3 research outputs found
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Use of nanoemulsion liquid chromatography (NELC) for the analysis of inhaled drugs. Investigation into the application of oil-in-water nanoemulsion as mobile phase for determination of inhaled drugs in dosage forms and in clinical samples.
There has been very little research into the bioanalytical application of Microemulsion High Performance Liquid Chromatography (MELC), a recently established technique for separating an active pharmaceutical ingredient from its related substances and for determining the quantity of active drug in a dose. Also, the technique is not good at separating hydrophilic drugs of very similar chemical structures.
Different phase diagrams of oil (octane or ethyl acetate), co-surfactant (butanol), surfactant (sodium dodecyl sulphate (SDS) or Brij-35) and buffer (Phosphate pH 3) were developed and several nanoemulsion mobile phases identified. Nanoemulsion mobile phase that is, prepared with SDS, octane, butanol and a phosphate buffer, failed to separate hydrophilic compounds with a very close chemical structure, such as terbutaline and salbutamol. A nanoemulsion mobile phase containing a non-ionic surfactant (Brij-35) with ethyl acetate, butanol and a phosphate buffer, was, however, successful in achieving a base line separation, and the method was validated for simultaneous determination of terbutaline and salbutamol in aqueous and urine samples.
An oil-in-water (O/W) NELC method was developed and validated for the determination of formoterol in an Oxis® Turbuhaler® using pre-column fluorescence derivatisation. Although the same mobile phase was extended for separation of formoterol in urine, the formoterol peak¿s overlap with endogenous peaks meant that fluorescence detection could not determine formoterol in urine samples. Solid phase extraction, concentrating the final analyte 40 times, enabled determination of a low concentration of formoterol in urine samples by UV detection. The method was validated and an acceptable assay precision %CV <4.89 inter-day and %CV <2.33 intra-day was achieved. Then after the application of O/W nanoemulsion mobile phase for HPLC was extended for the separation of lipophilic drugs. The nanoemulsion liquid chromatography (NELC) method was optimised for the determination of salmeterol and fluticasone propionate in good validation data was achieved.
This thesis shows that, in general, the performance of O/W NELC is superior to that of conventional High Performance Liquid Chromatography (HPLC) for the analysis of both hydrophilic and lipophilic drugs in inhaled dosage formulations and urine samples. It has been shown that NELC uses cheaper solvents and that analysis time is faster for aqueous and urine samples. This considerable saving in both cost and time will potentially improve efficiency within quality control
Development of a Microemulsion High Performance Liquid Chromatography (MELC) Method for Determination of Salbutamol in Metered-Dose Inhalers (MDIS)
NoA sensitive and rapid oil-in-water (O/W) microemulsion high performance liquid chromatography (MELC) method has been developed. The water-in-oil (w/o) microemulsion was used as a mobile phase in the determination of salbutamol in aqueous solutions. In addition, the influence of operating parameters on the separation performance was examined. The samples were injected into C18, (250mmx4.6mm) analytical columns maintained at 25(o)C with a flow rate 1 ml/min. The mobile phase was 95.5% v/v aqueous orthophosphate buffer 20 mM (adjusted to pH 3 with orthophosphoric acid), 0.5% ethyl acetate, 1.5% Brij35, and 2.5% 1-butanol, all w/w. The salbutamol and internal standard peaks were detected by fluorescence detection at the excitation and emission wavelengths of 267 and 313 nm respectively. The method had an accuracy of > 97.78% and the calibration curve was linear (r2 = 0.99) over salbutamol concentrations ranging from 25 to 500 ng/mL. The intra-day and inter-day precisions (CV %) were <1.6 and <1.8, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) were 9.61ng/ml and 29.13ng/ml, respectively. The method reported is simple, precise and accurate, and has the capacity to be used for determination of salbutamol in the pharmaceutical preparation
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Microemulsion High Performance Liquid Chromatography (MELC) for Determination of Terbutaline in Urine Samples
NoAn isocratic oil-in-water microemulsion High Performance Liquid Chromatography (MELC) was developed and validated for the
determination of terbutaline in urine samples. A solid phase extraction (SPE) method which used Oasis HLB cartridges was optimised
to isolate terbutaline from a urine matrix followed by HPLC with fluorescence detection. The urinary assay was performed in
accordance with FDA and ICH regulations for the validation of bioanalytical samples. The method uses the isocratic oil-in-water
micro emulsion to separate the terbutaline from the endogenous urine components. The chromatographic separation was carried
out on C18-Spherisorb (250mm×4.6mm) analytical column maintained at 30 °C. The mobile phase was 94.4% aqueous
orthophosphate buffer (adjusted to pH 3 with orthophosphoric acid), 0.5% ethyl acetate, 1.5% Brij35, 2.5% 1-butanol and 1.1%
Octanesulfonic acid (OSA), all w/w. The terbutaline peak was detected by fluorescence detection, using excitation and emission
wavelengths of 267 and 313 nm, respectively. The linearity of response was demonstrated at six different concentrations of
terbutaline which were extracted from spiked urine, ranging from 60 to 1000ng/ml. The terbutaline was extracted from urine by a
solid phase extraction clean-up procedure on Oasis HLB cartridges, and the relative recovery was >87.64% (n = 5). The limit of
detection (LOD) and limit of quantitation (LOQ) in urine were 20.21 and 61.24ng/ml, respectively. The intra-day and inter-day
precisions (in term of % coefficient of variation) were <3.56% and <2.87%, respectively. In the method development the influence of
the composition of the microemulsion system was also studied and the method was found to be robust with respect to changes of
the microemulsion components