A test method for determining palladium in chloride solutions on the solid phase of a fibrous anion exchanger

The sorption of palladium(II) from chloride solutions on polyacrylonitrile fiber filled with the AV-17 anion exchanger (PANF-AV-17) and its subsequent determination with p-nitrosodiethylaniline on the solid phase were studied. The results of determining palladium with this reagent on the solid phase of polyacrylonitrile fiber filled with the KU-2 cation exchanger and the AV-17 anion exchanger were compared. A test method was developed for determining palladium on the PANF-AV-17 solid phase. Sorption was performed in the batch mode; the analytical signal was estimated by measuring the diffuse reflection coefficient or visually using a color scale. The detection limit was 0.005 µg/mL; the range of the calibration scale was 0–0.2 µg/mL at the volume of the test solution 10–20 mL. The accuracy of the procedure was verified by the added-found method in the analysis of tap water and a standard reference sample of natural sodium chloride water. The relative standard deviation was no more than 25%; the time of the analysis of 5 or 6 samples was 25–30 min.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 85–90.Original Russian Text Copyright © 2005 by Dedkova, Shvoeva, Savvin.     

Rapid immunoanalytical method for the determination of atrazine residues in olive oil

A sensitive, simple and reliable method has been developed for the determination of atrazine in extra virgin olive oil. The analytical procedure involves direct extraction of the target analyte from oil matrix with methanol and a freezing clean-up step (–80 °C) followed by plate or sensor immunoassay determination. A detection limit of 0.7 ng/mL, with a dynamic range from 1.0 to 10.4 ng/mL, was reached. The method was highly selective for atrazine and propazine, showing little or no cross-reactivity to other similar compounds. The excellent recoveries obtained (mean value 91.3%) confirm the potential of this approach to detect atrazine in olive oil for application as screening and complementary method in pesticide regulatory and food safety programs. The proposed method correlates well with the reference gas chromatography (GC-MS) technique.     

Catalytic Determination of Trace Amounts of Iridium As Chloride Complexes

A procedure was developed for the determination of iridium as chloride complexes by its catalytic action on the oxidation reaction of Sulfarsazene with potassium periodate at pH 5.6. The analytical range was 1 × 10^–5–1 × 10^–3 g/mL iridium. The accuracy of the procedure developed was confirmed in the determination of iridium in model solutions by the standard addition method. The relative standard deviation did not exceed 6%.     

A new procedure for the spectrophotometric determination of nitrogen(II) oxide in solutions

A new simple and reliable procedure was developed for the spectrophotometric determination of nitrogen(II) oxide. The procedure is based on the determination of excess oxygen after its reaction with NO. Alkaline solutions of thiourea dioxide were used for the determination of oxygen. It was found that the decomposition of an alkaline solution of thiourea dioxide under aerobic conditions is accompanied by the formation of dithionite, and its concentration is proportional to the concentration of oxygen in the solution. The absorbance of the resulting dithionite was measured at 315 nm. The solutions obeyed Beers law at oxygen concentrations of 1 × 10^–5–1.5 × 10^–3 M. The analytical range for NO was 1 × 10^–5–1.5 × 10^–3 M. The proposed procedure was also used for the determination of nitrogen(II) oxide in aqueous-ethanolic solutions.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 27–29.Original Russian Text Copyright © 2005 by Pukhovskaya, Guseva, Makarov, Naidenko.     

Determination of the chloroacetanilide herbicides in waters using single-drop microextraction and gas chromatography

In this article, a new method using single-drop microextraction (SDME) and gas chromatography micro-electron capture detection (GC-μECD) for the determination of chloroacetanilide herbicides (alachlor, acetochlor, metolachlor, pretilachlor and butachlor) residues was developed. The effects of SDME parameters such as extraction solvent, stirring rate, ionic strength, microdrop volume and extraction time were optimized. The optimum experimental conditions found were: 1.6 μl toluene microdrop, 5 ml water sample, 400 rpm stirring rate, 15 min extraction time and no salt addition. Analytical parameters such as linearity, repeatability and limit of detection were also evaluated. The proposed method was proved to be a simple and rapid analytical procedure for chloroacetanilide herbicides in water with limits of detection 0.0002–0.114 μg/l. The relative recoveries range from 80% to 102% for all the target analytes, with the relative standard deviations varying from 3.9% to 11.7%.     

An enzymatic method for determining magnesium

The effect of magnesium ions on the catalytic activity of alkaline phosphatases from three different sources in the reaction of p-nitrophenyl phosphate hydrolysis was studied. It was found that magnesium in concentrations of 0.6 ng/mL-20 µg/mL significantly activated alkaline phosphatase from chicken intestine; in higher concentrations (0.02–0.2 mg/mL), it weakly activated the enzyme from E. coli and had no effect on the catalytic activity of the enzyme from the small intestine of the Greenland seal. The strongest activating effect was observed in a Tris-HCl buffer solution at pH 9.8. The activating effect of magnesium on alkaline phosphatase from chicken intestine was used as the basis for developing a highly sensitive and selective enzymatic procedure for determining magnesium (0.6–6.0 ng/mL; RSD = 4% at c _min; n = 5) by spectrophotometrically monitoring the rate of enzymatic reaction. The developed procedure was applied to the determination of magnesium in urine.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 4, 2005, pp. 425–433.Original Russian Text Copyright © 2005 by Zhavoronkova, Muginova, Shekhovtsova.     

Evaluation of an Element-Tagged Duplex Immunoassay Coupled with Inductively Coupled Plasma Mass Spectrometry Detection: A Further Study for the Application of the New Assay in Clinical Laboratory

Background: Element-tagged immunoassay coupled with inductively coupled plasma mass spectrometry (ICP-MS) detection has the potential to revolutionize immunoassay analysis for multiplex detection. However, a further study referring to the standard evaluation and clinical sample verification is needed to ensure its reliability for simultaneous analysis in clinical laboratories. Methods: Carcinoembryonic antigen (CEA) and α-fetoprotein (AFP) were chosen for the duplex immunoassay. The performance of the assay was evaluated according to guidelines from the Clinical and Laboratory Standards Institute (CLSI). Moreover, reference intervals (RIs) of CEA and AFP were established. At last, 329 clinical samples were analyzed by the proposed method and results were compared with those obtained with electrochemiluminescent immunoassay (ECLIA) method. Results: The measurement range of the assay was 2–940 ng/mL for CEA and 1.5–1000 ng/mL for AFP, with a detection limit of 0.94 ng/mL and 0.34 ng/mL, respectively. The inter-assay and intra-assay imprecision were all less than 6.58% and 10.62%, respectively. The RI of CEA and AFP was 0–3.84 ng/mL and 0–9.94 ng/mL, respectively. Regarding to clinical sample detection, no significant difference was observed between the proposed duplex assay and the ECLIA method. Conclusions: The ICP-MS-based duplex immunoassay was successfully developed and the analytical performance fully proved clinical applicability. Well, this could be different with other analytes.     

Determination of chloramphenicol in milk by a fluorescence polarization immunoassay

A procedure for the determination of the drug chloramphenicol using a fluorescence polarization immunoassay (FPIA) was proposed. The optimum pairs of antibodies and antigens labeled with fluorescein were chosen, and the analytical characteristics of the procedure were determined. A rapid procedure for milk sample preparation with the use of a saturated solution of ammonium sulfate was optimized. The total time of sample preparation and determination of chloramphenicol in milk was no longer than 10 min. The detection limits of chloramphenicol in water and milk were 10 ng/mL and 20 μg/kg, respectively. The procedure developed for the determination of chloramphenicol was tested in the analysis of model and real milk samples. It was found that some milk samples contained chloramphenicol in concentrations of 38–41 μg/kg, which are several times higher than the maximum permissible concentration (MPC) (10 μg/kg).     

Retention Time Locking in the Determination of Narcotic Drugs by Chromatography and Chromatography–Mass Spectrometry

The use of retention time locking (RTL) in the development of unified procedures for the detection and quantitative determination of drugs in biological fluids was considered. With consideration for the use of RTL, a chromatographic procedure with flame-ionization and mass-selective detection was developed for the detection and quantitative determination of opiates and their synthetic analogs; phenylalkylamine derivatives; cocaine; ketamine; and other narcotic drugs, their derivatives, and metabolites in urine. The analytical ranges for chromatography–mass spectrometry were 0.05–1000 and 0.005–1000 g/mL under the conditions of total ion current (TIC) scanning and selected ion monitoring (SIM), respectively. With flame-ionization detection (GC–FID), the analytical range was 0.5–1000 g/mL.     

Liquid Chromatographic Determination of Glutamine in Cerebrospinal Fluid Using 2-Hydroxynaphthaldehyde Derivatizing Reagent

Summary An analytical procedure has been developed for the selective determination of glutamine from cerebrospinal fluid (CSF) using 2-hydroxynaphthaldehyde derivatizing reagent. Arginine and tyramine could also be determined simultaneously. Separation was on a Phenomenex C-18, (150 × 4.6 mm i.d.) column with methanol: water (63:38 v/v) mobile phase at 1mL min^–1 and UV detection at 330nm. Detection limits for glutamine, arginine, and tyramine were 2.8 ng, 17.4 ng and 3.45 ng injection^–1 (5 L), respectively. A large number of amines and amino acids eluted did not affect the determination of glutamine. The analysis of CSF of four patients suffering from hydrocephalus for glutamine indicated concentrations within range 37.4–11.24 g mL^–1 with coefficient of variation 3.0–6.2%.     

On-line preconcentration and determination of cobalt by DPTH-gel chelating microcolumn and flow injection inductively coupled plasma atomic emission spectrometry

This paper reports the development of a new methodology for the determination of cobalt in biological samples by using a flow injection system with loaded DPTH-gel as solid phase to preconcentrate analytes. The procedure is based on the on-line preconcentration of cobalt on a microcolumn of 1,5-bis(di-2-pyridyl)methylene thiocarbohydrazide immobilized on silica gel (DPTH-gel). The trapped cobalt is then eluted with 1% tartaric acid and 1% citric acid (7.1 mL) and determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The analytical figures of merit for the determination of cobalt are as follows: detection limit (3S), 8.5 ng mL^–1; precision (RSD), 5.8% for 100 ng mL^–1 of cobalt; enrichment factor, 13 (using 7.3 mL of sample); sampling frequency, 40 h^–1 using a 60-s preconcentration time. For a 120-s preconcentration time (14.6 mL of sample volume) a detection limit of 5.7 ng mL^–1, an RSD under 5% at 50 ng mL^–1, an enrichment factor of 25, and a sampling frequency of 24 h^–1 were reported. The precision and accuracy of the method were checked by analysis of biological certified reference materials.     

Determination of Gentamicin with an Amperometric Enzyme Immunosensor

A new version of enzyme immunoassay with the use of an amperometric immunosensor was proposed for the determination of an aminoglycoside antibiotic gentamicin. The biosensing part of the enzyme immunosensor simultaneously incorporates immobilized enzyme cholinesterase and antibodies against gentamicin. The detection limit for gentamicin in this method is 1 × 10^–9 mg/mL. The time of determination is no longer than 20 min. The stability constants of the immunocomplex and the kinetic parameters of the enzymatic reaction in its presence were determined. Gentamicin was determined in samples of pharmaceutical preparations and foodstuffs (milk).     

Extraction by reversed micelles of triton N-42 for the spectrophotometric determination of cetyltrimethylammonium bromide

Micellar preconcentration of 1 : 2 associates of Bromophenol Blue with cetyltrimethylammonium bromide is proposed to improve the procedure for the spectrophotometric determination of cationic surfactants. The preconcentration procedure involves quantitative extraction by reversed micelles of Triton N-42 in decane followed by the decomposition of the micellar solution with chloroform. The loss of 10^–7–10^–5 M cetyltrimethylammonium bromide in 5–100-fold preconcentration was not supported by the added-found method (RSD = 3–5%). The determination limit for cetyltrimethylammonium bromide is 2 × 10^–7 M.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 17–21.Original Russian Text Copyright © 2005 by Demidova, Bulavchenko.     

Activation of solid electrodes made of platinum,gold, and a graphite-epoxy resin composite by mechanically cutting their surfaces <Emphasis Type="Italic">In Situ</Emphasis> in the anodic voltammetry of ascorbic acid

The oxidation of ascorbic acid (AA) was studied at the electrodes made of platinum, gold, and a graphite-epoxy resin composite. Cutting the surface electrode layer in situ in solution before each polarization activated the electrode surface. This activation manifested itself in a more negative potential of the AA anodic peak, a change in the current peak shape, and an increase in the current density at the electrodes as compared to the polished electrodes. The in situ renewal of electrodes allowed us to develop a rapid voltammetric procedure for determining AA at an electrode made of a graphite-epoxy resin composite in different samples. The analytical range for AA was 0.1–200 mg/L, the determination limit for AA was 0.05 mg/L, and the RSD was 3–5%.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 64–68.Original Russian Text Copyright © 2005 by Tarasova, Kiryushov.     

Determination of caffeine in black tea leaves by Fourier transform infrared spectrometry using multiple linear regression

A simple and fast analytical procedure was developed for the determination of caffeine in black tea leaves. The method is based on multiple linear regression treatment of Fourier transform infrared spectrometric data obtained in the wave number range 1800–1300 cm⁻¹ after extraction of caffeine in CHCl₃ from tea samples, wetted with an aqueous solution of NH₃ (0.1 M). The procedure requires no complex sample preparation. It provided a limit of detection of 0.035 mg/ml, a sampling frequency of 6 h⁻¹ and a coefficient of variation of 0.8% for five independent measurements of a tea sample with 3.68% w/w caffeine content. This procedure provides a drastic reduction in the consuming organic solvent for each sample compare to that of the reference chromatographic determination. The accuracy of technique is evaluated by comparing the obtained results with those of a reference HPLC technique. An average value of 3.60±0.07% w/w was obtained by HPLC for a powdered tea sample which is compromising when is compared to 3.68±0.03% (w/w) obtained by this FTIR technique.     

Determination of total thallium in soils by atomic emission spectrography using a two-jet arc plasmatron

A procedure is proposed for the direct determination of total thallium in solid soil samples by atomic emission spectrography with spectral excitation in an two-jet argon-arc plasmatron. The conditions for spectrum excitation and registration have been optimized. The analytical possibilities of the two zones in the plasma jet, before and after the jet confluence, were compared using the determination of thallium in soils as an example. Reference samples were artificial mixtures prepared on the basis of real soils. The accuracy of the results was estimated using the t-test in the analysis of samples with the known analyte concentrations. The experimentally found detection limit is 0.3–0.5 mg/kg. The relative standard deviation at an insignificant systematic error is 12–15% (n = 20; P = 0.95).Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 2, 2005, pp. 165–170.Original Russian Text Copyright © 2005 by Cherevko, Polyakova.This revised version was published online in April 2005 with corrections to the author names and book review format.     

Gas Chromatography–Mass Spectrometry Determination of Morphine and Codeine in Blood as Their Propionic Esters

A gas-chromatographic separation procedure with mass-spectrometric detection was developed for the detection of opiates in whole blood and the quantitative determination of morphine and codeine as their propionic esters. The detection limit for morphine and codeine in blood was 0.02 g/mL. The analytical range was 0.05–2.0 g/mL. The maximum intraseries relative errors were 15.6 and 11.2% for concentrations of 0.05 and 1.0 g/mL, respectively. The interseries relative errors were no higher than 8 and 3% for concentrations of 0.05 and 1.0 g/mL, respectively. The procedure is intended for forensic chemical analysis in cases of opiate poisoning.     

Comparison of Different Sorbents for Solid-Phase Extraction of Phenoxyalkanoic Acid Herbicides

An HPLC procedure for determination of phenoxyalkanoic acid herbicides in water samples is proposed. The analytical column Phenomenex C18(2) Luna 5 µm and UV detection at 225 nm were applied. Baseline resolution was achieved in isocratic mode with a mobile phase consisting of acetonitrile/acetic acid (40/60, v/v), adjusted to pH 2.5. SPE sorbents – C₁₈ BondElut, phenyl-silica, LiChrolut SAX and polymeric sorbents – were compared for isolation and preconcentration of 6 phenoxyalkanoic acid herbicides. Higher (above 95%) and more reproducible recoveries were obtained with polymeric and phenyl-silica sorbents using pure methanol for elution. The method was tested for river water samples with the limit of detection in the range of 2–3 µg L⁻¹ (for 50 mL sample) and a reproducibility of 5% RSD.     

气相色谱法测定土壤中酰胺类除草剂

建立了从土壤中同时提取甲草胺、乙草胺和丁草胺并采用气相色谱法测定的分析方法.采用丙酮-石油醚(2:1,V/V)为提取液,经弗罗里矽硅土固相萃取柱净化,超声30 min、振荡10 min.测定结果显示,甲草胺、乙草胺、丁草胺的保留时间分别为16.333,16.019,20.249 min;线性相关系数>0.9990;6个...     

Amperometric Enzyme Immunosensors for Diagnosing Certain Infectious Diseases

Amperometric enzyme immunosensors based on planar electrodes were developed for the rapid determination of some bacterial antigens. Conditions for the operation of analytical devices (matrix component, pH of the buffer solution, and the dilution of antibodies in the biosensing part of the sensor) were selected. The analytical characteristics of enzyme immunosensors (analytical ranges and determination limits) were estimated. The analytical devices were tested in determining pyogenic streptococcus and aurous staphylococcus antigens in the blood serum of patients suffering from infectious diseases. It was shown that the developed sensors can be used for diagnosing diseases caused by these microorganisms.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 616–623.Original Russian Text Copyright © 2005 by Safina, Medyantseva, Fomina, Glushko, Budnikov.Presented at the VI All-Russia Conference (with international participation) on Electrochemical Methods of Analysis (EMA-2004, Ufa, May 23–27, 2004).