Sequential Injection Chromatography with Monolithic Column for Phenothiazines Assay in Human Urine and Pharmaceutical Formulations

Methods:

Sequential injection chromatography (SIC) with monolithic column has been proposed with potential benefits for separation and quantification.

Objective:

To utilize SIC to develop a new assay method for the separation and quantification of some phenothiazines (promethazine, chlorpromazine and perphenazine) in human urine and synthetic pharmaceutical formulations.

Methods:

The 32 full-factorial design was adopted to study the effect of mobile phase composition on separation efficiency, retention time, peak height and baseline. The separation was conducted on a C18 monolithic column (100 × 4.6 mm) using a mobile phase composition of phosphate: acetonitrile:methanol (60:28:12) at pH 4.0. The detection was carried out using a miniaturized fiber optic spectrometer at 250 nm.

Results:

Satisfactory analytical features, including number of theoretical plates (1809-6232), peak symmetry (1.0-1.3), recovery (95.5-99.1% in pharmaceutical formulations and 91.6-94.7% in urine), intra-day precision (0.36-1.60% for pharmaceutical formulation and 2.96-3.67 for urine), inter-day precision (1.47-2.28% for pharmaceutical formulation), limits of detection (0.23-0.88 μg/ml) and limits of quantification (0.77-2.90 μg/ml), were obtained.

Conclusion:

The remarkable advantages of the proposed SIC method are the inexpensiveness in terms of instrumentation and reagent consumption.

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

BACKGROUND

Sequential 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.

RESULTS

The 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.

CONCLUSIONS

Besides 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.

Screening of conditions controlling spectrophotometric sequential injection analysis

Background

Despite 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.

Results

The 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).

Conclusions

Despite 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.