Abubakr M. Idris

Capillary electrophoresis for the determination of norfloxacin and tinidazole in pharmaceuticals with multi-response optimization

Capillary electrophoresis (CE) with UV photo-diode array detection technique was utilized to adopt new method for the analysis of norfloxacin and tinidazole in pharmaceuticals. Many CE aspects including separation, rapidity, sensitivity, ruggedness as well as the repeatability of qualitative and quantitative analyses were considered simultaneously for the purpose of optimization. Experimental design approach including factorial design and response surface methods were applied to optimize electrolyte concentration and the pH while injection time, voltage and column temperature were optimized using the univariate method. Successful results were obtained using 32.5mmoll(-l) phosphate electrolyte at pH 2.5, injection time 8.0s, voltage 25kV and column temperature 25 degrees C with detection at wavelength 301nm. The analytical characteristics including recovery, intermediate precision, linear dynamic ranges, linearity and selectivity as well as limits of detection and quantification were demonstrated and the applicability to pharmaceuticals was studied. The newly provided method enjoys the advantages of CE over HPLC with respect to rapidity, ruggedness, simplicity in reagents and sample preparation as well as saving in reagents and samples.

An Overview of the Generations and Recent Versions of Flow Injection Techniques

The ever increasing demand for rapid, cost-effective, practically-safe, and environmentally-benign analytical methods has aroused researchers to develop automated, miniaturized, versatile, and inexpensive analytical techniques. Flow injection (FI) techniques were well-established to meet the requirements of modern chemical analysis. The family of FI techniques includes three generations, flow injection analysis (FIA), sequential injection analysis (SIA), and bead injection analysis (BIA). In addition, new versions of SIA, micro-SIA-lab-on-valve (μSIA-LOV), and sequential injection chromatography (SIC), have recently been developed for more downscaling analysis and broadening applications. In the literature, we have not found a comprehensive and updated manuscript presenting all generations and recent versions of FI techniques. Therefore, the current manuscript briefly demonstrates the principles, developments, and applications of the FI techniques along with their consequent generations and recent versions.

Flow Injection, Overlooked Techniques in Forensic Analysis

Since their introduction in the mid-1970s, flow injection (FI) techniques have gained a world-wide popularity. FI techniques are automated, miniaturized, versatile, and inexpensive analytical tools for handling reagents and samples and consequently for conducting procedures related to wet chemical analysis. Due to their tremendous benefits, FI techniques have proven to be significant applications to such analytical fields as pharmaceutical, environmental, biochemical, and food. Currently, more than 10,000 publications reporting various applications of FI techniques can be retrieved from the literature. However, FI techniques have not yet received an adequate attention to the field of forensic analysis; less than 30 publications were reported. The main objective of the current article is to draw attention to the potential of FI techniques to forensic analytical chemists. The article provides a comprehensive review of the applications of FI techniques to forensic chemical analysis, which covers the literature since the inception of the techniques. The article also offers a brief historical background on the developments of the generation and versions of the techniques while highlighting their advantages. In addition, future perspectives in the applications of FI techniques to forensic analysis are discussed.

Rapid inexpensive assay method for verapamil by spectrophotometric sequential injection analysis.

Sequential injection analysis (SIA) technique with a miniaturized fibre optic spectrophotometry was exploited to optimize and validate a new method for the assay of verapamil in pharmaceutical formulations. The reduction of acidified permanganate by verapamil was spectrophotometrically detected at 546 nm. The 2(3) full-factorial design was adopted for screening the effect of conditions controlling the proposed method, and accordingly for the purpose of optimization. The remarkable advantages of the method are high rapidity (sample frequency was 10.6 samples/h), saving in reagents and sample (total consumed volume was 190 µl) and better safety for the environment (total waste production volume was 2140 µl). Additionally, the method was selective in the presence of excipients usually found in tablet and injection formulations. The average of recovery in synthetic samples as well as dosage forms was 98.8-103.0%. The obtained results were realized by the British Pharmacopoeia method and comparable results were obtained.

Factorial design and response surface optimization of spectrophotometric sequential injection analysis of olanzapine formulations

A new spectrophotometric sequential injection analysis (SIA) method for the assay of olanzapine in pharmaceutical formulations was optimized by the factorial design and the response surface approaches. The method was based on the oxidation of olanzapine by an excess amount of permanganate in sulfuric acid media. The reduction of permanganate was spectrophotometrically detected at 570 nm. The 23 full factorial design was adopted for the optimization of permanganate concentration, sulfuric acid concentration and flow rate. The method was validated based on the IUPAC guidelines. Real pharmaceutical samples were subjected to the proposed SIA method and the results were in satisfactory agreement with those obtained by a previous spectrophotometric method. The full-automation of SIA empowered the proposed method with high repeatability (RSD 1.74%, n = 7) and intermediate-precision (RSD 2.53%, n = 5). Additionally, both automation and miniaturization offered high sampling frequency (26 samples/h). Furthermore, the employment of chemometric optimization enhanced sensitivity of the method with limits of detection and quantification of 1.07 and 3.57 mg/L, respectively. Comparing with previous olanzapine assay methods, which employing conventional analytical techniques, the new SIA method is inexpensive in terms of instrumentation, consumption of reagents and samples as well as effort and manpower. The SIA method is also safer for handling solutions and for the environment.

Screening of conditions controlling spectrophotometric sequential injection analysis

BackgroundDespite its potential benefits over univariate, chemometrics is rarely utilized for optimizing sequential injection analysis (SIA) methods. Specifically, in previous vis-spectrophotometric SIA methods, chemometrically optimized conditions were confined within flow rate and reagent concentrations while other conditions were ignored.ResultsThe current manuscript reports, for the first time, a comprehensive screening of conditions controlling vis-spectrophotometric SIA. A new diclofenac assay method was adopted. The method was based on oxidizing diclofenac by permanganate (a major reagent) with sulfuric acid (a minor reagent). The reaction produced a spectrophotometrically detectable diclofenac form. The 26 full-factorial design was utilized to study the effect of volumes of reagents and sample, in addition to flow rate and concentrations of reagents. The main effects and all interaction order effects on method performance, i.e. namely sensitivity, rapidity and reagent consumption, were determined. The method was validated and applied to pharmaceutical formulations (tablets, injection and gel).ConclusionsDespite 64 experiments those conducted in the current study were cumbersome, the results obtained would reduce effort and time when developing similar SIA methods in the future. It is recommended to critically optimize effective and interacting conditions using other such optimization tools as fractional-factorial design, response surface and simplex, rather than full-factorial design that used at an initial optimization stage. In vis-spectrophotometric SIA methods those involve developing reactions with two reagents (major and minor), conditions affecting method performance are in the following order: sample volume > flow rate ≈ major reagent concentration >> major reagent volume ≈ minor reagent concentration >> minor reagent volume.

Sequential injection chromatography with a miniaturized multi-channel fiber optic detector for separation and quantification of propranolol and hydrochlorothiazide

BackgroundSequential injection chromatography (SIC) is a new alternative separation technology. It has some advantages over high performance liquid chromatography (HPLC) regarding simplicity, inexpensiveness, portability, ease of use, maintenance requirement and operation time. In contrast, SIC has had suffered from some limitations.ResultsThe current work involves four achievements. (a) One of the limitations of SIC has been overcome. A higher pressure resistant selection valve with additional ports was installed in an SIC system. This development allows propelling solution without showing solution leakage. (b) A new inexpensive rapid and green method for the separation and quantification of propranolol (PRP) and hydrochlorothiazide (HTZ) in their formulations was optimized and validated. (c) A miniaturized multi-channel fiber optic detector was coupled with the newly developed SIC system to detect PRP and HTZ at 270 and 290 nm, respectively. This issue enhanced the sensitivity rather than using a single-channel detector. (d) A comparative study on the efficiency of the SIC method with that of previous HPLC methods was conducted.ConclusionsBesides the benefits of the instrumentation of SIC, the proposed method is rapider and more reagent-saving than previous HPLC methods. The total volume of consumed reagents and sample was 4.04 mL. The sample frequency was 22 samples/h. Other such analytical characters of the SIC method as resolution, peak symmetry, numbers of theoretical plates, linearity range, accuracy, precision and limits of detection and quantification recorded comparable results.

Experimental Design Optimization of a Sequential Injection Method for Promazine Assay in Bulk and Pharmaceutical Formulations

Experimental design optimization approach was utilized to develop a sequential injection analysis (SIA) method for promazine assay in bulk and pharmaceutical formulations. The method was based on the oxidation of promazine by Ce(IV) in sulfuric acidic media resulting in a spectrophotometrically detectable species at 512 nm. A 33 full factorial design and response surface methods were applied to optimize experimental conditions potentially controlling the analysis. The optimum conditions obtained were 1.0 × 10−4 M sulphuric acid, 0.01 M Ce(IV), and 10 μL/s flow rate. Good analytical parameters were obtained including range of linearity 1–150 μg/mL, linearity with correlation coefficient 0.9997, accuracy with mean recovery 98.2%, repeatability with RSD 1.4% (n = 7 consequent injections), intermediate precision with RSD 2.1% (n = 5 runs over a week), limits of detection 0.34 μg/mL, limits of quantification 0.93 μg/mL, and sampling frequency 23 samples/h. The obtained results were realized by the British Pharmacopoeia method and comparable results were obtained. The provided SIA method enjoys the advantages of the technique with respect to rapidity, reagent/sample saving, and safety in solution handling and to the environment.

The Second Five Years of Sequential Injection Chromatography: Significant Developments in the Technology and Methodologies

Sequential injection chromatography was proposed in 2003 to perform a simple, rapid, reagent-saving, environmentally benign, on-site, and instrumentally inexpensive separation procedure. Sequential injection chromatography is a version of sequential injection analysis, which is the second generation in the family of flow injection techniques. Despite its advantages over high-performance liquid chromatography, sequential injection chromatography has confronted some challenges. Furthermore, the applications of sequential injection chromatography in its first five years are almost all limited to pharmaceutical analysis. Interestingly, in its second five years, various developments in sequential injection chromatography technology were achieved. The developments have enhanced the efficiency of sequential injection chromatography and hence its applications have extended to biological, food, and environmental analyses. The main objectives of this review are to examine recent developments (2008–2013) in sequential injection chromatography and to describe how these developments improve the efficiency of the technology. The sequential injection chromatography methodologies reported during that period are also discussed along with controlling conditions and analytical results. The review also describes the principles, instrumentation, and procedure behind sequential injection chromatography.