An immobilized immuno-stirrer for the determination of creatine kinase-mb isoenzyme in blood serum

An immobilized immuno-stirrer is described for the determination of creatine kinase-MB isoenzyme in blood serum. The IgG antibodies are immobilized on alkylamine glass beads using glutaraldehyde as cross-linking reagent, and the beads are packed into a rotating porous cell. After incubation with stirring, the CK-M isoenzymes in the blood serum sample are inhibited and are bound to the antibodies inside the stirrer. The residual CK-B isoenzyme activity is then determined spectrophotometrically or electrochemically. The binding capacity of the immuno-stirrer to CK-M isoenzyme was estimated to be 800 Ul^-1 with an average inhibitory efficiency of 97.8%. The within-day and day-to-day coefficients of variation were 5% and 4%, respectively, over a period of 52 days. An immuno-stirrer loaded with antibodies attached to cyanogen bromide-activated cellulose beads was also characterized, but the antibodies were not as stable as on glass beads.     

A computer-based storage and retrieval system for electronic absorption spectra

A computer-based system for storage and retrieval of spectra in the ultra-violet region, with absorbance as the observed variable, is described. Differences in concentration between solutions relating to observed and stored spectra are automatically adjusted. The entire spectral curve is stored, not only selected points such as maxima etc.; this makes it possible to investigate the spectral range continuously during the retrieval procedure. The increment between two observations (absorbance values) is 2 nm on the wavelength axis.The input medium is punched cards containing values taken directly from observed (catalogued) spectra. The output is a printed list, giving information about observed and retrieved spectra, system parameters used during the retrieval procedure, etc. An important feature of the system is that displacements between observed and stored spectra are allowed for, in two dimensions during comparison, thus taking into account 'chromic' effects. Information about partial identity between observed and stored (retrieved) spectra is given, even if this partial identity exists in dislocated wavelength regions. To test the program, constructed (test) curves as well as real spectra were used. The system is capable of collecting in groups substances with common spectral characteristics, and thus substances belonging to the same class of chemical compounds. This makes the system a valuable tool not only for identification work but also for the study of spectral behaviour in general.     

Characteristics of the background emission spectrum from a miniature inductively-coupled plasma

The spectral characteristics of the background radiation emitted by a miniature inductively-coupled plasma (i.c.p.) are carefully examined and methods for reducing undesirable features discussed. The complex nature of the background emission spectrum for the mini-i.c.p. indicates that careful line selection criteria and background correction procedures should be employed. Extending the torch coolant tube to the bottom of the region being observed in the plasma proved to be the most effective method for reducing undesirable spectral band features. Acute changes in background emission levels with r.f. power and nebulizer gas flow rates emphasize the need for careful control of these parameters to achieve high precision. Comparison between mini-i.c.p. and conventional i.c.p. spectra reveals the basic similarity of the two sources.     

The electronic structure of heteroaromatic molecules; non-empirical calculations and photoelectron spectra for the isomeric-thiazoles and -thiadiazoles

The He(I) and MgKα photoelectron spectra are reported for the isomeric thiazoles, and He(I) spectra for the isomeric-thiadiazoles. Marked fine structure is apparent on some of the spectra. Comparison with the earlier spectra for thiophen and the azoles, and with ab initio calculations for the seven compounds, has led to assignment of the spectra. The calculations suggest that 1,3,4-thiadiazole is less aromatic than the other title compounds. As expected, the role of the 3d_s orbitals is found to be that of polarisation functions for all of the compounds, but inclusion of these orbitals leads to much better agreement with the observed dipole moments, both in magnitude and direction.     

Temperature and velocity distributions in an inductively coupled plasma

Computer simulations of inductively coupled plasma discharges (ICP) with flow patterns similar to those found in spectrochemical analysis were reported previously. In this investigation temperature and velocity distributions are measured under conditions which allow direct comparison with computer calculations for pure argon central gas flows without solution aerosols. Based upon these comparisons, a refined ICP gas flow model is proposed and its application provides agreement within experimental error between measured and calculated velocity and temperature profiles in most regions of the discharge.     

Potentiometric studies of dithiooxamide with a sulphide-selective membrane electrode

The sulphide-selective electrode is applicable to the determination of dithiooxamide by titration with silver nitrate. The effect of the alkali content of the solutions on the reaction has been studied. The reaction products are silver sulphide, oxalic acid, and nitric acid. If the alkali concentration of the solution is lower than that equivalent to the acid formed during the titration, the amount of sulphide produced by hydrolysis decreases and the equilibrium potential is established more slowly.The determination is rapid and accurate in the presence of 1 M sodium hydroxide.     

Differential determination of arsenic(III) and arsenic(V), and antimony(III) and antimony(V) by hydride generation-atomic absorption spectrophotometry,and its application to the determination of these species in sea water

A method is described for the differential determination of As(III) and As(V). and Sb(III) and Sb(V) by hydride generation-atomic absorption spectrophotometry with hydrogen-nitrogen flame using sodium borohydride solution as a reductant. For the determination of As(III) and Sb(III), most of the elements, other than Ag⁺, Cu²⁺, Sn²⁺, Se⁴⁺ and Te⁴⁺, do not interfere in an at least 30,000 fold excess with respect to As(III) or Sb(III). This method was applied to the determination of these species in sea water and it was found that a sample size of only 100 ml is enough to determine them with a precision of 1.5–2.5%. Analytical results for surface sea water of Hiroshima Bay were 0.72 μgl^?1, 0.27 μgl^?1 and 0.22 μgl^?1 for As(total), As(III) and Sb(total), respectively, but Sb(III) was not detected in the present sample. The effect of acidification on storage was also examined.     

Use of ir and 13c-nmr data in the retrieval of functional groups for computer-aided structure determination

Computer-aided interpretation of ¹³C-n.m.r. and i.r. spectra of organic molecules (m.w. ? 500) is done by an artificial intelligence approach. The output of the proposed ASSIGNER system is a list of functional groups which are reasonable candidates for the final structural isomers. The procedure of finding possible functional groups and the main features of the filtering steps are outlined. One search is worked out in detail to demonstrate the capability of the system.     

Determination of ten trace elements in meteorites and lunar materials by radiochemical neutron activation analysis

A procedure is reported for the determination of Ni, Ge, Ru, Au, Ir, Zn, Ga, Cd, In and U in meteorites and lunar materials. The precision in multiple determinations at the 95% confidence level is less than 10% except for gold (15%). Ruthenium and uranium are determined by counting ⁹⁷Ru and ¹⁰³Ru x-rays; the chemical yield is determined from ¹⁰⁶Ru added before sample dissolution. The activity of ^116mIn is determined with improved sensitivity from integral counts in the region 1.5–3.0 MeV on a NaI(TI) detector.     

Thermodynamic properties of the solvent extraction of ion pairs of metal chelate cations with some anions

Thermodynamic quantities were determined for the extraction of ion pairs of tris(1,10-phenanthroline)iron(II) and tris(2,2'-bipyridine)iron(II) chelate cations with halide, pseudohalide and polythionate anions from aqueous phase into nitrobenzene. Ion pairs with larger anions have more negative enthalpy changes with higher extractability. No clear trend was observed for the entropy changes. Linear relationships were observed between the free energy changes and the reciprocal radii of monovalent counter anions.     

A salicylate ion-selective membrane electrode based on aliquat 336s and the assay of acetylsalicylic acid

The construction and the general performance of a salicylate ion-selective PVC membrane electrode based on Aliquat 336S are described. The electrode is applied for the assay of aspirin in tablets after hydrolysis of acetylsalicylic acid to salicylate. The method has the advantage of simplicity and speed compared to standard procedures.     

Energy ordering of the B and C states in XeCl,XeBr, and KrCl,from temperature dependence of emission spectra

Inert-gas halide emission spectra from a Tesla discharge are studied as a function of pressure and temperature. From the temperature dependence of the infinite pressure ratio of broad-band (C → A and B → A) emission to B → X emission, the energy separations, T_eC - T_eB, are found to be ?130 cm^?1 (XeCl), ?80 cm^?1 (XeBr) and 375 cm^?1 (KrCl). Estimates of the (C → A)/(B → X) spontaneous emission branching ratios agree well with theoretical predictions.     

Structure,hydrogen bonding and vibrational spectra of pyruvic acid

The complete vibrational spectra of liquid pyruvic acid and the infrared spectrum of crystalline pyruvic acid at about 20 K have been recorded and analyzed. A vibrational assignment is proposed based on these spectra and comparison with spectra of derivatives of pyruvic acid.The spectra of pyruvic acid can best be interpreted in terms of a cyclic hydrogen-bonded dimer structure in which the two carbonyl groups are in a trans configuration in the pure liquid phase. A similar structure has been reported for crystalline pyruvic acid by X-ray diffraction. In dilute solution the structure appears to be monomeric with an internal hydrogen bond, in essential agreement with the structures of the monomer reported from microwave spectroscopic measurements.     

The observation of a picosecond transient in the relaxation of an iron porphyrin

Iron(III)tetraphenylporphyrin chloride, excited at 353 nm, showed significant bleaching and new absorption at 445 and 55 550 nm, which relaxed in 50 ps. Ground-state recovery occurs in ?100 fs; the bottleneck is populated with 3% efficiency. The photoproduct spectrum resembles a porphyrin ππ^* triplet, and provides evidence for intersystem crossing in an iron heme.     

Kinetic treatment of unsegmented flow systems : Part 1. Subjective and semiquantitative evaluations of flow-injection systems with gradient chamber

A variable-time kinetic model is used to evaluate a single-channel flow-injection system with gradient chamber that has been identified as a continuous-flow titration. A physical model, mathematical equations, computed concentration vs. time profiles, experimental data, and formal definitions are used to identify qualitative and quantitative features of the method that have not been apparent from the titration model for the system. It is shown that determinations can be performed with and without reactant in the flow stream and when reactant is in the flow stream, with and without reactant in the gradient chamber when the sample is introduced. It is shown that lowest concentrations with shortest cycle times can be achieved when determinations are performed without reagent in the gradient chamber initially. Characteristics unique to each of three different data processing options are used to evaluate the validity of equations presented. It is suggested that some methods previously identified as continuous-flow titrations are most accurately identified as variable-time kinetic methods, and it is shown that this semantic differentiation can provide improved insight into the methods and can expand the scope of the methods by suggesting new experimental approaches with potential advantages relative to previously described procedures.     

Raman spectra of pyridine adsorbed on a copper electrode

The surface enhanced Raman scattering (SERS) of pyridine adsorbed on a copper electrode was observed with 647.1 nm excitation and the dependence of the Raman intensity as a function of electrode potential was obtained for the most intense bands. The results are compared with reported intensity and frequency values for the silver/pyridine system.     

Kinetic treatment of unsegmented flow systems : Part 2. Detailed Treatment of Flow-Injection Systems with Gradient Chamber

A kinetic model is utilized for a detailed mathematical treatment and experimental evaluation of single-channel and dual-channel flow injection systems that include a gradient chamber. The kinetic model includes three distinct stages in the process, namely clearing reactant from the gradient chamber by first portions of sample, continued entry of sample into the gradient chamber, and decrease of determinant concentration in the gradient chamber via dilution and reaction with reagent. Equations predict entirely different behavioral patterns for different conditions and these predictions are verified experimentally for a wide range of conditions. The data show that the variable-time kinetic model is superior to the titration models previously utilized to describe these flow systems. The principal limitation of the kinetic equations involves an assumption of plug flow that is not completely valid. The extent of deviations from ideal behavior depend on conditions, but are negligible at low concentrations (0–50 mmol l^-1) and can be 10% or larger at higher concentrations (100 mmol l^-1). While equations are not exact, they are useful in predicting performance characteristics for a variety of conditions and experimental approaches.     

Spectrophotometric determination of manganese utilizing metal ion substitution in the cadmium-α,β,-γ,δ -tetrakis(4-carboxyphenyl)porphine complex

Manganese(II) reacts quickly with α, β, γ, δ-tetrakis(4-carboxyphenyl)porphine [T(4-CP)P] at room temperature by metal substitution with a cadmium—T(4-CP)P complex in weakly alkaline medium containing imidazole. Oxidation by dissolved oxygen gives a manganese(III) complex having the Soret band at 469 nm. This forms the basis of a spectrophotometric method for the determination of manganese in the range 25–560 μg l^-1. The sensitivity (0.001 absorbance) is 0.56 ng cm^-2. Interferences of 17 cations and 8 anions were examined; only Cu²⁺, Co²⁺, Cr³⁺ and Pb²⁺ interfered markedly. The method was successfully applied to the determination of manganese in tea leaves.