Portable Voltammetry: A Rapid and Efficient Technique for Determining UV Filters in Cosmetics: A Comparative Study with HPLC-PDA and HPLC-MS/MS.

This study addresses the widespread use of UV filters (UVFs) in cosmetic and solar products due to the negative effects of UV radiation, particularly in relation to melanoma risk. While these filters offer protection, their extensive application raises concerns about their environmental and health impacts. Organic UVFs, in particular, have been associated with endocrine disruption in aquatic species and coral reef damage. To mitigate these concerns, regulatory limits have been imposed on certain UVFs. Current analytical techniques for UVF determination, such as HPLC-PDA and HPLC-MS/MS, offer high accuracy but are expensive and lack on-site monitoring capabilities. In response, this research aims to develop a rapid and cost-effective method, utilizing voltammetry for organic UVF quantification in complex matrices like sunscreens. Additionally, HPLC-PDA and HPLC-MS/MS are employed for electrochemical methods and device validation. This approach not only addresses the need for efficient UVF analysis but also provides a basis for regulatory compliance and environmental stewardship in the cosmetics industry.

Enantiomeric separation of thiourea derivatives of naringenin on amylose and cellulose polymeric chromatographic chiral columns.

Due to a great demand for amylose and cellulose polymeric chromatographic chiral columns, the enantiomeric separation of thiourea derivatives of naringenin was achieved on the different amylose (Chiralpak-IB) and cellulose chiral (Chiralcel-OJ and Chiralcel-OD-3R) columns with varied chromatographic conditions. The isocratic mobile phases used were ethanol and methanol, where ethanol/hexane and methanol/hexane were used as gradient mode and were prepared in volume/volume relation. The separation and resolution factors for all the enantiomers were in the range of 1.25 to 3.47 and 0.48 to 1.75, respectively. The enantiomeric resolution was obtained within 12 min making fast separation. The docking studies confirmed the chiral recognition mechanisms with binding affinities in the range of -4.7 to -5.7 kcal/mol. The reported compounds have good anticoagulant activities and may be used as anticoagulants in the future. Besides, chiral separation is fast and is useful for enantiomeric separation in any laboratory in the world.

A stability indicating RP-HPLC-UV assay method for the simultaneous determination of hydroquinone, tretinoin, hydrocortisone, butylated hydroxytoluene and parabens in pharmaceutical creams.

Multicomponent drugs are medications that combine two or more active pharmaceutical ingredients in a single dosage form. These dosage forms improve the patient compliance, reduce the risk of drug interactions, and simplify dosing regimens. However, quality control of these multicomponent dosage forms can be challenging, especially if the final product contains four or more ingredients that are active (comprise stabilizers, preservatives, excipients, and other components). This problem can be more pronounced if the excipients can interfere with the analysis. In this work, a stability indicating assay method was developed and validated (according to the ICH International Guidelines) for the simultaneous determination of hydroquinone (HQ), tretinoin (TRT), hydrocortisone (HCA), butylated hydroxytoluene (BHT), methyl paraben (MP) and propyl paraben (PP) in commercially available pharmaceutical creams. The proposed method is based on gradient elution using X-Bridge C18 (150 × 4.6 mm, 5 µm) column with a flow rate of 1 mL/min. The linear ranges (µg/mL) were 240-560 for HQ, 24-56 for MP, 132-308 for HCA, 6-14 for PP, 12-28 for BHT, 6.6-15 for TRT. During the validation process, the intra- and interday precision and trueness (evaluated as recovery) were found to be below 2.0% and between 100-102%, respectively. System suitability tests (SST) allow validating the herein proposed procedure specifically for pharmaceutical and industrial applications. SST test shows that the reported procedure fulfill with the Guidelines, allowing excellent separation of the analytes with very sensitive, accurate (precise and true) and reproducible quantitation of each analytes. The method was successfully applied in forced degradation studies of the six analytes. Specifically, acid degradation slightly affected HCA and BHT (91% recovery), while alkaline degradation drastically reduced HCA recovery (5.5%) and moderately affected BHT (85%). Photodegradation primarily influenced TRT quantity, and oxidative degradation intensified the BHT peak (130%).

Titania-based fabric phase sorptive extraction approach for the determination of antiepileptic drugs, levetiracetam and lamotrigine in urine samples using high-performance liquid chromatography-photo diode array detection.

A new fabric phase sorptive extraction (FPSE) based separation and enrichment method was developed for sensitive determination of two antiepileptic drug molecules, Levetiracetam (LEV) and Lamotrigine (LTG). The analysis of these drug molecules was performed with high-performance liquid chromatography equipped with photodiode array detector (HPLC-PDA) after FPSE. HPLC analysis was carried out by using phenyl hexyl column, under isocratic conditions with the mobile phase composed of pH 3.0 buffer-acetonitrile (77:23 v: v). All parameters affecting the separation and enrichment process were studied and optimized step by step. The linear working range of the developed method was calculated in the range of 10.0-1000.0 ng mL-1 for both the drug molecules (LEV and LTG). The limits of detection of the method (LODs) were calculated as 2.72 and 3.64 ng mL-1, respectively. The relative standard deviation (%RSD) values of the developed method as an indicator of precision were varied between 4.0 and 7.3. The accuracy of the optimized FPSE method was determined by the recovery tests utilizing spiked samples and results were assessed in the range from 94.6 to 106.3%. This is the first application of sol-gel Titania polycaprolactone-polydimethylsiloxane-polycaprolactone (Ti-PCAP-PDMS-PCAP) based FPSE membrane in the determination of antiepileptic drug molecules.

A facile fabric phase sorptive extraction method for monitoring chloramphenicol residues in milk samples.

Determination of pharmaceutical active molecules in the biological matrices is crucial in various fields of clinical and pharmaceutical chemistry, e.g., in pharmacokinetic studies, developing new drugs, or therapeutic drug monitoring. Chloramphenicol (CP) is used for treating bacterial infections, and it's one of the first antibiotics synthetically manufactured on a large scale. Fabric phase sorptive extraction (FPSE) was used to determine Chloramphenicol antibiotic residues in milk samples by means of validated HPLC-DAD instrumentation. Cellulose fabric phases modified with polyethylene glycol-block-polypropylene glycol-block-polyethylene glycol triblock copolymer was synthesized using sol-gel synthesis approach (Sol-gel PEG-PPG-PEG) and used for batch-type fabric phase extractions. Experimental variables of the FPSE method for antibiotic molecules were investigated and optimized systematically. The HPLC analysis of chloramphenicol was performed using a C18 column, isocratic elution of trifluoroacetic acid (0.1%), methanol, and acetonitrile (17:53:30) with a flow rate of 1.0 mL/min. The linear range for the proposed method for chloramphenicol (r2 > 0.9982) was obtained in the range of 25.0-1000.0 ng/mL. The limit of detections (LOD) is 8.3 ng/mL, while RSDs% are below 4.1%. Finally, the developed method based on FPSE-HPLC-DAD was applied to milk samples to quantitatively determine antibiotic residues.