Ion-exchange High-performance Chromatography Research Articles

Efficient separation of uranium and lanthanides based on high-performance ion exchange chromatography

Efficient separation of uranium and lanthanides based on high-performance ion exchange chromatography

A-326 Argininosuccinic Acid - is it Routinely Detectable in the Urine of Healthy Individuals?

Abstract Background Argininosuccinic aciduria is a genetic disorder that results in elevated levels of argininosuccinic acid (ASA) in urine and blood. While there is seemingly a consensus within the clinical literature that any detectable amount of ASA in blood/plasma is diagnostic for argininosuccinic aciduria, yet there is conflict as to whether ASA in urine can be found in unaffected individuals. Some literature states that ASA should not be found in the urine of a healthy individual, while other literature reports low levels of ASA in the urine of healthy individuals. Additionally, many laboratories do not have a normal range for ASA within urine, which implies that any level of ASA found within urine is indicative of argininosuccinic aciduria. This conflict may in part be due to differences in the methods used to determine ASA levels. Newer liquid chromatography tandem mass spectrometry (LCMSMS) methods have been shown to be more sensitive than ion-exchange chromatography (IEC) based amino acid methods for detection of ASA. Additionally, the detection of ASA via IEC requires the heating and acidification of the sample to convert ASA into a single peak for quantitation. Heating and acidification is not routinely done for urine amino acid analysis with IEC; with routine IEC urine amino acid analysis, ASA migrates as three small peaks that may go unnoticed. In our clinical laboratory, which utilizes the less sensitive IEC method, our procedure describes the presence of any ASA in urine as diagnostic for argininosuccinic aciduria. Given the conflicting literature, we set forth to determine whether low levels can be detected in unaffected individuals with an IEC method, and if so, establish a normal range of ASA levels in urine with IEC. Methods Twenty waste urine samples from patients with no prior diagnoses of argininosuccinic aciduria were evaluated. ASA levels within the samples were determined via high performance ion exchange chromatography for separation of compounds followed by derivatization with ninhydrin for spectrophotometric detection with a Hitachi Amino Acid analyzer. The samples were acidified and heated, which converts ASA into a single anhydride peak for accurate quantitation, and the results were normalized to urine creatinine. Results ASA was detected in all twenty urine samples, with an average ASA concentration of 27.2 μmol/g Cr and a range of 11.3–47.7 μmol/g Cr. Conclusion Given these findings, our clinical laboratory procedure has been updated to include the information that ASA can be present in the urine of healthy individuals up to a concentration of 50 μmol/g Cr. Other clinical laboratories that analyze urine to identify argininosuccinic aciduria should be aware of the misinformation in the literature that claims that ASA is not present in the urine of healthy individuals.

Utilizing augmented artificial intelligence for aminoacidopathies using collaborative laboratory integrated reporting- A cross-sectional study

IntroductionPlasma amino acids profiling can aid in the screening and diagnosis of aminoacidopathies. The goal of the current study was to analyze and report the metabolic profiles of plasma amino acid (PAA) and additionally to compare PAA-reference intervals (RI) from Pakistan with more countries utilizing Clinical Laboratory Integrated Reports (CLIR).MethodsThis was a cross sectional prospective single center study. Twenty-two amino acids were analyzed in each sample received for one year at the clinical laboratory. Data was divided into reference and case data files after interpretation by a team of pathologists and technologists. All PAA samples were analyzed using ion-exchange high-performance chromatography. The CLIR application of Amino Acid in Plasma (AAQP) was used for statistical analysis for both data sets and post-analytical interpretive tools using a single condition tool was applied.ResultThe majority of 92% (n = 1913) of PAA profiles out of the total 2081 tests run were non-diagnostic; the PAA values were within the age-specific RI. The PAA median was in close comparison close to the 50th percentile of reference data available in CLIR software. Out of the total 2081 tests run, one hundred and sixty-eight had abnormal PAA levels; 27.38% were labeled as non-fasting samples, and the main aminoacidopathies identified were Phenylketonuria and Maple Syrup Urine Disorder.ConclusionAn agreement of >95% was observed between the reporting done by the pathologists and technologists’ team and then after the application of CLIR. Augmented artificial intelligence using CLIR can improve the accuracy of reporting rare aminoacidopathies in a developing country like ours.

Diversity of bacterial community in Jerusalem artichoke (Helianthus tuberosus L.) during storage is associated with the genotype and carbohydrates.

Jerusalem artichoke (JA) is a fructan-accumulating crop that has gained popularity in recent years. The objective of the present study was to determine the dynamics of the JA-microbiome during storage. The microbial population on the surface of the JA tuber was determined by next-generation sequencing of 16S rRNA amplicons. Subsequently, the changes in carbohydrate and degree of polymerization of fructan in tubers during storage were measured. Among different genotypes of JA varieties, intergeneric differences were observed in the diversity and abundance of bacterial communities distributed on the surface of tubers. Additionally, bacterial diversity was significantly higher in storage-tolerant varieties relative to the storage-intolerant varieties. Redundancy analysis (RDA) and the correlation matrix indicated a relationship between changes in the carbohydrates and microbial community succession during tuber storage. The tuber decay rate correlated positively with the degree of polymerization of fructan. Moreover, Dysgonomonas and Acinetobacter in perishable varieties correlated significantly with the decay rate. Therefore, the bacteria associated with the decay rate may be involved in the degradation of the degree of polymerization of fructan. Furthermore, Serratia showed a significant positive correlation with inulin during storage but a negative correlation with the decay rate, suggesting its antagonistic role against pathogenic bacteria on the surface of JA tubers. However, the above correlation was not observed in the storage-tolerant varieties. Functional annotation analysis revealed that storage-tolerant JA varieties maintain tuber quality through enrichment of biocontrol bacteria, including Flavobacterium, Sphingobacterium, and Staphylococcus to resist pathogens. These results suggested that crop genotype and the structural composition of carbohydrates may result in differential selective enrichment effects of microbial communities on the surface of JA varieties. In this study, the relationship between microbial community succession and changes in tuber carbohydrates during JA storage was revealed for the first time through the combination of high-throughput sequencing, high-performance liquid chromatography (HPLC), and high-performance ion-exchange chromatography (HPIC). Overall, the findings of this study are expected to provide new insights into the dynamics of microbial-crop interactions during storage.

Pourbaix Diagram of Astatine Revisited: Experimental Investigations.

The Pourbaix diagram of an element displays its stable chemical forms with respect to the redox potential and pH of the solution, whose knowledge is fundamental for understanding and anticipating the chemistry of the element in a specified solution. Unlike most halogens, the Pourbaix diagram in the aqueous phase for astatine (At, Z = 85) is still under construction. In particular, the predominant domains of two astatine species assumed to exist under alkaline conditions, At- and AtO(OH)2-, need to be refined. Through high-performance ion-exchange chromatography, electromobility measurements, and competition experiments, the existence of At- and AtO(OH)2- has been confirmed and the associated standard potential has been determined for the first time (0.86 ± 0.05 V vs the standard hydrogen electrode). On the basis of these results, a revised version of astatine's Pourbaix diagram is proposed, covering the three oxidation states of astatine that exist in the thermodynamic stability range of water: At(-I), At(I), and At(III) (as At-, At+, AtO+, AtO(OH), and AtO(OH)2-).

Pasting Properties of Various Waxy Rice Flours: Effect of α-Amylase Activity, Protein, and Amylopectin

Waxy rice has a long history of being cultivated and consumed in China. In this study, the effect of different factors including α-amylase activity, protein, and amylopectin structure on the pasting properties of four waxy rice varieties were investigated. Rice flours were divided into four groups (Vietnam indica (VI), Jiangxi indica (JI), Anhui japonica (AJ), and Dongbei japonica (DJ) group) and treated with AgNO3 solution, DL-dithiothreitol (DTT), or protease (n = 3). Results suggested that both α-amylase activity and protein significantly decrease the pasting viscosity of waxy rice flours. Chain length distribution of amylopectin as measured by high performance ion exchange chromatography (HPAEC-PAD) showed that starch with a higher ratio of short chain leads to a higher pasting viscosity. X-Ray diffractograms showed that the crystal type of all the four varieties of rice starches were characteristic A-type. Relative crystallinity of each rice starch was further calculated, and higher crystallization resulted in a higher viscosity. Our study would provide a fundamental knowledge of the relationship between different factors and waxy starch pasting properties, as well as be a reference for controlling the quality of waxy rice starch-based food products.

Undeclared (Poly)phosphates Detection in Food of Animal Origin as a Potential Tool toward Fraud Prevention

(Poly)phosphates are approved as water-preserving and emulsifying agents that improve the appearance and consistency of many food products. The labelling of added (poly)phosphates is essential for protecting vulnerable population groups and to prevent unfair trade practices resulting in economic fraud. The problems with (poly)phosphates’ utilisation concerns both analytical and legislative issues, such as: (1) their straightforward detection; (2) excessive addition altering freshness perception and misleading consumers; (3) uncontrolled usage increasing foodstuff weight; (4) application in products where they are not permitted; and (5) no indication on the label. Bearing all these issues in mind, the main purpose of this study was the quantification and screening of the (poly)phosphates profile in meat, marine and dairy products (160 samples), of which 43 were without declared (poly)phosphate treatment. Analysis was completed by high-performance ion-exchange chromatography either with conductometric detection or coupled to Q-Exactive Orbitrap high-resolution mass spectrometry. Although the (poly)phosphates profiles varied greatly according to species and processing type, the following criteria for detection of illicit treatment were established: high orthophosphate level, quantified short-chain (poly)phosphate anions and the presence of long-chain forms. In conclusion, the instrumental platforms used in this study can be recommended to inspection bodies as reliable methods for the detection of food adulteration with (poly)phosphates.

Assessment of Diadenylate Cyclase and c-di-AMP-phosphodiesterase Activities Using Thin-layer and Ion Exchange Chromatography.

All living cells use cyclic nucleotides as second messengers for signal sensing and transduction. Cyclic di-3',5'-adenosine monophosphate (c-di-AMP) is primarily involved in the control of bacterial and euryarcheal osmoadaptation and is produced by diadenylate cyclases from two molecules of ATP. Specific phosphodiesterases hydrolyze c-di-AMP to the linear phosphoadenylate adenosine 5'-pApA or to AMP. Different methods including high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC) and ion exchange chromatography (IEX) can be used to determine activities of c-di-AMP-synthesizing and degrading enzymes. Here, we describe in detail the TLC and IEX methods adapted for characterization of the diadenylate cyclase DisA and the phosphodiesterase AtaC from Streptomyces venezuelae. TLC allows quick and easy separation of radioactive-labeled substrates and products, while IEX avoids utilization of potentially hazardous radioactive substrates and can be used as a good substitute if an HPLC system is not available. Unlike in TLC assays, samples cannot be analyzed in parallel by using the IEX assay, thus it is more time consuming.

Detection of polyphosphates in seafood and its relevance toward food safety.

Polyphosphates are permitted as food additives (Regulation EC No 1129/2011) but their undeclared utilisation is considered fraudulent. They improve water holding capacity of the seafood, preventing biochemical/physical changes during commercialization. The key objective of this study was the detection of polyphosphate in various seafood categories, by means of high-performance ion-exchange chromatography with suppressed conductometry (HPIEC-SCD) coupled to Q-Exactive Orbitrap high resolution mass spectrometry (HRMS-Orbitrap). Ten frozen cuttlefish samples did not reveal any treatment, while in ten frigate tunas, high concentration of orthophospate was found. Unambiguous hexametaphosphate presence was demonstrated in four prawn samples, while triphosphate was quantified (11.2±4 ug/g) in another four prawn samples that contained orthophosphate (10225±1102 ug/g), as well. Other samples sporadically encompassed polyphosphates profiles that varied according species and processing type. This analytical approach provided sustenance in better understanding regarding utilization of polyphosphates through HRMS fingerprinting of anionic species that would be specific in food safety control.

Quality consistency evaluation of Kudiezi Injection based on multivariate statistical analysis of the multidimensional chromatographic fingerprint

Traditional Chinese Medicine Injection (TCMI) was restricted due to the batch-to-batch variability caused by the variable compositions of botanical raw materials and complexities of the current manufacturing process. To evaluate and control the quality of Kudiezi Injection (KDZI), a comprehensive and practical method based on multidimensional chromatographic fingerprint associated with multivariate statistical analysis was proposed. The multidimensional chromatographic fingerprint was established by integrating three kinds of chromatographic fingerprints, including High Performance Liquid Chromatography-Ultraviolet spectrum (HPLC-UV), Gas Chromatography-Mass Spectrometer (GC–MS) and High performance ion-exchange chromatography (HPIEC), which were used to detect flavones, nucleosides, organic acids, amino acids and saccharides in KDZI. In addition, four main multivariate statistical analyses were compared to assess the batch-to-batch consistency of samples. Results showed that the cosine method, which has been widely used in the quality evaluation of TCM, failed to distinguish the differences among batches based on neither chromatographic peaks’ area nor contents information. t-test and Bayes’ theorem could reveal the content difference among batches, while hierarchical clustering analysis could differentiate KDZI batches, and Luteolin-7-O-β-D-glucuronopyranoside, Tau, Ser, guanine and allose were the main indicators. In conclusion, multidimensional chromatographic fingerprints could reflect the quality information of KDZI comprehensively and hierarchical clustering analysis was suitable to identify the differences among batches. This could provide an integrated method for consistency evaluation of TCMI, process improvement of TCMI and solving similar problems in TCMI.

Detection of nitrate and nitrite in different seafood

High-performance ion-exchange chromatography with suppressed conductivity (HPIEC-SCD) was validated for the determination of nitrite (NO2−) and nitrate (NO3−) in the edible part of diverse seafood species. Samples analyzed by HPIEC-SCD that were devoid of nitrite and nitrate were subjected to HRMS using a Q-exactive Orbitrap platform. As NO2− is not detectable in Q-Exactive Orbitrap, it was necessary to perform the oxidation of NO2− to NO3−. Accordingly, suitability of NO2− oxidation by H2O2 as a part of sample preparation for HPIEC-HRMS was elaborated. The difference in the concentration of NO3− before and after H2O2 treatment was used for the evaluation of eventual NO2− presence. The edible part of 53 fish, shrimp and bivalve species presented significant differences in NO3− levels especially between farmed (median = 44 μg/g) and wild species (median = 16 μg/g). The highest concentration of NO3− was found in smoked salmon samples (median = 60 μg/g) while NO2− was not revealed in any of the samples studied.

Synthesis, molecular docking and biological evaluation of novel phthaloyl derivatives of 3-amino-3-aryl propionic acids as inhibitors of Trypanosoma cruzi trans-sialidase

In the last two decades, trans-sialidase of Trypanosoma cruzi (TcTS) has been an important pharmacological target for developing new anti-Chagas agents. In a continuous effort to discover new potential TcTS inhibitors, 3-amino-3-arylpropionic acid derivatives (series A) and novel phthaloyl derivatives (series B, C and D) were synthesized and molecular docking, TcTS enzyme inhibition and determination of trypanocidal activity were carried out.From four series obtained, compound D-11 had the highest binding affinity value (−11.1 kcal/mol) compared to reference DANA (−7.8 kcal/mol), a natural ligand for TS enzyme. Furthermore, the 3D and 2D interactions analysis of compound D-11 showed a hydrogen bond, π-π stacking, π-anion, hydrophobic and Van der Waals forces with all important amino acid residues (Arg35, Arg245, Arg314, Tyr119, Trp312, Tyr342, Glu230 and Asp59) on the active site of TcTS. Additionally, D-11 showed the highest TcTS enzyme inhibition (86.9% ± 5) by high-performance ion exchange chromatography (HPAEC). Finally, D-11 showed better trypanocidal activity than the reference drugs nifurtimox and benznidazole with an equal % lysis (63 ± 4 and 65 ± 2 at 10 μg/mL) and LC50 value (52.70 ± 2.70 μM and 46.19 ± 2.36 μM) on NINOA and INC-5 strains, respectively. Therefore, D-11 is a small-molecule with potent TcTS inhibition and a strong trypanocidal effect that could help in the development of new anti-Chagas agents.

Analysis of the heterogeneity of Ralstonia solanacearum avirulent espD-mutant by high performance ion-exchange chromatography

The heterogeneity of Ralstonia solanacearum avirulent espD-mutant, virulent wildtype strain FJAT-91 and spontaneous avirulent strain FJAT-1458 were compared and analyzed by using high performance ion-exchange chromatography (HPIEC). Their colony and cell morphologies were observed, and the contents of their extracellular polysaccharides (EPS) were determined. The results showed that the colony and cell morphologies of FJAT-91 ⊿epsD were different from the original strain FJAT-91, but were similar to the spontaneous avirulent strain FJAT-1458. The EPS content of FJAT-91 ⊿epsD was (12.64±1.46) μg/mL, which was much lower than FJAT-91 with (30.49±2.97) μg/mL. The strain FJAT-91 were separated into single peak of P3 at the retention time of 6.04 min, and FJAT-91 ⊿epsD had two peaks (P1 and P2) at the retention times of 0.59 min and 4.62 min, respectively. FJAT-1458 formed single peak of P1 at the retention time of 0.59 min. Then, the bacteria eluents from different chromatographic peaks were collected and their pathogenicities were detected with bioassay test using potted tomatoes in the greenhouse. The results showed that the tomato plants began to wilt 4 d after inoculation of strain FJAT-91-P3 eluted from P3, and the disease incidence reached 100% at 10 d post inoculation. The strain FJAT-91 ⊿epsD-P2 eluted from P2 caused tomato plants wilting 9 d after inoculation, and the disease incidence reached 100% at 20 d. During 20 d of observation, none of tomato plants caused wilting while inoculation with FJAT-1458-P1 and FJAT-91 ⊿epsD-P1 eluted from P1 of FJAT-1458 and FJAT-91 ⊿epsD, respectively. In this paper, the morphologies, EPS contents and chromatographic behaviors of FJAT-91, FJAT-91 ⊿epsD and FJAT-1458 were compared, which would provide theoretical basis for using FJAT-91 ⊿epsD to control bacterial wilt disease.

Factors associated with glycemic status and ability to adapt to changing demands in people with and without type 2 diabetes mellitus: A cross-sectional study.

Objectives:Type 2 diabetes mellitus studies focus on metabolic indicators and different self-reported lifestyle or care behaviors. Self-reported instruments involve conscious process therefore responses might not reflect reality. Meanwhile implicit responses involve automatic, unconscious processes underlying social judgments and behavior. No studies have explored the combined influence of both metabolic indicators and implicit responses on lifestyle practices in type 2 diabetes mellitus patients. The purpose was to investigate the explained variance of socio-demographic, metabolic, anthropometric, clinical, psychosocial, cognitive, and lifestyle variables on glycemic status and on the ability to adapt to changing demands in people with and without type 2 diabetes mellitus in Monterrey, Mexico.Methods:Adults with (n = 30, mean age 46.90 years old, 33.33% male) and without (n = 32, mean age: 41.69 years old, 21.87% male) type 2 diabetes mellitus were studied. Glycemic status was assessed using Bio-Rad D-10 Hemoglobin A1c Program, which uses ion-exchange high-performance chromatography. Stroop 2 test was used to assess the ability to changing demands.Results:In participants with type 2 diabetes mellitus, less years of education, negative self-actualization, and higher levels of cholesterol and triglycerides explained more than 50% of the variance in glycemic status. In participants without type 2 diabetes mellitus, the variance (38.7%) was explained by total cholesterol, metabolic syndrome, high-density lipoprotein, and self-actualization scores; the latter in opposite direction. The ability to adapt to changing demands was explained by total cholesterol, malondialdehyde, insulin resistance, and triglycerides. In participants without type 2 diabetes mellitus, the contributing variables were metabolic syndrome and nutrition scores.Conclusion:Results showed significant effect on at least one of the following variables (socio-demographic, metabolic, or lifestyle subscale) on glycemic status in people with and without type 2 diabetes mellitus. The ability to adapt to changing demands was explained by metabolic variables but only in participants without type 2 diabetes mellitus. Preference for unhealthy behaviors (implicit or automatic responses) outweighs healthy lifestyle practices in people with and without type 2 diabetes mellitus.

Teleomorph–anamorph connection of Macalpinomyces spermophorus with Pseudozyma tsukubaensis and corresponding erythritol production

A basidiomycetous yeast, Pseudozyma tsukubaensis, has been isolated from a variety of plant materials. Previous molecular phylogenetic analyses have suggested this yeast is an asexual stage of the smut fungus Macalpinomyces spermophorus (synonym Ustilago spermophora, Ustilaginales). To reveal the teleomorph–anamorph connection, yeast-like isolates from germinated teliospores of morphologically identified M. spermophorus on Eragrostis ferruginea from Japan were analyzed. The internal transcribed spacer region of rDNA of the yeast isolates was mostly identical with that of known isolates of P. tsukubaensis. Physiological analysis showed that the characteristics of the yeast isolates correlated well with P. tsukubaensis. These data revealed that P. tsukubaensis is the anamorph of M. spermophorus and should be treated as a synonym of M. spermophorus. In addition, the erythritol-producing ability of the yeast isolates derived from teliospores of M. spermophorus were confirmed by high-performance ion-exchange chromatography and 13C NMR analyses.

An in vitro investigation of immunomodulatory properties of Lactobacillus plantarum and L. delbrueckii cells and their extracellular polysaccharides.

Many probiotic lactobacilli and their extracellular polysaccharides (EPS) have beneficial immunological properties. However, it is unclear how they elicit the host immune response. We thus investigated the immunological properties of UV-killed Lactobacillus delbrueckii TU-1 and L. plantarum KM-9 cells as well as their extracellular polysaccharides (EPSs). High-performance liquid chromatography and ion exchange chromatography analyses showed that their EPSs differ in sugar composition and sugar fractionation. The immunological properties were evaluated in a semi-intestinal model using a Transwell co-culture system that employed human intestinal epithelial (Caco-2) cells on the apical side and murine macrophage (RAW264.7) cells on the basolateral side. The UV-killed cells and EPSs were added to the apical side to allow direct contact with Caco-2 cells and incubated for 6 hr. After incubation, the amounts of tumor necrosis factor-α and several cytokines released by RAW264.7 or Caco-2 cells were quantified by cytotoxic activity on L929 cells (murine fibrosarcoma cell line) and quantitative reverse-transcriptase PCR. We found that the UV-killed cells and their EPSs had immunological effects on RAW264.7 cells via Caco-2 cells. The RAW264.7 cells showed different cytokine production profiles when treated with UV-killed cells and EPSs. The UV-killed cells and EPSs promoted a Th1-type cellular response. Furthermore, we found that the UV-killed cells sent positive signals through Toll-like receptor (TLR) 2. Meanwhile, neither EPS sent a positive signal through TLR4 and TLR2. This evidence suggests that both UV-killed cells of the lactobacillus strains and their EPSs trigger a Th1-type immune response in a human host, with the former triggering the response via the TLRs expressed on its epithelium and the latter employing a mechanism yet to be determined, possibly involving a novel receptor that is designed to recognize specific patterns of repeating sugar in the EPSs.

Determination of succinic acid in desvenlafaxine succinate by high performance ion-exclusion chromatography and high performance ion-exchange chromatography

New methods were developed for the determination of succinic acid in desvenlafaxine succinate (DVS) by high performance ion-exclusion chromatography (HPIEC) and high performance ion-exchange chromatography (HPIC). HPIEC and HPIC methods were used separately to determinate the succinic acid in DVS. With HPIEC, the sample was diluted with 2. 50 x 10(-3) mol/L sulfuric acid solution and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIEC directly without any further pretreatment. The analytical column was Phenomenex Rezex ROA-organic Acid H+(8%) (300 mmx7. 8 mm). The mobile phase was 2. 50x10(-3) mol/L sulfuric acid solution at the flow rate of 0. 5 mL/min. The column temperature was set at 40 °C, and the detection wavelength was 210 nm. The injection volume was 10 KL. The assay was quantified by external standard method. With HPIC, the sample was diluted with ultrapure water and filtrated by 0. 22 µm polyether sulfone filter membrane, and then analyzed by HPIC directly without any further pretreatment. The analytical column was Dionex IonPac AS11-HC (250 mm x 4 mm) with a guard column IonPacAG11-HC (50 mm x 4 mm). Isocratic KOH elute generator was used at the flow rate of 1. 0 mL/min. The detection was performed by a Dionex suppressed (DIONEX AERS 500 4-mm) conductivity detector. The injection volume was 10 µL. The content computation was performed with peak area external reference method. The results of HPIEC method for succinic acid were 28. 8%, 28. 9% and 28. 9%, while the results of HPIEC method were 28. 2%, 28. 6% and 28. 6%. The results of HPIEC and HPIC methods were not significantly different. The two methods can both be used to determine the contents of succinic acid in DVS. The surveillance analytical method should be chosen according to the situation.

Optimization of rapid separation conditions of Ralstonia solanacearum using high performance ion-exchange chromatography

Optimization of rapid separation conditions of <i>Ralstonia solanacearum</i> using high performance ion-exchange chromatography

Simultaneous detection of perchlorate and bromate using rapid high-performance ion exchange chromatography-tandem mass spectrometry and perchlorate removal in drinking water.

Perchlorate and bromate occurrence in drinking water causes health concerns due to their effects on thyroid function and carcinogenicity, respectively. The purpose of this study was threefold: (1) to advance a sensitive method for simultaneous rapid detection of perchlorate and bromate in drinking water system, (2) to systematically study the occurrence of these two contaminants in Missouri drinking water treatment systems, and (3) to examine effective sorbents for minimizing perchlorate in drinking water. A rapid high-performance ion exchange chromatography-tandem mass spectrometry (HPIC-MS/MS) method was advanced for simultaneous detection of perchlorate and bromate in drinking water. The HPIC-MS/MS method was rapid, required no preconcentration of the water samples, and had detection limits for perchlorate and bromate of 0.04 and 0.01μg/L, respectively. The method was applied to determine perchlorate and bromate concentrations in total of 23 selected Missouri drinking water treatment systems during differing seasons. The water systems selected include different source waters: groundwater, lake water, river water, and groundwater influenced by surface water. The concentrations of perchlorate and bromate were lower than or near to method detection limits in most of the drinking water samples monitored. The removal of perchlorate by various adsorbents was studied. A cationic organoclay (TC-99) exhibited effective removal of perchlorate from drinking water matrices.

Speciation Determination of Selenium in Seafood by High-Performance Ion-Exchange Chromatography-Hydride Generation-Atomic Fluorescence Spectrometry

A high-performance ion-exchange chromatography coupled with hydride generation-atomic fluorescence spectrometry (HPIEC-HG-AFS) method was developed for simultaneous speciation of selenium in seafood. Three selenium species including of selenocystine (Se-Cys), selenome-thionine (Se-Met), and selenite Se(IV) were separated on an anion-exchange column (PRP-X100) with eluent of 30 mM NH4H2PO4 and methanol (39:1, v/v) in 10 min at the flow rate of 1.0 mL min−1. Variables affecting the HG-AFS detection of selenium species were optimized. The optimum conditions found were the following: reducing agent, 2.0 % of KBH4, and 5.0 % of HCl; lamp current, 90 mA; photomultiplier tube voltage, 280 V; flow rate of carrier gas, 300 mL min−1; and shielding gas, 800 mL min−1. Under the optimized conditions, the good linearity of calibration curves (R 2 > 0.999) between signal of fluorescence and concentration of selenium species was obtained in the range of detection limits (DLs), 80 μg L−1, and the DLs of Se-Cys, Se-Met, Se(IV) were 1.66, 0.990, 1.10 μg L−1, respectively. The repeatability of the method, expressed as relative standard deviation, was less than 5.0 % (n = 10), and the average recoveries for spiked test were from 87.3 to 103 % for three analytes in real seafood samples. The developed HPIEC-HG-AFS method was successfully applied for the speciation of selenium in seafood samples.