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PubMedDate not supplied

Determination of chromium in feeds by automated microwave digestion and atomic absorption spectrophotometry.

Chromium, as trivalent organic form, has been recently proposed as feed additive to improve animal welfare and the quality-quantity of meat productions. To control its use in animal production we developed an analytical method that consisted of sample digestion by a commercially available focused microwave system and, subsequently, metal determination by graphite furnace atomic absorption spectrophotometry. The mineralization step was performed by treating the samples with a nitric acid-sulphuric acid-hydrogen peroxide mixture. Complete sample digestion was achieved in 26 min, as compared to 8-12 h or more required by dry ashing. To determine method accuracy and precision, we analyzed both feeds spiked at different Cr concentrations and a reference plant material. We found that mean metal recoveries ranged from 98.7 to 102.7% and for the reference material we obtained an excellent agreement between calculated and certified value. Quantitative Cr yields and relative coefficients of variation between 0.77 and 9.7% were very good and accounted for method accuracy and reliability. Finally, we applied the developed method to Cr analysis of some commercial feeds and the results were compared with those obtained by dry-ashing procedure.

Animal Feed↗
PubMedDate not supplied

Determination of lead in wine by graphite furnace atomic absorption spectrophotometry: interlaboratory study.

An interlaboratory study of a graphite furnace atomic absorption spectrophotometry (GFAAS) method for the determination of lead in wine was conducted. Seventeen laboratories from France, United States, and the United Kingdom, using a variety of GFAAS instruments, took part in the study. The method incorporated a novel matrix-matching procedure to minimize matrix effects between standards and samples. Six wine test materials were prepared and sent to participants as 12 blind duplicate or split level samples. There was good agreement between results obtained from participants and target values (24-279 micrograms/L) obtained with an inductively coupled plasma-mass spectrometry method. The precision of the GFAAS method was well within the range predicted by the Horwitz equation for the 6 test materials analyzed. Repeatability standard deviations ranged from 3 to 17%. Reproducibility standard deviations were in the range of 10 to 30%. The method is recommended for use for official purposes.

Food Analysis↗
PubMed1997

[Spectrophotometry of thiols in the blood serum].

The technique of spectrophotometry of thioldisulfide (TDS) ratio in the plasma by methods making use of Ellman's reagent is described. TDS test is regarded as an indicator of the nonspecific resistance of the organism.

Humans↗
PubMedDate not supplied

Merging zones standard addition technique for determination of copper in beer by flow injection atomic absorption spectrophotometry.

A flow injection system for determination of copper in beer by atomic absorption spectrophotometry by the standard additions method is described. The manifold, based on the merging zone technique, prevents the burner head from clogging, as observed with the conventional reference method. With 5 standard additions, results are comparable with those of the reference method. Relative deviations were less than 5.8%, precision was better than 6.4%, and sampling rate was about 30 samples/ h. A less precise, less accurate, but faster procedure (75 samples/h) is possible with only 2 standard additions. The detection limit was 5 micrograms/L.

Beer↗
PubMed1998

[Comparison of two methods of ultraviolet spectrophotometry methods of a mixture of paracetamol/acesulfam-K].

Ultraviolet spectrophotometry can help determined the quantity of paracetamol and acesulfam-K when mixed. The isosbestic wavelength (lambda iso) and the absorbency at the wavelength (Aiso) determined with equimolecular solutions or by annulation of the first derivative at 226 nm for paracetamol determination and at 242.5 nm for acesulfam-K determination can be used.

Acetaminophen↗
PubMed1998

[Atomic absorption spectrophotometry study of copper ion release by copper-bearing intrauterine devices].

Copper release from copper-bearing IUD's was studied in vitro and in vivo using atomic absorption spectrophotometry in deionized water, normal saline solution and normal ovulatory cervical mucus. In these media, copper release from a 375 mm2 DIU occurs without latency, showing comparable amounts for identical time intervals. Daily copper release was shown to be respectively 8 and 11 times higher in cervical mucus and normal saline solution than in deionized water. Although copper ions are detectable in ovulatory cervical mucus under physiological conditions, the copper content appears 5 to 6 times higher in women bearing a copper IUD. Obviously, the copper amount is dependent on the copper exposed surface: the daily in vitro release from a 250 mm2 IUD is 18% inferior to that observed from a 375 mm2 model. In vivo, the daily copper release in ovulatory mucus of 380 or 200 mm2 IUD users is respectively 5 and 3.5 times higher than in controls.

Adult↗
PubMed1976

[Determination of the initial stage of fat auto-oxidation in dry dairy products by ultraviolet spectrophotometry].

Studied were the values of the conjugated dienes using ultraviolet spectrophotometry of fats contained in the dry dairy products produced in this country, such as powdered milk for children, Vitalakt 1, Bébé 1, and Biolakton in the first months of storage. It was found that the extinction maximum values characteristic of the conjugated dienes for the fats of all studied dry milk products were at 227 nm. The juxtaposition of changes taking place with conjugated dienes and peroxide numbers of the fats during storage revealed the greater stability of conjugated dienes in comparison with the hydroperoxides.

Animals↗
PubMed1998

Comparison of absolute cerebral haemoglobin concentration in neonates measured directly and by the oxygen swing method both based on near infrared spectrophotometry.

The total cerebral haemoglobin concentration (tHb in mumol/l) as a major indicator of the oxygen transport capacity is investigated in neonates. Two methods to determine tHb by near infrared spectrophotometry (NIRS) have evolved so far: The first method requires a slow oxygenation change with reference to arterial oxygen saturation (tHbo-method). The second method is based on a geometrical principle and a two channel NIRS instrument (tHbg-method). The aim of this study was to compare both methods quantitatively. 15 clinically stable preterm infants needing supplemental oxygen were included in this study. For each method the measurements of three infants were excluded due to unsatisfactory measurement quality. The remaining 9 neonates had a mean gestational age of 29 (range 25.1 to 31.4) weeks, birthweight of 1272 (740 to 1690) g and a postnatal age of 2.6 (0.5 to 5) days. In each infant 6 tHbo measurements were carried out. During each tHbo measurement the mean of the continuously available tHbg (Cerebral Redox Monitor 2020, Johnson & Johnson Medical) was calculated. The mean of all successful tHbo and corresponding tHbg was determined for each infant. The mean tHbg was 151 mumol/l (range 62 to 223 mumol/l) and the mean tHbo was 59 mumol/l (27 to 113 mumol/l). The regression line between the two methods was tHbg = 1.34 x tHbo + 72 mumol/l. The r was 83.6%. The correlation suggests, that both methods can be applied to measure tHb. However, it has to be taken into account that the tHbg-method returns significantly higher values than the tHbo-method.

Birth Weight↗
PubMed2002

Comparison of potentiometric titration, IR spectrophotometry and segmented micro-flow analysis to determine inorganic C in alkaline solutions.

A segmented micro-flow analysis procedure was described for the determination of total carbonates in alkaline solutions. The method is based on CO(2) diffusion from an acidified sample through a silicone membrane. The gas is then collected in a coloured acceptor solution. The decolouration of the solution due to the trapped CO(2) is then determined by spectrophotometry at a wavelength of 550 nm. The method was evaluated for the range 0-1000 mg C CO(2) L(-1) at a sampling frequency of 60 h(-1). The method was repeatable (RSD better than 1%), accurate (1.5 and 2.5% for standards) and the limit of detection was close to 6 mg C CO(2) L(-1). The results were also compared with those obtained by the potentiometric reference method (PT) and an infrared spectrometric method (IRS). The measurements obtained showed good agreement with those obtained using PT and IRS methods, the PT method being the most accurate. The SFA method appeared to be a really efficient and a more suitable technique for routine C CO(2) determination, although some results showed that for standard solutions, the measured concentrations were significantly different from those obtained with the PT method for concentrations higher than or equal to 800 mg C CO(2) L(-1). For 0.25 M NaOH samples, the three methods tested gave similar results in the range 0-600 mg C CO(2) L(-1).

Journal Article↗
PubMed2003

SEM/EDX and vis spectrophotometry study of the stability of resin-bound mortars used for casting replicas and filling missing parts of historic stone fountains.

A study by SEM/EDX and spectrophotometry in the visible region attempting to assess the stability of new resin-bound mortars used for casting replicas of marble historic fountains is presented in this paper. Different accelerating tests such as thermal ageing, UV light ageing, ageing in an SO(2) pollutant chamber, freezing cycles ageing, salt crystallisation ageing, natural ageing and biological attack have been applied to a series of test specimens prepared with polyester-, epoxy- and gel-coat-bound mortars. Examination of morphology, measurement of chemical composition and chromatic coordinates before and after ageing treatments establish the higher stability and resistance properties of these resin-bound mortars by comparison to those from the natural marbles.

Journal Article↗
PubMed2001

A new method of Fourier-transform smoothing with ratio spectra derivative spectrophotometry.

A new method which combines Fourier-transform smoothing with ratio spectra derivative spectrophotometry has been developed for analysis of binary and ternary mixtures. The method proposed has been applied to the simultaneous determination of a binary mixture of 0.974-2.026 x 10(-2) g L(-1) nitrate and nitrite and to a ternary mixture of 1.840-3.888 x 10(-3) g L(-1) histidine, phenylalanine, and tryptophan. The relative standard derivations are between 0.07 and 5.3% for the former system, and between 0.5 and 7.3% for the latter. The results show that the method proposed is more accurate than multiple linear regression.

Journal Article↗
PubMed1996

Derivative spectrophotometry in the determination of metal ions with 4-(pyridyl-2-azo)resorcinol (PAR).

Derivative spectrophotometry has been applied for the elimination of the mutual spectral interferences and the analysis of binary, ternary and quaternary mixtures of complexes of microgram amounts of divalent ions of cobalt, copper, lead, manganese, nickel, zinc and iron with 4-(pyridyl-2-azo)resorcinol (PAR) in the range of 0.05-1 microg/ml (0.2-4 microg/ml for lead). The first derivative spectra can be used for the determination of both components in the majority of binary mixtures except of Cu(II) and Co(II) and systems containing Fe(II). The second and the third derivative spectra allow to determine one constituent in some ternary and quaternary mixtures.

Journal Article↗
PubMed1997

Effect of aging on the amide group of bone matrix, measured by FTIR spectrophotometry, in adult subjects deceased as a result of violent death.

In order to determine the effects of age on bone quality, human bone tissue taken from adult subjects deceased from violent death was analyzed by means of fast Fourier transform infrared spectrophotometry (FTIR) in the Diffuse Reflectance mode (DR). This technique allows the characterization of both the mineral and organic parts of bone in a nondestructive manner. Only the organic part is discussed in this report. A quantitative change in the entire organic part of bone tissue is observed with the aging of subjects. The effects of these changes on bone strength were not measured.

Adolescent↗
PubMed1984

Spectrophotometry of cerebral cytochrome a, a3 in bloodless rats.

Bloodless, anesthetized Sprague-Dawley rats produced by perfluorochemical exchange transfusion and splenectomy were used to obtain cerebral mitochondrial difference spectra directly through the skull by both reflectance and transmission spectrophotometry. Reflectance peaks were about one-third in amplitude compared to transmission peaks, however percentage reduction levels of cytochrome a, a3 in animals breathing 100% oxygen were comparable. Cytochrome a, a3 was 13-14% reduced under these conditions as determined by the ratio of the optical density difference at 605 minus 620 nm to the optical density difference at the same wavelength pair with maximal cytochrome a, a3 oxidation during respiration on 95% oxygen + 5% carbon dioxide at 3 and 4 atm. absolute pressure.

Animals↗
PubMed1995

Measurement of vascular permeability in spinal cord using Evans Blue spectrophotometry and correction for turbidity.

Vascular permeability can be visualized by Evans Blue (EB) extravasation and quantified by spectrophotometry after formamide extraction of the tissue. However, formamide extracts show significant turbidity, which may contribute to the total optical density at the wavelength of measurement (e.g., 620 lambda). We developed a simple method for estimating the component of the total optical density of a dyed specimen contributed by turbidity. Our method, which uses a determination of turbidity made at another point of the light spectrum (740 lambda), was more precise than two other EB quantification techniques. We therefore recommend it for individual correction of formamide extracts of spinal cord specimens. The application of this technique to the brain remains to be determined.

Animals↗
PubMed1988

Determination of p-aminosalicylic acid and m-aminophenol by derivative UV-spectrophotometry.

A direct method for the simultaneous determination of p-aminosalicylic acid (PAS) and its major decomposition product, m-aminophenol (MAP), is described. The analysis is based on the use of derivative UV-spectrophotometry and is a rapid procedure which gives accurate and precise results. A simple purity test which utilizes the third derivative spectrum is also reported and compared with the USP XX spectrophotometric method for the estimation of MAP in PAS formulations.

Journal Article↗