Fast HPLC methods

Hertog et al. (119) developed a fast HPLC method for the identification and quantification of five major flavonoid aglycones (quercetin, kaempferol, myricetin, luteolin, and apigenin) in freeze-dried vegetable and fruits. However, due to the inadequate resolution of quercetin and luteolin on RP-HPLC on Nova-Pak C]8, two different eluents of different solvent strength and viscosity were utilized. The conditions for hydrolysis and extraction were tested based on different conditions of hydrochloric acid concentration (1.2-2.0 M), reaction period (0.5-6 h), and meth-... 

Trace acetone in water may be determined by a fast HPLC method (Takami et al., 1985) aqueous sample passed through a cartridge packed with a moderately sulfonated cation-exchange resin charged with 2,4-dinitrophenylhydrazine (DNPH) DNPH derivative eluted with acetonitrile and analyzed by HPLC with a 3-mm ODS column. 

HPLC is another convenient method for measurement of the NCE pKa values. As was shown by Melander and Horvath [13], the retention of any ionizable analyte closely resembles the curve shown in Figure 12-3. Chromatographic determination of the pKa could be accurately performed with very limited amount of sample. Fast HPLC method with optimum analyte retention is suitable for this purpose, but the influence of the organic mobile-phase modifier on the mobile phase pH and analyte Ka should be accounted for in order to provide the accurate calculation of the respective Ka value. Detailed discussion of the HPLC-based methods for the Ka determination is given in Chapter 4. 

HPLC methods are preferred if excipients would interfere, if nonspecific detection techniques (mainly in UV) would be used, or when multiple APIs (combination product) are present in a drug product. Since dissolution sample set analysis can be very long due to six samples per bath as well as multiple time points for prohle testing, fast run times are preferred to quickly determine the results. If a fast HPLC method for CU is available, then the identical HPLC method can be utilized for dissolution analysis. 

Acetone is analyzed by GC-FID. A Car-bowax 20 M, Carbopack, fused-silica capillary column, or any equivalent column may be suitable. It may be analyzed by GC/MS using a purge and trap technique or by direct injection. Characteristic ions are 43 and 58 (electron-impact ionization) (U.S. EPA 1986, Method 8240). Acetone in air is adsorbed over coconut shell charcoal, desorbed with CS2, and analyzed by GC-FID using a 10% SP-2100 or DB-1 fused-silica capillary column (NIOSH 1984, Method 1300). Airflow rate 10 to 200mL/min volume 0.5-3 L of air. Trace acetone in water can be determined by the fast HPLC method discussed in Chapter 5. 

Gleize, B., M. Steib, M. Andre, and E. Reboul. 2012. Simple and fast HPLC method for simultaneous determination of retinol, tocopherols, coenzyme QIO and carotenoids in complex samples. Food Chem. 134 2560-2564. 

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