results demonstrate that even in a complex medium like human blood serum, electrochemical characterization can be achieved through the use of advanced voltammetric techniques in conjunction with an appropriate commercially available electrode, such as the edge plane pyrolytic graphite electrode, which boosts superior electrocatalytic properties. Without undergoing any chemical treatment of the serum sample, the square-wave voltammetry technique reveals, for the first time, the electrode reactions of uric acid, bilirubin, and albumin in a single experiment, as represented by well-defined, separated, and intense voltammetric signals. All electrode processes are surface-confined, indicating that the edge plane sites of the electrode serve as an ideal platform for the competitive adsorption of electroactive species, despite the extensive chemical complexity of the serum samples. The speed and differential nature of square-wave voltammetry are crucial for obtaining an outstanding resolution of the voltammetric peaks, maintaining the quasi-reversible nature of the underlying electrode processes, while reducing the impact of follow-up chemical reactions that are coupled to the initial electron transfer for all three detected species, and minimizing fouling of the electrode surface.

A simple, rapid and reliable RP-HPLC-DAD method for the analysis of 19 amino acids in the protein hydrolysate of chemically treated hair is developed. The pre-column dansylation and RP-HPLC separation were optimized and peak resolution was improved as compared to previously published HPLC methods. The developed method showed excellent linearity for all tested amino acids in the concentration range 0.05-0.5 mmol/l. The obtained results show that the concentration of all amino acids detected in bleached hair decreases with increasing the concentration of hydrogen peroxide, this is most significant for cystine, compared to virgin hair. Higher amounts of the typical amino acids for keratin have been measured after exposure of hair to protein treatments. The method has been shown as very useful for amino acids analysis in a protein hydrolisate and it can be also used for establishing the amino acid profiles of other protein samples using this optimized procedure.