A New Approach on the Amino Acid Lysine Quantification by UV-Visible Spectrophotometry

Abstract

The methodology of the amino acid lysine (Lys) analysis using ninhydrin (Nin) reagent by spectrophotometric method was in-depth studied and improved. The optimization of time, Lys to Nin volume ratio and temperature were explicitly investigated. A specific wavelength of 479 nm was set according to the peak of the absorbance spectrum. The reaction time between Lys and Nin, in aqueous solution, occurs during 50 min. The Lys/Nin ratio 1.67 appeared most effective for this reaction. Moreover, the absorbance increased with temperature until a stable value was achieved nearly at 85�C. It was also found that the reaction is more efficient at initial pH 6 corresponding to formation of high amount of coloured product. Furthermore, the pH of post-reaction mixture was around 4 for different concentrations of lysine and initial pH range 3�10. For lysine solution contaminated with potassium (a representative interfering species) and after variation of the reaction conditions, the maximum wavelength (479 nm) was not affected. Mastering the use of these parameters leads to a good usage of this analytical technique which is simple, fast, accurate, less expensive and especially less harmful towards the environment and human health.

Synthesis, structure, Hirschfeld surface analysis and Molecular docking studies of polymorphus of 4-amino 3-nitrobenzoic acid

“…In this area, n→π* transitions of unshared electron pairs in nitro group (-NO 2 ) oxygens in 4-amino-3-nitrobenzoic acid was observed. In the UV-C region (280 − 100 nm), the highest increase was observed due to n→σ* transitions in the amine (-NH 2 ) group under the in uence of UV rays with a wavelength of 259 nm [12][13]. The n→π* transition in the carboxyl group and the π→π* transitions in the aromatic ring were recorded in < 200 elds, so it is not possible to obtain complete information [14].…”

Water-soluble total sugars and total free amino acids of the two varieties of teff [Eragrostic tef (Zuccagni) Trotter] cultivated in different regions of Ethiopia

“…Amino acids (AAs) are indispensable nutritional constituents for body growth and many biological activities. They function in regulating gene expression, preventing tumorigenesis, suppressing obesity, and reducing blood pressure [21][22][23]. In human organisms, amino acids take part in building the protein chain, but there is always a pool of free amino acids (FAA) [23] required for survival, growth and development, reproduction, lactation and maintaining health throughout life.…”

“…The apparent relationship reported between the food levels of the free amino acids (FAAs) and organoleptic qualities has prompted scientific research in to FAA composition in food [26,27]. On top of this, there is also growing demand for amino acids as value added substances since they have many potential applications in the food, clinical, pharmaceutical and cosmetic industries, among others [22].…”