Establish Calibration Curves Research Articles

Comparison of the nuclear magnetic resonance and infrared spectroscopic methods for the quantitative analysis of polydimethylsiloxane

A method based on nuclear magnetic resonance spectroscopy is described for the quantitative determination of polyimethylsiloxane (PMS) in a variety of pharmaceutical preparations. An extraction procedure using deuterochloroform within the sample tube was devised. In the presence of an internal standard, the PMS concentration was determined directly using integrated peak areas, without the necessity of establishing calibration curves. Accurate quantitative results were achieved with sample, containing at least 2mg PMS, extracted from formulations containing greater than 0.5% PMS. The extraction procedure and nmr assay were both more efficient and convenient than the B.P.C. method.

Determining the water content of concrete panels by using a microwave moisture meter

Synopsis Sections of 1 × 2 m, sawn from full-size commercial concrete panels, were tested with a microwave moisture meter to establish calibration curves for different types of concrete cladding panel. The tests confirmed that the relationship between microwave attenuation and percentage of absorhed water for such panels was linear, but it was also found that the slope of the curve depended upon the particular construction of the concrete panel. With 10% absorbed water, the microwave attenuation varied between approximately 10 and 20 dB. Anomalous results were obtained during freezing weather and these were attributed to molecular orientation of the water in the concrete.

A New and Rapid Determination of Pyridinium Aldoximes in Blood and Urine

Abstract A rapid and accurate method for analyzing pyridinium oximes—N-methylpyridinium-2-aldoxime chloride, N,N'-trimethylene-(pyridinium-4-aldoxime) dihalide, and N,N'-oxydimethyl-(pyridinium-4-aldoxime) dichloride—in plasma, urine, and whole blood is described. The method is completely automated and requires small sample volumes. Concentrations ranging from 3 to 120 µEq./L. in biologic fluids can be determined at a rate of 40 samples per hour. This technic can be applied to oximes which are unstable in basic solution. The average variation of the oxime concentration used to establish calibration curves, as determined by the ratio of the standard deviation to the mean, was ± 1.5%. Plasma and albumin increase the transfer rate of the oximes through the dialyzing membrane. Theoretical concentrations to explain this phenomenon are presented.

APPLICATION OF THE X-RAY SPECTROGRAPH TO THE NEEDS OF THE INDUSTRIAL HYGIENE LABORATORY.

Abstract A method is described for the direct analysis of air samples collected on filter paper. The method has sufficient sensitivity to be used without any sample concentration for most air samples. A simple method of preparation of filters for use in establishing calibration curves is also described.

STUDIES ON RDX AND RELATED COMPOUNDS: VI. THE HOMOGENEOUS HYDROLYSIS OF CYCLOTRIMETHYLENETRINITRAMINE (RDX) AND CYCLOTETRAMETHYLENETETRANITRAMINE (HMX) IN AQUEOUS ACETONE, AND ITS APPLICATION TO ANALYSIS OF HMX IN RDX(B)

Measurements of the rates of alkaline hydrolysis of cyclotrimethylenetrinitramine (RDX) and cyclotetramethylenetetranitramine (HMX) in aqueous acetone show these two reactions to involve consecutive steps, the first of which is second order and rate controlling. Activation energies were estimated as 14 and 25 kcal. respectively. By establishing calibration curves, and controlling temperature, alkali concentration relative to concentration of explosive, and reaction time, the differential hydrolysis permits analysis of the HMX content of RDX(B) with an error of approximately ±0.2% HMX.