научный журнал по химии Журнал аналитической химии ISSN: 0044-4502

JELINSKA A., KIASZEWICZ I., LESNIEWSKA M.A., MUSZALSKA I., RABIEGA K., SOBCZAK A. — 2015 г.

A selective ultraviolet and visible spectrophotometric method (UV-Vis) for the determination of memantine (MM) and rimantadine (RM) hydrochlorides after derivatization with 1,2-naphtoquinone-4-sulfonic acid sodium salt (NQS) and extraction with dichloromethane was developed and optimized. The reaction of the NQS (0.7%, w/v solution) with memantine was carried out for 40 min in a buffer medium of NaOH/KCl (pH 12.0) at 80°C. A mixture of NQS (0.2%) and rimantadine was heated for 20 min at 50°C, in a medium of NaOH/KCl (pH 12.0). The linearity of the determinations of MM (0.05–0.60 mg/mL) and RM (0.05–0.30 mg/mL) was evaluated. LOD (28 mg/mL for MM, 11 mg/mL for RM) and LOQ (84 mg/mL for MM, 32 mg/mL for RM) values and parameters of precision and accuracy were determined. The UV-Vis method for the determination of rimantadine hydrochloride tablets was validated (selectivity, linearity, precision, accuracy).

BEHROOZ MAJIDI, EHSAN MOHAMMADIFAR, FARZANEH SHEMIRANI — 2015 г.

A simple method for separation and preconcentration of trace amount of palladium from aqueous medium prior to its flame atomic absorption spectrometric determination was developed. 4,4-Bis(dimethylamino)thiobenzophenone-modified multiwalled carbon nanotubes (MWCNTs) as a new solid phase extractant has been packed in a column. The modification process was fast and simple and the sorbent showed relatively fast kinetics of sorption of the target analyte. Various parameters inuencing the preconcentration of Pd were optimized, including pH of the solution, ow rate of sample and eluent, type and concentration of eluent and breakthrough volume, also interferences were stutied. The sorption capacity of oxidized MWCNTs for Pd(II) was 19.8 mg/g. Under optimum experimental conditions, linearity range was from 1.2 to 200 ng/mL, the limit of detection of this method for Pd was 0.4 ng/mL with an enrichment factor of 200, and the relative standard deviation (RSD) was 3.7% at the 50 ng/mL Pd level. The method was validated by the extraction and determination of Pd(II) in rain water, blood, dry tea and road dust samples.

BANSAL P., MEDHE S., RANI R., SINGH K., SRIVASTAVA M.M. — 2015 г.

The essential oils of seed and whole plant of Coriandrum sativum were examined for their in vitro antioxidant activities which were found to be higher compared to different extracts of this plant. A simple, precise and specific HPTLC method has been developed for the determination of important phytomarkers of essential oils. The proposed method was validated in terms of linearity, precision, accuracy, limits of detection, and quantification.

ANDRUCH V., BALOGH I.S., ELECKOVA L., IMRICH J. — 2015 г.

The method is based on the reaction of Co(II) with 3-[4-(dimethylamino)cinnamoyl]-4-hydroxy-6-methyl-2H-pyran-2-one (ligand) and a dimethylindocarbocyanine dye, followed by dispersive liquid–liquid microextraction of the ion associate formed and subsequent spectrophotometric detection. The appropriate experimental conditions were found to be: pH 9, 0.14 mM dye, toluene (extraction solvent) containing 2.25 mM of ligand, acetonitrile (dispersive solvent) and carbon tetrachloride (auxiliary solvent). Beers law is obeyed in the range 0.06–0.42 mg/L of Co(II) at a wavelength of 558 nm. The limit of detection, calculated as three times the standard deviation of the blank test (n = 10), was found to be 9 g/L for Co(II). The method was applied to the determination of cobalt in spiked water samples and a vitamin B12 pharmaceutical injection.

FATEMEH GHASEMI-MOGHADDAM, MAHMOOD CHAMSAZ, TAHEREH HEIDARI — 2015 г.

This paper proposes the possibility of applying first order calibration methods to unknown sample(s) with unmodeled component(s) using the differential spectra obtained from subtracting of the absorbance spectra of sample that are recorded in two different environments. The main interest is that the method can be performed to quantify systems if the spectra of their unmodeled component(s) are the same in two different phases using first order calibration methods. The procedure demonstrates simultaneous determination of new fuchsine, crystal violet and malachite green in the presence of sunset yellow, tartarazine and amaranth as unmodeled interferences, whose spectra differ in aqueous and nonionic micellar solution of Triton X-100. The obtained satisfactory results indicate the successful applicability of the proposed method to complex samples.

KIM H., KIM J.-H., KIM S. — 2015 г.

Nonporous silicone flat-sheet membrane extraction with a cryofocusing (–30°C) sorbent interface coupled to gas chromatography–mass spectrometry was applied to the determination of trihalomethanes in chlorinated drinking water. The flow rates of the donor and acceptor phases in the membrane extraction module were optimized at 28–30°C to 1.5 and 55 mL/min, respectively. The methodology as established showed method detection limits of 0.2 or less, high-linearity calibration curves, and high accuracy and precision.

ANETA JASTRZBSKA, ANNA PIASTA, EDWARD SZLYK — 2015 г.

Ion chromatography procedure for the simultaneous determination of histamine, tyramine, phenylethylamine, cadaverine and putrescine in different food samples is described. The simple procedure based on isocratic elution, 5 mM HNO3 without organic modifier as mobile phase and conductometric detection without suppression was proposed and discussed in details. The linearity of the tested procedure was between 0.5–5 and 5–100 mg/L, ave-rage recoveries for the standard solutions of amines varied between 98–100%, whereas in standard addition method between 96–99%, that indicated acceptable accuracy of the discussed method. The satisfactory reproducibility was proved by values of coefficient of variations (CV) in the range 0.2–5.0% for all tested food samples. The proposed method reveals a number of advantages: fast elution of analytes without mobile phase conductivity suppression, lack of derivatization step, simple sample preparation and environmentally friendly character.

LI WANG — 2015 г.

A microdialysis method followed by a capillary electrophoresis (CE) procedure has been performed for the determination of metoprolol in rabbit blood. A microdialysis probe was inserted into the ear vein for blood sampling. The electrophoresis conditions were: 47 (40) cm ? 50 m silica capillary, 50 mM acetate buffer solution (pH 4.0), 10 s hydrodynamic load, detection wavelength 214 nm, run voltage 18 kV, temperature 25°C. The calibration was linear within the range of 1.0 100 g/mL (r > 0.999). The limit of detection (LOD) was 0.5 g/mL. Intra-day and inter-day repeatabilities with relative standard deviations (RSDs) 5.1% were obtained. The method was then applied to pharmacokinetics profiling of metoprolol in the blood following oral administration of metoprolol to rabbits.

DAVUDABADI FARAHANI M., GOLSHAEI R., SHEMIRANI F. — 2015 г.

A new simple and reliable method for rapid and selective extraction and determination of the trace Pd(II) was developed. Combination of solid phase extraction (SPE) and liquid–liquid extraction (LLE) of trace amounts of palladium in food and water samples has been done successfully. By coupling of SPE with LLE, advantages of both can be combined including high extraction recovery and preconcentration factor (PF), environmental friendliness, low cost and appropriate time of analysis. All conditions for SPE and LLE were optimized in order to reach high PF and extraction recovery. The metal ion was eluted completely with 1.5 mL 2 M HClO4 in acetylacetone and measured by ame atomic absorption spectrometry (FAAS). The optimum experimental conditions such as pH, sample volume, amount of sorbent and concentration of eluent on the sorption of Pd(II) were evaluated. Under the optimized conditions, the sorption capacity of the modied nano- -alumina for Pd(II) was 13.5 mg/g. Preconcentration from 200 mL sample solution permitted a preconcentration factor of 266. The limit of detection of this method for Pd(II) was 0.2 g/L and the relative standard deviation (RSD) of 100 ng/mL of Pd(II) was 2.3% (n = 10).

BENJAMIN SAUER, ISAAC AFREH, MONTY CHELSEA N., NATHANIEL BLASDEL, STEPHEN DUIRK, SUSAN KAYA, WUJCIK EVAN K. — 2015 г.

The purpose of this paper is to report on the detection of toxic halogenated organic compounds in water using their inhibitory action on a pyridine-catalyzed reaction between dimethyl acetylenedicarboxylate (DMAD) and 4-methyl-2-nitroacetate (MNA). Previous work has shown that similar techniques can successfully lower the detection limit of sulfides and arsines in water samples, compared to their standard photometric detection methods. This paper highlights the optimization, selectivity, and sensitivity studies of the proposed sensing scheme. Optimization shows that the pyridine-catalyzed reaction is more favorable at 4 mM DMAD and 8 mM MNA. It was also determined that the inhibitory effect of halogenated organic compounds is more pronounced when carried out at 60°C. Using optimized reaction conditions, the limit of quantification for the four regulated trihalomethanes (THMs) was approximately 80 ppm. In addition, the sensing method is selective to THMs and a few other halogenated organics. These promising results demonstrate the further success of this technique for sensitive, selective detection, and future work will be carried out to incorporate the technique in sensing applications for THMs in drinking water.

JEROMEL A., MASLOV L., MIHALJEVIC ZULJ M., TOMAZ I. — 2015 г.

The unpleasant odor of an off-flavor is mostly caused by only one or, sometimes several volatile compounds with very low odor threshold values giving the typical unpleasant odor taint of the spoiled food product. 2-Aminoacetophenone is an aroma compound which causes the untypical aging off-flavor in Vitis vinifera white wines. Ultrasound assisted headspace solid phase microextraction (UA-HS-SPME) and direct immersion solid phase microextraction (DI-SPME) coupled with gas chromatography-mass spectrometry (GC–MS) were tested and optimized for determination of 2-aminoacetophenone in Riesling wines fermented by different yeast strains.

JIE XU, MEI-E YUE, WAN-GUO HOU — 2015 г.

A simple, reproducible and sensitive micellar electrokinetic chromatography method was developed for the separation and determination of dimethyl phthalate (DMP), diethyl phthalate (DEP), dibuthyl phthalate (DBP), dihexyl phthalate (DHP) and bis(2-ethylhexyl) phthalate (DEHP) in running water and milk. Field-enhanced sample injection with reverse migrating micelles was used for on-line preconcentration of the analytes. The buffer contained 50 mM H3PO4 NaOH, 160 mM sodium dodecyl sulfate (SDS), 15% acetonitrile and 20% 2-propanol, at the pH of 2.0. The sample solution was diluted with water containing 5 mM SDS and injected for 5 s with –20 kV after gravity injection of 5 s water plug at 20 cm high. Under the optimum conditions, the analytes were well separated and by optimizing the stacking conditions, about 51, 62, 57, 48 and 43 fold improvement in the detection sensitivities were obtained for DMP, DEP, DBP, DHP and DEHP, respectively. The instrument detection limits (S/N = 3) of DMP, DEP, DBP, DHP and DEHP were 0.1, 0.05, 0.05, 0.02 and 0.05 , respectively. The recoveries of DMP, DEP, DBP, DHP and DEHP in water were 86.9–98.7, 88.9–105.2, 91.7–109.4, 93.0–108.2 and 91.0–99.2%, respectively. The phthalates were successfully determined in running water and milk with satisfactory repeatability and recovery. The contents of DEHP and DHP in the running water were 0.45 and 1.23 , respectively. The other analytes were not detected in the analyzed running water and milk.

EDA SATANA, HASAN BASAN, NILGUN GUNDEN GOER, SEVILAY CAMALAN TURK — 2015 г.

A flow-injection UV spectrophotometric method for the determination of ibuprofen in tablets was developed. The proposed method was achieved by using a flow cell which was located in a UV spectrophotometer and a peristaltic pump helped maintaining the carrier solvent, 0.1 M NaOH. During the study, flow rate, loop volume and the number of injections per hour were 15 mL/min, 193 and 100, respectively. The analytical signal of ibuprofen was linear in the concentration range of 400 1200 . The detection limit and limit of quantification were determined as 27 and 91 g/mL, respectively. Results for the determination of ibuprofen in tablets, 600 ± 2 mg/tablet (mean ± SD), were in good agreement with the labeled quantities, 600 mg/tablet. A relatively high recovery value, 100.4 ± 0.6%, proves the accuracy of the proposed method. The spectrophotometric method and reference HPLC method were shown to be comparable when Students t-test and Fisher test were applied to both methods. In addition, a fourth order derivative UV spectrophotometric method (at 268.8 nm and n = 9) for the determination of ibuprofen and a first order (at 271 nm and n = 1) derivative UV spectrophotometric method for the determination of paraben in pediatric syrups were developed. Recovery values for the determination of ibuprofen and paraben were 102.4 ± 1.1% and 100.2 ± 2.3%, respectively.

AMIT SRIVASTAVA, JAGDEEP GROVER, KHEMRAJ BAIRWA, SANJAY MADHUKAR JACHAK, SOMENDU KUMAR ROY — 2015 г.

Negundoside and agnuside are reported as marker constituents for standardization of Vitex negundo (V. negundo) leaves. This is the first report on determination and quantification of negundoside and agnuside by qNMR in the leaves of V. negundo, collected from various regions of India. The developed qNMR method showed good linearity (r2 0.9994), high precision (RSD < 5%) and a good recovery (99.79 and 101.35%) for both the compounds. Therefore, the developed qNMR method is accurate and reliable for the quality control of V. negundo. The qNMR method is useful in quality control of plant extracts without the need of extensive sample preparation and chromatographic separation.

ARMINDA ALVES, JOSE LUIS MOREIRA, MADEIRA LUIS M., SANTOS MONICA S.F. — 2015 г.

Dispersive liquid–liquid microextraction (DLLME) is an extraction procedure gaining popularity in the recent years due to the easiness of operation, high enrichment factors, low cost and low consumption of organic solvents. This extraction method, prior to gas chromatography with mass spectrometry detection (GC–MS), was optimized for the analysis of polybrominated diphenyl ethers (PBDEs) in aqueous samples. These were extracted with chlorobenzene (extraction solvent) and acetonitrile (dispersive solvent), allowing an enrichment factor of about 470 for BDE-100. The calibration curve for BDE-100 was linear in the range of 0.005 10 g/L, with an average reproducibility of 12% (RSD, %). The LOD, calculated by the signal-to-noise ratio, was 0.5 ng/L for BDE-100 and the recovery ranged from 91–107% for all spiked samples. Relative expanded uncertainty was concentration-dependent, reaching high values near the limit of quantification and decreasing until 14% for concentrations higher than 1 g/L of BDE-100. The dispersive liquid–liquid microextraction combined with gas chromatography with mass spectrometry detection (DLLME–GC–MS) method could be successfully applied to the determination of other PBDEs in water samples.

YASUHIKO HIGASHI, YOUICHI FUJII — 2015 г.

o-Phenylphenol is generally utilized as a disinfectant for citrus fruits. The purpose of this study is to develop a high-performance liquid chromatography coupled with ultraviolet detection (380 nm) method for simultaneous determination of o-phenylphenol, and its analogues (m-phenylphenol and p-phenylphenol) in grapefruit juice after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). 2-Hydroxyfluorene was used as an internal standard (IS). Standard curves were obtained after derivatization with NBD-F in borate buffer (pH 8.0) at room temperature for 5 min. The three NBD-F derivatives were almost completely separated on a Cholester column (5 m, 3.0 mm i.d. ? 150 mm). Calibration plots were linear in the range of absolute amount of 1.04 2.08 to 41.6 ng/50 L injection volume, with r2 values 0.9981, for the three compounds. The lower limits of detection were 0.3 to 0.7 ng/50 L injection volume (signal-to-noise ratio of 3 : 1). The coefficients of variation were less than 11.1%. After extraction of grapefruit juice (2.0 mL) with n-pentane, the level of o-phenylphenol in the juice was estimated to be 20.2 ± 2.0 ng/mL (n = 6, mean ± SD), while m-phenylphenol and p-phenylphenol were below the lower limits of quantification. The recovery values of the three phenylphenols from samples spiked with a standard mixture of authentic compounds and IS were satisfactory (99.1 to 118.7%).

AJUAN YU, BAOGUO SUN, LIU YANG, SHUSHENG ZHANG, WEI TANG, WENFEN ZHANG, XIANGYU TIAN, YANHAO ZHANG, YAXIAO GUO — 2015 г.

The associations of nitric oxide (NO) with many diseases are still being discovered, and sometimes, NO levels in the body fluids are too low to be detected. Thus, the determination methods for trace nitrites and nitrates in urine and plasma of healthy volunteers and rheumatoid arthritis (RA) patients are necessary. Using trimethylamine aminated polychloromethyl styrene nano-latex coated capillary column (ccc-TMAPL) and field-amplified sample stacking (FASS) injection, the sensitive open-tubular capillary electrochromatography (OT-CEC) methods for determining trace nitrites and nitrates in urine and plasma of healthy volunteers and RA patients were set up. The limits of detection for both nitrite and nitrate were 1 ng/mL. The intra- and inter-day relative standard deviations (RSDs) of the methods were less than 1.9%, and recoveries were between 89 and 96%. Plasma nitrate (diluted 10 times) levels were 93–301 ng/mL for healthy volunteers and 222–421 ng/mL for RA patients, respectively. Meanwhile, plasma nitrite levels were 7–18 and 40–82 ng/mL, respectively. The urinary nitrite levels were significantly elevated in RA patients. The proposed sensitive FASS-OT-CEC methods for trace nitrites and nitrates hold the promise of practical applications in a wide array of biological analyses, clinical and pathophysiology studies of the diseases related with NO hyperproduction and metabolites.

EFFAT SOURI, MALIHEH BARAZANDEH TEHRANI, MASSOUD AMANLOU, SEYED ADEL MOUSAVI NASAB — 2015 г.

A zero-crossing derivative spectrophotometric method was used for the simultaneous determination of acetaminophen, ibuprofen and caffeine. The derivative spectra of standard solutions of each compound were obtained at different orders to find out the suitable zero-crossing points. Under the optimized conditions, determination of acetaminophen was performed at wavelengths of 311 and 270 nm using the third order ( = 24.5) and fourth order ( = 12.0) derivative spectra, respectively. Ibuprofen and caffeine were determined at wavelengths of 235 and 300 nm using the second order ( = 21.0) and fourth order ( = 27.0) derivative spectra. The method was found to be linear (r2 > 0.998) in the range of ( g/mL) 5–50 for acetaminophen, 5–30 for ibuprofen and 1–7 for caffeine in the presence of other compounds. The within-day and between-day precision and accuracy of the proposed method were acceptable (CV < 3% and error < 2%) for all three components and the proposed method was satisfactory for quality control purposes. The method was successfully applied to the simultaneous determination of acetaminophen, ibuprofen and caffeine in pharmaceutical dosage forms without any interference from excipients and there was no need to any prior separation before analysis.

DURIC SVETLANA LJ., MILENOVIC DRAGAN M., NASKOVIC DANIELA C., VELICKOVIC DRAGAN T. — 2015 г.

A simple, sensitive and accurate HPLC method has been developed and validated for determination impurities in maprotiline solid dosage forms. Chromatographic separation was achieved on Lichrospher RP Select B column (250 mm ? 4.6 mm i.d., particle size 5 m, maintained at 40°C) by a mobile phase consisted of ammonium hydrogen carbonate (pH 8.1; 0.05 M)–acetonitrile–methanol–tetrahydrofuran (20 : 80 : 32 : 4.5, v/v/v/v) and a flow rate of 1.0 mL/min. The detection wavelength was set at 215 nm and injection volume was 10 L. The drugs were subjected to oxidation, hydrolysis, photolysis and heat to apply stress conditions. The degradation products, when any, were well resolved from the pure active substance with significantly different retention time values, thus proved the stability indicating power of the method. The method met the International Conference on Harmonisation (ICH) regulatory requirements. The results demonstrated that the method would have a great value when applied in quality control and stability studies for maprotiline tablets.

KAVRAKOVSKI Z.S., RAFAJLOVSKA V. GJ. — 2015 г.

Thin layer chromatography (TLC) densitometric method for simultaneous determination of seven chlorophenoxy and benzoic acid herbicides (2,4-D; 2,4,5-T; MCPA; 2,4-DP; MCPP; Dicamba and MCPB) in water samples was developed and validated. A mobile phase consisted of benzene–dioxane–glacial acetic acid in ratio of 45 : 10 : 2 and TLC silica gel 60 F254 aluminium plate were used. Detection was carried out densitomLetrically at 280 nm. The linearity was obtained in the range 20–200 ng per band with the correlation coefficient between the peak area and concentration for each analyte higher than 0.9976. The limits of detection and quantification were 18 and 60 ng per band, respectively. The recoveries of analyzed herbicides varied from 84.5 to 92.7%. The method can be used for routine quality analysis of chlorophenoxy and benzoic acid herbicides in natural surface and ground water samples.