Gas-solid chromatographic determination of moisture in lyophilized pharmaceutical products.

A gas-solid chromatographic procedure is described for the analysis of low levels of moisture in individual lyophilized vials of pharmaceutical products. Dry ethanol, which contains methanol as the internal standard, is injected through the septum of the vial to dissolve the lyophilized contents. An aliquot of this solution is then withdrawn and injected onto a Porapak QS column at 110 degrees C where the components are separated and detected using thermal conductivity detection. A solvent blank correction allows quantitation of the water in the individual vial. The method is conveniently applied to samples containing as little as 50 microgram water/vial, and as many as 25 vials can be assayed/day. A simple technique is also described for removing water from the ethanol solvent to less than 100 ppm, using a molecular sieve.     

Technical note: using calcium carbonate as an osmolar control treatment for acid-base studies in horses

The efficacy of using calcium carbonate as an osmolar control treatment for acid-base studies in horses receiving alkalizing compounds was evaluated. Six mares were nasogastrically intubated with isomolar quantities of sodium or calcium as sodium bicarbonate or calcium carbonate or with water during three treatment periods. Doses of the carbonic acid salts were 500 mg/kg sodium bicarbonate mixed with 4 L of distilled water (positive control) and 595 mg/kg calcium carbonate mixed with 2 L of distilled water to yield isoosmolar treatments. Four liters of distilled water served as the negative control. Jugular venous blood samples were drawn before intubation and at hourly intervals for 6 h after intubation. The serum electrolytes Na+ and K+, blood pH, and HCO3- were determined. The sodium bicarbonate treatment increased blood pH and HCO3- (P < 0.01) above both the water and CaCO3 treatments. No differences (P > 0.05) were found between the water and CaCO3 treatments. These data indicate that calcium carbonate may serve as a suitable osmolar control treatment for studying the effects of treatments that affect acid-base status of horses.