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At least 145 records · Page 8Linked to original sources
PubMed1993

[Monitoring of peripheral tissue oxygenation with near infrared spectrophotometry during abdominal or iliac aortic cross-clamping surgery].

Peripheral tissue oxygenation was monitored with near infrared spectrophotometry during abdominal or common iliac aortic cross-clamping surgery. Six patients who had abdominal aortic aneurysm (AAA) and eight patients who had aortic sclerotic occlusive disease (ASO) were studied. At the beginning of cross-clamping, oxyhemoglobin was decreasing and deoxyhemoglobin was increasing in all AAA patients. Average of 37 minutes following cross-clamping of abdominal aorta, both hemoglobin values were stabilized. On the other hand, changes in both hemoglobin values were delayed or missing in ASO patients. The results suggest that the duration from cross-clamping to stabilization is related to co-lateral blood flow. During operation, monitoring of peripheral blood flow with near infrared spectrophotometry is useful for detection of peripheral ischemia and for the estimation of postoperative local blood flow.

Aorta, Abdominal↗
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↗
PubMed1997

Use of lightguide spectrophotometry to investigate the effect of postural changes on skin oxygenation in deep venous insufficiency.

BACKGROUND: Postural changes play an important role in the development of venous disease. The aim of this study was to investigate skin oxygenation in patients with deep venous insufficiency. METHODS: Haemoglobin oxygen saturation (SO2) was measured with macro- and micro-lightguide spectrophotometry in clinically normal skin at the gaiter area with the leg in the supine position, raised to 45 degrees and on standing. Similarly, transcutaneous oxygen tension (PtcO2) and laser Dopper flux (LDF) values were obtained. SO2 was also measured after heating the skin to 44 degrees C in the supine and standing positions. RESULTS: SO2 and PtcO2 decreased on leg raising (P < 0.05 and P < 0.01 respectively). SO2 fell on standing (P < 0.05) while PtcO2 rose (P < 0.05). On heating the skin, SO2 increased (P < 0.05) on standing. LDF fell on standing (P < 0.005) but increased on leg raising (P < 0.05). CONCLUSION: Lightguide spectrophotometry showed a profound decrease in skin oxygenation on standing and leg raising; PtcO2 measurements may miss the role of vasoconstriction with postural changes.

Adult↗
PubMed2002

Derivative spectrophotometry in the determination of phenyl-beta-naphthylamine used as an antioxidant in rubber mixtures.

A method for the determination of phenyl-beta-naphthylamine (PBN) in ternary mixtures by second-derivative spectrophotometry is described. The procedure works without any separation step of PBN from the other polymer additives. By applying the second-derivative spectrophotometry, Beer's law was valid over the range 0.25-10 micro g mL(-1). The proposed method has been applied to the determination PBN in synthetic ternary mixtures and rubber samples. A comparative study of the results obtained using the second and the third-derivative spectrophotometric methods is presented and evaluated. The derivative spectrophotometric method indicated that the amount of PBN found after extraction from the rubber samples was 0.97+/-0.02 g/100 g of sample.

Journal Article↗
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↗
PubMed1985

The use of derivative and least-squares methods to analyse a polypharmaceutical product by UV spectrophotometry.

Derivative UV spectrophotometry is well established for analysing pharmaceutical products containing more than one drug. By contrast, the least-squares method for over-determined systems is rarely used, because it is assumed that measurements at a large number of wavelengths are needed to obtain good results. Both methods have advantages, and their use in combination is useful for analysing polypharmaceuticals. A combination of derivative and least-squares methods was used to analyse tablets containing pseudoephedrine hydrochloride, triprolidine hydrochloride and dextromethorphan hydrobromide. Pseudoephedrine was determined by derivative spectrophotometry. The other drugs were determined by the least-squares method at higher wavelengths where pseudoephedrine does not absorb. Satisfactory precision for the least-squares method was obtained with a manual spectrometer measuring at six wavelengths and calculating the results with a microcomputer.

Journal Article↗
PubMed2005

Identification of isomers and subsidiary colors in commercial Fast Green FCF (FD&C Green No. 3, Food Green No. 3) by liquid chromatography-mass spectrometry and comparison between amounts of the subsidiary colors by high-performance liquid chromatography and thin-layer chromatography-spectrophotometry.

The existence of five of the six expected isomers in commercial Fast Green FCF (G3: Food Green No. 3, FD&C Green No. 3, CAS No. 2353-45-9, C.I. No. 42053), the main product of which is m,m-G3 and the sub-products of which are presumed to be m,p-G3, o,m-G3, p,p-G3, o,p-G3 and o,o-G3, was confirmed using LC/MS, and the levels of the isomers, m,m-G3, m,p-G3, p,p-G3, o,m-G3 and o,p-G3, were determined by analytical HPLC. The existence of seven subsidiary colors that were decomposed from G3 was also confirmed using LC/MS. The levels of the subsidiary colors in ethanol extracts from TLC were determined by HPLC and spectrophotometry, and these results were compared. It was clear that the values determined by TLC-spectrophotometry were higher than those by HPLC. It was recommended that the levels of subsidiary colors in G3 should be determined by HPLC.

Chromatography, High Pressure Liquid↗
PubMed2001

A comparison of international silica (alpha-quartz) calibration standards by Fourier transform-infrared spectrophotometry.

Seven international silica (alpha-quartz) standards were examined for relative purity to the US National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1878 Respirable alpha-quartz by Fourier Transform-Infrared Spectrophotometry (FT-IR). The standards examined have been used in North America, the UK, Australia and Germany. The 189 samples analyzed included NIST-SRM 1878, Min-U-Sil 5, Ottawa Silica Sand, Sikron F-600, A9950 (AUST 1), DQ12-Robock, DQ12-Bergbau. Size distributions of the standards were determined by Coulter Counter to be broadly similar with equivalent spherical volume median diameter ranging between 1.2 and 3 microm. The results showed the standards to differ by as much as 30% in relative purity. Consequently, an internationally agreed upon calibration standard is urgently needed. Min-U-Sil 5 based NIST-SRM 1878 or Sikron F-600 are the two most likely candidates. Any agreed standard must have a well characterized size distribution and closely match the respirable dust criteria. It should also be studied by both infrared spectrophotometry and X-ray diffraction techniques.

Calibration↗
PubMed1997

Determination of extent of formaldehyde-induced crosslinking in hard gelatin capsules by near-infrared spectrophotometry.

PURPOSE: To predict the degree of crosslinking from formaldehyde-stressed hard gelatin capsules (HGCs) using near-infrared spectrophotometry (NIR). METHODS: HGCs were exposed to a 150 ppb atmosphere of formaldehyde for 2.25, 4.60, 9.42, 16.0 and 24.0 hours. The capsules were filled with fresh amoxicillin, placed in a 90 degrees conical reflector cone, and scanned in a NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the intact capsules. Dissolution profiles were then obtained for each experimental group. RESULTS: The dissolution of amoxicillin from the capsules at pH 1.2 was found to decrease with increasing time of exposure to the formaldehyde atmosphere. A set of principal components (PCs) was formed by a linear combination of the absorbance values at each wavelength scanned. A good correlation was established (r2 = 0.963) when PC values from the NIR spectra of the HGCs were regressed against percentage of amoxicillin dissolved at 45 minutes, at pH 1.2. Water content of the capsules was found to be the largest determinant in the variation between HGC spectra at each exposure time. CONCLUSIONS: NIR spectrophotometry, combined with PCR, was successful at not only predicting dissolution of HGCs exposed to formaldehyde, but also at determining which wavelengths contributed most to spectral variation of these stressed HGCs.

Amoxicillin↗
PubMed2003

Micro-lightguide spectrophotometry as an intraoral monitoring method in free vascular soft tissue flaps.

PURPOSE: The aim of this prospective study was to measure the hemoglobin oxygen saturation (HbO(2)%) and relative Hb concentration of free vascular soft tissue flaps using micro-lightguide spectrophotometry. The objective was to measure the normal range and topographic differences in HbO(2)% and rel. Hb conc. in tissue transfers before establishing this as a clinical method for monitoring perfusion and vitality. PATIENTS AND METHODS: In 39 patients who had received free vascular soft tissue flaps (34 radial forearm flaps; 8 latissimus flaps) to cover defects after tumor surgery, the capillary HbO(2)% in transferred tissue was measured spectrophotometrically preoperatively at the donor site and postoperatively up to the third postoperative day. On average about 500 hemoglobin spectra (200 to 800 spectra) were measured over each 24-hour period. Additionally, the relative Hb concentration was determined for the individual measuring times. The measurements were carried out topographically on the flap base, flap center, and flap periphery. RESULTS: The preoperative HbO(2) values at the donor site of free soft tissue flaps were between 20% and 40% in all topographic regions. In the case of clinically successful flaps, a normal distribution of the HbO(2) values of 20% to 80% was obtained in the immediate postoperative period, and from the second day on, a normal distribution of 45% to 60%. In the case of 2 flaps with partial necrosis, HbO(2) values of less than 10% to 15% were measured from the second postoperative day on. The relative Hb concentration had no influence on the amount of HbO(2)% measured in the transferred capillaries. In the postoperative phase, here was no topographic difference between the individual flap regions. CONCLUSIONS: As a noninvasive method, micro-lightguide spectrophotometry permits quantitative determination of HbO(2)% and relative Hb concentration over the entire surface of soft tissue flaps. In the case of partially unsuccessful flaps, HbO(2) values of less than 10% to 15% were measured beforehand, thus indicating that these HbO(2) values are not sufficient to support the vitality of the free tissue transfer. When combined with clinical observation, application can be recommended for the vitality measurement of free soft tissue flaps and permits more information to be obtained on topographic capillary perfusion conditions.

Adolescent↗
PubMed2004

Influence of pH and time on organic substance release from a model dental composite: a fluorescence spectrophotometry and gas chromatography/mass spectrometry analysis.

In this study we assessed the influence of pH and time on the degradation and elution of organic substances from the composite resin material, Z-100. To accomplish this, fluorescence spectrophotometry was evaluated as an appropriate technique for the identification of six organic substances (methacrylic acid, methyl methacrylate, hydroquinone, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate and 4,4'-isopropylidenediphenol) that were eluted from resin composite material stored for 24 h or 6 months at pH 4.0, 6.0 or 8.0. In addition, complementary analyses (solid-phase microextraction/gas chromatography/mass spectrometry) were carried out to identify and quantify the substances. The main substances leached from the resin composite were methacrylic acid, triethylene glycol dimethacrylate and hydroquinone. It was concluded that fluorescence spectrophotometry seems to be a suitable, non-destructive technique for the qualitative analysis of eluted organic components. Critical combinations of time and pH allowed the elution of several organic substances, predominantly methacrylic acid, triethylene glycol dimethacrylate and hydroquinone, from the model resin composite, Z-100.

Acrylates↗
PubMed1998

Detection of formaldehyde-induced crosslinking in soft elastic gelatin capsules using near-infrared spectrophotometry.

The purpose of this research was to monitor the migration of formaldehyde from a polyethylene glycol (PEG) fill into the gelatin shell of a soft elastic gelatin capsule (SEGC) using near-infrared (NIR) spectrophotometry. SEGCs were filled with five solutions of aqueous formaldehyde in PEG (0, 0.05, 0.10, 0.20, and 0.40 v/v%), stored at ambient conditions for 48 hr, emptied, and scanned in NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the empty capsules. Good correlation was established (r2 = 0.988) when actual concentrations of formaldehyde in the PEG fill of the capsules were regressed against the principal component (PC) values from NIR spectra of the emptied and washed capsules. The loadings of the first PC describe a baseline shift in the spectra that arises from a change in water concentration. Lower PC loadings reveal the presence of signals at 1780 and 2200 nm that are not due to water absorbance, confirming the hypothesis that chemical bonds are formed during the formaldehyde-induced crosslinking of the gelatin in SEGCs. Gelatin crosslinking, initiated by formaldehyde migration from the PEG fill into the shell of an SEGC, was detected by NIR spectrophotometry. When NIR was coupled to principal component analysis, a linear relationship was found between the NIR spectra of empty SEGCs and the amount of crosslinking induced by concentrations of formaldehyde in the original fill material.

Capsules↗
PubMed2000

[The determination of ofloxacin by fluorescence spectrophotometry].

This paper reports the assay of ofloxacin by fluorescence spectrophotometry. The fluorescence strength of ofloxacin is proportional to its concentration within the range from 0.500-25.0 ppm. The linear regression coefficient equals to 0.9999, and the recovery ratio is 99.0%. The results of determination for the samples of ofloxacin capsule from China and Japan are very close to that determined by the ultraviolet spectrophotometry, there isn't any obviously difference which was examined by Student's test. This method is both simplicity and accuracy, also it needs only one kind of reagent. It's believable that this method would be suitable for the use in clinical medicine and pharmaceutical industry.

Anti-Infective Agents↗
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↗
PubMed1999

[Research into simultaneous determination of five components by ridge regression spectrophotometry].

Ridge regression spectrophotometry (LHG) is one of the computational spectrophotometry developed recently. It is used in this paper to the analysis of five component s--acetaminophen, p -aminophenol. p -nitrophenol. p -acetaminophenol acetic acid ester and p -nitrophenol acetic acid ester. The choose of medium and the determination of the amount of mixed standard solution were described in detail. The experimental results show that in the medium of 0.1 mol x L(-1) HCI, the recovery ratio of each component ranges from 95.5% to 106.1% and the RSD ranges from 0.8% to 9.8%. This approach is simple and suitable for the computer-aid analysis. The approach has been used to the analysis of the sample in the course of synthetic acetaminophen.

English Abstract↗
PubMed1998

[Analysis of alpha-Oxo ketene cyclic dithioacetals compounds by using Kalman filtering and UV spectrophotometry].

The Kalman filtering and UV spectrophotometry have been used to analyte the alpha-Oxo ketene cyclic dithioacetal compounds in the present paper. The innovation sequence and concentration trends in the Kalman filtering process have been investigated, results show that the combination of the Kalman filtering and UV spectrophotometry is an applicable and reliable means in analysis of this kind of compounds.

English Abstract↗
PubMed1986

Measurement of aflatoxin B1, its metabolites, and DNA adducts by synchronous fluorescence spectrophotometry.

Sensitive and specific methods are needed for measuring human exposure to carcinogens. Synchronous fluorescence spectrophotometry can be used to measure fmol of aflatoxins, their metabolites, and DNA adducts. Computer-assisted analysis of spectra of these agents obtained by synchronous fluorescence spectrophotometry can be displayed as contour maps which are highly specific for each agent. Individual agents in mixtures, e.g. aflatoxins B1 and M1, can be identified by fourth derivative spectral analysis. This physical method should complement immunological and other methods to measure aflatoxin B1, its metabolites, and nucleic acid adducts.

Aflatoxin B1↗
PubMed2003

[Study and determination of trace Fe (III) with resin-phase spectrophotometry in Mongolian medicine].

Under the buffer medium of HAc-NaAc of pH = 6.00, Fe(III) and 4-(5-chloro-2-pyridylazo)-1, 3-Diaminobenzene form a colored complex which can be quantitatively absorbed on the strong acid cation exchange resin, and the amount of trace Fe(III) is determined by spectrophotometry. The maximum absorption wavelength is at 540 nm, the apparent molor absorptivity is 1.35 x 10(5) L.mol-1.cm-1. The Beer's law is obeyed in the range of 0-18 micrograms.25 mL-1 for Fe(III). The proposed method has been applied to the determination of trace Fe(III) in mongolian medicine with satisfactory results.

Drugs, Chinese Herbal↗