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At least 19 recordsLinked to original sources
PubMedDate not supplied

Comparative sensitivities of flame atomic absorption spectrophotometry (AAS) and molecular absorption spectrophotometry (MAS).

A sensitivity comparison was made between conventional atomic absorption spectrophotometry (AAS) and conventional molecular absorption spectrophotometry (MAS) for the serum trace metals, copper, iron, and zinc. The sensitivity aspect considered was absorbances was obtained for concentrations in the solutions analyzed using unit lightpaths of 1 cm and 10 cm for MAS and AAS, respectively. A distinction was made between procedural sensitivity and measurement sensitivity where the latter represents molar absorptivity. Some was given to the concepts of procedural sensitization by concentration of the analyte through the use of lyophilization, extraction or ashing. The misuse of data obtained with scale expanders is described as a commonly occurring phenomenon of both AAS and MAS and a source of confusion in the understanding of measurement sensitivity.

Copper↗
PubMed1975

Heavy metal-nucleoside interactions. Binding of methylmercury(II) to inosine and catalysis of the isotopic exchange of the C-8 hydrogen studied by 1-H nuclear magnetic resonance and raman difference spectrophotometry.

Raman difference spectrophotometry reveals that CH3HgII binds quantitatively to N(1) of inosine at pH 8, substituting for the proton. When N(1) is saturated, binding occurs at a second site. Measurements of the 1-H nuclear magnetic resonance spectra of both inosine and of CH3Hg-II are in agreement with the N(1) binding and indicate that the second site for mercuriation is N(7). This second binding reaction is observed to increase the rate of exchange of the C(8) hydrogen with solvent, consistent with results observed for alkylation at N(7). Coordination of the electrophilic CH3Hg-II to N(7) increases the acidity of H(8), facilitating OHminus--catalyzed proton abstraction and reprotonation by themedium. For comparison, the reaction of CH3Hg-II with [8-2-H]inosine has been studied. Displacement of the N(1) hydrogen upon mercuriation of inosine causes a significant electron delocalization into the ring, increasing the basicity of N(7), and accounting for the synergic effect in metal binding observed originally by Simpson. In contrast, 1-methylinosine interacts only slightly with CH3Hg-II at pH 8. Coordination appears to be at N(7), since H(8) again is observed to exchange rapidly with solvent protons. In acidic solution, pH less than 2, binding to inosine is almost quantitative and exclusively to N(7). The behavior of CH3Hg-II is compared with that of Pt(II) and with Ni(II), Co(II), AND Zn(II). A brief comparison is made among ultraviolet absorption spectrophotometry, nuclear magnetic resonance (NMR), and Raman difference spectrophotometry for studying reactions of nucleosides and nucleotides.

Binding Sites↗
PubMed1975

Computer tomography compared with spectrophotometry of cerebrospinal fluid in cerebrovascular diseases.

Eighty patients with cerebrovascular diseases were examined by computer tomography and spectrophotometry of CSF, most cases being followed by repeat examinations. Specific diagnoses were obtained in 76 per cent of the cases at tomography and in 95 per cent at spectrophotometry, generally at one examination. In cases examined angiographically or by isotope encephalography, the corresponding figures were 60 and 58 per cent. Twenty patients with confirmed haemorrhage or infarction examined only at tomography further indicated the high diagnostic significance of this method. The combination of tomography and spectrophotometry, being complementary to each other, obviously means a break-through in the diagnosis of cerebrovascular diseases, which is a prerequisite for a more rational therapy of these common and frequently disabling disorders.

Brain↗
PubMed1978

Computer tomography of the brain and spectrophotometry of the CSF in cerebral concussion and contusion.

Computer tomography (CT) and spectrophotometry of CSF were performed in 30 patients with the clinical diagnosis of cerebral concussion or contusion. The patients with concussion all had normal CT-findings. Spectrophotometry of CSF was sometimes positive for cerebral contusion with normal CT-findings, but the two methods were complementary so that the extent of the lesion was determined by CT and spectrophotometry of CSF indicated the cause.

Brain Concussion↗
PubMed1976

Differentiation between chelated and non-chelated DNA-Pt complexes by atomic absorption spectrophotometry.

As a continuation of our study of the properties of the cis-trans platinum series we have investigated the DNA-Pt complexes of [Pt(dien)Cl]Cl, cis-Pt (en)Cl2, cis-Pt (NH3)2Cl2 and K2[PtCl4] by atomic absorption spectrophotometry. The DNA-Pt complexes correspond to the saturation of the N7-(Guanine) sites. It has been found that the chelate complexes obtained with cis-Pt(en)Cl2, cis-Pt(NH3)2Cl1 and K2[PtCl4] show the same absorbance. The [Pt(dien)Cl]Cl and trans-Pt (NH3)2Cl2 which are bound to the N7 (tuanine) site only, show an absorbance greater than the chelate complexes by a factor of two. In addition, it has been possible in the case of the trans-Pt (NH3)CCl1 complex to follow the fixation of platinum to DNA by atomic absorption spectrophotometry. The result is similar to the ionic chlorine liberation procedure reported previously.

Binding Sites↗
PubMed1975

Difference-derivative absorbance spectrophotometry as a technique to measure state changes of phenylalanine residues in proteins.

The first derivatives of difference absorbance spectra of several proteins were measured to examine the applicability of this technique as a tool to investigate state changes of phenylalanine residues in proteins. It was found by this technique that phenylalanine residues in insulin and those in lysozyme are exposed to more aqueous environment by denaturation with guanidine hydrochloride. Heat denaturation of collagen caused similar changes of some of its phenylalanine residues. It was thus demonstrated that difference-derivative absorbance spectrophotometry gives the information about state changes of phenylalanine residues in native proteins, which are hardly detected by common difference spectrophotometry.

Air Sacs↗
PubMed1992

Dual wavelength spectrophotometry as a diagnostic test of the pulp chamber contents.

The purpose of this in vitro study was to determine the feasibility of using dual wavelength spectrophotometry to identify teeth with pulp chambers that are either empty, filled with fixed pulp tissue, or filled with oxygenated blood. In phase I of the experiment, a human third molar was prepared so that its pulp space could be filled with oxygenated blood and later emptied. In phase II, the lower jaw of a beagle dog was removed and placed in formalin, thereby fixing the pulps of the teeth. The pulp of the right canine was removed via an apical approach, and attachments were placed in a similar position to those on the human tooth, to allow filling and emptying of the pulp space. Cavit was placed over the exposed fixed pulp in the left canine. Ten readings, which were separated by light source and detector removal and replacement, were taken of the right canine pulp space when it was empty or filled with oxygenated blood, or the left canine pulp space when it was filled with fixed tissue. Distinct and reproducible changes were measured for pulp spaces filled with air, tissue, or oxygenated blood. In phase III, simulated pulp testing on a dog tooth model was performed. Blood was introduced into the root canal space, the chamber was rinsed with water and replaced with air, according to a predetermined code. Spectrophotometer readings were recorded. The identification of pulpal contents was correctly determined in all 20 of the predetermined conditions. The findings indicate that continuous wave spectrophotometry may become a useful pulp testing method.

Animals↗
PubMed1978

Lithium neurotoxicity. I. The concentration of lithium in dopaminergic systems of rat brain determined by flameless atomic absorption spectrophotometry.

Severe neurotoxicity has been reported in patients receiving combinations of lithium and butyrophenones and halogenated phenothiazines and the suggestion has been made that lithium is preferentially concentrated in dopamine systems in brain. Conventional flame atomic absorption spectrophotometry does not allow analysis of sufficiently small samples of brain tissue to allow accurate association with specific transmitter systems, although previous reports have suggested that lithium is concentrated in the striatum. A method has been developed using flameless atomic absorption spectrophotometry to allow accurate measurement of lithium concentrations in 10--100 ng fresh weight of brain tissue. Using this technique in experiments where rats were fed lithium over a period of three weeks, we could not confirm a direct association of lithium with an area predominetly served by dopamine transmitters.

Animals↗
PubMed1978

Determination of urinary manganese by the direct chelation-extraction method and flameless atomic absorption spectrophotometry.

The direct chelation-extraction method, originally developed by Hessel (1968) for blood lead analysis, has been successfully applied to urinalysis for manganese. The analyses of 35 urine samples containing up to 100 microgram/1 of manganese from manganese-exposed workers showed that the data obtained by this method agree well with those by wet digestion-flame atomic absorption spectrophotometry and also by flameless atomic absorption spectrophotometry.

Chemical Industry↗
PubMed1975

[Infrared spectrophotometry of culture broth and toxins of enteropathogenic strains of Escherichia coli].

Lyophilized preparations of sterile broth, broth used for cultivation of enteropathogenic E. coli strains from which endotoxin and enterotoxin had been removed, were prepared for spectrophotometry by mixture with potassium bromide, and examined in heavy water. Despite basic biochemical differences, all the preparations showed similar or identical curves, with the same absorption maximum and wave length. The substances present in broth (proteins, lipids, sugars, etc.) were so dominant that that completely masked substances specific for E. coli and its toxins. Spectrophotometry revealed only the pattern belonging to broth, so that toxins can be only examined by this method after they have been separated from the broth. It is hoped to do this in the future.

Carbohydrates↗
PubMed1976

Radioimmunoassay, enzyme immunoassay, spectrophotometry, and gas-liquid chromatography compared for determination of phenobarbital and diphenylhydantoin.

Sera from epileptic patients were assayed for phenobarbital and diphenylhydantoin by four different analytical procedures. Quantitative results obtained by radioimmunoassay (I) and enzyme immunoassay (II) were compared to each other and to the results obtained on aliquots of the same sample by gas-liquid chromatography (III) and ultraviolet spectrophotometry (IV). For phenobarbital the correlation coefficients were I vs. II, 0.909; I vs. III, 0.947; II vs. III, 0.917; I vs. IV, 0.950; II vs. IV, 0.953. For diphenylhydantoin the correlation coefficients were I vs. II, 0.953; I vs. III, 0.951; II vs. III, 0.957; I vs. IV, 0.862; II vs. IV, 0.898. The immunoassays can be substituted for liquid chromatography or ultraviolet spectrophotometry without changing the resulting clinical interpretations.

Chromatography, Gas↗
PubMedDate not supplied

[Detection of early cataract changes in the crystalline lens by using in vivo spectrophotometry of the eye].

The aim of the paper was to study with the use of in vivo spectrophotometry of the eye the threshold values of the registered light above which one can observe clinically visible opacities of the lens. The performed experiments did not however show any major differences in the values of the registered light between persons with early cataract and control group because of considerable scattering of the results in both these groups. In order to explain the prognostic value of the in vivo spectrophotometry of the eye it is necessary to perform long-term observations of the further fate of persons with high values of the registered light.

Adult↗
PubMed1978

Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay.

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.

Chromatography, Gas↗
PubMed1978

Leak in evaporated milk by anodic stripping voltammetry and atomic absorption spectrophotometry: cooperative interlaboratory study.

The results of a cooperative study on the determination of lead in evaporated milk, using a double blind referee technique, are reported. This study was designed to determine the normal variability of methods currently used for lead analysis by canned food industry laboratories. Twenty-three laboratories participated in this study. Each laboratory was instructed to use atomic absorption spectrophotometry (AOAC 25.065), anodic stripping voltammetry, or carbon rod atomic absorption spectrophotometry. Overall, the results appear to be in close agreement with the spiking levels. The coefficient of variation for all laboratories was 36.0% at the 0.15 ppm lead level and 16.8% at the 0.40 ppm lead level.

Animals↗
PubMedDate not supplied

Diagnostic significance of CSF spectrophotometry and computer tomography in cerebrovascular disease. A comparative study in 231 cases.

Two hundred and thirty-one patients with cerebrovascular disease were examined by spectrophotometry of the cerebrospinal fluid (CSF) and by computer tomography. Many were followed by repeated examinations. Specific diagnoses --- bleeding as opposed to non-hemorrhagic or hemorrhagic infactions --- were indicated in 97% by spectrophotometry and in 65% by CT scan in 201 of the 231 cases (excluding 25 patients with transient ischemic attacks and five patients with cerebral tumors with cerebrovascular onset). Comparison between the two methods revealed agreement in most cases, with disagreement in only a few. The specific diagnosis was generally established on only one examination by both methods: repeated examinations were necessary in only a few cases. The results indicated that a combination of the two complementary methods established the diagnosis in almost all cerebrovascular disorders. This was particularly evident if the examinations were performed 24 hours to 21 days after onset of disease.

Cerebral Hemorrhage↗
PubMed1975

Heavy metal-nucleotide interactions. III. The participation of amino groups in the binding of methylmercury (II) to cytidine and adenosine 5'-phosphate in aqueous solution: studies by Raman difference spectrophotometry.

Raman difference spectrophotometry has been used to study the interaction of CH3Hg(II) with cytidine and Ado-5'-P at high pH. In contrast to the binding reactions which occur at lower pH or in non-aqueous solvents such as dimethyl sulfoxide, a proton is transferred from the amino group; and the complexes are CH3HgCydH-1 and CH3HgAdoH-1-5'-P. The spectra are significantly different from those of the cationic complexes. The integrated intensities of ligand modes which shift upon metalation can be used to measure the concentration of unreacted ligand and consequently the extent of the reaction. Equilibrium constants for the reactions CH3HgOH + L yields CH3HgLH-1 + H2O were estimated to be log KCyd equals 0.63 plus or minus 0.05 and log KAdo-5'-P equals 0.85 plus or minus 0.05, in fair agreement with values determined under very different conditions by ultraviolet spectrophotometry. The vibrational spectrum of the ligand in CH3HgCydH-1 is virtually the same as that of UrdH-1- which is isoelectronic. The spectrum of the ligand in CH3HgAdoH-1-5'-P is more similar to the isoelectronic base InoH-1-than to Ado-5'-P, although the resemblance is not so close as in the CydH-1---UrdH-1-case. The structures of these complexes are discussed on the basis of their vibrational spectra and similarities in the spectra of related compounds. It is concluded that the CH3Hg(II) binds to the amino nitrogen at high pH with both cytidine and Ado-5'-P. In neutral solution with excess CH3Hg(II), metalation occurs on the amino groups, on the ring, and also on the ribose.

Adenosine Monophosphate↗
PubMedDate not supplied

[Effect of cataract extraction on the results of in vivo spectrophotometry of the eye].

The authors compared the results of in vivo spectrophotometry of the eye in persons with a normal lens, in patients with aphakia and after an operation of intraocular lens implantation. The results received show that in the range of 400-500 microns half of the light registered by the spectrophotometer is connected with the lens in the eye. This speaks for the assumption that in vivo spectrophotometry in this range of the wave length may be one more method enabling an objective evaluation of the transparency of the lens. In the case of patients after operation of implantation of an intraocular lens the quantity of of the light reaching the retina is only slightly larger than in persons with a normal lens.

Adult↗
PubMed1992

Determination of aluminum in biological fluids by furnace atomic absorption spectrophotometry.

Detailed procedures were developed for the furnace atomic absorption spectrophotometry (FAAS) determination of aluminum (Al) in serum, urine, cerebrospinal fluid (CSF), and proportionated dialysate. Of particular note were the use of Mg (NO3)2.6H2O as a matrix modifier and the employment of the standard additions routine in analysis. The accuracy of the method(s) used is supported by work with assayed controls and by recovery studies. The use of a "clean room" was shown to be unnecessary. Normal serum, urine, and CSF Al ranges observed were 4.8-8.9, 5.1-9.1, and 1.0-5.8 micrograms L-1 respectively.

Aluminum↗