[Polyamidoamine dendrimer-functionalized silica nanocomposite with polydopamine coating for dispersive micro solid-phase extraction of benzoylurea insecticides in water samples].

Pesticides are used in the agricultural production process to ensure the yield and quality of agricultural products. However, in recent years, environmental pollution issues caused by pesticide residues have sparked widespread concern in society. It is important to develop convenient and efficient approaches to detect and monitor pesticide residues. In this study, targeting benzoylurea insecticides (BUs), polyamidoamine dendrimer-functionalized silica nanocomposite with polydopamine coating (SiO2-PAMAM-PDA) was designed and successfully synthesized. First, monodisperse silica nanoparticles were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in mixed solution of ethanol, water and ammonia. The silane coupling agent (3-aminopropyl)triethoxysilane was then employed to introduce amino groups into the silica. Silica with the zeroth generation of polyamidoamine (PAMAM) modification (SiO2-PAMAM-G0) was obtained through Michael addition reaction of methyl acrylate. Ethylenediamine was added to polymerize with methyl acrylate using an amidation reaction to form the first-generation PAMAM (SiO2-PAMAM-G1). Finally, by polymerizing dopamine under alkaline conditions (pH=8.5), the SiO2-PAMAM-G1 was coated with PDA. Thus, the final product named SiO2-PAMAM-PDA was obtained. The composite was characterized using a transmission electron microscope (TEM) and an increase in surface roughness indicated the successful grafting of PDA coating. Dopamine structure contains abundant benzene rings and amino and hydroxyl groups. It could bind with BUs through multiple secondary interactions, such as hydrogen bond and π-π stacking interaction. Therefore, the introduction of PDA could effectively enhance the affinity of the material toward benzoylurea insecticides. The prepared nanocomposites were used as sorbents in a dispersive micro solid-phase extraction approach (D-µ-SPE). The established approach was employed to extract and enrich the BUs in water samples before high-performance liquid chromatography (HPLC) analysis. Diflubenzuron, triflumuron, hexaflumuron, and teflubenzuron were chosen as target analytes. The following was a typical D-µ-SPE procedure. The prepared adsorbents measuring 40 mg were first dispersed in an 8-mL sample solution containing 150 g/L NaCl. The dispersion was assisted by 120-s vortexing to ensure full contact between the SiO2-PAMAM-PDA and the targets. Next, the adsorbents were separated from the liquid phase by 4-min centrifugation (5000 r/min). Thereafter, the adsorbed benzoylureas were eluted using 1 mL acetonitrile as desorption solvent by 120-s vortexing. Separated by centrifugation, the eluate was dried under a mild nitrogen stream. The solid remains were redissolved in 0.1 mL of acetonitrile, filtered by filter membrane (0.22 µm), and then analyzed by HPLC. The experimental conditions in the D-µ-SPE process could have a great impact on the extraction efficiency. Experimental conditions were optimized using a single factor optimization approach to further enhance the extraction recoveries. The optimized conditions included adsorbent amount, extraction time, desorption solvent type, desorption solvent volume, desorption time, and NaCl addition amount. Under the optimal conditions, a linearity range of 10-500 µg/L and limits of detection (LODs, S/N=3) of 1.1-2.1 µg/L were obtained. The extraction recoveries and relative standard deviations (RSDs) of the four BUs were 82.8%-94.1% and 2.1%-8.0%, respectively. The established approach was compared with reported approaches targeting benzoylurea insecticides. It was discovered that this approach consumed less sample, material, organic solvent, and pretreatment time. It provided a more rapid and green choice for the determination of benzoylurea pesticides. To determine the applicability, the proposed approach was applied to analyze the four benzoylurea insecticides in three river water samples. The real water samples were pretreated using the developed approach ahead of instrumental analysis, and no benzoylurea pesticides residue was detected. Next, standard addition experiments were performed under three spiking levels, including 15, 50, and 200 µg/L. The established approach had good accuracy and feasibility with satisfactory recoveries (69.5%-99.4%) and RSDs (0.2%-9.5%).

Development of paper-based microfluidic device for the determination of nitrite in meat.

This study employed the use of a microfluidic paper-based analytical device (µPAD) to determine the concentration of nitrite in pork and enhanced the limit of detection by analyzing the coffee-ring effect. The µPAD was fabricated by designing and embedding wax channels onto the cellulose-based filter paper through printing and subjecting the paper to heat treatment to allow wax penetration. Nitrite concentration was determined by monitoring the colorimetric reaction that occurred between nitrite and the added Griess reagent. The limit of detection of this device for nitrite in pork was determined to be 19.2 mg kg-1 by analyzing the inner-chamber reaction, while it could be as low as 1.1 mg kg-1 if the coffee-ring region was analyzed. The overall analysis could be completed within 15 min. This µPAD-based method has potential applications to routinely screen the nitrite concentration of meat products and ensure food safety and consumer health.

[Determination of N,N'-ethylenediamine disuccinic acid in bioconversion reaction solution using high performance liquid chromatography].

A method was developed for the determination of N,N'-ethylenediamine disuccinic acid (EDDS) in bioconversion samples by high performance liquid chromatography (HPLC). An InertSustain AQ-C18 column (250 mm×4.6 mm, 5 µm) was used in the analysis. The mobile phase was 25% (v/v) methanol with 1.0 g/L Cu(CO2CH3)2·H2O, 2.0 g/L tetrabutylammonium hydroxide, and the pH was adjusted to 2.80 with phosphoric acid. The flow rate of the mobile phase was 1.0 mL/min, and the column temperature was set at 30℃. The detection wavelength was 254 nm. EDDS, fumaric acid, citric acid, malic acid and ethylenediaminetetraacetic acid (EDTA) were separated from one another within 8 min. EDDS showed good linearity in the range of 0.06-0.6 g/L. About 0.25 g/L EDDS was detected in the biosynthesis reaction solution catalyzed by recombinant EDDS-lyase, while 36.56 g/L malic acid was formed as the by-product from fumaric acid. The catalytic activity of the enzyme was confirmed in the hydrolysis of 10 g/L EDDS, which produced 3.05 g/L malic acid in 3 h. This analytical method is simple, rapid, sensitive, reliable, and suitable for the analysis in the research of EDDS bioconversion process.

Optimized Griess Reaction for UV-Vis and Naked-eye Determination of Anti-malarial Primaquine.

Primaquine (PMQ), an important anti-malarial drug, has been recommended by the World Health Organization (WHO) for the treatment of life-threatening infections caused by P. vivax and ovale. However, PMQ has unwanted adverse effects that lead to acute hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. There is a need to develop simple and reliable methods for PMQ determination with the purpose of dosage monitoring. In early 2019, we have reported an UV-Vis and naked-eye based approach for PMQ colorimetric quantification. The detection was based on a Griess-like reaction between PMQ and anilines, which can generate colored azo products. The detection limit for direct measurement of PMQ in synthetic urine is in the nanomolar range. Moreover, this method has shown great potential for PMQ quantification from human serum samples at clinically relevant concentrations. In this protocol, we will describe the technical details regarding the syntheses and characterization of colored azo products, the reagent preparation, and the procedures for PMQ determination.

Zn homeostasis in genetic models of Parkinson's disease in Caenorhabditis elegans.

While the underlying mechanisms of Parkinson's disease (PD) are still insufficiently studied, a complex interaction between genetic and environmental factors is emphasized. Nevertheless, the role of the essential trace element zinc (Zn) in this regard remains controversial. In this study we altered Zn balance within PD models of the versatile model organism Caenorhabditis elegans (C. elegans) in order to examine whether a genetic predisposition in selected genes with relevance for PD affects Zn homeostasis. Protein-bound and labile Zn species act in various areas, such as enzymatic catalysis, protein stabilization pathways and cell signaling. Therefore, total Zn and labile Zn were quantitatively determined in living nematodes as individual biomarkers of Zn uptake and bioavailability with inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) or a multi-well method using the fluorescent probe ZinPyr-1. Young and middle-aged deletion mutants of catp-6 and pdr-1, which are orthologues of mammalian ATP13A2 (PARK9) and parkin (PARK2), showed altered Zn homeostasis following Zn exposure compared to wildtype worms. Furthermore, age-specific differences in Zn uptake were observed in wildtype worms for total as well as labile Zn species. These data emphasize the importance of differentiation between Zn species as meaningful biomarkers of Zn uptake as well as the need for further studies investigating the role of dysregulated Zn homeostasis in the etiology of PD.

Carbazole and fluorene polyaniline derivatives: Synthesis, properties and application as multiple stimuli-responsive fluorescent chemosensor.

Development of conjugated polymers with fluorescence sensing characteristics has received close attention from researchers in fields of environmental protection, biosensing and toxins detection on food. In this paper, novel polyaniline derivatives of poly(9-methyl-9H-carbazol-3-amine) and poly(9,9-dihexyl-9H-fluoren-2-amine) are prepared by facile chemical polymerization. Then they are characterized with NMR (Nuclear Magnetic Resonance), GPC (Gel Permeation Chromatography), XRD (X-Ray Diffraction), FT-IR (Fourier Transform Infrared spectroscopy), FL (Fluorescence spectrometry) and UV-vis (Ultraviolet-visible spectroscopy) characterizations and further applied to the fluorescence detection of different acids and amines. Moreover, the obtained poly(9-methyl-9H-carbazol-3-amine) displays excellent fluorescence properties in the detection for both acids and amines. Besides, this poly(9-methyl-9H-carbazol-3-amine) can not only be used for fluorescence detection in solution, but also can be prepared into solid state and applied in the gas phase fluorescence detection. This work has greatly expanded the scope of application to these polyaniline derivatives materials, opening a new path for the researches on multi-functional chemosensor.

Zinc-Chelating Small Molecules Preferentially Accumulate and Function within Pancreatic ß Cells.

Diabetes is a hyperglycemic condition characterized by pancreatic ß-cell dysfunction and depletion. Whereas methods for monitoring ß-cell function in vivo exist, methods to deliver therapeutics to ß cells are lacking. We leveraged the rare ability of ß cells to concentrate zinc to preferentially trap zinc-binding molecules within ß cells, resulting in ß-cell-targeted compound delivery. We determined that zinc-rich ß cells and islets preferentially accumulated TSQ (6-methoxy-8-p-toluenesulfonamido-quinoline) in a zinc-dependent manner compared with exocrine pancreas. Next, we asked whether appending a zinc-chelating moiety onto a ß-cell replication-inducing compound was sufficient to confer preferential ß-cell accumulation and activity. Indeed, the hybrid compound preferentially accumulated within rodent and human islets in a zinc-dependent manner and increased the selectivity of replication-promoting activity toward ß cells. These data resolve the fundamental question of whether intracellular accumulation of zinc-chelating compounds is influenced by zinc content. Furthermore, application of this principle yielded a proof-of-concept method for ß-cell-targeted drug delivery and bioactivity.

[Determination of ethylenediamine in the air of workplace by Ion chromatography].

Objective: To establish a method to detect the concentrations of ethylenediamine in the air of workplace by Ion chromatography. Methods: Ethylenediamine in the air of workplace adsorpted by Silicone tube, then ultrasonic desorped by Sulfuric acid solution (0.1 mol/L) , the desorption solution qualitative and quantitative determination by Ion chromatography. Results: For ethylenediamine, the calibration curves were liner in the range of 0.1-100.0 µg/ml, the method detection limit is 0.1 µg/ml, the minimum detectable concentration is 0.13 mg/m(3) (in terms of sampling 7.5 L) . The desorption efficiency is more than 90% on spiked levels of 2.0, 4.0 and 8.0 µg/ml, the average desorption efficiency of the method was 96.1%, the precision was 1.8%-2.1%. The recovery rate of the added standard is 98.5%-104.2%. Conclusion: The method simplifies the preprocessing steps and improves the sensitivity. All the indexes are in conformity with the requirements of the method formulation guide. It is suitable for the determination of ethylenediamine in the air of the workplace.

[Comparative Characteristics of Optical Absorption in Waters from Yiluo River and Huntai River in Spring].

The absorption characteristics, composition, spatial variability, and relative contribution of optically active constituents over the range of photosynthetically active radiation (PAR, 400-700 nm) were analyzed from samples collected in the Yiluo and Huntai Rivers in May 2017 and 2013, respectively. Results demonstrated that the absorption curves of total suspended particulates[ap(λ)] were similar to those of non-algae particles[ad(λ)]. Significant correlations between ap(λ) and ad(λ) were obtained, especially at 440 nm, with r=0.968 in the Yiluo River and r=0.899 in the Huntai River. Meanwhile, positive correlations between ap(λ) and the absorption of phytoplankton[aph(λ)] were observed at 675 nm. ap(λ) in the two basins was dominated by ad(λ). Moreover, the composition of auxiliary pigments and chloropyhll a concentration[Chla] showed more significant spatial variations based on aph(440)/aph(675) in the Yiluo River than in the Huntai River. In addition, CDOM absorption slopes (SCDOM) indicated that CDOM composition in the Yiluo River was dominated by exogenous substances; in comparison, the Huntai River had more endogenous substances. SCDOM in the Yiluo River was lower than in the Huntai River, indicating that the CDOM composition of the Yiluo River was inclined towards high molecular weights. Furthermore, Mr[aCDOM(250)/aCDOM(365)] showed greater ranges and lower mean values in the Yiluo River than in the Huntai River, confirming that CDOM molecular weight varied greatly in the former. CDOM molecular weight in the Huntai River was also lower than in the Yiluo River, in accordance with SCDOM results.

Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall.

Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R 2) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg-1 soil, pH 4.5), and rhamnolipid (pH 6.5).

Electromembrane extraction of diamine plastic restricted substances in soft drinks followed by capillary electrophoresis with contactless conductivity detection.

Ethane-1,2-diamine (EA) and hexane-1,6-diamine (HA) are two important plastic restricted substances commonly existing in food contact materials. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) method has been developed for direct determination of above analytes, and the detection sensitivity has been significantly improved based on electromembrane extraction (EME). Under the optimum conditions, EA and HA could be well separated from their aliphatic diamine homologs as well as the common inorganic cations within 25min. The limits of detection could reach sub-ng/mL level, and good linearity (r>0.998) between peak area and analyte concentration could be obtained at three orders of magnitude. This EME/CE-C4D method provided a novel application for determining these plastic restricted substances in different bottled soft drinks, providing an alternative for the sensitive analyses of diamine substances.

BACKGROUND TRACK DENSITY REDUCTION OF 50-HZ-HV ECE-PROCESSED THICK POLYCARBONATE DETECTORS TO IMPROVE LOWER DETECTION LIMIT.

A recent novel development of 50-Hz-HV ECE of 1-mm-thick and 250-µm-thick polycarbonate track detectors (PCTDs) has proved some promising results for some health physics, dosimetry and ion-beam-related applications. The method while proved having some good characteristics for some applications provided a relatively higher background track density (BGTD) in particular when very high voltages are applied to the PCTDs. In order to decrease the minimum detection limit (MDL) of the PCTDs and to further promote its applications for low dose, the BGTD was reduced by applying a layer removal methodology applying ethylendiamine (EDA). The effects of EDA concentrations (50, 60, 65, 70, 75, 80, 85 and 90 %) in water at room temperature (26°C) and soaking durations up to 100 min at different EDA concentration on BGTD reduction were studied. The thickness of the layer removed from the surface of a PCTD highly depends on the soaking time and EDA concentration; it increases as the EDA concentration increases up to for example 700 µm after 2 h of soaking in the EDA solution. After ∼10 min of soaking duration at any of the above-stated concentrations, the BGTD reaches its minimum value, a value which differs from concentration to concentration. An EDA concentration of 85 % in water provided the lowest BGTD of 64.06 ± 3.12 tracks cm- 2; ∼6 times lower than that of its original value. It is shown that the layer removal process does not change the registration characteristics of the PCTD and its appearance significantly. The MDL of the PCTDs depends strongly on the BGTD. The MDL values for a desired confidence level were also studied by three calculation methods. The results of the BGTD and the MDL studies under different conditions applied are presented and discussed.

Sensitivity enhancement of pH indicator and its application in the evaluation of fish freshness.

The sensitivity of pH indicators is always confined in acidic solvents used during the immobilization because of the large deviation from their color transition points. By regulating the pH of indicators using organic acid or base, the color transition points of indicators could be readily achieved and the sensitivity could be greatly enhanced. In this study, bromophenol blue was selected as an example to interpret this improvement. And Hue, Saturation and Value (HSV) color model was applied to obtain digital color information of pH indicators. In addition, other two kinds of pH indicators were chosen and regulated to their color transition points as well. The resultant indicators together with the original ones were composed to a colorimetric sensor array and utilized to determine fish freshness. Compared with the original indicators, much higher sensitivity in the detection of fish freshness was obtained by the pH regulated indicators.

Facile characterization of the immobilization of streptavidin on magnetic submicron particles with a fluorescent probe of streptavidin.

To characterize streptavidin immobilization on magnetic submicron particles (MSPs), residual streptavidin after magnetic removal of immobilized streptavidin was quantified with N-biotinyl-N'-(1-naphthyl)-ethylenediamine (BNEDA) based on Förster resonance energy transfer. Residual BNEDA after magnetic removal of bound BNEDA was measured by its own fluorescence. Streptavidin was immobilized at about 12 mg per gram of MSPs and easily retained over 50% of its original activity. These assays facilitated optimized streptavidin immobilization on MSPs.

Hot topic: investigating the risk of violative meat residues in bob veal calves fed colostrum from cows treated at dry-off with cephapirin benzathine.

The objective was to conduct a study to investigate if violative meat residues are detected in very young bob veal calves that are fed first-milking colostrum harvested from cows that were dry treated, on-label, with cephapirin benzathine. First-milking colostrum was collected from cows that were given intramammary treatment at dry off, on-label, with cephapirin benzathine (ToMORROW, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO). Newborn bull calves meeting study inclusion criteria were removed from their dams shortly after birth and before suckling, and assigned to 1 of 2 trials. For the first trial, 6 treated calves were fed 3.8L of fresh maternal colostrum and 1 control calf was fed 1.5 doses of a plasma-derived colostrum replacer (Secure Calf Colostrum Replacer, VitaPlus Inc., Madison, WI) within 1h after birth. For the second trial, 5 treated calves were fed 3.8L of fresh maternal colostrum and 1 control calf was fed 1.5 doses of Secure Calf Colostrum Replacer within 1h after birth. All calves were humanely euthanized at 24h (trial 1) or 48h (trial 2) of age, and tissues were harvested for antimicrobial residue testing. Samples of maternal colostrum and colostrum replacer were also submitted for antimicrobial residue testing. Kidneys collected from all study calves tested negative for cephapirin benzathine residues when using both the KIS assay (Charm Sciences, Lawrence, MA) and liquid chromatography-tandem mass spectrometry analysis. The potential transfer of cephapirin from cows treated on-label at dry off to calves via colostrum may not be a significant source of cephapirin residues in veal tissues.

Eigenvalue equation and core-mode cutoff of weakly guiding tapered fiber as three layer optical waveguide and used as biochemical sensor.

The core-mode cutoff plays a major role in evanescent field absorption based sensors. A method has been proposed to calculate the core-mode cutoff by solving the eigenvalue equations of a weakly guiding three layer optical waveguide graphically. The variation of normalized waveguide parameter (V) is also calculated with different wavelengths at core-mode cutoff. At the first step, theoretical analysis of tapered fiber parameters has been performed for core-mode cutoff. The taper angle of an adiabatic tapered fiber is also analyzed using the length-scale criterion. Secondly, single-mode tapered fiber has been developed to make a precision sensor element suitable for chemical detection. Finally, the sensor element has been used to detect absorption peak of ethylenediamine. Results are presented in which an absorption peak at 1540 nm is observed.

Development and validation of a multiclass method for the determination of veterinary drug residues in chicken by ultra high performance liquid chromatography-tandem mass spectrometry.

A multiclass method has been optimized and validated for the simultaneous determination of 20 veterinary drug residues belonging to several classes, as quinolones, sulfonamides, macrolides, anthelmintics, avermectins and diamino derivatives, and benzathine, used as a marker of the presence of penicillin, in muscle chicken. It has been based on QuEChERS methodology (quick, easy, cheap, effective, rugged and safe) and ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-MS/MS). Several chromatographic conditions were optimized, obtaining a running time <8.5 min. The developed method was validated on the basis of international guidelines. Mean recoveries ranged from 70 to 120%, except for benzathine (65.6% at 20 µg kg(-1)) and sulfadimidine (69.0% at 100 µg kg(-1)). Repeatability was lower than 20.0% except for sulfachlorpyridazine (22.1% at 20 µg kg(-1)) and tylosin (20.5% and 20.6% at 30 and 50 µg kg(-1), respectively), whereas reproducibility was lower than 25% except for flumequine (27.4% at 20 µg kg(-1)) and benzathine (37.8% and 27% at 20 and 50 µg kg(-1), respectively). Limits of detection (LODs) and quantification (LOQs) ranged from 3.0 to 6.0 µg kg(-1) and 10.0 to 20.0 µg kg(-1), respectively, except for tylosin that showed a LOD and LOQ of 9.0 and 30.0 µg kg(-1). Decision limit (CC(α)) and detection capability (CC(ß)) were calculated and CC(ß) ranged from 24.1 µg kg(-1) (mebendazole) to 423.6 µg kg(-1) (flumequine). Finally, the method was applied to real samples and traces of some compounds were found in eight samples of chicken and benzathine was detected in one sample at 29.9 µg kg(-1).

In-tube solid-phase microextraction and liquid chromatography using a monolithic column for the selective determination of residual ethylenediamine in industrial cationic polymers.

The selective determination of the diamine ethylenediamine (EDA) in the presence of a higher amount of residual dimethylamine in cationic polymers has been developed. The strategy uses both a solution derivatization with a selective agent of primary amines such as o-phthaldialdehyde-N-acetyl-L-cysteine (OPA-NAC) and an in-tube solid-phase microextraction (IT-SPME) coupled to liquid chromatography (LC). A 70 cm long, 0.32 mm internal diameter, and 3 microm thick commercially available capillary column coated with 95% polydimethylsiloxane and 5% polydiphenylsiloxane was employed to replace the injection loop of a Rheodyne injection valve. A volume of 1 mL of derivatized sample was passed through the capillary, and 100 microL of water was later used for cleaning and filling the capillary. After, the injection was effected and the desorption of the derivative from the capillary was carried out in the dynamic mode using the mobile phase. Chromatographic separation was performed in less than 2 min using a monolithic silica column Onyx (100 mm x 3.0 mm i.d.) under isocratic conditions. The effect of several parameters affecting derivatization and IT-SPME was investigated. The quantification of EDA was realized over the range of 0.07-2 microg/mL with adequate linearity, accuracy, and reproducibility, and the limit of detection was 20 ng/mL. The method is rapid and low in cost, and sample handling and organic solvent consumption have been minimized. Its application to polymeric cationic surfactants used in water treatment allowed the selective quantification of residual EDA at low microgram per milliliter levels of concentration without off-line preconcentration.

Simultaneous determination of ethylenediamine-N,N,N',N'-tetrakismethylene phosphonate and ascorbic acid in "cold" radiopharmaceutical kit.

Ethylenediamine-N,N,N',N'-tetrakismethylene phosphonate (EDTMP) and ascorbic acid (AA) were determined in two batches of lyophilized experimental radiopharmaceutical kits by using ion chromatography with UV detection. The separation of EDTM and AA was carried out on PRP-X 800 weak cation exchange column and as an eluant 0.0025 mol L(-1) sodium sulfate was used. Validation parameters of both analytical procedures: limit of detection (LOD), limit of quantitation (LOQ), linearity, precision, accuracy and system suitability test (SST) parameters are presented.

High-performance liquid chromatography-post-column chemiluminescence determination of aminopolycarboxylic acids at low concentration levels using tris(2,2'-bipyridyl)ruthenium(III).

A simple, selective and sensitive method for the determination of aminopolycarboxylic acids [diethylenetriaminepentaacetic acid (DTPA), S,S-ethylenediamine N,N'-disuccinic acid (EDDS), ethylenediaminetetraacetate (EDTA) and nitrilotriacetate (NTA)] has been developed using high-performance liquid chromatography with chemiluminescence detection. The aminopolycarboxylic acids were separated on a C18 reversed-phase column with an aqueous sulfuric acid mobile phase at a pH lower than 1.5. The eluate was mixed with tris(2,2'-bipyridyl)ruthenium(III), which was on-line generated by photooxidation of the ruthenium(II) complex in the presence of peroxydisulfate, and the generated chemiluminescence was detected. Calibration graphs, based on standard solutions, were linear over the range 8x10(-9) to 4x10(-5) M. The detection limits at a signal-to-noise ratio of 3 ranged from 9x10(-10) to 8x10(-8) M. The relative standard deviations of intra- and inter-day precision were below 1.3% and 2.1%, respectively. This HPLC system was successfully applied to the determination of aminopolycarboxylic acids in three different types of water samples. The low pH of the mobile phase limits interference from metal ions in natural waters. When such interference occurs, a cation-exchange column can be used to suppress it. The lowest amounts measurable were: 75 pg for NTA, 0.7 ng for EDDS, 0.8 ng for DTPA and 12ng for EDTA. The method was also applied for the EDTA assay in canned foods.