On the use of the fluorescence, ultraviolet-visible and near infrared spectroscopy with chemometrics for the discrimination between plum brandies of different varietal origins

This paper investigates the use of synchronous fluorescence, UV-Vis and near infrared (NIR) spectroscopy coupled with chemometric methods to discriminate samples of high-quality plum brandies (Slivovica) of different varietal origins (Prunus domestica L.). Synchronous fluorescence spectra (SFS) for wavelength differences in the range of 70-100nm, NIR spectra in the wavenumber range of 4000-7500cm^-1 and UV-Vis spectra in the wavelength interval of 220-320nm were compared. The best discrimination models were created by linear discriminant analysis based on principal component analysis applied to SFS recorded with wavelength difference either 80nm or 100nm, allowing the classification of plum brandy according to harvest time as early (summer) and late (autumn) plum varieties; the total correct classifications were 96% and 100% for the calibration and prediction steps, respectively.

Spectrofluorimetric determination of fendiline in tablets

A simple, sensitive and accurate spectrofluorimetric method was developed for the assay of fendiline in tablets. Validation of the method provided good results concerning linearity, precision and accuracy. The linearity range was found to be 0.1-0.8 mg/l. The fluorescence intensity was measured at 288 nm for fendiline tablet solutions. It was also found that the excipients in the commercial tablets did not interfere with the method.

Effects of non-ionic surfactants on isotachophoretic separations of 2-arylpropionic acids

Non-ionic surfactant (Brij 35, Tween 20, Tween 80 and Tergitol NPX) modified capillary isotachophoresis was investigated for the separation of 2-arylpropionic acids (fenoprofen, flurbiprofen, ibuprofen, ketoprofen and naproxen) and benzoic acid and its derivatives (salicylic, acetylsalicylic and gallic acids). The relative step height (RSH) values of analytes were found to be dependent on the type and concentration of the surfactant. The strength of the affinity of the 2-arylpropionic acids to the non-ionic micelles was found to be as follows: flurbiprofen > fenoprofen > ibuprofen > naproxen > ketoprofen. In general, the RSH values of 2-arylpropionic acids increase with an increase in the concentration of surfactants. However, the RSHs of benzoic, salicylic and gallic acids are not considerably affected. Separation of all acids was obtained with the Tween 20 (1.5%, w/v) in the leading electrolyte 10 mmol L(-1) hydrochloric acid/L-histidine (pH 6.0). Changes in the fluorescence intensity of fenoprofen, flurbiprofen and naproxen were also investigated in micellar media (Tween 20, Tween 80 and Brij 35). The strength of the affinity of the 2-arylpropionic acids to the Tweens micelles was found to be as follows: flurbiprofen > fenoprofen > naproxen, which is consistent with the isotachophoretic results. On the contrary, the strength of the affinity to the Brij micelles was found to be as follows: fenoprofen > naproxen > flurbiprofen.

Determination of ibuprofen and naproxen in tablets

Ibuprofen and naproxen have been quantified in tablets by capillary isotachophoresis. Hydrochloric acid (10 mmol/l) adjusted with creatinine to pH 5.0 plus 0.1% polyvinylpyrrolidone was used as the leading electrolyte and 10 mmol/l 4-morpholineethanesulfonic acid as the terminating electrolyte. Linearity was observed from 40.0 to 200.0 mg/l of ibuprofen (naproxen), with a coefficient of determination (r2) of 0.999. Good quantitation was obtained in short analysis time. The isotachophoretic results were compared with those obtained by the fluorescence spectrometry. Experimental parameters for ibuprofen were: lambdaEX=224 nm and lambdaEM=290 nm. Experimental parameters for naproxen were: lambdaEX=230 nm and lambdaEM=355 nm. The calibration plot was found to be linear in the range 0.4-2.4 mg/l for ibuprofen and 5.0-20.0 microg/l for naproxen. The minimal sample pretreatment and relatively low running cost make isotachophoresis a good alternative to existing methods.

Isotachophoretic determination of naproxen in the presence of its metabolite in human serum

An isotachophoretic method with conductivity detection was developed to determine naproxen in the presence of its metabolite 6-O-desmethylnaproxen in human serum. The leading electrolyte contained 10 mM hydrochloric acid, beta-alanine, pH 4.0 and 0.1% methylhydroxypropylcellulose. The terminating electrolyte was 10 mM 2-(N-morpholino)ethanesulfonic acid-tris(hydroxymethyl)aminomethane, pH 6.9, containing 20% (v/v) of ethanol. Naproxen was determined in serum supernatant after simple deproteination of the sample with ethanol. The isotachophoretic results were compared with those obtained by synchronous fluorescence spectrometry.

Determination of some antirheumatics by capillary isotachophoresis

Isotachophoresis (ITP) was applied for the determination of some antirheumatic drugs (fenoprofen, naproxen, ibuprofen, and ketoprofen) in human serum. The leading electrolyte contained hydrochloric acid (10 mmol x L(-1)), creatinine (pH 4.5) and methylhydroxyethyl cellulose (0.1%). The terminating electrolyte was 2-(N-morpholino)ethanesulfonic acid (10 mmol x L(-1)) adjusted with tris(hydroxymethyl)aminomethane to pH 6.9. The ITP separations were carried out in column-coupling configuration of the separation unit provided with a preseparation column of 160 x 0.8 mm inner diameter (ID) and analytical column of 160 x 0.3 mm ID. The limit of detection for ibuprofen, fenoprofen, and naproxen in serum by direct sampling was 0.008, 0.005 and 0.004 mmol x L(-1). The limit of detection for ketoprofen in serum after ethanol precipitation was 0.001 mmol x L(-1).

Electrophoretic methods in the analysis of beverages

A review of the applications of electrophoresis to the determination of various compounds in beverage samples, namely beer, hard drinks, juice, milk, soft drinks, tea and wine, is presented.

Determination of fenoprofen in serum by capillary isotachophoresis

A isotachophoretic method with conductivity detection was developed and validated to directly determine fenoprofen in human serum. The leading electrolyte contained hydrochloric acid (10 mmol/l), 6-aminocaproic acid (pH 4.8) and polyvinylpyrrolidone (0.1%). The terminating electrolyte was 4-morpholineethanesulfonic acid (5 mmol/l). The calibration curve was linear over the concentration range 0.02-0.40 mmol/l. Within-day standard deviation ranged from 0.001 to 0.004 and between-day standard deviation ranged from 0.001 to 0.004. The limit of determination was 0.02 mmol/l. The assay was employed to determine serum concentration of fenoprofen in patients.

Determination of inorganic ions in food and beverages by capillary electrophoresis

A review of the applications of electrophoresis to the determination of inorganic anions (sulphate, sulphite, phosphate, nitrate, nitrite and halides) and inorganic cations (ammonium, alkali and alkaline metals and trace elements) in food and beverages is presented.

Isotachophoretic determination of bisoprolol, clonidine, disopyramide and tolazoline in human fluids

Separation and determination of bisoprolol, clonidine, disopyramide and tolazoline in control serum and in human urine was investigated by capillary isotachophoresis. The drugs were separated by using the cationic electrolyte system. viz., sodium acetate buffer (pH 4.64) (c1 = 10 mM)-beta-alanine. The compounds were almost totally isolated from serum by solid-phase extraction using a Sep-Pak C18 cartridge. The recovery of compounds varied from 87 to 99%. The linear calibration range was studied to apply the method to real human fluids. The limit of determination of the drugs was 40.0 micrograms/ml serum. The limit of determination by direct sampling for bisoprolol is 3 micrograms/ml urine.

Determination of some cardiovascular drugs in serum and urine by capillary isotachophoresis

The separation and determination of amiloride, metoprolol, deacetylmetipranolol, labetalol and furosemide in human serum and urine by capillary isotachophoresis were investigated. Amiloride and beta-blockers were separated by cationic isotachophoresis in the electrolyte system sodium morpholinoethanesulfonate buffer (pH 5.5) (cL = 10 mM)-glutamic acid. Furosemide was separated using the anionic electrolyte system histidine hydrochloride buffer (pH 6.2) (cL = 10 mM)-morpholinopropanesulfonic acid. Endogenous and the possible exogenous compounds were almost totally removed from serum and urine by solid-phase extraction using a Separon SGX C18 cartridge. The recovery of compounds varied from 98.2 to 103.2%. The linearity range for the compounds was 50-1000 ng/ml. The relative standard deviations varied from 0.1 to 5.6%. The overall limits of determination ranged from 32 to 46 ng/ml of urine and from 39 to 46 ng/ml of serum, depending of the type of drugs.

[Determination of serum vancomycin using capillary isotachophoresis]

The paper aims to study the possibilities of determining vancomycin in the serum by the method of capillary isotachophoresis. The leading electrolyte contained Na+ as the leading ion, morpholinoethanesulphonic acid as the counter-ion (pH 6,2), and methylhydroxyethyl cellulose as the additive. The terminating electrolyte was morpholinoethanesulphonic acid. The conductivity detector was employed for detection. Ethanol was selected for precipitation of proteins. The yield of vancomycin from the serum was 89-91%. The calibration curve is linear in an interval of 0.02-0.5 microgram (the absolutely dosed amount). The limit of vancomycin determination in the serum is 4 micrograms/ml. The method was employed to determine vancomycin in the serum of patients. The obtained results correlated well with those obtained by fluorescent polarizing immunoanalysis (TDx) in a concentration interval of 4-30 micrograms/ml.