Determination of anabolic steroids in pharmaceuticals by liquid chromatography with a microemulsion of sodium dodecyl sulfate and pentanol as mobile phase

1995 ◽  
Vol 302 (2-3) ◽  
pp. 163-172 ◽  
Author(s):  
S.Torres Cartas ◽  
M.C.García Alvarez-Coque ◽  
R.M.Villanueva Camañas
2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Irena Malinowska ◽  
Katarzyna E. Stępnik

Micellar liquid chromatography (MLC) with the use of high performance liquid chromatography (HPLC) was used to determine some physicochemical parameters of six biogenic amines: adrenaline, dopamine, octopamine, histamine, 2-phenylethylamine, and tyramine. In this paper, an influence of surfactant’s concentration and pH of the micellar mobile phase on the retention of the tested substances was examined. To determine the influence of surfactant’s concentration on the retention of the tested amines, buffered solutions (at pH 7.4) of ionic surfactant—sodium dodecyl sulfate SDS (at different concentrations) with acetonitrile as an organic modifier (0.8/0.2 v/v) were used as the micellar mobile phases. To determine the influence of pH of the micellar mobile phase on the retention, mobile phases contained buffered solutions (at different pH values) of sodium dodecyl sulfate SDS (at 0.1 M) with acetonitrile (0.8/0.2 v/v). The inverse of value of retention factor () versus concentration of micelles () relationships were examined. Other physicochemical parameters of solutes such as an association constant analyte—micelle ()—and partition coefficient of analyte between stationary phase and water (hydrophobicity descriptor) () were determined by the use of Foley’s equation.


1994 ◽  
Vol 77 (1) ◽  
pp. 41-45 ◽  
Author(s):  
William A Moats

Abstract A method is described for determination of am-piciitin and amoxicillin in milk by using an automated liquid chromatographic (LC) cleanup. Milk was deproteinated by adding tetraethylammonium chloride solution and acetonitrile. The filtrate was concentrated by evaporation, filtered, and loaded into a 4 mL autosampler vial. For LC cleanup, a Waters W1SP 712 autosampler, a Varian 9010 pump, a Supelcosil LC-18 column, and an ISCO FOXY fraction collector were used. The cleanup program, where A is 0.01 M KH2PO4 and B is acetonitrile, was 100A + OB for 0-3 min and then 70A + 30B for 24 min. Sample concentrate (2 mL) was loaded onto the column for cleanup. Fractions containing amoxicillin and ampicillin were collected, partially acidified, and concentrated to 1 mL. Analysis was done on the LC-18 column, with a mobile phase of 0.015M H3PO4–{0.0075M sodium dodecyl sulfate-acetonitrile (70 + 30)] for amoxicillin and 0.0067M H3PO4–0.0033M KH2PO4–[0.005M sodium dodecyl sulfate–acetonitrile (67 + 33)] for ampicillin. Recoveries were generally 80–90% at a concentration range of 1–0.01 ppm, with a detection limit of 2–5 ppb. By collecting appropriate fractions, the method can be applied to the determination of any amphoteric β-lactam.


2020 ◽  
Vol 18 (1) ◽  
pp. 377-390
Author(s):  
Dina El Sherbiny ◽  
Mary E. K. Wahba

AbstractA stability-indicating hybrid micelle liquid chromatography accompanied by UV detection was developed for the simultaneous analysis of either paracetamol (PCA) or pseudoephedrine hydrochloride (PSU) with their synthetic impurities. Mixture I contains PCA with p-amino phenol and p-nitro phenol, while mixture II involves the estimation of PSU with benzaldehyde and benzoic acid. Both mixtures were separated using a C18 column that was thermostatically maintained at 40°C and operating under a flow rate of 1.5 mL/min, applying UV detection at 240 nm for mixture I and 220 nm for mixture II. In both cases, the mobile phase consisted of 0.1 M sodium dodecyl sulfate, acetonitrile, and triethylamine (90:10:0.3, v/v/v) and adjusted to pH 4 (mixture I) or pH 3.7 (mixture II) using 2.0 M O-phosphoric acid. The proposed method was validated and successfully applied to assay different pharmaceuticals containing PCA or PSU. Moreover, the stability-indicating nature of the proposed method was proved through applying photolytic degradation procedures for PCA.


Author(s):  
Abolfazl Darroudi ◽  
Saeid Nazari ◽  
Seyed Ali Marashi ◽  
Mahdi Karimi-Nazarabad

Abstract An accurate, rapid, simple, and novel technique was developed to determine simvastatin (SMV). In this research, a screen-printed electrode (SPE) was deposited with graphene oxide (GO) and sodium dodecyl sulfate (SDS), respectively. For the first time, the handmade modified SPE measured the SMV by differential pulse voltammetry (DPV) with high sensitivity and selectivity. The results of cyclic voltammetry indicated the oxidation irreversible process of SMV. Various parameters (pH, concentration, scan rate, support electrolyte) were performed to optimize the conditions for the determination of SMV. Under the optimum experiment condition of 0.1 M KNO3 as support electrolyte and pH 7.0, the linear range was achieved for SMV concentration from 1.8 to 36.6 µM with a limit of detection (LOD), and a limit of quantitation (LOQ) of 0.06 and 1.8 µM, respectively. The proposed method was successfully utilized to determine SMV in tablets and urine samples with a satisfactory recovery in the range of 96.2 to 103.3%.


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