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

Abstract

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.

L-ascorbic acid and α-tocopherol content in apple pulp: a comparison between 24 cultivars and annual variations during three harvest seasons

“…[35] So far, several analytical techniques have been reported for the determination of AsA in food, including titration, spectrophotometry, and HPLC. [36][37][38][39][40][41] The latter is preferred for the analysis of complex food matrixes because of its efficiency, separating power, accuracy, sensitivity, and specificity. [42][43][44] Similarly, numerous analytical methods for tocopherols are reported, [9,[45][46][47][48][49][50][51] involving organic solvents, alkaline solutions, liquid-liquid extraction and others for extracting the vitamin from food, fruit, or vegetables.…”

“…For the present work, HPLC was chosen as a technique for the analysis of vitamins in apple pulp. Abe-Matsumoto et al [40] stated that HPLC is preferable to iodometric titration for the analysis of complex matrices containing other water-soluble vitamins than ascorbic acid. Recent works report the use of HPLC-DAD for the quantification of vitamin C in diverse fruits [53] of water-soluble vitamins in edible plants [54] and of water-and fat-soluble vitamins in fruits , [55,56] berries and leaves.…”

Box–Behnken Design Based Development of UV-Reversed Phase High Performance Liquid Chromatographic Method for Determination of Ascorbic Acid in Tablet Formulations

“…In addition, the greenness points of the reported HPLC methods were calculated and are given in Table 9. It is evident from the table that the proposed HPLC method was found to be greener (66 greenness points) than the majority of the reported HPLC methods [33,35,36,[39][40][41][42][43][45][46][47][48][49][50]52,61], or similar to the reported HPLC method [38] but less green than four reported HPLC methods [34,37,44,51]. In all three reported methods [34,37,44] where the greenness points of 71 were obtained, each has a lower linear dynamic range than the proposed HPLC method.…”

“…The limits of detection (LOD) and quantitation (LOQ) of the proposed and reference methods were calculated as per the ICH guidelines [49] for the validation of analytical procedures using the following formula:…”

“…Analytical methods based on HPLC are also popular because of high accuracy, specificity, sensitivity, separation capability and short analysis time [31,32]. Several HPLC methods [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] have been reported for the determination of ascorbic acid in fruits, vegetables, indigenous spice plants, drug formulations and biological fluids. Moreover, several factors, such as composition of the mobile phase, pH, column temperature and flow rate, affect the performance of HPLC methods.…”