PubMed · 10269135
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P S Lederer. 1984. Sensor performance evaluation.. https://pubmed.ncbi.nlm.nih.gov/10269135/
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Antidepressant, neuroleptic and antiepileptic drugs were identified and determined in pharmaceutical formulations (tablets, capsules and oral solutions) by a rapid high-performance liquid chromatography method. The sample pretreatment consisted of a one-step extraction, filtration and dilution. The chromatographic conditions were: reversed-phase C8 column (150 x 4.6 mm i.d., 5 microm); acetonitrile-tetramethylammonium perchlorate aqueous solution (pH 2.8; 12.6 mM) (45:55, v/v) as the mobile phase; detection wavelength, 230 nm. Calibration curves were linear in the 100-1000 ng ml(-1) range for all tested drugs except for phenobarbital. The repeatability (or intra-day precision), expressed by the relative standard deviation, was better than 2.0%. The accuracy, resulting from recovery studies, was between 98.1 and 101.3%. The amount of drug found agreed with the declared content within the limits specified by United States Pharmacopeia and British Pharmacopeia.
Semiconductor etchants are concentrated-acid mixtures that are prepared under tight specifications. Assay procedures are needed to ensure that the proportion of each component is within a small percentage (usually 10 relative percent or less) of the target concentration. One such etchant class contains chromium trioxide, usually in combination with HF and HNO3, While several ion-chromatographic columns can be used to analyze most mineral acids, chromium(VI) presents a problem. This latter species is highly retained by many separators and may also degrade the resins. This paper compares two columns that showed potential for success with these assays: the AS 11 and the AS16 separators (both from Dionex). These columns permit elution of chromium(VI) as chromate in 25 min or less. A representative mixture of HF, HNO3 and CrO3 was used in the research. Simultaneous calibration studies were conducted and the data sets analyzed statistically. Also investigated was the effect on the columns of repeated exposure to chromate.
Groundwater is a significant source of water for both domestic and agricultural use in some regions of the Maracaibo lake basin in Venezuela. Chemically suppressed ion chromatography with a Dionex Model 2000i/sp, lonpac AS11, ASRS-I system was used for the analysis of major inorganic anions in groundwater samples. About 50 samples of groundwater, taken over several months in three different locations, were analyzed after filtration and sometimes dilution. In all the samples, the separation between the peaks of chloride, nitrate and sulfate showed good resolution (symmetrical peaks, not broadened), even when the chloride concentration was as high as 850 mg l(-1) and reproducibility (RSD) was -2%. No other peaks (i.e. fluoride, nitrite and phosphate) were observed at selected experimental conditions. With the chosen parameters, the method is well-suited for the routine determination of these anions in groundwater samples, giving results in less than 10 min (including column clean-up). With an appropriate combination of detector output ranges (300 and 1,000 microS), only one set of calibration solutions was needed for all samples. In the Sierra Maestra location, the groundwater samples, were significantly different in total anion levels. Mean total chloride plus sulfate concentrations (approximately 525 mg l(-1)) were about 100 times higher than in the other sites. Some water quality implications of these groundwater samples are also discussed.