Spectrofluorometrical Determination of Vitamin B1 in Different Matrices Using Box‐Behnken Designed Pipette Tip Solid Phase Extraction by a Carbon Nanotube Sorbent

Abstract This study describes development of a method for spectrofluorometrical determination of thiamine (vitamin B 1 ) in vitamin tablets, cactus fruits, multivitamin syrups, and human plasma after its extraction by pipette tip micro‐solid phase extraction using carbon nanotube as sorbent. A response surface methodology was used for experimental design to obtain optimal response. Ten variables including pH of the sample solution, type and volume of eluent solvent, volume of sample solution, effect of ionic strength, concentration of K 3 [Fe(CN) 6 ] (as derivatizing agent), concentration of NaOH, number of cycles of extraction and elution and amount of sorbent were regarded as factors in the optimization study by Box‐Behnken design. Figures of merit were calculated as: detection limit; 0.16 μg L −1 , enrichment factor; 91, linear calibration curve in the range of 0.5‐130.0 μg L −1 ; and reproducibility (as RSD %) better than 2.4%. The method was applied to the determination of different real samples successfully.