HPLC-DAD quantification of favipiravir in whole blood after extraction from volumetric absorptive microsampling devices

Favipiravir is a prodrug of T-1105 made by modifying the pyrazine group as a COVID-19 therapy. During the pandemic, a safe and comfortable biosampling technique is needed for the subject or patient. Volumetric Absorptive Microsampling (VAMS) is a biosampling technique with a small blood volume and minimum hematocrit effect. The aims of this study were to develop and validate an analytical method for quantifying favipiravir extracted from VAMS using High Performance Liquid Chromatography - Photodiode Array with remdesivir as an internal standard. Analysis of favipiravir was performed using a C₁₈ column (Waters, Sunfire™ 5 µm; 250 × 4.6 mm), with injection volume of 50 µL, flow rate of 0.8 mL/min, column temperature 30 ℃, and wavelength 300 nm. The separation was conducted under gradient elution with mobile phase consists of acetonitrile-0.2 % formic acid-20 mM sodium dihydrogen phosphate pH 3.5 and run time 12 min. Sample preparation was carried out using a protein precipitation method with 500 µL of methanol as precipitating agent. Samples were mixed on vortex for 30 s, sonicated for 15 min, and centrifuged at 10,000 rpm for 10 min. Lower Limit of Quantification (LLOQ) obtained was 0.5 µg/mL and the calibration curve ranged from 0.5 to 160 µg/mL. Sensitivity, linearity, selectivity, carry-over, accuracy, precision, recovery, and stability were validated by the guideline from Food and Drug Administration 2018. The method developed has successfully met the full validation requirements by FDA 2018 with the LLOQ obtained was 0.5 µg /mL.

Development of a Simple High-Performance Liquid Chromatography-Based Method to Quantify Synergistic Compounds and Their Composition in Dried Leaf Extracts of Piper Sarmentosum Roxb

There is a growing demand to enhance pharmaceutical and food safety using synergistic compounds from Piper sarmentosum Roxb., such as polyphenols and water-soluble vitamins. However, information on standardized analytical methods to identify and quantify these compounds of interest is limited. A reversed-phase high-performance liquid chromatography with diode-array detection (HPLC-DAD)-based method was developed to simultaneously detect and quantify the amounts of tannin, flavonoid, cinnamic acid, essential oil, and vitamins extracted from P. sarmentosum leaves using methanol, chloroform, and hexane. Commercially and non-commercially-cultivated P. sarmentosum leaves were subjected to seven different drying treatments (shade; sun; air oven at 40 °C, 60 °C, 80 °C, and 100 °C; and freeze-drying) for three consecutive months. Most compounds were detected most efficiently at a detection wavelength of 272 nm. The developed method displayed good detection limits (LOD, 0.026–0.789 µg/mL; LOQ, 0.078–2.392 µg/mL), linearity (R2 > 0.999), precision (%RSD, <1.00), and excellent accuracy (96–102%). All P. sarmentosum leaf extracts were simultaneously tested and analytically compared without time-consuming fractionation. Methanolic plant extracts showed better peak area and retention time splits compared to chloroformic and hexanoic extracts. Differences in synergistic compound composition were dependent on the type of drying treatment but not on cultivation site and time of sampling. Flavonoid was identified as the dominant phytochemical component in P. sarmentosum leaves, followed by the essential oil, cinnamic acid, ascorbic acid, and tannin. Overall, we present a simple and reproducible chromatographic method that can be applied to identify different plant compounds.

Disperse Solid-Phase Extraction Cleanup for the Determination of 1-Deoxynojirimycin in Mulberry Leaves with Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry

A new determination method of 1-deoxynojirimycin (1-DNJ) in mulberry leaves based on ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been developed. Dried and crushed mulberry leaves’ sample was extracted by MeCN-water solvent, purified by graphitized carbon black (GCB) and primary secondary amine (PSA) to remove organic acids and pigments, and then analyzed after attenuation and filtration. The calibration curve showed linearity in the concentration range of 10–500 ng/mL, with the correlation coefficient of 0.998. Recoveries of spiked 1-DNJ at three fortification levels ranged from 94.6% to 96.4%, with relative standard derivation below 1.2%. Additionally, the matrix effect was assessed as negligible. Compared with methods by gas chromatography (GC) and liquid chromatography (LC) via real sample detection, the proposed method acquired better stability and detection efficiency. These results proved that this method has advantages of simple operation, complete purification, small pretreatment loss, good precision and accuracy, and high determination specificity, which is suitable for massive monitoring and precise quantitation of 1-DNJ in mulberry leaves.

Linear flow-velocity gradient chromatography-An efficient method for increasing the process efficiency of batch and continuous capture chromatography of proteins

A new method was proposed for increasing the capture chromatography process efficiency, linear flow-velocity gradient (LFG). The method uses a linear decreasing flow-velocity gradient with time during the sample loading. The initial flow velocity, the final flow velocity and the gradient time are the parameters to be tuned. We have developed a method for determining these parameters by using the total column capacity and the total loaded amount as a function of time. The capacity can be calculated by using the relationships between dynamic binding capacity (DBC) and residence time. By leveraging the capacity, loading amount, and the required conditions, the optimum LFG can be designed. The method was verified by ion-exchange and protein A chromatography of monoclonal antibodies (mAbs). A two-fold increase in the productivity during the sample loading was possible by LFG compared with the constant flow-velocity (CF) operation. LFG was also applied to a 4-column continuous process. The simulation showed that the cost of resin per unit amount of processed mAbs can be reduced by 13% while 1.4 times enhancement in productivity was preserved after optimization by LFG compared to CF. The process efficiency improvement is more pronounced when the isotherm is highly favorable and the loading volume is large.

Synthesis and Characterisation of a Monolithic Imprinted Column Using a Methacrylic Acid Monomer with Porogen Propanol for Atenolol Analysis

A monolithic imprinted atenolol column was constructed by in situ polymerisation using a methacrylic acid monomer and a 1 : 1 (v/v) porogen of propanol: toluene with two template: monomer: crosslinker combinations, namely, MIP 1 (1 : 4 : 20) and MIP 2 (1 : 5 : 20). Physical characterisation of the monolithic columns consisted of permeability testing, Fourier transform infrared (FTIR) testing, surface area analysis (SAA), and scanning electron microscopy (SEM). The permeability value of four monolithic columns was in the good category: MIP 1 (24.01 mD), NIP 1 (56.43 mD), MIP 2 (23.03 mD), and NIP 2 (14.47 mD). The polymerisation process of these four monolithic imprinted columns was carried out perfectly, as shown by the absence of vinyl groups (1000 cm^-1 and 900 cm^-1) during FTIR testing. Based on SAA testing, the pores of the four polymers were classified as mesopores. The best monolithic column was MIP 1, as seen from the intercolumn and intracolumn reproducibility values and a % RSD <2.0%. The MIP 1 column was selective towards atenolol, as seen from the selectivity factor, imprinting factor (IF), and resolution (Rs) values. The IF values of MIP 1 were atenolol (204.62), metoprolol (3.36), and propranolol (1.27). The Rs value between atenolol and the analogue compounds was 7.23. The MIP 1 column can be used for the analysis of atenolol in blood serum samples with an average percentage recovery rate of 94.88 ± 4.43%.

Bioanalytical methods for the detection of antidiabetic drugs: a review

Type 2 diabetes mellitus, a disease which prevalence has been progressively increasing worldwide, is characterized by chronic hyperglycemia resulting from the combination of inappropriate insulin secretion and/or resistance to insulin action. If left uncontrolled, diabetes is associated with complications such as dysfunction and failure of various organs, and even premature death. Along with lifestyle-modification strategies, several classes of oral antidiabetic agents can be employed for glycemic control. Thus, therapeutic drug monitoring of these drugs is essential to maintain appropriate treatment. This review discusses the most frequently employed analytical techniques and sample preparation systems to obtain a reliable and trustworthy method to quantify antidiabetic drugs in biological matrices. An adequate choice of internal standard, ideal chromatography conditions and most suitable analytical detector are reported.

Reversed-phase ion-pair chromatography-diode array detection of the bispyridinium compound MB327: plasma analysis of a potential novel antidote for the treatment of organophosphorus poisoning

In the case of poisoning by organophosphorus nerve agents or pesticides, there is still a lack of pharmacological treatment of the cholinergic crisis selectively targeting the nicotinic acetylcholine receptor. Recently, the compound MB327 was identified as a potential novel lead structure to close this gap, thus demanding a quantitative assay for initial pharmacokinetic (PK) studies. MB327 is a salt consisting of the dicationic bispyridinium compound (BPC) 1,1´-(propane-1,3-diyl)bis(4-tert-butylpyridinium) and two iodide counter ions. Due to the permanent positive charge of the BPC, an isocratic reversed-phase ion-pair chromatographic separation (RPIPC) was developed using heptanesulfonic acid as ion-pairing reagent and 45% v/v methanol as organic modifier (1 mL/min). Selective UV-detection (230 nm) was done by a diode array detector (DAD) for reliable, rugged, precise (RSD < 7%) and accurate (96-104%) quantitative analysis of 50 μL swine plasma (linear range 1-1000 µg BPC/mL plasma, lower limit of quantification 2 µg/mL). During method validation, diverse parameters essential for the chromatographic process were investigated to generate van´t Hoff, van Deemter and width plots allowing calculation of thermodynamic data like the distribution constant K (5.7 ± 0.3), change in enthalpy, ΔH(0) : -23.66 kJ/mol, and entropy, ΔS(0) : -65 J/(mol*K). In addition, RPIPC-DAD analysis enabled calculation of molar absorptivities of the BPC, ε230 : 17 400 ± 1100 L/(mol*cm), and iodide, ε230 : 9900 ± 400 L/(mol*cm), which determination was hampered by interference with each other in conventional cuvette UV-spectrophotometric measurements. Finally, the RPIPC-DAD procedure was applied to samples from an in vivo study of swine.