Artificial and natural fiber fabrics with immobilized di-and triaminotriarylmethane reagents in chemical test methods

The potentials of fabrics made of artificial and natural fibers as supports for the di-and triaminotriarylmethane reagents were shown for their possible use in chemical test methods. Malachite Green, Brilliant Green, Methyl Violet, Crystal Violet, and Parafuchsine were immobilized on viscose, calico, coarse calico, and a mixed fabric. The reagent retention was 70–90%. The indicator fabrics are resistant to strong acids and alkalies and can be used for the test determination of 0.01–10 mg/L of phosphates, 1–80 mg/L of silicates, 0.01–8 mg/L of dissolved oxygen, biological oxygen demand for 5 days (BOD₅), 0.5–10 mg/L of formaldehyde, and 0.1–10 mg/L of anionic surfactants. The analysis time was 10–15 min. The relative standard deviation did not exceed 30%.     

Plates for thin-layer chromatography with adsorption-immobilized reagents in chemical test analysis methods

The use of plates for thin-layer chromatography (TLC) with adsorption-immobilized organic reagents in chemical test methods for analysis is considered. Triarylmethane, triazine, eirodine, acridine, and rhodamine dyes are used for immobilization. The degree of retention of the reagents is 52–98%. It is found that the absorption spectra of these reagents on TLC plates exhibit a hypsochromic shift of absorption bands by 8–30 nm in comparison with their absorption spectra in solutions. The retention is higher for the reagents that exhibit a hypsochromic shift of absorption bands on TLC plates. The sorption isotherms of the reagents on TLC plates are obtained and analyzed. Test methods have been developed for the determination of 1–200 mg/L Au(III) and 0.1–5 M acids and alkalies with the use of reagent TLC plates. The relative standard deviation of the results of analysis is no larger than 10%; the time of analysis is 3–7 min.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 3, 2005, pp. 291–296.Original Russian Text Copyright © 2005 by Amelin, Tretyakov.     

Use of immobilized enzymes in chemical analysis

Immobilized enzymes are becoming increasingly popular as analytical reagents because of their reusability, stability, and sensitivity to many inhibitors that would seriously interfere in assays using soluble enzymes. In this article, some of the kinetic and catalytic effects of immobilized enzymes in analysis will be discussed. The shift of the activity-pH profile curves on immobilization, the changes in temperature dependence, the inhibitor constants (K_i), Michaelis constants (K_m), and the maximum velocity ( V_max), plus others, will be discussed. Finally, the use of these immobilized enzymes in fluorometric and electrochemical monitoring systems will be shown, and the future of these reagents in various areas will be discussed. A survey of enzyme electrodes will be presented as an example of the use of immobilized enzymes. Application of immobilized enzyme technology to the assay of BUN, glucose, uric acid, amino acids, ethanol, and other metabolites will be discussed.     

Solid-phase fluorescence in chemical test methods of analysis based on the principles of planar chromatography

Morin immobilized on cellulose matrices was used as a reagent for determining Al, Be, and Zr(IV) by the length of the fluorescent zone on a test strip after its contact with the test solution and by the fluorescence intensity of the reaction zone of the indicator matrix after passing the test solution through it. A test procedure was developed for determining 0.2–200 mg/L Al in potable water using paper test strips sealed in a polymer film. Test procedures were developed for determining 0.0001–1 mg/L Al and 0.00001–0.1 mg/L Be in river water by the intensity of the fluorescent zone on the indicator viscose fabric after passing 100 mL of the test solution through it, using a test facility. The time of analysis was 15–20 min. The relative standard deviation did not exceed 40% in the former case and 60% in the latter case.     

试剂固定化的流动注射化学发光测定盐酸伊托必利

基于盐酸伊托必利在碱性条件下对铁氰化钾鲁米诺化学发光体系有较强的抑制作用,并采用离子交换固定法将鲁米诺和铁氰化钾全部固定在阴离子交换树脂上,联用流动注射技术建立了测定盐酸伊托必利的新方法。本法的线性范围为1.0~100.0μg/mL,检出限0.2μg/mL,对20μg/mL的盐酸伊托必利11次平行测定,其相对标准偏差为2.1%。单次测定在45 s内完成。此固定化柱可使用200次以上。可用于盐酸伊托必利片剂中盐酸伊托必利的质量检测。     

Primary methods of measurement in chemical analysis

 Primary methods of measurement have a central function in metrology. They are an essential component in the realisation of the SI units and therefore are indispensable for establishing traceability of measurements of all kinds of physical quantities to the corresponding SI units. This is also true for chemical analysis. Gravimetry, titrimetry, coulometry, and isotope dilution mass spectrometry (IDMS) are evaluated with regard to their potential to be primary methods according to a general definition of primary methods recently given by the Comité Consultatif pour la Quantité de Matière (CCQM). Optical absorption spectrometry and methods based on colligative properties are also considered. A general scheme for establishing traceability of chemical measurements to the SI units using primary methods is discussed. Received: 17 April 1997 · Accepted: 9 August 1997     

2,3,7-Trihydroxyfluorones immobilized on cellulose matrices in test methods for determining rare elements

It was shown that 2,3,7-trihydroxyfluorones immobilized by adsorption on cellulose matrices can be used as reagents for the test determination of Mo(VI), Ti(IV), Ge(IV), Hf(IV), Nb(V), Ta(V), W(VI), Bi(III), V(IV), and Zr(IV). The change of the protolytic and complexing properties of trihydroxyfluorones immobilized on cellulose matrices was considered in comparison to corresponding properties in a solution. It was found that the reactions of trihydroxyfluorones with rare elements on cellulose matrices and in a solution exhibit similar effects upon the addition of cetylpyridinium. These effects are the bathochromic shift of the absorption maxima of the reagents and their complexes with analytes and the extension of the range of optimum acidity for complex formation. The complexation of salicylfluorones with the titanium(IV) in solution and on cellulose paper was studied by IR spectrometry. Phenylfluorone immobilized on a mixed-fiber cloth as used in test determinations of (mg/L) 0.05–5 Ti(IV), V(IV), Hf(IV), Nb(V), and Mo(VI); 0.01–5 Ge(IV) and Zr(IV); 0.05–1 Bi(III) and W(VI); and 0.1–5 Ta(V) by the color intensity of the indicator matrix after passing through 20 mL of a test solution. It was shown that phenylfluorone immobilized on cellulose paper can be used to determine (mg/L) 0.05–50 Ti(IV), 0.5–1000 Ge(IV), 0.5–500 Zr(IV), 5–200 Bi(III), 0.1–50 Mo(VI), 0.1–1000 V(IV), 0.1–100 Nb(V), 0.1–800 Hf(IV), 1–100 Ta(V), and 1–800 W(VI) by the length of the colored zone of a test strip after it was brought into contact with a test solution.     

Chemiluminescence flow sensor for the determination of ascorbic acid with immobilized reagents

A novel flow sensor based on chemiluminescence (CL) for the determination of ascorbic acid has been proposed. The analytical reagents, luminol and ferricyanide, were both immobilized on an anion-exchange resin column. The CL signal produced by the reaction between luminol and ferricyanide, which were eluted from the column through sodium phosphate injection, was decreased in the presence of ascorbic acid. The CL emission intensity was linear with ascorbic acid concentration in the range 0.01-0.8 mug ml(-1); the detection limit was 5.5 x 10(-3) mug ml(-1). The whole process, including sampling and washing, could be completed in 1 min with a relative standard deviation of less than 5%. The sensor could be reused more than 100 times and has been applied successfully to the analysis of ascorbic acid in pills and vegetables.     

Series analysis methods in enumeration of chemical isomers

Summary Methods of series analysis are used to interpret the results of a computer enumeration of chemical isomers. It is demonstrated how a typical asymptotic behavior that controls the number of isomers arises from singular points of the generating function. The approach is tested on the examples of the isomers of alkanes, alkenes, alkyl radicals and polyenes.     

Sensing elements of optical sensors based on polystyrene with covalently immobilized reagents

A procedure was developed for the preparation of sensing elements for optical sensors based on pressed membranes of optically transparent polystyrene 250 μm in thickness. The procedure for assembling reagents on a matrix surface involved the operating sequence of nitration, reduction, diazotization, and azo coupling with organic reagents from the class of monoazochromotropic acid. This allowed us to prepare sensing elements with reproducible properties. The optical properties of immobilized reagents and their complexes with metal ions are practically analogous to those of compounds formed in solutions. External diffusion is a rate-determining step in the reactions with metal ions. The time constants of various sensing elements at metal concentrations of 4 × 10^?7 mol/mL were about 30 s, and the time taken to produce a signal at a 95% level was 50–56 s.     

Ion-molecule reactions of oxygenated chemical ionization reagents with vincamine

The ion-molecule reactions of ions from acetone, dimethyl ether, 2-methoxyethanol, and vinyl methyl ether with vincamine were investigated. Reactions with dimethyl ether result in [M+13]⁺ and [M+45]⁺ products, reactions with 2-methoxyethanol produce [M+13]⁺ and [M+89]⁺ ions, and reactions with acetone or vinyl methyl ether ions generate predominantly [M+43]⁺ ions. Collision-activated dissociation and deuterium labeling experiments allowed speculation about the product structures and mechanisms of dissociation. The methylene substitution process was shown to occur at the hydroxyl oxygen and the phenyl ring of vincamine for dimethyl ether reactions, but the methylene substitution process was not favored at the hydroxyl oxygen for the 2-methoxyethanol reactions, instead favored at the 12 phenyl position. The reaction site is likely different for the 2-methoxyethanol ion due to its capability for secondary hydrogen-bonding interactions. For the [M+45]⁺ and [M+89]⁺ ions, evidence suggests that charge-remote fragmentation processes occur from these products. In general, the use of dimethyl ether ions or 2-methoxyethanol ions for ionmolecule reactions prove highly diagnostic for the characterization of vincamine; both molecular weight and structural information are obtained. Limits of detection for vincamine with dimethyl ether chemical ionization via this technique on a benchtop ion trap gas chromatography-tandem mass spectrometer are in the upper parts per trillion range.     

Critical examination of some common reagents for reducing selenium species in chemical analysis

In an attempt to resolve apparently conflicting statements in the literature, a study has been made of the action of various reductants on selenium(VI) and selenium(IV). Chloride in hot non-oxidizing acid medium will reduce Se(VI) to Se(IV) but not further. Sulphur dioxide will reduce Se(IV) to Se, but has no effect on Se(VI). Hydrazinium salts reduce both Se(VI) and Se(VI) to Se, but hydroxylammonium salts reduce only Se(IV) to Se. Hydrogen peroxide partially reduces Se(VI) to Se(IV) but not further. If chloride is also present [to reduce Se(VI) to Se(IV)], sulphur dioxide or hydroxylammonium salts can then reduce the Se(IV) to Se, and this combined effect has led to some confusion in interpretation of experimental observations.     

Calculation of the detection limit in chemical test methods of analysis based on the principles of planar chromatography

Microsoft Office Excel and CorelDraw Graphics Suite were used for the statistical treatment of experimental data in the chemical test methods of analysis. A simple and available method for calculating the detection limit was demonstrated by the example of test systems for determining molybdenum(VI), bismuth( III), and titanium(IV). The use of Pantone Hexachrome Coated enabled us to construct calibration curves for the main color intensity of the reaction zone on the indicator matrix as a function of analyte concentration. The approximation of experimental data using the Microsoft Office Excel software was considered; it eliminated the complicated and laborious calculation of the coefficients of approximation equation and the correlation coefficient. It was found that, for the studied test systems, the detection limit was close to the determination limit. In the use of test strips, the detection limit for Mo(VI) and Bi(III) was 0.04 and 1.0 mg/L, respectively, and in the determination of Mo(VI) and Ti(IV) using a test facility, it was 0.03 and 0.02 mg/L, respectively.     

New radioisotope methods of analysis based on the application of radioactive reagents

Graph-Calculation Method of analysis has been developed. The new method considerably increases (in comparison with Radioactive Reagent Method) the sensitivity of determinations and allows to enlarge the list of suitable reagens as well as permissible limits of relative quantities of radioactive reagent applied. The equations have been derived which allow to calculate the degree of interaction of the reacting substances and to carry out model calculations for any radioisotope method of analysis applying radioactive reagents.     

Chemiluminescence assay for uric acid in human serum and urine using flow-injection with immobilized reagents technology

A novel chemiluminescence (CL) flow sensor for the determination of uric acid in human urine and serum has been developed by using controlled-reagent-release technology. The reagents involved in the chemiluminescence (CL) reaction, luminol and periodate, are immobilized on anion-exchange resin packed in a column. After injection of water, chemiluminescence generated by released luminol and periodate in alkaline media is inhibited in presence of uric acid. By measuring the decreased chemiluminescence (CL) intensity the uric acid is sensed. The decreased response is linear in the 5.0-500.0 ng mL(-1) range, with a detection limit of 1.8 ng mL(-1). The flow sensor showed remarkable operational stability and could be easily reused for over 80 h with sampling frequency of 100 h(-1). The proposed sensor was applied to the determination of uric acid in human urine and serum, and monitoring metabolic uric acid in human urine with RSD less than 3.0%.     

Selective reagents in chemical ionization mass spectrometry: Tetramethylsilane with ethers

Chemical ionization mass spectra of several ethers obtained with He/(CH₃)₄Si mixtures as the reagent gases contain abundant [M + 73]⁺ adduct ions which identify the relative molecular mass. For the di-n-alkyl ethers, these [M + 73]⁺ ions are formed by sample ion/sample molecule reactions of the fragment ions, [M + 73 ? C_nH_2n]⁺ and [M + 73 ? 2CnH_2n]⁺. Small amounts of [M + H]⁺ ions are also formed, predominantly by proton transfer reactions of the [M + 73 ? 2CnH_2n]⁺ or [(CH₃)₃SiOH₂]⁺ ions with the ethers. The di-s-alkyl ethers give no [M + 73] ⁺ ions, but do give [M + H]⁺ ions, which allow the determination of the relative molecular mass. These [M + H]⁺ ions result primarily from proton transfer reactions from the dominant fragment ion, [(CH₃)₃SiOH₂]⁺ with the ether. Methyl phenyl ether gives only [M + 73]⁺ adduct ions, by a bimolecular addition of the trimethylsilyl ion to the ether, not by the two-step process found for the di-n-alkyl ethers. Ethyl phenyl ether gives [M + 73]⁺ by both the two-step process and the bimolecular addition. Although the mass spectra of the alkyl etherr are temperature-dependent, the sensitivities of the di-alkyl ethers and ethyl phenyl ether are independent of temperature. However, the sensitivity for methyl phenyl ether decreases significantly with increasing temperature.     

Highly parallel dispensing of chemical and biological reagents

We present a technology for the highly parallel dispensing of a multitude of reagents. It allows one to dispense up to 96 different reagents simultaneously in a fixed array, in a volume range of 100 pL up to several nL. The pitch of the dispensed droplets can be as small as 500 µm. All channels are fired simultaneously, giving an unprecedented throughput. The system was originally developed for the high-throughput fabrication of microarrays, but can easily be adopted for other applications such as highly parallel filling of nanotiterplates. Based on our standard configuration we achieved droplets with 125-µm in-flight diameter (1.2 nL) with a CV of <1%.     

A review of methods for the chemical characterization of cannabis natural products

Cannabis has garnered a great deal of new attention in the past couple of years in the United States due to the increasing instances of its legalization for recreational use and indications for medicinal benefit. Despite a growing number of laboratories focused on cannabis analysis, the separation science literature pertaining to the determination of cannabis natural products is still in its infancy despite the plant having been utilized by humans for nearly 30 000 years and it being now the most widely used drug worldwide. This is largely attributable to the restrictions associated with cannabis as it is characterized as a schedule 1 drug in the United States. Presented here are reviewed analytical methods for the determination of cannabinoids (primarily) and terpenes (secondarily), the primary natural products of interest in cannabis plants. Focus is placed foremost on analyses from plant extracts and the various instrumentation and techniques that are used, but some coverage is also given to analysis of cannabinoid metabolites found in biological fluids. The goal of this work is to provide a collection of relevant separation science information, upon which the field of cannabis analysis can continue to grow.