Valbenazine isomers and enantiomer determination by chiral normal phase liquid chromatography.

A novel, simple, specific, rapid, enantioselective normal phase chiral high-performance liquid chromatographic method with amylose-based Chiral Pak IG-3(250 × 4.6 mM) 3.0 µM column was developed and validated for separation and quantification of isomers and enantiomer of Valbenazine. The mobile phase composed of n-Heptane, isopropyl alcohol, dichloromethane, ethanol, and diethylamine in the ratio of 70:10:15:5:0.1 (V/V/V/VV) with a gradient flow rate was applied. The injection volume was 10 µl, and detection was carried out using a photodiode array detector at 282 nM. The column compartment was set at 35°C. The resolution between the enantiomer and isomers was found to be more than 2.0. The method was linear over the concentration range of limit of quantitation to 250% for isomers and enantiomers. The method was found to be robust with column temperature. The proposed chiral method is applicable for the determination of isomers and enantiomer of Valibenazine and was successfully used in the quality control of bulk drug manufacturing and pharmaceuticals.

Estimation of purity of antimicrobial lead compound sulfonamide-anthranilate derivative methyl-ester-toluene-sulfonamide using LC to develop a new drug application.

The newly synthesized lead molecule methyl-ester-toluene-sulfonamide is the combined derivative of sulfonamide-anthranilate. It was estimated by gradient elution using 0.1% triethylamine in water with pH 2.0 as mobile phase A and the mixture of acetonitrile and tetrahydrofuran in the ratio of 975:25 (v/v) as mobile phase B at a flow rate of 0.8 ml/min and 210 nm wavelength on an Agilent 1260 infinity series HPLC system equipped with a diode array detector. The column used was ACE 3 C18-PFP (250 × 4.6 mm, 3 µm i.d.) operating at 40°C. The gradient program was time (min)/% B: 0.0/50, 3.0/50, 15.0/70, 25.0/90, 30.0/90, 31/50, and 38/50. The method is simple, accurate, rapid, and selective. The method was linear with a concentration range of 1.6-240 µg/ml. The accuracy data obtained were 98.5-100.5%. The method validation data and quality by design-based robustness study results indicate that the developed method is robust and fit for routine use in the quality control laboratory. Therefore, the ready availability of the method can be useful in pharmaceutical new drug development.

Determination of methylcellulose and hydroxypropyl methylcellulose food gums in food and food products: collaborative study.

A collaborative study was performed to determine the reproducibility of a method for the determination of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) in food. These widely used food gums possess unusual solubility characteristics and cannot accurately be determined by existing dietary fiber methods. The new method uses the enzyme-digestion procedure of AOAC Official Method 991.43. Digestate solutions must be refrigerated to fully hydrate MC or HPMC. The chilled solutions are filtered and analyzed by size-exclusion liquid chromatography. Collaborating laboratories received 28 samples containing MC or HPMC in the range of 0-100%. The sample set included blind duplicates of 5 food matrixes (bread, milk, fish, potato, and powdered juice drink). Cochran and Grubbs tests were used to eliminate outliers. For food samples containing MC, values for within-laboratory precision, repeatability relative standard deviation (RSDr), ranged from 4.2 to 16%, and values for among-laboratories precision, reproducibility relative standard deviation (RSDR), ranged from 11 to 20%. For HPMC samples, RSDr values ranged from 6.4 to 27%, and RSDR values ranged from 17 to 39%. Recoveries of MC and HPMC from the food matrixes ranged from 78 to 101%. These results show acceptable precision and reproducibility for the determination of MC and HPMC, for which no Official AOAC Methods exist. It is recommended that this method be adopted as AOAC Official First Action.