Abstract
A method has been developed for the simultaneous determination of Al, Fe, Ca, and Mg in wet-process phosphoric acid by dc argon plasma emission spectrometry. The suppression of Ca and Mg emission by phosphate encountered in flame analyses was nonexistent, and other interferences were minimal. Results obtained by the procedure were compared with those obtained by atomic absorption spectrometry. The paired t-test showed no significant difference between the 2 methods at the 95% confidence level.
Abstract
In the described method, water in phosphoric acid is determined by in situ coulometric generation of Karl Fischer reagent with automated end point detection. The variables associated with visual end point detection among different operators are eliminated. Sample size is limited by the generation rate of available coulometers and is 50 mg for samples containing more than 20% water and 100 t o 150 m g for samples containing less than 20% water for a 20 min analysis time . The precision at 99% confidence ranges from 0.43 ± 0.05% for superphosphoric acid to 36.8 ± 0.81% for untreated 10–34–0 base solution; for polished wet process phosphoric acid the precision is 16.49 ± 0.19% compared to 16.70 ± 0.64% by azeotropie distillation. The method is applicable in all systems which do not normally interfere with Karl Fischer reagent; the generating efficiency at the 100% water level is >99%. Coulometer power tube fatigue is the most serious limitation unless a careful check and replacement program is initiated.
Abstract
A method for determining uranium, based on extraction with trioctylphosphine oxide and measurement by argon plasma emission spectrometry at 424.17 nm, is described. Results from the argon plasma method compare favorably with results from other methods and are within 1 standard deviation of the composite average of all methods used in an 11-laboratory study.
A RP-HPLC-UV method was developed and validated for simultaneous determination of florfenicol and diclazuril in compound powder. The separation involved using a SinoChoom ODS-BP C18(5 μm, 4.6 mm × 250 mm) analytical column. The mobile phase was a mixture of acetonitrile-0.2% phosphoric acid (pH was adjusted to 3.0 with triethylamine). The ratio of acetonitrile and 0.2% phosphoric acid in the mobile phase was 60 : 40 (v/v) from 0 minutes to 6 minutes and 70 : 30 (v/v) from 6.1 minutes to 15 minutes. The flow rate was 1 mL/min. The temperature of the analytical column was maintained at 30°C. The detection was monitored at 225 nm and 277 nm for florfenicol and diclazuril, respectively. The excipients in the compound powder did not interfere with the drug peaks. The calibration curves of florfenicol and diclazuril were fairly linear over the concentration ranges between 50.0–500.0 μg/mL (r=0.9995) and 10.0–100.0 μg/mL (r=0.9992), respectively. The RSD of both the intraday and interday variations was below 2.1% for florfenicol and diclazuril. The method was successfully validated according to International Conference on Harmonisation and proved to be suitable for the simultaneous determination of florfenicol and diclazuril in compound powder.
Simultaneous Determination of Florfenicol and Diclazuril in Compound Powder by RP-HPLC-UV Method