Rapid and Reliable HPLC Method for the Determination of Vitamin C in Pharmaceutical Samples

Purpose: To develop and validate an accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantitation of vitamin C in pharmaceutical samples. Method: The drug and the standard were eluted from Superspher RP-18 (250 mm x 4.6 mm, 10µm particle size) at 20 0C. The mobile phase was prepared by carefully adding acetic acid (500 ml) to 1.5g of 1-hexanesulfonic acid sodium salt and mixing well (pH 2.6). The flow rate was 0.7 mL min-1. UV detector, set at 280 nm, was used to monitor the effluent. Results: Each analysis required no longer than 4 min. The limit of quantitation was 1.95 µg mL-1 . Recovery (%) for different concentrations ranged from 99.58 to 101.93. Conclusion: The simplicity of this low-cost, rapid technique and its high specificity to ascorbic acid, even in the presence of a variety of excipients, demonstrate that this HPLC method would be particularly suitable for the determination of ascorbic acid in the investigated preparations as well as other similar pharmaceutical/veterinary formulations without prior sample preparation

Determination of Benzalkonium Chloride in Nasal Drops by High-Performance Liquid Chromatography

A high-performance liquid chromatography (HPLC) system was used in the reversed phase mode for the determination of benzalkonium chloride (BKC) in nosal drops. A Chromolit RP-18e, 100 x 4.6, (UM6077/035) column was used at 40 °C. The mobile phase, optimized through an experimental design, was a 70:30 (v/v) mixture of 0.057M Na-heksansulphonate potassium, dihydrogen orthophosphate buffer (pH 2.9) and acetonitrile, pumped at a flow rate of 1.75 mL/min at maintaining column temperature at 40 °C. Maximum UV detection was achieved at 215 nm. The method was validated in terms of selectivity, linearity, repeatability, precision and accuracy. The method was successfully applied for the determination of BKC in a pharmaceutical formulation of nasal drop solution without any interference from common excipients and drug substance. All the validation parameters were within the acceptance range, concordant to ICH guidelines

RAZVOJ I VALIDACIJA KINETIČKO SPEKTROFOTOMETRIJSKE METODE ZA ODREĐIVANJE HERBICIDA BROMFENOKSIMA

A kinetic spectrophotometric method for determining the residues of herbicide bromofenoxim (BrFX) has been developed and validated. The proposed method is based on the inhibitory effect of BrFX on the oxidation of sulfanilic acid (SA) by hydrogen peroxide in the presence of Cu(II) ion, which was monitored at 370 nm. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. BrFX can be measured in the range of 0.041 – 0.46 μg/ml and 0.46 – 13.86 μg/ml. The detection limit of the method with 3σ criteria is 0.0077 μg/ml. The relative standard deviations for five replicate determinations of 0.041, 0.24 and 0.46 μg/ml BrFX are 3.0, 5.32 and 2.85%, respectively. This method can be successfully used to determine BrFX concentration in baby juice samples. The HPLC method is used to verify the results. The results obtained for the same samples by the two methods are quite comparable.  Razvijena je i validirana kinetičko-spektrofotometrijska metoda za određivanje rezidua herbicida bromfenoksima (BrFX). Predložena metoda bazira se na inhibitornom dejstvu bromfenoksima u reakciji oksidacije sulfanilne kiseline vodonik peroksidom u prisustvu Cu(II jona) kao katalizatora. Merenja su vršena na talasnoj dužini od 370 nm. Određeni su optimalni eksperimentalni uslovi ispitivanjem uticaja svakog reagensa pojedinačno na brzinu indikatorske reakcije. Konstruisana je kalibraciona kriva u dva intervala koncentracija bromfenoksima od 0,041 do 0,46 μg/cm3 i od 0,46 do 13.86 μg/cm3 . Granica detekcije metode prema 3σ kriterijumu je 0.0077 μg/cm3 . Određeni su optimalni eksperimentalni uslovi pri kojima BrFX pokazuje najjači inhibitorni efekat na indikatorsku reakciju. Postavljene su kinetičke jednačine za katalitički i katalitičko-inhibitorni proces. Relativna standardna devijacija (RSD) izračunata je za tri koncentracije BrFX 0,041, 0,24 i 0,46 μg/ml u pet ponavljanja i iznosi 3,0, 5,32 i 2,85%. Kinetičko-spektrofotometrijska metoda primenjena je za određivanje bromfenoksima u sokovima za bebe nakon ekstrakcije na čvrstoj fazi (SPE). Za potvrdu rezultata kinetičke metode rađena je HPLC analiza kao uporedna metoda. Obe metode su dale uporedive rezultate