Journal of Chromatography B (v.879, #20)

Metal-binding thiols, involved in detoxification mechanisms in plant and other organism under heavy metal stress, are receiving more and more attentions, and various methods have been developed to determine related thiols such as cysteine (Cys), glutathione (GSH) and phytochelatins (PCs). In present study, an HPLC method was established for simultaneous determination of Cys GSH and PC2–6 after treatment with disulfide reductant of tris (2-carboxyethyl) phosphine hydrochloride (TCEP) and thiolyte reagent of monobromobimane (mBBr). The separation of thiol derivatives was performed on an Agilent Zorbax Eclipse XDB-C18 column (4.6 mm × 30 mm, 1.8 μm) with a linear gradient elution of 0.1% (v/v) trifluoroacetic acid (TFA)–acetonitrile (ACN) at 0.8 mL min−1. The temperature of the column was maintained at 25 °C. The excitation and emission wavelengths were set at 380 and 470 nm, respectively. The thiol derivatives were well separated in 19 min, and the total analysis time was 30 min. The established method was proved selective, specific and reproducible, and could be applicable to determine Cys, GSH and PC2–6 and to evaluate their roles in detoxification mechanisms in Cd-treated Lolium perenne L. under ambient and elevated carbon dioxide (CO2). It was found that the total SH contents and proportions of thiols in roots and shoots were dependent on Cd concentration, whereas the total SH contents decreased and the proportions of thiols altered without significance at elevated CO2 level.
Keywords: Thiols; Monobromobimane; HPLC;

Simultaneous determination of lipoic acid (LA) and dihydrolipoic acid (DHLA) in human plasma using high-performance liquid chromatography coupled with electrochemical detection by Abad Khan; Zafar Iqbal; David G. Watson; Amirzada Khan; Inamullah Khan; Naveed Muhammad; Salar Muhammad; Hashmat Ara Nasib; Naveed Iqbal; Faiz-ur-rehman; Muhammad Kashif (1725-1731).
A fast, simple, and a reliable high-performance liquid chromatography linked with electrochemical detector (HPLC–ECD) method for the assessment of lipoic acid (LA) and dihydrolipoic acid (DHLA) in plasma was developed using naproxen sodium as an internal standard (IS) and validated according to standard guidelines. Extraction of both analytes and IS from plasma (250 μl) was carried out with a single step liquid–liquid extraction applying dichloromethane. The separated organic layer was dried under stream of nitrogen at 40 °C and the residue was reconstituted with the mobile phase. Complete separation of both compounds and IS at 30 °C on Discovery HS C18 RP column (250 mm × 4.6 mm, 5 μm) was achieved in 9 min using acetonitrile: 0.05 M phosphate buffer (pH 2.4 adjusted with phosphoric acid) (52:48, v/v) as a mobile phase pumped at flow rate of 1.5 ml min−1 using electrochemical detector in DC mode at the detector potential of 1.0 V. The limit of detection and limit of quantification for lipoic acid were 500 pg/ml and 3 ng/ml, and for dihydrolipoic acid were 3 ng/ml and 10 ng/ml, respectively. The absolute recoveries of lipoic acid and dihydrolipoic acid determined on three nominal concentrations were in the range of 93.40–97.06, and 93.00–97.10, respectively. Similarly coefficient of variations (% CV) for both intra-day and inter-day were between 0.829 and 3.097% for lipoic acid and between 1.620 and 5.681% for dihydrolipoic acid, respectively. This validated method was applied for the analysis of lipoic acid/dihydrolipoic acid in the plasma of human volunteers and will be used for the quantification of these compounds in patients with oxidative stress induced pathologies.
Keywords: Lipoic acid; Dihydrolipoic acid; Liquid–liquid extraction; Plasma; Analysis; Oxidative stress;

In order to improve its stability, immobilized Concanavalin A (Con A) on Toyopearl adsorbents was conjugated with monomethoxy poly(ethylene glycol) succinimidyl propionate (mPEG-SPA) with different molecular weight. A colorimetric method using ninhydrin is proposed to determine the degree of PEGylation; this method has proved to be easy applicable and reproducible. The PEGylation reaction was studied in detail to elucidate how parameters such as molar ratio of mPEG-SPA to Con A and molecular weight of mPEG-SPA affect the degree of PEGylation. The adsorption isotherms of glucose oxidase (GOD) onto native and PEGylated Con A adsorbents showed that the modification did not alter substantially the specificity of the carbohydrate binding ability of Con A. However, the binding capacity for GOD was slightly reduced probably due to the steric hindrance caused by mPEG chains. Adsorption kinetic studies revealed a lower adsorption rate after PEGylation which was attributed to the steric effect. The dynamic adsorption capacity for modified Con A depended very much on the degree of PEGylation and the molecular weight of mPEG derivatives. The adsorption capacity could be highly preserved for Toyopearl Con A modified by mPEG2k (90% of the original adsorption capacity) even with a degree of PEGylation up to 20% (the ratio of primary amino groups of PEGylated immobilized Con A to that of native immobilized Con A). Studies show that the binding capacity of PEGylated Con A was highly preserved under mild process conditions. PEGylated Con A also exhibited obviously higher stability against more stressful conditions such as the exposure to organic solvents and high temperatures. Conjugation of Con A with mPEG2k provided better adsorption performance thus has greater potential for application in affinity separation processes compared with mPEG5k. The fact that PEGylation stabilizes the properties of Con A may greatly expand the range of applications of unstable proteins to bioprocessing (e.g. biocatalysis and downstream separation) as well as other protein applications (e.g. medication, industrial use, etc.).
Keywords: Protein stability; PEGylation; Concanavalin A; Glucose oxidase; Affinity adsorption;

Separation and identification of norcantharidin metabolites in vivo by GC–MS method by Chunmin Wei; Yanni Teng; Benjie Wang; Xiumei Zhang; Guiyan Yuan; Xiaoyan Liu; Rong Li; Ruichen Guo (1741-1747).
Norcantharidin (NCTD), the demethylated analogue of cantharidin, inhibits the proliferation of a variety of human tumor cell lines, and appears to cause the least nephrotoxic and inflammatory side effects. Although NCTD has been used to treat human cancers in China for years, there is no report regarding its metabolism up to now. This is the first report to separate and identify the main metabolites of NCTD in vivo by GC–MS using TMS derivatives. Two hydrolyzed products and five phase I or phase II metabolites were found in rat by the chromatogram comparisons of the blank with incurred biological samples. Multiple stages of fragmentation patterns were used to confirm the metabolites characterizations. The established GC–MS method can also be applied to identifying unknown metabolites of the drugs containing hydroxyl or carbonyl groups in molecular structure.
Keywords: Norcantharidin; Metabolites; GC–MS; Derivate; Metabolism;

To study the roles of estrogens and estrogen metabolites (EMs) in breast carcinogenesis, we reported a quantitative liquid chromatography–tandem mass spectrometry (LC–MS/MS) method utilizing selective reaction mode (SRM) to analyze estrogens and EMs in the extracellular and intracellular compartments of endogenous MCF-7 breast cancer cells through simple ethyl acetate (EA) extraction and dansyl chloride derivatization. Under a 35-min LC gradient elution on a reversed phase C18 column, the method was shown to simultaneously quantify 12 estrogens and EMs: estrone (E1) and its 2-, 4-, 16α-hydroxy derivatives (2-OHE1, 4-OHE1, 16α-OHE1), and 2-, 4-methoxy derivatives (2-MeOE1, 4-MeOE1); 17β-estradiol (E2) and its 2-, 4-hydroxy derivative (2-OHE2, 4-OHE2) and 2- and 4-methoxy derivatives (2-MeOE2 and 4-MeOE2); and estriol (E3), using ethinylestradiol (EE2) as the internal standard (IS). Using a calibration curve–standard addition hybrid method, we were able to determine the amount of estrogens and EMs in not only the treated cells but also the non-treated cells. The limits of quantification (LOQs) were determined to range from 0.05–80 pg on column with an inter-batch accuracy around 72–123% and precision around 1–10%. Results indicated that trace amounts (<0.9 fg/cell) of E1 and E2 were present in both the extra- and intra-cellular compartments under non-treated condition but DMSO could induce E1 and E2 as well as trace amounts (<2.25 fg/cell) of EMs in the cell. E2 treatment substantially increased not only E1 and E2 in the intra-cellular (60 fg/cell) and extra-cellular (3000 fg/cell) compartment but also substantially induced EMs primarily in the extracellular compartment (0.6–25 fg/cell). These data implied that EMs could be quickly generated and distributed to the extracellular compartment by E2 within 24 h of treatment and DMSO solvent could potentially induce slight estrogen effects.
Keywords: Liquid chromatography–tandem mass spectrometry; Estrogens; Estrogen metabolites; MCF-7 cells;

A new procedure has been described for the extraction of diclazuril (DIZ), toltrazuril (TOZ) and its two main metabolites toltrazuril sulphoxide (TZSO) and toltrazuril sulphone (TZS) from poultry tissues and eggs, using gel permeation chromatography (GPC). The analytes and the deuterated internal standard were extracted from the samples with ethyl acetate. The analytes were measured by LC coupled to an electrospray ionization tandem mass spectrometer operating in the negative ion mode. Excellent linear dynamic range was observed from 1 to 500 μg/L with the correlation coefficients (R 2) better than 0.99 for all analytes. The method LOQ of the four analytes in real samples was 1.2 μg/kg for DIZ and TOZ, and 1.8 μg/kg for TZSO and TZS. These values are far lower than the maximum residue limits (MRLs) established by several control authorities. The developed method was accurate with overall recoveries in four matrices.
Keywords: GPC; LC–MS/MS; Diclazuril; Toltrazuril; Metabolites; Poultry tissues;

Quantitative structure–activity relationship (QSAR) analysis of 20 drugs with affinity for serotonin (5-HT) receptors was carried out. A set of physicochemical parameters calculated by HyperChem 7.0 and ACDLabs 8.0 programs and chromatographic data were applied in the analysis. Thin layer chromatography was performed on silica gel NP 60F254 and silica gel RP2 60F254 (silanized) plates impregnated with solutions of aspartic acid, serine, phenylalanine, tryptophan, tyrosine, asparagine, threonine and their mixtures (denoted as S1–S11 models), with two mobile phases – the systems were chosen as models of drug-5-HT-receptor interaction. Relationships between chromatographic data and molecular descriptors and biological activity data were found by means of regression analysis. The correlations obtained for the compounds with serotoninergic activity represent their interaction with the proposed biochromatographic models (S1–S11). The presented regression models based on biochromatographic studies can be an efficient tool in the QSAR analysis for initial prediction of compounds activity direction within 5-HT receptors.
Keywords: Thin layer chromatography; Biochromatography; 5-HT receptors; Molecular descriptors; Multiple regression analysis; Quantitative structure–activity relationships;

A novel method using column chromatography on oligo-β-cyclodextrin-Sepharose HP for the preparation of high purity daidzin from crude soybean samples was proposed in this work. The isoflavone of daidzin in sample A and B was purified under the optimum mobile phase composed of methanol/acetic acid/water = 20.0/8.0/72.0 (v/v/v) at a flow-rate of 1.0 mL/min in one-step operation with a purity of 97.2% and 98.1%, a recovery of 95.3% and 96.3% respectively. The target products in isolated fraction were detected and characterized by HPLC analysis and ESI-MS spectrum. Preparative separation with sample-load of up to 2.42 mg/mL medium gave satisfactory results for daidzin with the purities over 97% and recoveries approximately 90%. Molecular docking simulations were utilized to help demonstrate the inclusion complexation between β-cyclodextrin and the isoflavones in samples through inclusion geometries and calculations of the binding energies. The prediction of the elution orders with AUTODOCK and SURFLEX-DOCK were validated by the chromatographic results.
Keywords: β-Cyclodextrin; Daidzin; Chromatography; Purification; Molecular docking; Inclusion complexation;

Online magnetic bead based dynamic protein affinity selection coupled to LC–MS for the screening of acetylcholine binding protein ligands by Lionel Pochet; Ferry Heus; Niels Jonker; Henk Lingeman; August B. Smit; Wilfried M.A. Niessen; Jeroen Kool (1781-1788).
A magnetic beads based affinity-selection methodology towards the screening of acetylcholine binding protein (AChBP) binders in mixtures and pure compound libraries was developed. The methodology works as follows: after in solution incubation of His-tagged AChBP with potential ligands, and subsequent addition of cobalt (II)-coated paramagnetic beads, the formed bead-AChBP-ligand complexes are fetched out of solution by injection and trapping in LC tubing with an external adjustable magnet. Non binders are then washed to the waste followed by elution of ligands to a SPE cartridge by flushing with denaturing solution. Finally, SPE-LC–MS analysis is performed to identify the ligands. The advantage of the current methodology is the in solution incubation followed by immobilized AChBP ligand trapping and the capability of using the magnetic beads system as mobile/online transportable affinity SPE material. The system was optimized and then successfully demonstrated for the identification of AChBP ligands injected as pure compounds and for the fishing of ligands in mixtures. The results obtained with AChBP as target protein demonstrated reliable discrimination between binders with pK i values ranging from at least 6.26 to 8.46 and non-binders.
Keywords: Acetylcholine binding protein (AChBP); Affinity selection mass spectrometry; Screening assay; Ligand chromatography; Magnetic beads;

Quantitative determination of buagafuran in human plasma by liquid chromatography–tandem mass spectrometry by Fen Yang; Hongyun Wang; Ao Peng; Ming Liu; Pei Hu; Ji Jiang (1789-1794).
A sensitive and selective high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method was developed for the determination of buagafuran in human plasma. The analyte was extracted from plasma samples with hexane after addition of isotopic internal standard and chromatographed on a RP-C8 column. The mobile phase consisted of methanol–water (90:10, v/v) and the flow rate was 0.2 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reactions monitoring (MRM) mode using positive electrospray ionization (ESI). The method was validated over the concentration range of 0.5–200 ng/mL. Inter- and intra-day precision (RSD%) were all within 15% and the accuracy (RE%) was equal or lower than 9.5%. The lower limit of quantitation (LLOQ) was 0.5 ng/mL. The extraction recovery was on average 38.1% and the detection was not affected by the matrix. The method was successfully applied to the pharmacokinetic study of buagafuran in healthy Chinese volunteers.
Keywords: Buagafuran; LC–MS/MS; MRM; Anxiety disorders;

A rapid method for the determination of para-phenylenediamine (PPD) in cosmetic products, such as henna tattoos has been developed and evaluated. This analytical procedure involved extracting a 10 mg test portion of cosmetic product in 10 mL of ethyl acetate, followed by determination by gas chromatography–mass spectrometry in the selected ion monitoring mode (GC/MS-SIM). 1,4-Phenylenediamine-2,3,5,6-d4 was selected as an internal standard that was added at the beginning of the extraction procedure and used to correct for recovery and matrix effects. The linearity ranged from 1.0 to 1275 μg/mL with a coefficient of determination (r 2) greater than 0.999. LOQ and LOD were 1.0 and 0.10 μg/mL, respectively. The recovery in a tattoo product containing PPD was 94% and that for a tattoo product containing no PPD reached 105%. Extraction efficiency of 98% was obtained. This method has been successfully applied to henna temporary tattoo and other henna-related cosmetic products for the determination and quantitation of PPD.
Keywords: Para-phenylenediamine; Henna tattoo products; GC/MS-SIM; 1,4-Phenylenediamine-2,3,5,6-d4;

An efficient and sensitive capillary electrophoresis with laser-induced fluorescence detection (CE–LIF) method has been developed for the simultaneous determination of phytohormones containing carboxyl group, including gibberellic acid, indole-3-acetic acid, abscisic acid, jasmonic acid, indole butyric acid, 1-naphthalene acetic acid and 2,4-dichloro-phenoxy acetic acid, based on the chemical derivatization with 6-oxy-(acetypiperazine) fluorescein. Using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as the condensing reagent, the derivatization reaction completed at 60 °C in 60 min and the derivatization limits could reach 20 nmol L−1. The formed derivatives of seven phytohormones have been separated and quantified within 20 min. The linearity was found in the range of 0.01–1 μmol L−1 and the limits of detection were 1.6–6.7 nmol L−1 (S/N = 3). The proposed method has been applied to analyze the crude extract of 0.5 g banana samples directly without further purification and the recoveries varying from 90.7 to 106.1%.
Keywords: 6-Oxy-(acetyl piperazine) fluorescein (APF); Capillary electrophoresis with laser-induced fluorescence detection (CE–LIF); Derivatization; Phytohormones;

An improved approach for extraction and high-performance liquid chromatography analysis of paraquat in human plasma by Yuangao Zou; Yunying Shi; Yangjuan Bai; Jiangtao Tang; Yao Chen; Lanlan Wang (1809-1812).
A simple, sensitive, reliable and economical HPLC method for quantifying paraquat concentration in human plasma has been developed, using diethyl paraquat as an internal standard. The drugs were extracted from the sample and separated on Xtimate C18 column with a mobile phase of 15% acetonitrile in 0.1 M orthophosphoric acid containing SDS (150 mg/l). The pH of the mobile phase was adjusted to 3 with triethylamine and the detection wavelength was 256 nm for both paraquat and the internal standard. The average extraction recoveries were 91.9%. Good linearity (R 2  = 0.9984) was observed throughout the range of 0.02–10 μg/ml in 0.5 ml plasma. The overall accuracy of this method was 97.6–107.3% and the lower limit of detection was 0.01 μg/ml. The intra- and inter-day variations were lower than 3.65% and 2.64%, respectively. We used this method to examine the paraquat concentrations of 53 patients with acute paraquat intoxication of whom 26 (49.1%) survived. In conclusion, this method was suitable for quantification of paraquat plasma concentration in toxicological samples. It was helpful in both assessing the severity of intoxication and predicting the outcome of paraquat poisoning.
Keywords: High-performance liquid chromatography; Paraquat; Intoxication;

Highly sensitive and accurate screening of 40 dyes in soft drinks by liquid chromatography–electrospray tandem mass spectrometry by Feng Feng; Yansheng Zhao; Wei Yong; Li Sun; Guibin Jiang; Xiaogang Chu (1813-1818).
A method combining solid phase extraction with high performance liquid chromatography–electrospray ionization tandem mass spectrometry was developed for the highly sensitive and accurate screening of 40 dyes, most of which are banned in foods. Electrospray ionization tandem mass spectrometry was used to identify and quantify a large number of dyes for the first time, and demonstrated greater accuracy and sensitivity than the conventional liquid chromatography–ultraviolet/visible methods. The limits of detection at a signal-to-noise ratio of 3 for the dyes are 0.0001–0.01 mg/L except for Tartrazine, Amaranth, New Red and Ponceau 4R, with detection limits of 0.5, 0.25, 0.125 and 0.125 mg/L, respectively. When this method was applied to screening of dyes in soft drinks, the recoveries ranged from 91.1 to 105%. This method has been successfully applied to screening of illegal dyes in commercial soft drink samples, and it is valuable to ensure the safety of food.
Keywords: Dyes; Solid-phase extraction; HPLC; ESI-MS/MS; Soft drink;

Structural identification of the metabolites for strictosamide in rats bile by an ion trap-TOF mass spectrometer and mass defect filter technique by Yan Liang; Wei Xiao; Chen Dai; Lin Xie; Gang Ding; Guangji Wang; Zhaoqing Meng; Juan Zhang; An Kang; Tong Xie; Yanna Liu; Yuanyuan Zhou; Wenjun Liu; Li Zhao; Jia Xu (1819-1822).
We report herein, a facile metabolite identification workflow on the antimicrobial strictosamide, which is derived from accurate mass measurement by a hybrid ion trap-TOF mass spectrometer. In step 1, the parent drug and metabolites in rat bile were separated on an HPLC column followed by ion trap-TOF mass spectrometer analysis after a single oral dose of 50 mg/kg strictosamide. In step 2, mass defect filter technique, which enables high-resolution mass spectrometers to be utilized for detecting drug metabolites based on well-defined mass defect ranges, was used to find metabolites in the mass spectrum. In step 3, the differences of accurate masses and their mass fragmentation pattern among the parent drug and metabolites used to assign structures for the metabolites successfully. As a result, five metabolites of strictosamide were found in rat bile, and all the metabolites were reported for the first time.
Keywords: Ion trap/TOF mass spectrometer; Mass defect filter; Strictosamide; Metabolites;

Quantification of riboflavin in human urine using high performance liquid chromatography–tandem mass spectrometry by Amanda M. Bishop; Carolina Fernandez; Ralph D. Whitehead Jr; Pilar Morales-A; Dana Boyd Barr; Lynn C. Wilder; Samuel E. Baker (1823-1826).
We developed a selective method to measure riboflavin in human urine. Sample preparation involved solid phase extraction and concentration of the target analyte in urine. The urine concentrate was analyzed using high performance liquid chromatography–tandem mass spectrometry. Riboflavin concentrations were quantified using an isotopically labeled internal standard. The limit of detection was 11 ng/mL, and the linear range was 4.4–20,000 ng/mL. The relative standard deviation at 100, 1000, and 5000 ng/mL was 17%, 17%, and 12%, respectively. The accuracy was 90%. On average, 100 samples, including calibration standards and quality control samples, were prepared per day. Using our method, we measured concentrations of riboflavin in human urine samples that were collected from participants in a study where riboflavin was used as a surrogate chemical to simulate exposure to an environmental toxicant.
Keywords: Riboflavin; Human urine; Surrogate; HPLC–MS/MS;

A fast, sensitive and selective ultra performance liquid chromatography–tandem mass spectrometric (UPLC–MS/MS) method was developed for the determination of nifedipine in human plasma. Nitrendipine was used as the internal standard. The sample preparation employed liquid–liquid extraction with a mixture of n-hexane–diethyl ether (1:3, v/v). Chromatographic separation was performed on an ACQUITY UPLC™ BEH C18 column. The mobile phase was composed of acetonitrile–10 mmol/L ammonium acetate (75:25, v/v) with a flow rate of 0.20 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. A high throughput was achieved with a run time of 1.4 min per sample. The linear calibration curves were obtained in the concentration range of 0.104–52.0 ng/mL (r 2  ≥ 0.99) with a lower limit of quantification (LLOQ) of 0.104 ng/mL. The intra- and inter-day precision (relative standard deviation, RSD) values were below 15% and the accuracy (relative error, RE) was −4.0% to 6.2% at three quality control levels. The method was fully validated and successfully applied to a clinical pharmacokinetic study of nifedipine sustained-release tablet in healthy male volunteers.
Keywords: Nifedipine; UPLC–MS/MS; Human plasma; Pharmacokinetics;

Shikonin and β,β′-dimethylacrylshikonin in Arnebia euchroma (Royle) Johnst. were extracted by ionic liquid-based ultrasonic-assisted extraction (IL-based UAE) and determined by high-performance liquid chromatography (HPLC). The dried powder of A. euchroma (Royle) Johnst. was mixed with a room temperature ionic liquid [C6MIM][BF4] to form a suspension, and then the ultrasonic extraction was performed in a water bath at ambient temperature. The calibration curve showed good linear relationship (r  > 0.9998) in the concentration range of 1.75–140 μg/mL for shikonin and 2.15–1360 μg/mL for β,β′-dimethylacrylshikonin. The recoveries were between 69.79% and 82.35%. The IL-based UAE is free of volatile organic solvents, and consumes less sample, time and solvent, compared with regular ultrasonic and Soxhlet extraction. There was no obvious difference in the extraction yields of active constitutions obtained by the three extraction methods.
Keywords: Arnebia euchroma (Royle) Johnst.; Shikonin; β,β′-Dimethylacrylshikonin; Ionic liquid-based ultrasonic-assisted extraction(IL-based UAE); High-performance liquid chromatography (HPLC);

Altered glycosylation and expression of plasma alpha-1-acid glycoprotein and haptoglobin in rheumatoid arthritis by Ashish Saroha; Sagarika Biswas; Bishnu P. Chatterjee; Hasi R. Das (1839-1843).
Altered glycosylation patterns in plasma proteins are found to be associated with the pathogenesis of various malignancies and autoimmune disorders. Our previous studies demonstrated the occurrence of some differentially glycosylated plasma proteins in rheumatoid arthritis (RA) patients. The current study was conducted to evaluate the alterations in expression and glycosylation of major acute phase proteins from wheat germ agglutinin enriched RA patients’ plasma. Immunoblotting studies revealed a significant enhancement in the plasma levels of alpha-1 acid glycoprotein (AGP) and haptoglobin (Hp) in RA patients with respect to healthy controls. Monosaccharide analysis by high performance anion exchange-chromatography with pulse amperometric detection showed significant variations in the relative percentage of galactose, glucosamine and mannose in AGP and of mannose in Hp in RA patients. Altered patterns of mannosylation in AGP and Hp were also established by enzyme linked immunosorbent assay and Western blotting using Concanavalin-A lectin. These results could give information for understanding the disease pathogenesis and may provide an insight into the development and progression of the disease.
Keywords: Glycosylation; High pH anion exchange chromatography-pulse amperometric detection; Lectins; Plasma proteins; Rheumatoid arthritis;

Corrigendum to “Certified reference materials (GBW09170 and 09171) of creatinine in human serum” [J. Chromatogr. B 879 (2011) 429] by Xinhua Dai; Xiang Fang; Mingwu Shao; Ming Li; Zejian Huang; Hongmei Li; You Jiang; Dewei Song; Yajuan He (1845).