Rapid and Convenient Method for the Determination of Sodium Nitroprusside in Aqueous Solution

Abstract

We propose a rapid and convenient method for the determination of sodium nitroprusside in aqueous solution. In alkaline medium and in the presence of dimethylsulfoxide, the concentration of the nitrite ions coming from the nitroprusside corresponds with the initial quantity of this compound.     

Activated Carbon Modified with Sodium Dodecyl Sulfonate as a Solid Phase Sorbent for the Separation and Preconcentration of Trace Cadmium in Water Samples with Detection by Electrothermal Atomic Absorption Spectrometry

A novel absorbent was prepared by sodium dodecyl sulfonate (SDS)-modified activated carbon (SDS-AC) and was employed as the microcolumn packing material for separation/preconcentration of trace Cd(II). The method based on Cd(II) was quantitatively retained by SDS-AC sorbent, which entailed cation exchange nature and negative charged surface, facilitating favorable retention of positively charged ions. The retained Cd(II) was effectively recovered with elution by 1 mol · L^?1 HNO₃, and the eluent was quantified by electrothermal atomic absorption spectrometry (ET-AAS). Under the optimized conditions, the limit of detection (LOD) for Cd(II) was 3 ng · L^?1 with the consumption of 20.0 mL sample solution. The relative standard deviation (RSD) for ten replicate measurements of 50 ng · L^?1 Cd(II) was 2.9%. The developed technique was demonstrated for the determination of trace Cd(II) in water samples and the recoveries for spiked samples were found to be in the range of 94.9–107.2%. For validation, two certified reference materials of water samples (GBW08607 and GBW08608) were analyzed, and the results obtained were in good agreement with the certified values.     

Development and Validation of an HPLC-UV Method for the Quantification of 4′-Hydroxydiclofenac Using Salicylic Acid: Future Applications for Measurement of In Vitro Drug–Drug Interaction in Rat Liver Microsomes

Salicylic acid is a key compound in nonsteroidal anti-inflammatory drugs that has been recently used for preventing the risk of hospitalization and death among COVID-19 patients and in preventing colorectal cancer (CRC) by suppressing two key proteins. Understanding drug–drug interaction pathways prevent the occurrence of adverse drug reactions in clinical trials. Drug–drug interactions can result in the variation of the pharmacodynamics and pharmacokinetic of the drug. Inhibition of the Cytochrome P450 enzyme activity leads to the withdrawal of the drug from the market. The aim of this paper was to develop and validate an HPLC-UV method for the quantification of 4′-hydroxydiclofenac as a CYP2C9 metabolite using salicylic acid as an inhibitor in rat liver microsomes. A CYP2C9 assay was developed and validated on the reversed phase C₁₈ column (SUPELCO 25 cm × 4.6 mm × 5 µm) using a low-pressure gradient elution programming at T = 30 °C, a wavelength of 282 nm, and a flow rate of 1 mL/min. 4′-hydroxydiclofenac demonstrated a good linearity (R² > 0.99), good reproducibility, low detection, and quantitation limit, and the inter and intra-day precision met the ICH guidelines (<15%). 4′-hydroxydiclofenac was stable for three days and showed an acceptable accuracy and recovery (80–120%) within the ICH guidelines in a rat liver microsome sample. This method will be beneficial for future applications of the in vitro inhibitory effect of salicylic acid on the CYP2C9 enzyme activity in rat microsomes and the in vivo administration of salicylic acid in clinical trials.