SALMEN ® - A COMPLEXATION REAGENT FOR Cr (III)

The biological activity of chromium (essential oligoelement) depends on its valence and on the chemical structure of the formed complex combinations. The present spectrophotometric method has been established for the quantitative assay of Cr (III), and it is based on its complexation with N,N’‐bis (salicyliden)-methylendiamine (noted Salmen ® ), when a stable complex is formed, which has a maximum of absorption at 326 nm. The developed method has been validated and was characterized by a good linearity in the range of 0.5‐5.0 µg/mL (correlation coefficient r = 0.9999). The established detection limit (LOD) was 0.066 µg/mL and the quantification limit (LOQ) was 0.22 µg/mL. There were determined the precision of the method (RSD = 1.63%) and the accuracy (the mean recovery was established at 100.17%, the recovery values being in the range 98.0‐102.3 %). The proposed and validated method was applied for the determination of Cr(III) from a nutritional supplement that contained the salt chromium picolinate, and the results were good. Rezumat Activitatea biologică a cromului (oligoelement esenţial) depinde de valenţa sa si de structura chimică a combinaţiilor complexe formate. Pentru determinarea cantitativă a cromului s-a elaborat o metodă spectrofotometrică ce constă in complexarea lui cu N,N‐bis (saliciliden)-metilendiamina (notat Salmen ® ) cu formarea unui complex stabil ce prezintă un maxim de absorbţie la 326 nm. Metoda propusă a fost validată si prezintă o bună liniaritate in domeniul 0,5‐5,0 µg/mL (coeficientul de corelaţie r = 0,9999). Limita de detecţie găsită este 0,066 µg/mL si limita de cuantificare 0,22 µg/mL. S-au determinat precizia metodei (RDS = 1,63%) si exactitatea (regăsirea medie fiind de 100,17% pe domeniul 98,0‐102,3%). Metoda propusă si validată, a fost aplicată la determinarea Cr(III) din suplimentul alimentar ce conţine sarea picolinat de crom cu bune rezultate.