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

QIN WANG, TIANLONG DENG, XIAOPING YU, YAFEI GUO — 2014 г.

A novel pretreatment system and method for arsenic species continuous analysis of arsenite, arsenate, monomethylarsenate (MMA) and dimethylarsonate (DMA) in freshwater using liquid chromatography combined to hydride generation atomic fluorescence spectrometry (LC-HG-AFS) was designed. Arsenic species of As(III), As(V), MMA and DMA in freshwater samples can be well separated, and the analytical time using the developed method is shortened twice compared to the conventional analytical procedure. Besides, the signal of As(V) can be increased by about 50% and the sensitivity to As(V) has been enhanced. The common coexisting ions in freshwater samples have no interferences with arsenic speciation analysis. A sensitive, low cost and interference-free procedure was developed and successfully applied to arsenic speciation in freshwater with the recoveries of four arsenic species within 89.2–106.2%. LC-HG-AFS has good prospects for speciation analysis of trace and ultra trace elements allowing for hydride generation.

EL-HOUSSINI O.M., ZAWILLA N.H. — 2014 г.

Two selective, reproducible methods were proposed for the simultaneous determination of Fluphenazine hydrochloride (Flu) and Nortriptyline hydrochloride (Nor) in the presence of its impurity Amitriptyline hydrochloride (Ami). The first method is TLC-densitometric on silica gel with ethyl acetate–methanol–concentrated ammonia 2 : 7 : 0.2 (v/v/v) as mobile phase. The linear range 0.5–20, 0.5–5 and 0.5 5 g per spot for Nor, Ami and Flu respectively. The second method is HPLC on Genesis C18 column with 0.1 M ammonium acetate–acetonitrile 1 : 1 (v/v) as mobile phase and Ultraviolet detection at 254 nm. The LC method was linear over concentration ranges 100–500, 50–300 and 10 250 g/mL for Nor, Ami and Flu respectively. The proposed methods were successfully applied for determination of these drugs in laboratory prepared mixtures, and in pharmaceutical dosage forms showing good accuracy and precision. The results obtained agreed statistically with those obtained by using the official methods.

HUI LIU, JI YE, JUAN SU, KEYU CHEN, WEIDONG ZHANG, XI YANG, YAJUN HE — 2014 г.

In approaches of HPLC coupled with diode array detector tandem multiple mass spectrometry (HPLC–DAD–ESI–MS/MSn) and GC–MS techniques, efficient comparative methods were developed to profile the chemical constituents in flower bud, leaf and stem parts of Lonicera japonica Thunb. (LJT). 22 polar compounds of various chemical structures and 19 volatile or semi-volatile compounds were tentatively identified from aerial parts of the plant. A number of common composition groups in three separate parts of the plant were proposed, including phenolic acids, flavonoids, iridoids, alkanes, olefins and sterols, the leaf showing higher similarity with the flower bud part via their chemical constituents. Considering the fact that the leaf part has a lot of similar components with the flower bud, this study indicates the leaf part of LJT can be expected to be used as an alternative medicinal resource to the flower bud and stem of the plant.

BEHERA A., MOITRA S.K., SANKAR D.G., SI S.C. — 2014 г.

The paper describes HPLC, UV spectrophotometric and non aqueous titrimetric method for the estimation of poorly water soluble protease inhibitor i.e. Ritonavir in raw material and tablet dosage form. HPLC an-alysis was carried out in a C18 column using acetonitrile, methanol, and buffer in the ratio 60 : 20 : 20 (v/v/v) at 240 nm. For the spectrophotometric determination methanolic solution of ritonavir was reacted with 3-Methyl Benzothiazolin-2-one hydrazone (MBTH). The oxidative coupled green coloured chromogen was analysed at 633 nm. Non aqueous titration was carried out using perchloric acid as titrant and the end point was determined using crystal violet as indicator. The three methods were validated and statistically evaluated to correlate the difference between the methods for estimation of Ritonavir in pharmaceutical dosage form.

HAK-JOO LEE, JUNG-SUB LEE, TAE-KEE HONG, WON-SIK HAN, YOUNG-HOON LEE — 2014 г.

A cyanide ion selective poly(aniline) solid contact electrode based on nickel complex of N,N-bis-(4-phenylazosalicylidene)-o-phenylenediamine ionophore was successfully developed. The electrode exhibits a good linear response of 58.7 mV / decade (at 20 ± 0.2°С, r2 = 0.998) with in the concentration range of 1 ? 10-1.0 1 ? 10-6.0 M cyanide. The composition of this electrode was: ionophore 0.300, polyvinylchloride 0.300, 2-nitrophenyloctyl ether 0.670 (mass). This 2-nitrophenyloctyl ether plasticizer provides the best response characteristics. The electrode shows good selectivity for cyanide ion in comparison with any other anions and is suitable for use with aqueous solutions of pH 4.6–6.3. The standard deviations of the measured emf difference were ±1.92 and ±1.87 mV for cyanide sample solutions of 1.0 ? 10-2 M and 1.0 ? 10-3 M, respectively. The stabilization time was less than 183 s and response time was less than 38 s.

AN X., CUI F.L., JIN J.H., YANG M.S. — 2014 г.

Resonance light scattering (RLS) of bismuth–iodide–quaternary ammonium salts and their analytical application have been studied. Bismuth can react with a large excess of I- to form [BiI4]- in the presence of Tween-20; [BiI4]- further reacts with quaternary ammonium salts such as tetramethyl ammonium bromide (TMAB), tetrapropyl ammonium bromide (TPAB) and tetrabutyl ammonium bromide (TBAB) to form an ion-association compound. Moreover, the characteristics of RLS spectra of the complexes, the optimum conditions and the influencing factors have been investigated. The method has been applied to determine Bi(III) in pharmaceutical products with satisfactory results which are in agreement with that of atomic absorbance spectrometry (AAS).

JAMALUDEEN A., NEELAMEGAM P., RAJENDRAN A. — 2014 г.

This paper discusses the determination of calcium in wine samples using Programmable System-on-Chip (PSoC) microcontroller. This embedded system uses a PSoC CY8C27443 integrated circuit (IC) spectrophotometer as core unit, high intensity orange LED as light source and photodiode as light detector having the relative spectral sensitivity above 93% in the range of 550–650 nm. This single-chip design reduces hardware complexity and increases the stability by miniaturizing the device. The instrument obeys Beers law up to the concentration of 160 mg/L. Coloring agent Methylthymol Blue (MTB) forms a complex with calcium in presence of alkali (pH 12); the complex exhibits maximum absorbance at 610 nm. The spectral range, concentration of MTB and pH of the solution at which the reaction is carried out are optimized. The results of the developed method are compared statistically with those obtained by a conventional method by applying Students t-test and F-test. The regression analysis reveals excellent correlation (R2 = 0.9998) and regression line equation obtained for that line Y = 0.29 + 0.99X with standard error of 0.62. It can be concluded that the obtained results are in good agreement with the reference method at 95% confidence level.

HSIEH P.F., HUANG P.W., LIN W.Y., PAN M.L., SU Y.L.O., TSAI S.C., WANG H.Y. — 2014 г.

We conducted a clinical trial to analyze human serum containing carbamazepine by using the differential pulse voltammetry (DPV) method with a glassy carbon electrode, and compared it with the fluorescence polarization immunoassay (FPIA). Thirty patients, who visited our hospital to have their serum carbamazepine level checked, were enrolled. Ten mL of venous blood was collected from each patient and analyzed by DPV and FPIA methods. The correlation between the carbamazepine concentrations determined by DPV and FPIA was good, with an RSQ of 0.998. The similarity of the results indicates that these two methods can be used interchangeably. The DPV method using a glassy carbon electrode may be a potential alternative method to determine the carbamazepine level in human serum.

SATTARY JAVID F., SHAFAATI A., ZARGHI A. — 2014 г.

A stability indicating capillary electrophoretic method for separation and determination of cetirizine dihydrochloride and its major impurities in bulk and a tablet dosage form was developed. The electrophoretic separation was performed in an uncoated fused-silica capillary (75 cm ? 50 m i.d.) using 75 mM sodium phosphate (pH 2.8) as background electrolyte, with an applied voltage of +25 kV at 25°C and UV detection at 230 nm. Fexofenadine was used as internal standard. The proposed method was found selective for determination of the main drug and its major impurities. The regression data obtained from the calibration plots indicated linear relationship (r2 = 0.998) over the concentration range of 40 240 g/mL of cetirizine. Repeatability and reproducibility of the method, assessed as intra-day and inter-day variation and expressed as RSD (%), were 1.3 and 2.6, respectively. Stress tests on cetirizine under acidic, basic, oxidative and heat incubating at 80°C conditions revealed that no major compound was formed under the applied conditions and the proposed CE method is applicable for stability studies on cetirizine. Then, the method was successfully applied to the determination of cetirizine in bulk and a tablet dosage form.

JIANG HONG TANG, NING LIAN, XIANG HONG HE — 2014 г.

A simple and sensitive method for the determination of gatifloxacin (GFLX) is developed by using flow injection analysis with potassium permanganate–sodium sulfite chemiluminescence (CL) detection based on the energy transfer from GFLX to terbium(III). Intense signal instead of the weak CL produced by potassium permanganate–sulfite–GFLX system can be observed when Tb(III) is added to the system. A narrow and intense emission band at 545 nm arising from the excited-state Tb(III) was obtained. Under the optimum conditions, a linear range was 5.0 ? 10-8 to 8.0 ? 10-6 M and the detection limit was 3.2 ? 10-9 M. The method has been successfully applied to the determination of gatifloxacin in drug formulations, urine and serum samples. There was no interference from some common excipients used in pharmaceutical preparations. The possible energy transfer mechanisms in the lanthanide complexes were discussed.

HARSHAL PATIL, PARAAG GIDE, SANDEEP SONAWANE — 2014 г.

A rapid, simple, selective and specific high performance liquid chromatography (HPLC) method with UV detection (230 nm) was developed and validated for estimation of guaifenesin from spiked human plasma. The analyte and internal standard (eplerenone) were extracted with dichloromethane. The chromatographic separation was performed on HiQSil C 18HS column (250 ? 4.6 mm, 5 ) with a mobile phase of methanol : water (60 : 40%, v/v) at a flow rate of 1 mL/min. Guaifenesin was well resolved from plasma constituents and internal standard. The calibration curve was linear in the range of 100–3200 ng/mL. The heteroscedasticity was minimized by using weighted least square regression with weighing factor of 1/x. The intra- and inter-day % RSD was less than 15. Results of recovery studies prove the extraction efficiency. Stability data indicated that guaifenesin was stable in plasma after three freeze thaw cycles and upon storage at –20°C for 30 days.

DA WU, JUN WANG, WANHONG ZHOU — 2014 г.

A simple and rapid determination of two Amadori compounds in cigarettes, 1-deoxy-1-L-proline-D-fructose (Fru-Pro) and 1-deoxy-1-L-alanine-D-fructose (Fru-Ala), which are the important intermediates in Maillard reaction, was achieved by HPLC–MS/MS. Eighty-eight commercial brand cigarettes of 5 different styles were employed to investigate their diversities on Fru-Pro and Fru-Ala. The contents of Fru-Pro and Fru-Ala in all cigarette samples correlate with each other. Comparison of the contents of two compounds reveals a substantial difference for different cigarettes: the contents of the two Amadori compounds in Chinese flue-cured cigarettes are remarkably higher than in British flue-cured, American, Japanese and Chinese blend cigarettes. This might be beneficial for using these two compounds as characteristic markers to identify the flavor-specific Chinese flue-cured cigarettes.

CHUN XIU HUANG, FENG YU DENG, YING LIU — 2014 г.

Based on the self-ordered ring (SOR) fluorescent microscopic imaging technique on a hydrophobic glass slide with Mn2+ and cetyltrimethyl ammonium bromide (CTMAB) as sensitizer, poly(vinyl alcohol)-124 (PVA-124) and NH3 NH4Cl buffer (pH 9.30) as the medium, a method has been developed for determining levofloxacin (LVFX) residues in chicken tissue, chicken manure and the concentrations in chicken serum. Sample preparation used the PBS and acetic acid-methanol as extracting agents for chicken breast muscle, liver and manure, respectively, the protein from chicken serum samples was removed with methanol. When the droplet volume is 0.2 , LVFX in the range of 5.7 ? 10-14 1.0 ? 10-13 mol/ring can be detected, and the limit of detection (LOD) can reach 5.7 ? 10-15 mol/ring (2.8 ? 10-8 M). Compared to reference [16], the sensitivity of SOR method enhances 1.7 times. It is a viable method for the determination of LVFX in chiken samples with the recoveries of 90.0–104.1% and relative standard deviations (RSDs) less than 3.6%. The results indicate that the method applied to chicken tissue, manure and serum is reliable and applicable.

DONGHUA CHEN, JIANGMAN LIU, JUDONG YOU, ZHENGHUA SONG — 2014 г.

A green, rapid and sensitive flow injection procedure based on the inhibition of the chemiluminescence (CL) intensity from the luminol–myoglobin (Mb) system is proposed for the determination of matrine. The decrement of CL signal was linear with the logarithm of the matrine concentration over the range from 10 to 1000 ng/mL (R2 = 0.9978) offering a detection limit of 3.5 ng/mL. At a flow rate of 2.0 mL/min, one analysis cycle, including sampling and washing, could be accomplished in 0.5 min with a relative standard deviation (RSD) of less than 5.0%. The sensitive flow injection method was successfully applied to the determination of matrine in pharmaceutical injection and human serum, with recoveries from 94.1 to 113.4% and RSDs of less than 5.0%.

BAKIRCIOGLU D., KURTULUS Y.B., UCAR G. — 2014 г.

Sorghum-agricultural waste in nature (SAWN) and chemically activated with phosphoric acid (SAWAC) was used as a solid phase extraction material for determination of cadmium, copper, manganese and lead ions in aqueous solutions by flame atomic absorption spectrometry (FAAS). The effect of pH, sample flow rate and volume, eluent type, volume and flow rate, and the effects of potentially interfering ions on the recovery of the analytes were investigated. Adsorption capacity of SAWN and SAWAC was determined by batch method under the optimized conditions. Adsorption capacity of SAWAC was found to be 9.53, 11.77, 11.64, and 15.01 mg/L for Cd, Cu, and Mn and Pb ions, respectively. The limit of detection (LOD) for the analytes was found in the range of 0.16 1.21 g/L with a theoretical preconcentration factor of 50. The method was validated by analyzing certified material (GBW 07605-Tea) and the results were in a good agreement with the certified value. In addition, the proposed method was applied to the determination of analytes in tea and river water samples.

BALD E., BOROWCZYK K., GLOWACKI R. — 2014 г.

Homocysteine (Hcy) is a sulfur-containing nonprotein amino acid, a metabolite of methionine. Mechanisms by which Hcy is involved in the pathogenesis of vascular diseases remain unclear. One of the potential mechanisms underlying harmful effects of Hcy is the protein N-homocysteinylation induced by Hcy-thiolactone. Proteolytic degradation of N-homocysteinylated protein yields N -homocysteinyl-lysine, a novel and important component of Hcy metabolism. Here we describe new high-performance liquid chromatography assay for the determination of N -homocysteinyl-lysine and -glutamylcysteine in plasma, based on a derivatization with 2-chloro-1-methyllepidinium tetrafluoroborate and UV detection. Baseline separation was achieved on an analytical column from Phenomenex (Kinetex C18, 100 ? 4.6 mm, 2.6 m) using gradient elution, with a mobile phase consisting 0.1 M trichloroacetic acid (pH 2.3) – acetonitrile. The quantification limits for N -homocysteinyl-lysine and -glutamylcysteine in plasma were 0.1 and 0.2 M, respectively. Other main endogenous thiols can also be measured during the same analytical run. The proposed method was applied for the analysis of 15 plasma samples for total form of N -homocysteinyl-lysine and -glutamylcysteine.

ARSALAN MADADJO, MOHAMMAD REZA JAMALI, REYHANEH RAHNAMA — 2014 г.

Cold-induced aggregation microextraction (CIAME) combined with flame atomic absorption spectrometry (FAAS) was applied to preconcentration and determination of nickel(II) ions in natural water samples. The proposed method used 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim] [PF6]) as the extraction solvent and 1-(2-thiazolylazo)-2-naphthol (TAN) as the complexing agent. The extraction solvent was dissolved in the sample solution at 45°C. After dissolving, the solution was cooled in the ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifugation, the fine droplets of extractant phase were settled at the bottom of the conical-bottom centrifuge tube. Analysis was carried out by a FAAS. Several important parameters influencing the CIAME extraction efficiency such as pH, complexing agent concentration, extraction solvent volume, salt effect, solution temperature, extraction time, centrifugation time and heating time were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 0.8 ng/mL, and the relative standard deviation (RSD) was 3.4% for 50 ng/mL of nickel. The performance of the method was evaluated for extraction and determination of nickel in tap, mineral and seawater samples, and satisfactory results were obtained.

LIJUN WU, QIANQIAN LI, SHENGFENG YE, SHUNGENG MIN, XIANGHONG HAO, YEWEI ZHU — 2014 г.

A simple and efficient approach as directly suspended droplet microextraction (DSDME) was applied to the determination of organochlorine pesticides in rice prior to analysis by gas chromatography–mass spectrometry (GC–MS). The extraction parameters such as organic solvent type and volume, extraction time, and ion strength were systemically optimized. Furthermore, method linearity, recovery, limits of detections (LODs), and precision were also investigated. The proposed method provided good linearity (R2 = 0.9900–0.9996). LODs determined by GC/MS in selected-ion monitoring (SIM) mode were between 0.0005–0.033 mg/kg. The relative standard deviations (RSDs) varied from 2.0–14.0%, while the enrichment factors were between 221–550. The experimental results suggest that DSDME followed by GC/MS is a simple, sensitive, low-cost and little solvent consumption for the determination of organochlorine pesticides in rice, and has high enrichment factors suitable to trace analysis.

FENG GUO, FUWEI YANG, GUOFANG ZUO, LINJUAN YANG, XINWEN LIU, YAN LIU, YUANCHENG ZHU — 2014 г.

A novel SPME–HPLC method was developed for the determination of trace amounts of polycyclic aromatic hydrocarbons (PAHs). It was found that the SPME device with C8H17 SBA-15 (C8-SBA-15) mesoporous silica coating had high extraction efficiency, sufficient chemical and hydrothermal stability and good reversibility. The determination conditions for environmental pollutants like PAHs including extraction and desorption time, extraction temperature, ionic strength and stirring rate were optimized. Under optimized experimental conditions, results with good accuracy (with a recovery of 97.5–101.7%), precision (with a standard deviation of 0.15–1.07%) and low detection limit (LOD, 0.05 0.25 g/L) were obtained, suggesting the SPME devices using chemical modified SBA-15 as coating material are promising in preconcentration, separation and determination of interested analytes in the future.

BINLUN YAN, FUQUAN XU, HUASHI GUAN, YUANYUAN FENG — 2014 г.

Tamarixetin and kaempferide, the major bioactive constituents of Xiheliu extract, have been simultaneously/quantitatively determined in rat plasma and urine by a sensitive high performance liquid chromatography method after oral administration the total flavonoids from Xiheliu. In this study, the biological samples were prepared by solid-phase extraction, then simultaneously detected at 254 nm and successfully separated and quantified using a reversed-phase C18 column with methanol-formic acid aqueous gradient solution, at a flow rate of 1 mL/min. Good linearity (r > 0.989) of tamarixetin was observed in plasma and urine with the calibration ranges both at 1.6 80 g/mL. For kaempferide, the correlation coefficient reached 0.994 in plasma at 1.4 70 g/mL. The RSD of intra- and inter-day were 1.9–6.5% for tamarixetin and 1.3–9.0% for kaempferide in plasma; in urine, the intra- and inter-day RSD for not only tamarixetin but also kaempferide was no more than 7.4 and 5.8%, respectively. The lowest extraction recovery was 87.6% for kaempferide and 93.2% for tamarixetin in plasma and urine for both low and high concentrations. Due to the high sensitivity (the LOQ for tamarixetin was 1.2 g/mL and for kaempferide 1.4 g/mL), accuracy, precision, and good selectivity, the assay was successfully applied to pharmacokinetic studies of both flavonols in rats. The half-lives of tamarixetin and kaempferide were 17.8 ± 1.4 and 92.5 ± 1.6 min, and the cmax were 3.1 ± 0.2 and 2.5 ± 0.4 g/mL, respectively.