Quantification of total sugars and reducing sugars of dragon fruit-derived sugar-samples by UV-Vis spectrophotometric method

In the present work, the phenol-sulfuric acid method and the 3,5-dinitrosalicylic acid (DNS) method were developed with the aim to quantitatively analyze total sugars and reducing sugars, respectively. In regard with the phenol-sulfuric acid assay, 1.0 mL of sample was treated with 1.0 mL of 5% phenol, 5.0 mL of concentrated H2SO4 and measured at 485 nm, with the linearity range of 10–100 ppm for total sugars. The DNS method was performed on 2.0 mL of sample, using 1.5 mL of DNS at 80 °C for 10 minutes and measured at 510 nm, with the linearity range of 50–400 ppm for reducing sugars. The sugar contents of white dragon fruit-derived sugar-samples (extracted from species in Binh Thuan province, Vietnam) were also estimated by the above measured methods, exhibiting the total sugars of above 90% and the reducing sugars of above 5%. The methods were well-performed with the acceptable relative standard deviations of repeatability in accordance with the Association of Official Analytical Chemists (AOAC).

ESTIMATION OF RESIDUAL SOLVENTS IN NETUPITANT API BY HEADSPACE GAS CHROMATOGRAPHY

Objective: Residual solvents are undesirable components present in Active Pharmaceutical Ingredients (API), excipients, or drug products. To meet the specific quality-based requirements, the presence of these solvents in pharmaceutical products should be monitored to ensure their safety. The main objective of this work is to develop a new method for the determination of residual solvents in netupitant API by an HS-GC method with an FID detector. Methods: An automated headspace GC method has been developed and validated for the estimation of the residual solvents-N-methyl pyrrolidine, xylene, toluene, and N, N Dimethylacetamide in netupitant API. The samples were dissolved in dimethyl sulfoxide and the equilibrium headspace gas was formed at 80 ᵒC, which was analyzed using a DB-624 column (30m*0.53 mm, 3.00 µm) with an injector and detector temperature set at 160 ᵒC and 230 ᵒC, respectively. The initial oven temperature was set at 60 ᵒC for 5 min and programmed at a rate of 10 ᵒC/min to the final temperature of 150 ᵒC, with a hold time of 5 min by maintaining the flow rate of 4.0 ml/min with a split ratio of 1:10, and total run time of 20 min. Nitrogen was used as carrier gas. The method developed was validated as per International Conference for Harmonization (ICH) guidelines for repeatability, linearity, range, ruggedness, detection limit, quantification limit, and recovery studies. Results: The linearity range selected was 50-350µg/ml and the correlation coefficient(γ2) values for all the solvents were found to be>0.99; recovery studies values were in a range of 90-110% and %RSD values were also found to be not more than 10 for the solvents. Conclusion: A novel, accurate, sensitive, and simple method was described for estimating residual solvents in Netupitant API by Headspace Gas Chromatography (HS-GC) coupled with a Flame Ionization Detector (FID). Excellent results have been observed for all the validated parameters with good peak resolution and lesser retention times.

DEVELOPMENT OF CLEANING METHOD VALIDATION TECHNIQUES FOR PIROXICAM AND TELMISARTAN

To determine effectiveness of cleaning, analytical methods were validated for piroxicam and telmisartan. The drugs were selected on the basis of solubility in water. Water is the major solvent used for cleaning of equipments. These drugs are practically insoluble in water, so they may leave product residue even after cleaning of the equipments and necessitate lot of water for cleaning. So, any analytical method used to determine the cleanliness should be effective. During analytical method validations, following parameters were evaluated i.e. linearity, specificity, LOQ, LOD, and recovery studies by swab sampling and rinse sampling techniques. The visual cleanliness criteria was also evaluated by spiking known amount of samples on SS plates. From the results it was concluded that the developed analytical method was sensitive and accurate. For piroxicam: UV spectrophotometric analytical method was developed which showed an absorption maxima λmax at 356 nm wavelength and linearity range 0 to 25 µg/mL. Recovery of drug from swab sampling and rinse sampling techniques were found satisfactory and within the acceptance criteria. For telmisartan, UV spectrophotometric analytical method was developed which showed an absorption maxima λmax at 226 nm wavelength and linearity range 0 to 10 µg/mL. Recovery of drug from swab sampling and rinse sampling techniques were found satisfactory and within the acceptance criteria

Avoiding non-linearity of optically pumped magnetometer MEG within an actively shielded two-layer mu-metal room

Some optically pumped magnetometer (OPM) sensors available for biomagnetic investigations have a linear range limited to +- 1 nT due to the specific properties of their open loop operation. In a two-layer magnetically shielded room of type Ak3b/Vacoshield Advanced with an external active compensation we studied how much sensor movement is allowed until amplitudes exceed the linearity range. Intentional movements were performed by a subject wearing an OPM-MEG sensor array. It was found that movements of 8 cm did yield non-linear amplitudes, but a reduction of the movement in half already preserves linearity. Despite movements, the heartbeat was found to generate a periodic signal, although the generating mechanism could not be identified so far.

Continuous Detection of Pb(II) utilizing Chitosan-Graphene Oxide Surface Plasmon Resonance Sensors based on Ag/Au and Au/Ag/Au Nanolayers

This work demonstrates the effect of Ag/Au and Au/Ag/Au nanolayers on the performance of chitosan (CS)-graphene oxide (GO) surface plasmon resonance (SPR) sensors for Pb(II) ion detection. The CS-GO SPR sensors are fabricated on a bi-metallic 40 nm Ag/10 nm Au and tri-metallic 10 nm Au/40 nm Ag/10 nm Au nanolayers. The sensors are tested with Pb(II) ion solution of concentrations 0.1 to 5 ppm using SPR spectroscopy. The results show that the CS-GO SPR sensor on the bimetallic Ag/Au gives a gradual shift in SPR angle from 0.1 to 1 ppm and slightly linear from 3 to 5 ppm. Meanwhile, the CS-GO SPR sensor on the tri-metallic Au/Ag/Au nanolayers provides an extended linearity range from 1 to 5 ppm with the highest shift in SPR angle of 1.8o. Additionally, the tri-metallic CS-GO SPR sensor also exhibits the greatest SNR of 0.25 as compared to 0.15 of the one on the bi-metallic nanolayers. Thus, the studies prove that the tri-metallic Au/Ag/Au nanolayer is an effective and simple approach to improve the performance of a CS-GO SPR sensor for Pb(II) ion detection.