Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Spectrophotometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Lacrimal sac dacryolith: a study wit atomic absorption spectrophotometry and scanning electron microscopy.

Dacryoliths are uncommon causes of partial or complete obstruction of the nasolacrimal drainage apparatus. We report our findings of a dacryolith that we studied by culture, light microscopy, atomic absorption spectrophotometry, and scanning electron microscopy. Although no fungi were recovered by culturing, hyphae-like structures were observed. No inorganic material was detected by atomic absorption spectrophotometry. Scanning electron microscopy of ultrastructure showed the stone was composed of lobes and lobules built on an amorphous core material.

Calculi↗
PubMed1990

Carbon dioxide-related changes in cerebral blood volume and cerebral blood flow in mechanically ventilated preterm neonates: comparison of near infrared spectrophotometry and 133Xenon clearance.

Carbon dioxide-induced changes in near infrared spectrophotometry recordings were compared with changes in cerebral blood flow estimated by 133Xenon clearance (global cerebral blood flow (infinity)) at serial measurements in 24 mechanically ventilated preterm infants (mean gestational age 30.2 wk). In all infants, three measurements were taken at different arterial carbon dioxide tension levels (mean 4.4 kPa, range 2.1-7.8) obtained by adjustment of the ventilator settings. Mean arterial blood pressure changed spontaneously, whereas arterial oxygen tension was kept within normal range. At all wavelengths (904, 845, 805, and 775 nm), the OD increased at higher arterial carbon dioxide tension levels, indicating cerebral vasodilation. This conclusion was supported by conversion of the data to changes in oxygenated and deoxygenated Hb concentration. A parallel increase in cerebral blood volume index and global cerebral blood flow (infinity) was found (p less than 0.0001). The oxygenation level of cytochrome aa3 increased with increases in oxygen delivery (p less than 0.0001). This observation, however, may have been artifactual due to cross-talk between the oxidized cytochrome aa3 and the oxygenated Hb signals, as these signals were closely interrelated in the present experimental design. We suggest that near infrared spectrophotometry may be used for estimation of the cerebral blood volume index/cerebral blood flow-CO2 reactivity within a wide range of arterial carbon dioxide tension. Knowledge of the light path length would put this estimation on a quantitative basis.

Birth Weight↗
PubMed2006

Spectrophotometry for cerebrospinal fluid pigment analysis.

The use of spectrophotometry for the analysis of the cerebrospinal fluid (CSF) is reviewed. The clinically relevant CSF pigments--oxyhemoglobin and bilirubin--are introduced and discussed with regard to clinical differential diagnosis and potentially confounding variables (the four T's: traumatic tap, timing, total protein, and total bilirubin). The practical laboratory aspects of spectrophotometry and automated techniques are presented in the context of analytical and clinical specificity and sensitivity. The perceptual limitations of human color vision are highlighted and the use of visual assessment of the CSF is discouraged in light of recent evidence from a national audit in the United Kingdom. Finally, future perspectives including the need for longitudinal CSF profiling and routine spectrophotometric calibration are outlined.

Bilirubin↗
PubMed1982

[Automated microdetermination of lead in capillary blood from earlobes by flameless atomic absorption spectrophotometry].

Recent development of flameless atomic absorption spectrophotometry has made possible more precise and sensitive determinations of metals including lead. This means that a sample size of microliter order of blood has come to give a sufficient analytic signal. Blood lead which has usually been determined using venous blood was determined in the present study using a small amount of capillary blood. The method developed is of lead determination in the capillary blood sample from earlobe by means of flameless atomic absorption spectrophotometry equipped with an automated microsampling system or autosampler. Thus, 70 microliters of heparinized whole blood sample from earlobe gave a satisfactory result in the lead analysis. The procedure is as follows. 1) Blood obtained from the earlobe is collected in a heparinized capillary tube. 2) The blood is diluted in the ratio of 1 : 9 with Triton 5000 X solution for complete hemolysis of erythrocytes, by which the matrix-bound lead is released and a better distribution of samples is made possible in the graphite tube. 3) Finally the sample is analyzed by a flameless atomic absorption spectrophotometer with an autosampler. Making sure the analytical method to be accurate and reliable for blood lead determination, the authors compared capillary blood lead levels (Pb-Bc) with venous ones (Pb-Bv) from the same subjects in the same sampling session. It was found that the correlation between Pb-Bc and Pb-Bv was highly significant (n = 144, r = +0.998, y = 0.97 x+0.32, p less than 0.001) and that they were almost of the same level. It was concluded that the method developed may be recommended for the routine clinical use.

Adult↗
PubMed1994

Clinical evaluation of severe ischemic limbs by tissue reflection spectrophotometry.

The clinical usefulness of tissue reflection spectrophotometry in the prognosis of ischemic limbs was evaluated. The diseased group (n = 12) consisted of 7 cases of femoral artery thrombosis, 4 cases of chronic obstructive arteriosclerosis and 1 case of femoral vein thrombosis. The normal control group consisted of 14 limbs in 7 normal subjects (n = 14). Index of tissue hemoglobin concentration (IHb) was 37.3 +/- 4.5 (n = 14) in the normal control group and 38.5 +/- 16.9 (n = 12) in the diseased group, which was not significantly different. In a subgroup of patients who required amputation or developed necrosis (severe subgroup), the value was 54.2 +/- 1.7 (n = 6). This was significantly higher than the value of 22.8 +/- 8.5 (n = 6) obtained in a subgroup of patients who received the conservative treatment of thrombectomy (mild subgroup) (p < 0.05). Index of tissue oxygen saturation (ISO2) was 28.0 +/- 4.9 (n = 14) in the normal control group, and 9.1 +/- 2.7 (n = 12) in the diseased group (p < 0.05). ISO2 was 7.0 +/- 1.6 (n = 6) in the severe subgroup which was significantly lower than 11.2 +/- 1.9 (n = 6) in the mild subgroup (p < 0.05). Tissue reflection spectrophotometry therefore appears to provide clinically useful information for the prognosis of ischemic limbs.

Adult↗
PubMed1986

Copper in seminal plasma: comparison of two processing methods for atomic absorption spectrophotometry.

Fifty-three randomly selected seminal plasma samples were assayed for copper by atomic absorption spectrophotometry. All the samples had undergone two accepted processing methods--wet oxidation and dilution. The results were compared, and a highly significant difference was seen (p less than 0.001). The dilution method gave the better reading and was simpler in processing. The author recommends the dilution method for elemental study in seminal plasma by using atomic absorption spectrophotometry.

Copper↗
PubMed2004

Accuracy of indocyanine green pulse spectrophotometry clearance test for liver function prediction in transplanted patients.

AIM: To investigate whether the non-invasive real-time Indocyanine green (ICG) clearance is a sensitive index of liver viability in patients before, during, and after liver transplantation. METHODS: Thirteen patients were studied, two before, three during, and eight following liver transplantation, with two patients suffering acute rejection. The conventional invasive ICG clearance test and ICG pulse spectrophotometry non-invasive real-time ICG clearance test were performed simultaneously. Using linear regression analysis we tested the correlation between these two methods. The transplantation condition of these patients and serum total bilirubin (T. Bil), alanine aminotransferase (ALT), and platelet count were also evaluated. RESULTS: The correlation between these two methods was excellent (r(2)=0.977). CONCLUSION: ICG pulse spectrophotometry clearance is a quick, non-invasive, and reliable liver function test in transplantation patients.

Coloring Agents↗
PubMed1999

[In vitro evaluation of mercury leakage from dental amalgam using atomic absorption spectrophotometry].

OBJECTIVE: The use of silver amalgam as a tooth filler is under constant critical review because of its mercury content. After a review of the literature on this subject, in vitro spectrophotometry was used to assay the release of mercury by these amalgams in basal conditions. METHODS: The experiment was conducted in two phases using standard doses of amalgam. In Phase 1 Black Class I cavities were created in extracted teeth that were big enough to take the required dose of amalgam. In some cases the material was inserted in a single operation, while in others the amalgam was introduced in three stages. Some of the cavities were cleansed with cotton buds bathed in ethyl alcohol, while others were not. All the drilled teeth were imbued in a bath of artificial saliva held at a constant temperature. In the second experiment, crushed amalgam was immersed in a similar bath of artificial saliva but otherwise untreated. The saliva was assayed after different time lapses using atomic absorption spectrophotometry and the FIAS technique. RESULTS: The results showed extremely variable but always modest quantities of free mercury in the artificial saliva. CONCLUSIONS: The findings suggest that not all the mercury available in the amalgamation phase is involved in the formation of the crystalline reticulum and that the percentage of mercury bonded is different every time. While the titre of free mercury encountered was always extremely low and hard to predict, it cannot be ignored.

Dental Amalgam↗
PubMed1997

[Application of spectrophotometry to evaluation of the levels and the influence of chemotherapeutic drugs on ATP of malignant cell lines].

To evaluate the value of ATP spectrophotometry for malignant tumor in vitro chemosensitivity test, Hela and L929 cell lines, which were derived from human cervical carcinoma and mouse fibroma respectively, were investigated. The results showed that when the cellular numbers were > or = 2 x 10(5), the linearity between the ATP concentrations and the cellular numbers was observed, with all 2 cell types studied, and that when L929 cells were incubated with cis-platinum (1x, 2x, 5x x plasma peak concentration, PPC), a marked fall in ATP concentrations was observed and a clear dose-response curve was obtained, but no decrease of ATP concentrations was measured after incubation with adriamycin (1x, 2x, 5x x PPC). This study suggests that ATP spectrophotometry is a cheap, feasible method for studying the energy metabolism and the influence of chemotherapeutic drugs on ATP concentrations of malignant tumor.

Adenosine Triphosphate↗
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↗
PubMedDate not supplied

Simultaneous determination of estradiol and medroxyprogesterone acetate in pharmaceutical formulations by second-derivative spectrophotometry.

This paper reports a simple and fast method for the simultaneous determination of estradiol (ED) and medroxyprogesterone acetate (MP) in pharmaceutical formulations by second-derivative spectrophotometry. Methanol was used to extract the drugs from formulations, and subsequently the extracts were evaluated directly by derivative spectrophotometry. The drugs were determined simultaneously by using the graphic method at 297.4 nm for ED and the zero-crossing method at 273.4 nm for MP. If both compounds are present together in a sample, it is possible to quantitate one in the presence of the other. The best signal-to-noise ratio was found when the second derivative of the spectrum was used. The linear ranges for determination of the drugs were 4.7 x 10(-6) to 1.6 x 10(-4) and 7.2 x 10(-6) to 2.0 x 10(-4) mol/L for ED and MP, respectively. The ingredients commonly found in commercial pharmaceutical formulations do not interfere with the determination. Chemical and spectral variables were optimized for the determination of both analytes. Good levels of repeatability (relative standard deviation), 1.4 and 1.9%, were obtained for ED and MP, respectively. The proposed method was applied to the determination of these drugs in pharmaceutical formulations.

Chemistry Techniques, Analytical↗
PubMedDate not supplied

Simultaneous determination of dapsone and pyrimethamine by derivative spectrophotometry in pharmaceutical formulations.

A simple and fast method was developed for the simultaneous determination of dapsone and pyrimethamine by first-order digital derivative spectrophotometry. Acetonitrile was used as a solvent to extract the drugs from the pharmaceutical formulations, and the samples were subsequently evaluated directly by digital derivative spectrophotometry. The simultaneous determination of both drugs was performed by the zero-crossing method at 249.4 and 231.4 nm for dapsone and pyrimethamine, respectively. The best signal-to-noise ratio was obtained when the first derivative of the spectrum was used. The linear range of determination for the drugs was from 6.6 x 10(-7) to 2.0 x 10(-4) and from 2.5 x 10(-6) to 2.0 x 10(-4) mol/L for dapsone and pyrimethamine, respectively. The excipients of commercial pharmaceutical formulations did not interfere in the analysis. Chemical and spectral variables were optimized for determination of both analytes. A good level of repeatability, 0.6 and 1.7% for dapsone and pyrimethamine, respectively, was observed. The proposed method was applied for the simultaneous determination of both drugs in pharmaceutical formulations.

Antimalarials↗
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↗
PubMed2003

[Simultaneous determination of ammonium thiocyanate and its isomeride by dual wavelength multiplication subtractive spectrophotometry].

A method was purposed for simultaneous determination of ammonium thiocyanate and its isomeride thiourea by dual wavelength multiplication subtractive spectrophotometry. The approach was based on the measurement of the absorbance of both standard solutions and mixture samples at 216 and 236 nm. The concentration of ammonium thiocyanate and thiourea was obtained through the calculation of balancing coefficient and slope. The method was successfully applied to the determination of ammonium thiocyanate and thiourea, which existed in isomerization reaction. A comparison was also made with the dual wavelength method and reversed ion-pair chromamotography, and the dual wavelength multiplication subtractive spectrophotometry offered the advantages of simple, rapid and accurate determination.

Isomerism↗
PubMed2000

[Determination of artificial synthetic pigment by excitation spectrophotometry].

Solid phase spectrophotometry is a mew, simple, fast and sensitive trace analytical method. In this report, it is presented with a method that the polyamide was used for the absorbance and the excitation spectra was measured directly. The background of the solid phase spectrophotometry was overcome, the sensitivity was increased in a big way. The method is good standard addition recovery and precision, high accuracy. Not only the trace inorganic ion can be analysed by the solid phase method, but also the artificial synthetic pigment, the result was satisfied.

Adsorption↗
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↗
PubMed2003

[Derivation absorption spectrophotometry in the ultraviolet range as an alternative to HPLC and other instrumental methods of drug analysis].

A comparison of the results obtained by derivation absorption spectrophotometry in the ultraviolet region and those obtained by HPLC and other instrumental methods of quantitative analysis of drugs reveals that derivation spectrophotometry can be an economically advantageous alternative in many cases. The results of the determination of one drug on an interfering background or of two substances beside one another are usually comparable; for the evaluation of the determination of three or more substances enough data are not available.

Chromatography, High Pressure Liquid↗
PubMed2004

[Determination of microamounts of palladium by triple-wavelength overlapping spectrophotometry].

The method for the determination of microamounts of palladium with 2-(3,5-dichlolor-2-pyridylazo)-5-dimethylaminoaniline (3,5-diCl-PADMA) by triple-wavelength overlapping spectrophotometry has been developed. It's shown that in the medium of 0.02-1.6 mol x L(-1) H2SO4, Pd reacts with 3,5-diCl-PADMA to form a stable 1:1 green-blue complex, which has two different positive absorption peaks and one negative absorption peak at 621 nm, 574 nm and 434 nm respectively, and their absorbance sum showed good linearity with Pd concentration. The apparent molar absorptivity is 2.03 x 10(5) L x mol(-1) x cm(-1), which is twice as high as that of single-wavelength spectrophotometry. Beer's law is obeyed in the range of 0-1.2 mg x L(-1) for palladium. Relatively large amounts of co existing elements, including other precious metal ions, can be tolerated. The method is simple, highly sensitive and selective, and has been used to the determination of microamounts of Pd in ore, alloy and molecular sieve with satisfactory results.

Light↗