0000000000285254
AUTHOR
Luisa Gallo-martinez
A comparison of various calibration techniques applied to the ninhydrin-cefoxitin determination
Abstract This report deals with spectrophotometric determination of cefoxitin from intact antibiotics or from its acid induced degradation product by means of their reaction with ninhydrin in a strong sulphuric acid medium. To obtain the calibration graphs four methods were used: absorbance of reacted cefoxitin against a reagent blank as an analytical signal, first-derivative signal of absorbance against a water blank as an analytical signal, first-derivative signal of absorbance against a reagent blank as an analytical signal and the H-Point Standard Additions Method (HPSAM) by using absorbance increment values as analytical signals. The HPSAM is applied to the determination of cefoxitin i…
Comparative Study on the Determination of Cephalexin in its Dosage Forms by Spectrophotometry and HPLC with UV-vis Detection
This paper discusses the spectrophotometric determination of cephalexin as the intact cephalexin or as its acid-induced degradation product. Cephalexin can be determined in the range 1 × 10−5−18 × 10−5M with relative standard deviations of 5-1%. The limits of quantitation and detection were 10−5 and 0.3 × 10−5M, respectively. These procedures were compared with reversed-phase HPLC determination. No interference was observed in the presence of common pharmaceutical adjuvants. The H-point standard additions method was applied in order to correct for the possible presence of the cephalexin precursor, 7-aminocephalosporanic acid; this improves the selectivity of the UV-vis spectrophotometric me…
Principal component analysis for the selection of variables in the application of the H-point and generalised H-point standard addition method
The present paper deals with the selection of variables for the H-point and generalised H-point standard additions methods (HPSAM and GHPSAM, respectively). Both methods are applied for the resolution of spectroscopic interfered signals in the UV-vis range. The HPSAM is a suitable method for the resolution of binary and ternary mixtures when the interferent is known. The GHPSAM is applied for the resolution of samples that contain unknown interferents. In this paper, a method based on the study of a principal components analysis (PCA) for the selection of variables for the HPSAM and GHPSAM is proposed. The PCA results show the isolation of the analyte signal from the sample signal, achieved…
A new derivatization procedure for the determination of cephalexin with 1,2-naphthoquinone 4-sulphonate in pharmaceutical and urine samples using solid-phase extraction cartridges and UV–visible detection
Abstract The present report shows how to derivatize cephalexin with 1,2-naphthoquinone-4-sulphonate (NQS) into solid-phase extraction cartridges (C18) using UV–visible detection. Optimum conditions for this new procedure are: hydrogen carbonate/carbonate buffer pH=10.5, 5 min reaction time at 25°C and NQS concentration of 7.1×10−3 mol l−1. The accuracy and the precision of the method were tested. The procedure was used to measure cephalexin in pharmaceutical and urine samples. The results obtained were contrasted with those reported by UV-spectrophotometric and HPLC methods for pharmaceutical samples and with HPLC method for urine samples. The H-point standard additions method was used to m…