Determination and Analysis of Metals in Freshwater Microalgae (Chlorella vulgaris and Spirulina platensis) through Total Reflection X-ray Fluorescence Spectroscopy (TXRF)

Abstract

This work investigates the concentration of some trace elements in freshwater microalgae ( Chlorella vulgaris and Spirulina platensis) through total reflection x-ray fluorescence spectroscopy (TXRF). Slurry samples were prepared from 3.4 ± 0.5 to 9.8 ± 0.5 mg of freeze-dried algae biomass for direct metals analysis. Gallium was used as internal standard at concentration of 500 µg/L and the solution was mixed for 15 second using vortex. The concentrations of different metals including Magnesium (Mg), Zinc (Zn), Phosphorus (P), Sulphur (S), Copper (Cu), Potassium (K), Calcium (Ca), Manganese (Mn) and Iron (Fe) were determined in the ranged 6.8 ± 1.7 – 15709 mg/kg. A similar study investigated the total macro and micronutrient profile Chlorella vulgaris and the published data agree with current study. Statistical analysis shows that only Ba has significant difference between Chlorella vulgaris and Spirulina platensis (P = 0.05) The two investigated algal species shows a measurable concentration using TXRF of metals such as manganese, iron, copper, and zinc. TXRF shows good accuracy with ability to determine sample in small quantities (µl) In conclusion, the sensitivity of TXRF technique can also be seen in determining elements with lower atomic number such as Ca, P and K.