A salting-out assisted liquid-liquid extraction method followed by high performance liquid chromatography with ultravio-let-visible detector(SALLE-HPLC-UV/Vis)has been proposed for determination of caffeine and nicoti...A salting-out assisted liquid-liquid extraction method followed by high performance liquid chromatography with ultravio-let-visible detector(SALLE-HPLC-UV/Vis)has been proposed for determination of caffeine and nicotinic acid in raw and roasted coffee samples.Various parameters affecting chromatographic separations including mobile phase composition,injec-tion volume,flow rate and column temperature were studied.Experimental parameters affecting the extraction efficiency of SALLE method such as type and volume of the organic solvent,type and amount of salt,pH of the sample,and concentration of the ion-pairing reagent were also studied and thereby optimum conditions were established.The calibration curves which were constructed at five different concentration levels using the optimum conditions exhibited good linearity,with the coef-ficient of determination(R2)0.999 and 0.995 for caffeine and nicotinic acid,respectively.The limits of detection(LOD)and quantification(LOQ)which were determined at 3 and 10 times signal-to-noise ratio were 0.05 and 0.13 mg/L for nicotinic acid and 0.20 and 0.63 mg/L for caffeine,respectively.Intra-and inter-day precision studies were demonstrated satisfactory precision with RSD values below 10.Relative recoveries were also studied,and their results were ranging from 82-122%for both raw and roasted coffee samples.The findings demonstrated that the proposed method could be used as an effective and best alternative for the determination of caffeine and nicotinic acid in raw and roasted coffee samples.展开更多
The use of dyes such as tartrazine (E102) and sunset yellow (E102) in food, beverages and health products for technological and commercial purposes is common. The adverse effects caused by these dyes, such as allergie...The use of dyes such as tartrazine (E102) and sunset yellow (E102) in food, beverages and health products for technological and commercial purposes is common. The adverse effects caused by these dyes, such as allergies and hyperactivity disorder have been reported, especially in children. In the present study, a chromatographic method was developed and validated for simultaneous determination of tartrazine and sunset yellow. The chromatographic separation was performed on a Lichrocart<sup>®</sup> C18 column (125 × 4.6 mm;5 μm) with a security Guard-C18 column (4 × 2.0 mm, 5 μm;Phenomenex, Torrance, CA, USA) maintained at 30°C. The mobile phase consisted of a mixture of acetonitrile/ammonium acetate buffer pH 6.8 in gradient mode with a flow rate of 1 mL/min. The injection volume was 10 μL. The detection wavelength was set at 455 nm. The parameters of specificity, linearity, precision, repeatability, accuracy and sensitivity were examined for validation. The developed method is linear in the range of 1 μg/mL to 100 μg/mL with a R<sup>2</sup>> 0.998. The intra-day and inter-day precisions (RSD) were less than 0.6% and 3.1% respectively. The detection limit was 0.03 μg/mL and the quantification limit was 0.1 μg/mL. The retention time of tartrazine was 2.86 min, while sunset yellow was detected at 5.67 min. A simple, rapid, accurate and robust HPLC/UV-Visible method was developed and validated for simultaneous identification and quantification of tartrazine and sunset yellow. This developed method was successfully applied for the simultaneous determination of tartrazine and sunset yellow in soft drinks sold in Benin.展开更多
For the production of a reference material from caffeine solution, one of the methods of characterization was HPLC-UV since caffeine is very sensitive to the UV. In this work, a batch solution of caffeine in water ref...For the production of a reference material from caffeine solution, one of the methods of characterization was HPLC-UV since caffeine is very sensitive to the UV. In this work, a batch solution of caffeine in water reference material of 1000 mg/kg has been gravimetrically prepared using a calibrated analytical balance. A sample of this solution was diluted to 25 mg/kg for measurement by HPLC-UV in the range 10 - 50 mg/kg. The chromatographic separation was carried out by C-18 column and a mobile phase assembled of 75% water and 25% methanol (v:v). The detection was made by the UV detector at 275 nm. The validation of this analytical method was carried out in accordance with requirements of the EURACHEM and ICH guidelines. The selectivity, linearity, accuracy, precision and trueness (recovery and bias) of the method were studied. The validation results proved that the method is fit-for-purpose of measuring the caffeine concentration in water in the range 10 - 50 mg/kg using HPLC-UV.展开更多
文摘A salting-out assisted liquid-liquid extraction method followed by high performance liquid chromatography with ultravio-let-visible detector(SALLE-HPLC-UV/Vis)has been proposed for determination of caffeine and nicotinic acid in raw and roasted coffee samples.Various parameters affecting chromatographic separations including mobile phase composition,injec-tion volume,flow rate and column temperature were studied.Experimental parameters affecting the extraction efficiency of SALLE method such as type and volume of the organic solvent,type and amount of salt,pH of the sample,and concentration of the ion-pairing reagent were also studied and thereby optimum conditions were established.The calibration curves which were constructed at five different concentration levels using the optimum conditions exhibited good linearity,with the coef-ficient of determination(R2)0.999 and 0.995 for caffeine and nicotinic acid,respectively.The limits of detection(LOD)and quantification(LOQ)which were determined at 3 and 10 times signal-to-noise ratio were 0.05 and 0.13 mg/L for nicotinic acid and 0.20 and 0.63 mg/L for caffeine,respectively.Intra-and inter-day precision studies were demonstrated satisfactory precision with RSD values below 10.Relative recoveries were also studied,and their results were ranging from 82-122%for both raw and roasted coffee samples.The findings demonstrated that the proposed method could be used as an effective and best alternative for the determination of caffeine and nicotinic acid in raw and roasted coffee samples.
文摘The use of dyes such as tartrazine (E102) and sunset yellow (E102) in food, beverages and health products for technological and commercial purposes is common. The adverse effects caused by these dyes, such as allergies and hyperactivity disorder have been reported, especially in children. In the present study, a chromatographic method was developed and validated for simultaneous determination of tartrazine and sunset yellow. The chromatographic separation was performed on a Lichrocart<sup>®</sup> C18 column (125 × 4.6 mm;5 μm) with a security Guard-C18 column (4 × 2.0 mm, 5 μm;Phenomenex, Torrance, CA, USA) maintained at 30°C. The mobile phase consisted of a mixture of acetonitrile/ammonium acetate buffer pH 6.8 in gradient mode with a flow rate of 1 mL/min. The injection volume was 10 μL. The detection wavelength was set at 455 nm. The parameters of specificity, linearity, precision, repeatability, accuracy and sensitivity were examined for validation. The developed method is linear in the range of 1 μg/mL to 100 μg/mL with a R<sup>2</sup>> 0.998. The intra-day and inter-day precisions (RSD) were less than 0.6% and 3.1% respectively. The detection limit was 0.03 μg/mL and the quantification limit was 0.1 μg/mL. The retention time of tartrazine was 2.86 min, while sunset yellow was detected at 5.67 min. A simple, rapid, accurate and robust HPLC/UV-Visible method was developed and validated for simultaneous identification and quantification of tartrazine and sunset yellow. This developed method was successfully applied for the simultaneous determination of tartrazine and sunset yellow in soft drinks sold in Benin.
文摘For the production of a reference material from caffeine solution, one of the methods of characterization was HPLC-UV since caffeine is very sensitive to the UV. In this work, a batch solution of caffeine in water reference material of 1000 mg/kg has been gravimetrically prepared using a calibrated analytical balance. A sample of this solution was diluted to 25 mg/kg for measurement by HPLC-UV in the range 10 - 50 mg/kg. The chromatographic separation was carried out by C-18 column and a mobile phase assembled of 75% water and 25% methanol (v:v). The detection was made by the UV detector at 275 nm. The validation of this analytical method was carried out in accordance with requirements of the EURACHEM and ICH guidelines. The selectivity, linearity, accuracy, precision and trueness (recovery and bias) of the method were studied. The validation results proved that the method is fit-for-purpose of measuring the caffeine concentration in water in the range 10 - 50 mg/kg using HPLC-UV.
