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PubMed1975

Improved method for densitometry of electrophoretic lipoprotein fraction.

We evaluated a method for the densitometric quantitation of the electrophoretic lipoprotein fractions that sets the limit of integration at the beta-lipoprotein peak maximum. Results were compared with the more conventional method of placing the limit of integration in the valley between the beta- and pre-beta-lipoprotein peaks. The criterion of symmetrical beta-lipoprotein peaks imposed by the method was tested, and manual determination of the beta peak maximum was compared to automatic computer analysis. Computer-generated curves stimulating increasing overlap of constant shape beta and pre-beta peaks were analyzed by the two methods. The conventional method introduces an error that increases with increasing overlap, but with the present method results agreed with those for completely resolved peaks. The beta peak was best approximated by an isosceles triangle (at least for the electrophoresis technique used in these studies), indicating symmetry of the beta peak. Values for the area under the lipoprotein peaks obtained by manual and computer placement of the integration limits agreed well (gamma = .892 to .998; SE of estimate = .0264 to .0306). The "beta peak maximum" method of densitometric quantitation avoids the problems associated with partial resolution of the beta- and pre-beta-lipoproteins. It is equally adaptable to either visual placement of the limits of integration or computer analysis.

Computers↗
PubMedDate not supplied

High-performance thin-layer chromatography with densitometry for the determination of ciprofloxacin and impurities in drugs.

A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform-methanol-25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO-methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 microg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.

Chromatography, Thin Layer↗
PubMedDate not supplied

Identification and quantitation of polymyxin B, framycetin, and dexamethasone in an ointment by using thin-layer chromatography with densitometry.

A new thin-layer chromatographic-densitometric method has been developed for rapid identification and quantitative determination of polymyxin B, framycetin, and dexamethasone in a dental ointment. Silica gel 60 and F254 silica gel 60 plates were used for separating antibiotics and dexamethasone acetate, respectively. When determining framycetin and polymyxin B, chromatograms were developed by using 2 mobile phases, namely methanol and methanol-n-butanol-ammonia (25%)-chloroform (14 + 4 + 9 + 12, v/v/v/v/). The densitometric measurements were made at 550 nm after detection with 0.3% ninhydrin solution. Dexamethasone was determined by using the mobile phase cyclohexane-ethyl acetate (2 + 3, v/v) and ultraviolet densitometric recording at 245 nm. The results obtained for individual constituents with the chromatographic-densitometric method demonstrate similar accuracy, relative standard deviation values from 1.49 to 2.47%, and relative error values from 0.02 to 0.81% and are comparable to those obtained with the reference methods.

Chromatography, Thin Layer↗
PubMedDate not supplied

Thin-layer chromatography-densitometry and liquid chromatography analysis of alkaloids in leaves of Papaver somniferum under stress conditions.

The effect of stress conditions on the concentrations of secondary metabolites were examined during various developmental stages of Papaver somniferum plants. P. somniferum plants were grown in laboratory conditions (Budakalász). The experiment consisted of 22 treatments. Significantly different alkaloid contents can be observed under different stress conditions. In general, the alkaloid contents of plants are very low; therefore, a highly sensitive and reliable method has to be developed for analysis. The amount of alkaloids was measured by 2 separation and detection techniques. Accuracy of the thin-layer chromatography method for quantitative analysis is limited. Without purification of samples the background is too noisy. Column liquid chromatography is a sensitive and relatively inexpensive method that allows precise quantitative determination of the alkaloid content.

Alkaloids↗
PubMedDate not supplied

[Role of densitometry and scintigraphy in post-traumatic algodystrophy of the arms. Initial diagnosis and monitoring during treatment with carbocalcitonin].

In 24 patients affected with post-traumatic reflex sympathetic dystrophy syndrome (RSDS) with upper limb involvement following humeral fractures, bone mineral density (BMD, mg/cm2) was measured by means of dual-photon absorptiometry in the distal radius of both the affected and the normal contralateral limbs. Subsequently, all patients underwent dynamic and static scintigraphic exams after i.v. injection of 99mTc-MDP (20 mCi), with gamma camera collimator centered in both limbs. BMD values were significantly lower in the affected sides than in the normal contralateral ones. Time-activity curves with MDP showed increased flow in the involved limbs. Significant increase in blood pool and in bone uptake was also observed. After carbocalcitonin treatment (80 U/q.d. i.m. in 12 cases and 40 U/q.d. i.m. in the other 12 cases for a month) all the patients presented improved clinical symptoms and significant increase in BMD, that was restored to normal values in 7 of the patients who had a longer treatment (40 U/q.d. i.m. for 2 months). Both local blood flow and bone uptake in the affected side significantly decreased after carbocalcitonin therapy while bone avidity index increased in those patients in whom this parameter had been measured. Our results confirm the usefulness of radioisotopic procedures in post-traumatic RSDS for both diagnosis (by demonstrating increased local blood flow and early bone demineralization) and monitoring response to treatment with carbocalcitonin, which seems to play an important role in this condition.

Adult↗
PubMed1990

Thin layer densitometry in the quantitative assay of drugs. Note V--Assay of reserpine and chlorthalidone in the presence of the potential impurities of their solid pharmaceutical forms.

Densitometric detection of compounds separated by thin layer was applied to the assay of a mixture of reserpine and chlorthalidone and their possible impurities. The method of analysis gave satisfactory results in the quality control of pharmaceutical preparations. Good results were obtained in urine tests for the detection of chlorthalidone, reserpine and methylreserpate. The times for the development of fluorescence in reserpine and methylreserpate directly in the chromatographic plate, are also described.

Chlorthalidone↗
PubMed1990

Bone densitometry.

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Absorptiometry, Photon↗
PubMed1990

Current and innovative methods for noninvasive bone densitometry.

This article summarizes a variety of noninvasive techniques for measuring bone density in the clinical setting. Although dual-energy x-ray absorptiometry and quantitative computed tomography are currently the most widely used methods, older techniques such as radiogrammetry and single-photon absorptiometry continue to have research applications, and experimental approaches such as compton scattering and proton activation analysis may be important in the future. The evaluation of bone mass measurement underscores continuing progress in our understanding of bone metabolism and biomechanics, and has provided valuable insight into improvements in the therapy of osteoporosis and other forms of metabolic bone disease.

Absorptiometry, Photon↗