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Analytical and Bioanalytical Chemistry (v.375, #6)

Spectroscopy Challenge 1 (pp. 719-724).

Semi-rotating cryogenic modulator for comprehensive two-dimensional gas chromatography by Minna Kallio; Tuulia Hyötyläinen; Matti Jussila; Kari Hartonen; Sami Palonen; Masahiko Shimmo; Marja-Liisa Riekkola (pp. 725-731).

A laboratory-made cryogenic modulator for comprehensive two-dimensional gas chromatography (GC×GC) was constructed and evaluated. Analytes were trapped with carbon dioxide and desorbed with heated GC oven air. The GC×GC system included a non-polar first-dimension column and a semi-polar second-dimension column connected to a flame ionisation detector. A laboratory-written Matlab-based program was used for the data analysis. Peak widths at half height for n-alkanes, obtained with use of new modulator, were at narrowest 60 ms.

Keywords: Comprehensive two-dimensional gas chromatography GC×GC Modulator Aerosol analysis

In vivo monitoring of the gastrooesophageal system using optical fibre sensors by Francesco Baldini (pp. 732-743).

In the present paper optical fibre sensors for the detection of foregut diseases are described, in particular, sensors for the detection of bile, carbon dioxide and pH. Bile-containing refluxes are measured by means of a sensor which uses bilirubin as natural marker. The sensor, which is already present on the market, has been clinically validated by various hospitals. The clinically relevant parameter is the exposure time of the stomach/oesophagus mucosa to the bile. When measured in the oesophagus, it has been shown to be closely correlated with the onset of Barrett's oesophagus or general oesophagitis. Recently, optical fibres have been proposed for the continuous monitoring of carbon dioxide in the stomach: an important parameter in critically ill patients. A clinically validated prototype has shown its superiority in comparison with the traditional method, that is based on gastric tonometry. For the sake of completeness, also gastric pH sensors are considered, although at the moment their development is stationary at the laboratory stage.

Keywords: Gut disease Optical fibre sensors Bile detection Carbon dioxide detection pH detection Bilirubin

[Methyl-D₃]₂hypericin as internal standard for quantification in human plasma by Georgios Piperopoulos; Andrea Kiehne; Arnd Ingendoh; Klaus-Peter Zeller (pp. 744-750).

The multistep synthesis and negative ion-ESI fragmentation pattern of [methyl-D₃]₂hypericin (1-d ₆) is described. The application of 1-d₆ as internal standard for the quantification of hypericin (1) in the ng mL⁻¹ range in human plasma by isotope-dilution LC–MS is demonstrated. The hypericin-containing plasma samples are spiked with 1-d ₆, deproteinized and extracted with ethyl acetate. The extracts are injected into a HPLC–ESI–ion-trap system and the mass-separated negative ions from 1 and 1-d ₆ are analysed. From their intensities linear standard curves over the concentration range from 1 to 10 ng mL⁻¹ are obtained. Accuracy, precision and recovery are discussed.

Keywords: Hypericin Deuteration Blood plasma Isotope dilution technique ESI–LC–MS Multiple reaction monitoring

A comparative study on gamma irradiation of unconjugated bilirubin in aqueous and non-aqueous solutions by A. E. Pillay; F. M. Salih (pp. 751-755).

Dilute aqueous and non-aqueous solutions of bilirubin were exposed to gamma radiation to examine the effects of ionizing radiation on the concentrations of a specimen of this nature. The ionising radiation emanated from a ¹³⁷Cs source, and was applied to 5.2×10⁻² mmol L⁻¹ solutions of the unconjugated specimen in 0.05 mol L⁻¹ aqueous NaOH and chloroform. Depletion of bilirubin after exposure was common to both solvents. Complete degradation was accomplished with doses in excess of 100 Gy. In the case of NaOH, it was found that the presence of molecular oxygen contributed more efficiently to the degradation process, than irradiation in air. When the experimental conditions were changed to nitrogen, the degradation process was suppressed. The sole by-product of merit originating from the NaOH work was the short-wavelength isomer of biliverdin, at 330 nm. In the case of chloroform, the exclusive product of interest was characterised as the long-wavelength isomer of biliverdin that absorbs in the broad region commencing from about 620 nm. The non-aqueous study was conducted in the presence and absence of molecular oxygen, with no significant changes in the results. Optimum production of the isomers in question occurred at a gamma dose of about 80 Gy. The general species of interest were monitored spectrophotometrically, and the results were treated mathematically to facilitate evaluation of the data. Our work represents the development of a facile gamma-ray method for the exclusive production of specific isomers of biliverdin, which are useful components in biosynthetic research.

Keywords: Spectrophotometry Bilirubin Biliverdin Sodium hydroxide Chloroform Gamma radiation 137Cs

Kinetic substrate quantification by fitting the enzyme reaction curve to the integrated Michaelis–Menten equation by Fei Liao; Kao-Cong Tian; Xiao Yang; Qi-Xin Zhou; Zhao-Chun Zeng; Yu-Ping Zuo (pp. 756-762).

The reliability of kinetic substrate quantification by nonlinear fitting of the enzyme reaction curve to the integrated Michaelis–Menten equation was investigated by both simulation and preliminary experimentation. For simulation, product absorptivity ε was 3.00 mmol⁻¹ L cm⁻¹ and K_m was 0.10 mmol L⁻¹, and uniform absorbance error σ was randomly inserted into the error-free reaction curve of product absorbance A_i versus reaction time t_i calculated according to the integrated Michaelis–Menten equation % MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaciiBaiaac6 % gadaWadaqaaiaadgeacaWGTbGaai4lamaabmaabaGaamyqaiaad2ga % cqGHsislcaWGbbGaamyAaaGaayjkaiaawMcaaaGaay5waiaaw2faai % abgUcaRiaadgeacaWGPbGaai4lamaabmaabaGaeqyTduMaey41aqRa % am4saiaad2gaaiaawIcacaGLPaaacqGH9aqpdaqadaqaaiaadAfaca % WGTbGaai4laiaadUeacaWGTbaacaGLOaGaayzkaaGaey41aqRaamiD % aiaadMgaaaa!572F! $$ ln left[ {Am/left( {Am - Ai} ight)} ight] + Ai/left( {varepsilon imes Km} ight) = left( {Vm/Km} ight) imes ti $$ . The experimental reaction curve of arylesterase acting on phenyl acetate was monitored by phenol absorbance at 270 nm. Maximal product absorbance A_m was predicted by nonlinear fitting of the reaction curve to Eq. (1) with K_m as constant. There were unique A_m for best fitting of both the simulated and experimental reaction curves. Neither the error in reaction origin nor the variation of enzyme activity changed the background-corrected value of A_m. But the range of data under analysis, the background absorbance, and absorbance error σ had an effect. By simulation, A_m from 0.150 to 3.600 was predicted with reliability and linear response to substrate concentration when there was 80% consumption of substrate at σ of 0.001. Restriction of absorbance to 0.700 enabled A_m up to 1.800 to be predicted at σ of 0.001. Detection limit reached A_m of 0.090 at σ of 0.001. By experimentation, the reproducibility was 4.6% at substrate concentration twice the K_m, and A_m linearly responded to phenyl acetate with consistent absorptivity for phenol, and upper limit about twice the maximum of experimental absorbance. These results supported the reliability of this new kinetic method for enzymatic analysis with enhanced upper limit and precision.

Keywords: Kinetic substrate quantification Integrated Michaelis–Menten equation Simulation Reaction curve Nonlinear fitting Predictor variable

Enantioselective separations in capillary electrophoresis with dextran sulfate as the chiral selector by Karen W. Phinney; Lane C. Sander (pp. 763-768).

Dextran sulfate, a polyanionic polysaccharide, was evaluated as a chiral additive in capillary electrophoresis. Structurally related compounds having a variety of functional groups were utilized to probe the selectivity of the chiral selector. The effects of pH, chiral selector concentration, and chiral selector composition on resolution were also studied. At low pH, the reversed polarity mode was employed to achieve separation of the probe compounds. The electrophoretic results provided insight into the chiral recognition of dextran sulfate in capillary electrophoresis. Several factors, including hydrophobic, steric, and electrostatic interactions, appeared to play a role in the observed enantioseparations.

Keywords: Capillary electrophoresis Chiral recognition Dextran sulfate Enantiomers Polysaccharide

Preparation of weak cation exchange packings based on monodisperse poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads and their chromatographic properties by Bolin Gong; Congyu Ke; Xindu Geng (pp. 769-774).

The monodisperse, macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads were synthesized by a single-step swelling and polymerization method. Based on this media, a weak cation exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages for biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The measured bioactivity recovery for lysozyme was 98±5%. The dynamic protein loading capacity of the WCX packings was 17.3 mg g⁻¹. The experimental results show that the synthesized WCX resin has very weak hydrophobicity.

Keywords: Monodisperse poly(glycidyl methacrylate-co-ethylene dimethacrylate) resins Weak cation exchange chromatography Protein separation

Determination of low molecular weight organic acids in soil, plants, and water by capillary zone electrophoresis by Ying-hui Li; Bi-xia Huang; Xiao-quan Shan (pp. 775-780).

Determination of low molecular weight organic acids in soils and plants by capillary zone electrophoresis was accomplished using a phthalate buffer and indirect UV detection mode. The influence of some crucial parameters, such as pH, buffer concentration and surfactant were investigated. A good separation of seven organic acids was achieved within 5 min using an electrolyte containing 15 mmol L⁻¹ potassium hydrogen phthalate, 0.5 mmol L⁻¹ myristyltrimethylammonium bromide (MTAB), and 5% methanol (MeOH) (v/v) at pH 5.60, separation voltage −20 kV, and temperature 25 °C. The relative standard deviation (n=5) of the method was found to be in range 0.18–0.56% for migration time and 3.2–4.8% for peak area. The limit of detection ranged between 0.5 µmol L⁻¹ to 6 µmol L⁻¹ at a signal-to-noise ratio of 3. The recovery of standard organic acids added to real samples ranged from 87 to 119%. This method was simple, rapid and reproducible, and could be applied to the simultaneous determination of organic acids in environmental samples.

Keywords: Determination Organic acids Capillary zone electrophoresis

Differentiation of the halogen content of peat samples using ion chromatography after combustion (TX/TOX-IC) by Anke Putschew; Frank Keppler; Martin Jekel (pp. 781-785).

The proposed method for the differential AOX analysis of water samples was tested for its applicability to differentiate the halogen content of peat samples. For determination of the total and the total organic-bound chlorine, bromine and iodine, peat samples were combusted, and the combustion gases trapped and analyzed by ion chromatography (TX/TOX-IC). The total and the organically bound chlorine, bromine and iodine, respectively, can be determined by two-fold analysis with deviations of around 10%. With respect to chlorine more than a double determination could be required. The limit of quantification is 20 mg kg⁻¹ for chlorine, 2 mg kg⁻¹ for bromine and 1 mg kg⁻¹ for iodine, if 25 mg of peat is combusted. The most crucial step of the analysis is the inorganic halogen removal, which is necessary if the organically bound fraction is determined. However, there are some uncertainties about the complete removal of the inorganic halides from the solid samples. Thus, the values of the organically bound fraction have to be discussed as maximal concentrations. Nevertheless, we suggest that the applied method can be useful as a tool for studying the fate of halogens in soils.

Keywords: Chlorine Bromine Iodine Ion chromatography Peat Halogens

Evaluation of denuder sampling for a mixture of three common gaseous diisocyanates by Y. Nordqvist; U. Nilsson; A. Colmsjö (pp. 786-791).

A denuder sampler has been evaluated for a mixture of three gaseous diisocyanates, i.e. toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). Sampling was performed at a total concentration of diisocyanates close to the Swedish occupational exposure limit (OEL), which is 10 ppbv (69–92 µg m⁻³), for a 5-min period. The denuder tube was coated with a chemosorptive stationary phase consisting of SE-30 (polydimethylsiloxane) and the derivatising reagent dibutylamine (DBA). It was shown that the denuder has a collection efficiency for HDI and IPDI comparable to that of an impinger method, while sampling of TDI resulted in an 8% lower concentration. Both short-term (15 min) and long-term (8 h) sampling periods were shown to yield reproducible results. For 8-h measurements, a sampling flow rate of 5 mL min⁻¹ was shown to be suitable for the investigated concentration range, i.e. 10–100 ppbv (69–921 µg m⁻³). A flow rate of 25 mL min⁻¹ or higher resulted in breakthrough after 8 h due to chromatography of the compounds in the adsorbent. The limit of detection (LOD) for the air sampling method is nearly 500 times lower than the OEL. The denuder tubes can be prepared at least 10 days prior to sampling without degradation of performance. Furthermore, they can be stored up to 6 days in a freezer after sampling without significant loss of analytes.

Keywords: Denuder sampling Polydimethylsiloxane adsorbent Derivatisation with dibutylamine Gaseous diisocyanates Toluene diisocyanate Hexamethylene diisocyanate Isophorone diisocyanate

Evaluation of an aqueous KOH digestion followed by hexane extraction for analysis of PCDD/Fs and dioxin-like PCBs in retailed fish by Tomoaki Tsutsumi; Yoshiaki Amakura; Kumiko Sasaki; Masatake Toyoda; Tamio Maitani (pp. 792-798).

Aqueous KOH digestion followed by hexane extraction has been employed in the extraction of dioxins (polychlorinated dibenzo- p -dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls) for biological samples, but there are no reports on its evaluation. Therefore, we report here the evaluation of this extraction for the analysis of dioxins in retailed fish. The effect of the alkaline digestion on dioxins was evaluated by estimation of recoveries. The recoveries of dioxins after the alkaline digestion were good (79–106%) in various kinds of retailed fish except tuna. In tuna, loss of octachlorodibenzofuran (OCDF) was clearly observed, however, the loss was corrected by internal-standard quantification; ¹³C12-labeled OCDF was added before the alkaline digestion. Comparative study showed that alkaline digestion followed by hexane extraction provides extraction efficiencies of dioxins equal to those of conventional Soxhlet extraction in fish. Additionally, in analysis of a certified reference fish sample with this extraction, the values obtained for certified isomers were almost equal to the certified values. Since the present method is very simple and inexpensive, it would be useful for analysis of dioxins in retailed fish.

Keywords: Alkaline digestion Polychlorinated dibenzo- p -dioxins (PCDDs) Polychlorinated dibenzofurans (PCDFs) Dioxin-like polychlorinated biphenyls (dioxin-like PCBs) Fish

Evaluation of glycoalkaloids in tubers of genetically modified virus Y-resistant potato plants (var. Désirée) by non-aqueous capillary electrophoresis coupled with electrospray ionization mass spectrometry (NACE–ESI–MS) by Giuliana Bianco; Philippe Schmitt-Kopplin; Aniello Crescenzi; Soccorsa Comes; Antonius Kettrup; Tommaso R. I. Cataldi (pp. 799-804).

The glycoalkaloid content of transgenic potatoes was evaluated by an optimised method based on non-aqueous capillary electrophoresis coupled on-line with electrospray ionization–mass spectrometry (NACE–ESI–MS). The potato material consisted of tubers from a conventional cv. Désirée and from three lines of modified plants resistant, intermediate and susceptible to infection by potato virus Y (PVY). The main glycoalkaloids were confirmed to be α-solanine and α-chaconine with parent ion masses m/z 852 and 868, respectively. In addition, an unknown minor peak at m/z 850.6 was found both in conventional (control) and susceptible line potato tubers. Such a compound exhibited an MS² spectrum with fragments ions at 704 and 396 m/z derived by loss of two ions, i.e. m/z 146 and 307, most likely corresponding to a rhamnose unit and a [glucose-(rhamnose)₂] moiety, respectively. Up to 30–80-fold higher concentrations of total glycoalkaloids were found in the peel compared to flesh samples of all tubers examined. TGA content was nearly doubled in peel samples of resistant compared to control lines, and these levels were lower than the limit recommended for food safety, i.e. 20–60 mg of TGA per 100 g fresh weight. Moreover, it was established that tubers produced by virus-resistant clones are substantially equivalent in glycoalkaloid contents to those produced by conventional potato varieties.

Keywords: Potato Solanum tuberosum Potato virus Y (PVY) Glycoalkaloids NACE CE MS

Analysis of eco-relevant elements and noble metals in printed wiring boards using AAS, ICP–AES and EDXRF by Tobias Ernst; Ralf Popp; Marion Wolf; Rudi van Eldik (pp. 805-814).

Different analytical procedures were developed to investigate the chemical composition of printed wiring boards. A set of 11 samples from different electronic devices were ground and prepared for ICP–AES and AAS analyses by extraction with aqua regia and microwave digestion. Several sample preparation techniques were used for the analyses by EDXRF; the best results were obtained by embedding the samples in Vaseline. Since no standard reference material is available for printed wiring boards, a model reference material was created to compare the applicability and limitations of the employed analytical techniques.

Keywords: Heavy metals Noble metals Printed wiring (circuit) boards Electronic scrap

Laser-induced fluorescence with an OPO system. Part II: direct determination of lead content in seawater by electrothermal atomization–laser-excited atomic fluorescence (ETA–LEAF) by A. Le Bihan; Y. Lijour; P. Giamarchi; L. Burel-Deschamps; L. Stephan (pp. 815-819).

Fluorescence was induced by coupling a laser with an optical parametric oscillator (OPO) to develop an analytical method for the direct determination of lead content, at ultra-trace level, in seawater by electrothermal atomization–laser-excited atomic fluorescence (ETA–LEAF). The optimization of atomization conditions, laser pulse energy, and mainly temporal parameters allowed us to reach a 3 fg detection limit (0.3 ng L⁻¹) despite the low repetition rate of the device. The expected error on predicted concentrations of lead, at trace levels, in seawater was below 15%.

Keywords: ETA–LEAF OPO Time-resolved spectroscopy Pb Seawater

Removal of heavy metals by using adsorption on alumina or chitosan by M. Luisa Cervera; M. Carmen Arnal; Miguel de la Guardia (pp. 820-825).

The removal of heavy metals from wastewater by using activated alumina or chitosan as adsorbers was evaluated. Cd(II) and Cr(III) were employed as models of the behaviour of divalent and trivalent metal ions. The adsorption of Cd(II) and Cr(III) onto the adsorbers evaluated was studied as a function of pH, time, amount of adsorber, concentration of metal ions and sample volume. A 0.4-g portion of activated alumina can retain 0.6 mg Cr(III) and 0.2 mg Cd(II) from 20 mL sample adjusted at pH 4 and stirred for 30 min. It is therefore possible to totally decontaminate 500 mL of a waste containing 5 mg L⁻¹ Cd(II) and Cr(III) with 10 g alumina. On the other hand, 0.4 g chitosan can totally decontaminate 20 mL of a pH 5 solution containing up to 50 mg L⁻¹ Cd(II) and Cr(III). A 99.2±0.1% retention of Cd(II) and 83±1% retention of Cr(III) was obtained from 500 mL of a laboratory waste. The aforementioned strategies were applied for the minimization of analytical chemistry teaching laboratories and atomic spectrometry laboratory wastes. On comparing both adsorbers it can be concluded that chitosan is more preferable than alumina due to the reduced price of chitosan and the absence of side-pollution effects.

Keywords: Metal ion removal Chitosan Alumina Cadmium Chromium

Potentiometric determination of equilibrium constants of bases and perchlorates of protonated bases in glacial acetic acid using Superquad by Giaan A. Álvarez-Romero; Alberto Rojas-Hernández; Guillermo A. Vázquez; Ma. Teresa Ramírez-Silva (pp. 826-830).

The traditional method of calculating equilibrium constants in glacial acetic acid medium was developed by Kolthoff and Bruckenstein in 1957; thenceforth, and even presently, few alternatives have been made available to undertake such studies. This paper presents the results obtained with the use of the program Superquad to assess the equilibrium constants of various bases and their protonated perchlorate salts in glacial acetic media. A model of formation equilibria is proposed and fed into the program, considering the species present during an acid–base titration. The calculations of the equilibrium constants using Superquad for pyridine and diethylamine are statistically in agreement with those reported in the literature, (for pyridine: pK_B=5.98±0.02, pK_PyHClO4=5.47±0.02 and for diethylamine pK_B=5.52±0.04, pK_DietHClO4=4.52±0.07). With the use of Superquad, the values found for the aniline were pK_B=6.95±0.06 and pK_AnilHClO4=4.89±0.06.

Keywords: Acetic acid Equilibrium constants Biedermann calibration Pyridine Aniline Diethylamine

Determination of copper, nickel, cobalt, silver, lead, cadmium, and mercury ions in water by solid-phase extraction and the RP-HPLC with UV-Vis detection by Qiufen Hu; Guangyu Yang; Yiyun Zhao; Jiayuan Yin (pp. 831-835).

A new method for the simultaneous determination of seven heavy metal ions in water by solid-phase extraction and reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The copper, nickel, cobalt, silver, lead, cadmium, and mercury ions were pre-column derivatized with tetra(m-aminophenyl)porphyrin (Tm-APP) to form colored chelates. The metal–Tm-APP chelates in 100 mL of sample were preconcentrated to 1 mL by solid-phase extraction with a C₁₈^{cartridge; an enrichment factor of 100 was achieved. The chelates were separated on a Waters Xterra}RP₁₈ column by gradient elution with methanol (containing 0.05 mol L⁻¹ pyrrolidine–acetic acid buffer salt, pH 10.0) and acetone (containing 0.05 mol L⁻¹ pyrrolidine–acetic acid buffer salt, pH 10.0) as mobile phase at a flow rate of 1.0 mL min⁻¹ and detected with a photodiode array detector. The detection limits of copper, cobalt, nickel, silver, lead, cadmium, and mercury are 2, 2, 3, 4, 3, 3, and 3 ng L⁻¹, respectively, in the original sample. The method was also applied to the determination of these metals in water with good results.

Keywords: RP-HPLC Tetra(m-aminophenyl)porphyrin Solid-phase extraction Heavy metal ions

Determination of platinum(IV) by UV spectrophotometry by M. Georgieva; B. Andonovski (pp. 836-839).

A simple, rapid and sensitive spectrophotometric procedure for the determination of platinum has been elaborated. Pt traces were determined in the form of the PtCl₆ ²⁻ complex in hydrochloric acid solution whose concentration varies from 0.01 to 2 mol L⁻¹ by measuring the absorbance at 260 nm. The detection limit is 4.7×10⁻⁷ mol L⁻¹, the linearity range from 2×10⁻⁶ mol L⁻¹ to 7×10⁻⁶ mol L⁻¹, and the correlation coefficient is r=0.9990. No significant interferences were observed from a majority of the investigated ions, such as Zn(II), Pb(II), Mn(II), Cd(II), Co(II) and Ni(II) with the exception of Cu(II), Sb(III), Fe(III), Pd(II), Sn(II) and I⁻ ions. The method was successfully applied for the determination of Pt traces in different solid samples and the recovery from inorganic materials was studied.

Keywords: Platinum UV spectrophotometry Chloroplatinates Determination

Determination of ferulic acid and adenosine in Angelicae Radix by micellar electrokinetic chromatography by Tao Guo; Yi Sun; Yin Sui; Famei Li (pp. 840-843).

A micellar electrokinetic chromatography for determining ferulic acid and adenosine in Angelicae Radix was developed. A buffer solution composed of 50 mmol L⁻¹ borax, 10 mmol L⁻¹ sodium deoxycholate, and 2% methanol was found to be the most suitable electrolyte for the separation. The contents of ferulic acid and adenosine in Angelicae Radix were determined within 20 min. Good linearity between peak area ratio and the concentration was found in the range of approximately 20–320 μg mL⁻¹ for ferulic acid and about 10–160 μg mL⁻¹ for adenosine (r >0.998), respectively. The recoveries were approximately 96.8–97.4% and 93.2–95.0%, and the RSD of this proposed method were 4.4% and 3.2% for ferulic acid and adenosine, respectively (n=5). The contents of ferulic acid and adenosine in Angelicae Radix from different sources were determined.

Keywords: Micellar electrokinetic chromatography Angelicae Radix Ferulic acid Adenosine

Colloquium Spectroscopium Internationale (CSI XXXIII) (pp. 844-844).

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Analytical and Bioanalytical Chemistry (v.375, #6)