A sequential injection analysis method for the determination of glutathione (GSH) in pharmaceuticals has been developed. It is based on the reduction of the Cu(II)-neocuproine complex by GSH and the formation of an orange-yellow colored Cu(I)-neocuproine complex with maximum absorbance at 458 nm. Under optimal conditions the method is characterized by a linear calibration range of 6.0 × 10⁻⁷–8.0 × 10⁻⁵ mol L⁻¹ (A_max = 3270 C_GSH − 0.0010; R² = 0.9983), limit of detection of 2.0 × 10⁻⁷ mol L⁻¹, limit of quantification of 6.7 × 10⁻⁷ mol L⁻¹, repeatability (expressed as relative standard deviation) of 3.8%, and sampling rate of 60 h⁻¹. The newly developed method has been successfully applied to the determination of GSH in pharmaceutical samples with no statistically significant difference between the results obtained and those produced by the standard Pharmacopoeia method.

N-acetyl-L-cysteine (NAC), a sulfhydryl-containing compound, is mainly used as a mucolytic and as an antidote for acetaminophen overdose. Flow injection and sequential injection systems were designed and optimized with the aim of providing precise, a...

Polymer inclusion membranes (PIMs) based on PVDF-HFP as the base polymer and Aliquat 336 as the carrier in a mass ratio of 6:4 with concentrations of embedded glass fibers up to 5 wt% were successfully fabricated. Their microstructure, as well as their mechanical and thermal properties, were characterized using scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), differential thermal analysis/thermogravimetric analysis (DTA/TGA), and tensile testing. Membrane performance and long-term stability in transporting thiocyanate ions were evaluated in a two-compartment transport cell. The results showed that the membranes retained their amorphous structure even with glass-fiber loadings of up to 5 wt%. The addition of glass fibers was found to primarily enhance the elastic modulus and tensile strength, while causing a moderate reduction in plasticity without negatively affecting membrane transport properties and long-term stability. Therefore, it was concluded that the incorporation of glass fibers could improve the suitability of PIMs for industrial applications.

A kinetic spectrophotometric method for the determination of penicillamine (PEN) in pharmaceuticals has been developed. It utilizes a one-step reduction of the Cu(II)-bathocuproine complex by PEN, which results in a yellow-orange-colored Cu(I)-bathocuproine complex with maximum absorbance at 483 nm. Under optimal conditions, the method is characterized by a linear calibration range of 3.0 × 10^-6–6.0 × 10^-4 mol L^-1 (A_max = 8.65×10³C_PEN; R² = 1.00), a limit of detection of 9.0 × 10^-7 mol L^-1, and an analysis time of 2 min. Using an unsegmented continuous flow analyzer, it has been established that in the linear calibration range, the analytical reaction is of pseudo-first order. The method has been applied to the determination of PEN in samples of pharmaceutical PEN tablets, and the results obtained have been found to be statistically indistinguishable from those produced by the standard Pharmacopoeia method.

N-acetyl-L-cysteine (NAC) is a precursor of glutathione and a natural antioxidant. It is used to treat paracetamol overdose and to dissolve thick bronchial mucus. A novel, simple, reproducible, and rapid kinetic spectrophotometric method for determining NAC in pharmaceutical formulations is proposed. The method is based on a redox reaction where NAC reduces bis(bathocuproinedisulfonate)cuprate(II), forming a yellow-orange complex of bis(bathocuproinedisulfonate)cuprate(I). The resulting stable complex exhibited maximum absorbance at λ = 483 nm. Under optimised chemical reaction parameters, both the fixed-time and initial-rate methods were used to generate calibration curves. For the fixed-time method, the curve was linear in the concentration range of 3.0 · 10−7 to 7.0 · 10−5 mol l−1, with the equation y = 13140x − 0.0005 and a coefficient of determination of R2= 0.9999. For the initial-rate method, the curve was linear in the concentration range of 7.0 · 10−7 to 7.0 · 10−5 mol l−1 with the equation y = 1.040x + 3.220 and R2 = 0.9991. The slope of the logarithmic form of the calibration curve (1.040) for the initial-rate method confirmed the pseudo-first order nature of the reaction. The proposed method was successfully applied for the determination of NAC in commercial pharmaceutical preparations, yielding results comparable to those obtained using the recommended method according to the pharmacopoeia.