Is Titration as Accurate as HPLC for Determination of Vitamin C in Supplements? <br/>—Titration versus HPLC for Vitamin C Analysis

Herein, the iodometric titration and HPLC-RP methods were compared for the determination of vitamin C in vitamin and mineral supplements. The methods were validated in terms of linearity, limits of detection (LOD), limits of quantification (LOQ), precision, and recovery by using vitamin standards and a reference material SRM 3280 (multivitamin/multimineral tablets) obtained from the National Institute of Standards and Technology (NIST). A total of 22 samples of vitamin supplements, randomly acquired in local markets of Sao Paulo (Brazil) were evaluated for content of vitamin C by these two methodologies. The precision expressed as RSD was lower than 5% for both methods. LOD was 3.6 μg/mL for HPLC and 1.0 mg for titration, while LOQ were 12.0 μg/mL and 3.0 mg for HPLC and titration, respectively. Percent recoveries (%) of spiked samples ranged from 98.7 to 100.5 for HPLC and from 98 to 104 for titration. The contents of vitamin C in SRM 3280 (Certified value = 42.2 ± 3.7 mg/g) were 40.2 and 42.1 mg/g when determined by HPLC and titration respectively. Statistically, there was no difference in the analysed vitamin C content for half of the samples, irrespective of the method applied. HPLC was more sensitive, but the titrimetric method was faster and consumed less reagent. Although both methods were accurate in determining the vitamin C content in SRM 3280, the matrix constituents of some vitamin supplements may have interfered with the analysis.

Biquinho pepper(Capsium chinense):Bioactive compounds,in vivo and in vitro antioxidant capacities and anti-cholesterol oxidation kinetics in fish balls during frozen storage

The present study reports bioactive constituents from biquinho pepper,such as carotenoids,capsaicinoids,and capsinoids,identified by UHPLC-MS.Biquinho pepper extract showed an antioxidant potential by DPPH(33.17±0.08%),ORAC(32.35±0.02μM TE/g),β-carotene/linoleic acid(55.80±1.30%),and FRAP(315.88±4.23μmol TE/g)assays.Additionally,in vivo antioxidant analyses demonstrated that the pepper extract(170μg/mL)decreased the damage promoted by H_(2)O_(2) in Saccharomyces cerevisiae cells.Fish balls were prepared using different concentrations of pepper(0.0%,0.5%,0.75%,1.0%)to investigate its antioxidant effect during frozen storage.Biquinho pepper effectively reduced the formation of cholesterol oxides and preserved essential fatty acids,mainly in samples containing 1.0%of pepper.Moreover,this treatment was more efficient than sodium erythorbate(p<0.05),which was used as standard.The kinetics of cholesterol oxidation was also determined,showing that both cholesterol degradation and cholesterol oxides formation fit a first-order kinetic model(R^(2)>0.8).