Renata Jasionowska

Capillary electrophoretic separation of phenolic acids

Phenolic acids such as syringic, p-coumaric, vanillic, caffeic, 3,4-dihydroxybenzoic and gallic acid, which are present in wines and other alcoholic drinks, were determined by capillary electrophoresis using an uncoated fused-silica capillary. The optimum conditions for their separation were investigated. Examples of electropherograms of phenolic acids contained in some Italian wines are reported.

Determination of nandrolone metabolites in human urine: comparison between liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry

Nandrolone (19-nortestosterone) is an androgenic anabolic steroid illegally used as a growth-promoting agent in animal breeding and as a performance enhancer in athletics. Therefore, its use was officially banned in 1974 by the Medical Commission of the International Olympic Committee (IOC). Following nandrolone administration, the main metabolites in humans are 19-norandrosterone, 19-norethiocolanolone and 19-norepiandrosterone, and their presence in urine is the basis of detecting its abuse. The present work was undertaken to determine, in human urine, nandrolone metabolites (phase I and phase II) by developing and comparing multiresidue liquid chromatography/tandem mass spectrometry (LC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) methods. A double extraction by solid-phase extraction (SPE) was necessary for the complete elimination of the interfering compounds. The proposed methods were also tested on a real positive sample, and they allow us to determine the conjugated/free fractions ratio reducing the risk of false positive or misleading results and they should allow laboratories involved in doping control analysis to monitor the illegal use of steroids. The advantages of LC/MS/MS over GC/MS (which is the technique mainly used) include the elimination of the hydrolysis and derivatization steps: it is known that during enzymatic hydrolysis several steroids can be converted into related compounds and deconjugation is not always 100% effective. The validation parameters for the two methods were similar (limit of quantification (LOQ) <1 ng/mL and percentage coefficient of variance (CV%) <16.4), and both were able to confirm unambiguously all the analytes, thus confirming the validity of both techniques.

Development and validation of an MEKC method for determination of nitrogen‐containing drugs in pharmaceutical preparations

A fast and accurate micellar electrokinetic capillary chromatography method was developed for quality control of pharmaceutical preparations containing cold remedies as acetaminophen, salicylamide, caffeine, phenylephrine, pseudoephedrine, norephedrine and chlorpheniramine. The method optimization was realized on a Beckman P/ACE System MDQ instrument. The baseline separation of seven analytes was performed in an uncoated fused silica capillary internal diameter (ID)=50 µm using tris‐borate (20 mM, pH=8.5) containing sodium dodecyl sulphate 30 mM BGE. On line‐UV detection at 214 nm was performed and the applied voltage was 10 kV. The operating temperature was 25°C. After experimental conditions optimization, the proposed method was validated. The evaluated parameters were: precision of migration time and of corrected peak area ratio, linearity range, limit of detection, limit of quantification, accuracy (recovery), ruggedness and applicability. The method was then successfully applied for the analysis of three pharmaceutical preparations containing some of the analytes listed before.

Rapid Analysis of Melatonin in Pharmaceutical Tablets by Capillary Electrophoresis with UV Detection

SummaryMelatonin content in pharmaceutical products was quantitatively determined by capillary electrophoresis within 4 min. Sample preparation required the simple dissolution in water and filtration. An internal standard was used a linear relationship between melatonin concentration andR(melatonin corrected peak area/I.S. corrected area) was obtained, withr2>0.998. Separations were carried out in coated capillaries with a borate running buffer. The method showed an high precision with a RSD value for migration times of 0.3% for intra-day and 1.4% for inter-day measures (n=48). For theR parameter RSD was 2.9% and refers to seven consecutive runs of the same sample on the same day. Two commercially available pharmaceutical products containg melatonin were analyzed. The method offers an easy and accurate routine option.

Application of CZE Method in Routine Analysis for Determination of B-Complex Vitamins in Pharmaceutical and Veterinary Preparations

A competitive CZE method for quality control analysis of multivitamin preparations and veterinary products containing B-group vitamins was developed. Vitamins of interest are thiamine hydrochloride (B1), thiamine monophosphate chloride (B1a), riboflavine (B2), riboflavine-5′monophosphate (B2a), nicotinamide (B3), d-pantothenic acid calcium salt (B5), pyridoxine hydrochloride (B6), folic acid (B9), and 4-aminobenzoic acid (B10). These analytes were separated optimizing the experimental conditions in 20 mM tetraborate buffer pH = 9.2 as a BGE (background electrolyte), on a Beckman P/ACE System MDQ instrument, using uncoated fused silica capillary. The effective capillary length was of 49.5 cm, I.D. = 50 μm, the applied voltage 20 kV and the temperature 25°C. Detection was performed by a diode array detector at 214 nm for all vitamins except B5 (190 nm) and B2a (260 nm). Separation time was about 9 min. After experimental conditions optimization, the proposed method was validated. Precision of migration time and corrected peak area, linearity range, LOD and LOQ, accuracy (recovery), robustness, and ruggedness were evaluated for each analyte demonstrating the good reliability of the method. Analyses of the pharmaceutical real samples were performed and confirmed the versatility of this method.

CZE determination of somatostatin in pharmaceutical preparations.

We propose a simple and accurate method for CE quantitative determination of somatostatin in pharmaceutical preparations. The method is specific for somatostatin as indicated by the resolution between the analyte and the analogue peptides which differ from somatostatin by one aminoacid. The linearity range is from 0.02 to 0.35 mg/ml. The recovery of the somatostatin from a pharmaceutical product is about 100.0%.

CZE separation of nitrogenous drugs in cationic form

A rapid and efficient capillary zone electrophoresis method was developed for Quality Control analysis of pharmaceutical preparations containing antihistamines, decongestants and anticholinergic remedies: chlorpheniramine, diphenhydramine, ephedrine, isopropamide, pheniramine. These analytes were separated in cationic form optimizing the experimental conditions in 60 mM tetraborate buffer pH = 9.2 as a BGE (Background Electrolyte) on a Beckman P/ACE System MDQ instrument. The effective capillary length was 48 cm, I.D. = 75 μm, the applied voltage 15 kV, and the temperature 25 °C. Detection was performed by a DAD (Diode Array Detector) at 210 nm. Separation time was less than 8 min. After experimental conditions optimization, the proposed method was validated. Precision of migration time (tm) ranging from 0.19% to 0.29% and corrected peak area (Ac) from 2.54% to 3.68%. The linearity of detector response was tested in the range 5–40 μg ml−1 obtaining the 0.9962 ≤ r2 ≤ 0.9982. LOD and LOQ, accuracy (recovery) and ruggedness were evaluated for each analyte demonstrating the good reliability of the method. Analysis of the pharmaceutical real sample was performed.