Lale Ersoy

Characterization and lime treatment of olive mill wastewater.

Seventeen olive mill wastewater (OMW) samples were characterized. For characterization of the samples, amount of total, fixed, volatile, suspended, volatile-suspended solids, COD, oil-grease, polyphenol, volatile phenol, nitrogen and reducing sugar were determined. Effects of lime treatment on the waste samples were investigated. Reduction of contents of the samples treated with the lime was described. The effect of the addition of lime on an artificial phenolic mixture was also examined.

An HPLC method for the determination of atorvastatin and its impurities in bulk drug and tablets.

A simple high-performance liquid chromatographic (HPLC) method was developed for the analysis of atorvastatin (AT) and its impurities in bulk drug and tablets. This method has shown good resolution for AT, desfluoro-atorvastatin (DFAT), diastereomer-atorvastatin (DSAT), unknown impurities and formulation excipients of tablets. A gradient reverse-phase HPLC assay was used with UV detection. Some solvent systems prepared using methanol or acetonitrile and water or buffer systems with different pH values were tested. Capacity factors of related substances were calculated at all tested systems. Best resolution has been determined using a Luna C18 column with acetonitrile-ammonium acetate buffer pH 4-tetrahydrofuran (THF) as mobile phase. Samples were eluted gradiently with the mobile phase at flowrate 1.0 ml min(-1) and detected at 248 nm. The proposed method was applied to the determination of impurities and were found to contain 0.057-0.081, 0.072-0.097, 0.608-0.664% of the DFAT, DSAT and total impurity, respectively.

A new spectrofluorimetric method for the determination of lisinopril in tablets.

An accurate and precise spectrofluorimetric method is presented for the determination of lisinopril based on the formation of a derivative formed with 7-chloro-4-nitrobenzofurazan. The derivatization reaction proceeds quantitatively at pH 8.5-9.0 and 60 degrees C in 70 min when the molar ratio of reagent to the drug is 170. After the extraction with ethyl acetate the fluorescence intensity of the derivative was measured at 528 nm with excitation at 465 nm. Calibration graph is rectilinear over the range of 50-1000 ng/ml with detection and determination limits of 20 and 50 ng/ml, respectively. The regression equation is I(f) = 0.198C-0.299 (r = 0.9999). The method was applied to the commercially available tablets and the results were statistically compared with those obtained by official HPLC method.

Determination of tyramine in cheese by LC–UV

An isocratic reversed-phase liquid chromatographic assay for tyramine has been developed. The method is based on the reaction of tyramine with 4-chloro-7-nitrobenzofurazan and measurement of the absorbance at 458 nm after chromatographic separation on a C-18 column. Optimum reaction conditions were investigated. A linear relationship was found between absorbance and concentration over the range 25-300 ng per 10 microl of tyramine. The method was applied to the determination of tyramine in cheese. The cheese sample was homogenized with 5% (w/v) HClO(4) extracted with ethyl acetate-acetone (2:1) and chromatographed on high performance liquid chromatography (HPLC) after derivatization reaction with NBD-Cl. The determination limit was 25 microg/g cheese. The mean recovery of tyramine from cheese was 98.0%.

Halogenated secondary metabolites from Laurencia Obtusa

A new sesquiterpene (1), and a halogenated C15 acetogenin (2), a stereoisomer of neoisoprelaurefucin were isolated from Laurencia obtusa. Four known compounds laurencienyne (3), rogiolenyne B (4), obtusenol (5), and (3E)-dactomelyne (6) were also isolated from this alga. Rogiolenyne B (4) and (3E)-dactomelyne (6) were found for the first from this species. The structures of these compounds were elucidated by spectroscopic methods. The unambiguous assignments of the 1H and 13C NMR spectral data of (5) and 13C NMR data of (6) were also reported for the first time.

Determination of poly(ethylene glycol)-400 in urine by fourier transform–infrared spectrometry

A simple and rapid method for the analysis of poly(ethylene glycol)-400 (PEG-400)(used in the study of intestinal physiology) in human urine is described using Fourier transform–infrared spectrometry. The quantitative measurements were carried out by using the absorbance value of the C—O—C band (wavenumber 1100 cm–1). The lower limit of determination of PEG-400 in human urine was 0.8 mg cm–3. Analytical recovery of PEG-400 added to urine controls was 99.6%. The results of the analyses of one urine sample were compared with those obtained by using high-performance liquid chromatography. Limitations and advantages of the two systems are discussed.

Development and validation of a GC-FID assay for determination of fluvastatin in pharmaceutical preparations

A gas chromatographic method has been developed for the assay of fluvastatin sodium (FLU). FLU was silylated with N,Obis(trimethylsilyl)trifluoroacetamide-1% trimethylchlorosilane at 90 oC for 30 min and analysed in a DB-1 column by capillary gas chromatograph with a flame ionization detector. The method was validated. The assay was linear over the concentration range at 10.0 to 50.0 mg mL-1. The limit of detection and the limit of quantitation were 1.0 and 3.0 mg mL-1, respectively. The recoveries of FLU derivatives were in the range of 99.25-99.80%. In inter-day and intra-day analysis, the values of relative standard deviation (%) and the relative mean error (%) were found between 0.20-0.80% and -0.20-0.75%, respectively. The developed method was succesfully applied to analyze the FLU content in tablet formulation. The results were statistically compared with those obtained by the official method, and no significant difference was found between the two methods. Therefore, it can be recommended for the quality control assay of FLU in pharmaceutical industry.