Solid-phase extraction cleanup and liquid chromatography with ultraviolet detection of ephedrine alkaloids in herbal products.

A solid-phase extraction (SPE) cleanup and a liquid chromatographic (LC) method with UV detection is presented for analysis of up to 7 ephedrine alkaloids in herbal products. Alkaloids from herbal products are extracted with acidified buffer, isolated on a propylsulfonic acid SPE column, eluted with a high-ionic-strength buffer, and separated by LC with detection at 255 nm. LC separation is performed by isocratic elution on a YMC phenyl column with 0.1 M sodium acetate-acetic acid (pH = 4.8) containing triethyl-amine and 2% acetonitrile. Ephedrine alkaloids are completely separated in 15 min. Average recovery of 5 common alkaloids from 3 spiked matrixes is 90%, with an average relative standard deviation (RSD) of 4.4% for alkaloid spikes between 0.5 and 16 mg/g. Average quantitation of ephedrine and pseudoephedrine from 6 herbal products is 97% of declared label claims, and average quantitation of synephrine from an herbal dietary product is 85% of label claim (RSD, 3.2%). Recoveries of synephrine, norephedrine, ephedrine, pseudoephedrine, N-methylephedrine, and N-methylpseudoephedrine spiked in 4 herbal products averaged 95%. Results of ruggedness testing and of a second laboratory validation of the procedure are also presented.

Liquid chromatographic determination of chlortetracycline hydrochloride in ruminant and poultry/swine feeds.

A liquid chromatographic (LC) method is described for the determination of chlortetracycline hydrochloride (CTC) in poultry/swine and ruminant feeds in the 10-100 ppm range and in premix. CTC is extracted from ground feed/premix with acidified acetone, and the extract is filtered through a Millex-HV filter or disposable C18 column. The filtrate is partitioned with methylene chloride when additional cleanup is necessary. A Nova-Pak C18 column is used for LC separation with determination at 370 nm. The average recovery of CTC from premix was 95% with a standard deviation (SD) of 1.70 and a coefficient of variation (CV) of 1.79%. The overall average recovery from feeds was 77% with an SD of 3.18 and a CV of 4.10%.