Multi-response optimization of sequential injection chromatographic method for determination of lisinopril and hydrochlorothiazide

Recently, a more efficient sequential injection chromatograph (SIC) with a high pressure selection valve has been developed at our laboratory. In the current work, the newly developed SIC system was exploited to optimize and validate a new method for the separation and quantification of lisinopril and hydrochlorothiazide in pharmaceutical preparations. A multi-response optimization study was conducted to screen the effect of mobile phase composition on resolution, reagent consumption, retention time, peak symmetry, peak height and baseline. The factorial design approach was adopted and the effect factors were determined. The SIC method has proven to be a competitor to high performance liquid chromatographic methods with respect to sample frequency, reagent consumption and safety for the environment, besides instrumentation benefits with respect to inexpensiveness, simplicity and portability. Short C-18 monolithic columns (30 x 4.6 mm) were used to offer a rapid and reagent-saving procedure. Miniaturized fiber optic spectrometric devices were coupled with the SIC system to provide more instrumentation portability. Satisfactory separation, peak symmetry and theoretical plates were achieved. The SIC method was also accurate (the recovery range was 98.8-101.8%), precise (the RSD range was 0.95-2.29) and sensitive (the limits of detection were below 1.5 mu g mL(-1)).