Determination of fosinopril in pharmaceutical formulations containing hydrochlorothiazide by multiwavelength UV spectrophotometry.

A sensitive, simple, rapid and precise method for the simultaneous determination of fosinopril (FOS) and hydrochlorothiazide (HCT) in pharmaceutical formulations is presented. These active ingredients are extracted in aqueous solution and measured by multiwavelength UV spectrophotometry using the program QUEST. HCT acts as an internal standard to verify the accuracy of the analysis. Some aspects of the chemical, spectroscopic and thermoanalytical behaviour of FOS are also reported.

Determination of lecithin drug specialties and diet integrators; by means of first or second derivative enzymatic-spectrophotometric analysis.

The possibility has been investigated of applying derivative analysis to a classical enzymatic-spectrophotometric method for lecithin determination for the purpose of developing an analytical direct method that does not require long pretreatment of the test sample even in the case of turbid samples. Several samples of drugs and food integrators containing lecithin were thus tested using both the standard and the derivative method and then comparing the results obtained. The RSD% values of measurements on real (food or drugs) samples were always <2.5. Using a first derivative spectrophotometric method, average recovery was always between 102 and 105%.

Determination of choline containing phospholipids in serum, bile and amniotic fluids by the derivative enzymatic-spectrophotometric method.

A comparison was performed of the analytical results obtained by applying a well-known enzymatic-spectrophotometric method for the determination of choline containing phospholipids in biological human fluids (sera, bile and amniotic fluids) following the standard procedure method, or else using the first or second derivative methods. In terms of result reproducibility the comparison was extended to include also a biosensor-based method developed in recent years by the present authors. Some advantages are associated with using the first derivative method in the case of serum samples containing blood traces, especially via the 'Gran's plot' method.