The Application of Atomic Absorption Method as a Flow Detector to Gel Chromatography

Abstract

The applicability of atomic absorption method as a flow detector to gel chromatography was discussed. The effluent from the outlet of a Sephadex G-15 column was directly introduced into a nebulizer of atomic absorption spectrometer. It was found that the atomic absorption flow detector was sensitive and highly selective so as to permit the quantitative determination of metal ions. Some advantageous aspects of this detector were also discussed.     

Dosage Du Mercure Dans Les Eaux Naturelles Non Ou Peu Polluees Apres Extraction Par Le Systems Pyrrolidinedithiocarba -Mate-Carbonate De Propylene

Abstract

A procedure for determination of mineral mercury in soft water and sea water is described for the concentrations in the range 5–500 ng. 1^?1. This method involves formation of the mercury-pyrrolidinedithiocarbamate complex which is extracted by propylene carbonate. The extracted mercury is reduced in this solvent by stannous chloride and quickly entrained by nitrogen. The amount of mercury is determined by atomic absorption spectrophotometry at 253. 7 nm.     

Atomic Absorption Determination of Some Amino Acids Containing a Sulphur Group

Abstract

A simple and rapid atomic absorption method for the determination of some amino acids containing a sulphur group is described. The studied compounds are cysteine, cystine and methionine. The method is based on the addition of an excess of mercury (II) chloride in phosphate buffer, pH 9, forming a white precipitate; the unreacted mercury is separated by centrifugation and the mercury ions in both precipitate and filtrate are determined by atomic absorption spectrophotometry at 253.6 nm. The concentration of the studied amino acids is then indirectly determined from a calibration curve for standard mercury (II) chloride solution.

The procedure has been successfully applied to the assay of the pharmaceutical preparations of the studied drugs after thin-layer chromatographic separation. The results of the studied compounds compare favourably with the official methods.     

The Determination of Trace Transition Elements in Biological Tissues Using Flameless Atom Reservoir Atomic Absorption

Abstract

The development of an analytical technique generally applicable to the determination of Ag, Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn in all biological tissues is described. All of these elements may readily be determined in tissue samples of less than 0.5 g using flameless atom reservoir atomic absorption with a Perkin-Elmer heated graphite atomizer. Some of the operational characteristics of this atomizer system are discussed. The utility of the method is illustrated by analyses of selected marine biota and of NBS standard orchard leaves.     

Spectral Interference in Antimony Analysis with High Temperature Furnace Atomic Absorption

Abstract

Background correction in atomic absorption spectrophotometry using a high temperature furnace has a close relation to the chemical treatment and the detection limit. Conventionally used for this correction is the D₂ lamp method, but spectral interference is inevitable in this method because the spectral bandwidth of the light from the D₂ lamp after passing through a monochromator is as wide as 0.1 to 5 nm. In the analysis of Sb in lead alloy or in steel, there is spectral interference due to high concentration of elements such as Pb, Cu or Fe, in the matrix, so accurate measurement is impossible unless these elements are removed at the pretreatment stage.

In polarized analyte Zeeman atomic absorption spectrophotometry developed by the authors, the wavelength of the measuring beam is the same as that of the reference and they are identical in spectral line profile as well as in geometrical shape. They differ only in the direction of polarization. For these reasons, we found that there is no spectral interference like that recognized in the D₂ lamp correction technique. As a result, a direct analysis was done simply by dissolving gunmetal or steel in acid without removing the matrix elements Pb, Cu or Fe.     

Determination of Bismuth in Geological Materials by Flow Injection Hydride Generation Atomic Absorption Spectrometry

Abstract

Flow injection analysis (FIA) has been applied to sample introduction in conjunction with automated hydride generation and AAS techniques for the determination of Bi in rock samples. The powdered rock sample is digested with a mixture of hydrofluoric, perchloric, and nitric acids. The evolved hydride is carried through to a heated quartz tube by a stream of argon, and the atomic absorption of Bi is measured at 223.2 nm.

Thiosemicarbazide and 1,10 - phenanthroline are used as masking agents to control interferences from Cu and Ni. The method permits the accurate determination of Bi in geological materials at levels as low as 10 ppb with an analysis rate of more than 50 digested samples per hour. Bi values on 13 international geological reference samples are reported.     

Application of High Pressure Liquid Chromatography to the Forensic Analysis of Several Benzodiazepines

Abstract

Eleven benzodiazepines are separated and measured by an HPLC adsorption system utilizing isocratic elution combined with dual wavelength detection at 254 nm and 280 nm. Powder and solid dosage forms of 10 benzodiazepines are simply ground and then extracted with chloroform and injected. Clorazepate dipotassium is not soluble in chloroform and is decarboxylated to N-desmethyldiazepam.     

THE ACTION SPECTRA FOR UV-INDUCED SUPPRESSION OF MLR and MECLR SHOW THAT IMMUNOSUPPRESSION IS MEDIATED BY DNA DAMAGE

-Ultraviolet-B (UVB,280–320 nm) radiation can promote the induction of skin cancer by two mechanisms: damage of epidermal DNA and suppression of the immune system, allowing the developing tumor to escape immune surveillance. The mixed lymphocyte reaction (MLR) and the mixed epidermal cell lymphocyte reaction (MECLR) are commonly used methods to study the immunosuppressive effects of UVB radiation. To obtain a better understanding of the mechanism by which UVB radiation decreases the alloactivating capacity of in vitro-irradiated cells, action spectra for the MLR and MECLR were determined. Suspensions of peripheral blood mononuclear cells or epidermal cells were irradiated with monochromatic light of 254, 297, 302 or 312 nm and used as stimulator cells in the MLR or MECLR. Using dose-response curves for each wavelength, the action spectra were calculated. Both MLR and MECLR action spectra had a maximum at 254 nm and a relative sensitivity at 312 nm that was a thousand times lower than at 254 nm. Strikingly, the action spectra corresponded very closely to the action spectra that were found by Matsunaga et al. (Photochem. Photobiol. 54,403–410, 1991) for the induction of thymine dimers and (6-4)photoproducts in irradiated calf thymus DNA solutions, strongly suggesting that the UV-induced abrogation of the MLR and MECLR responses is mediated by UV-induced DNA damage. Furthermore, the action spectra for the MLR and MECLR were similar, suggesting that they share a common mechanism for UV-induced suppression.     

Determination of Aluminium in Dialysis Fluids and Graphite-Tube Furnace Atomic Absorption Spectroscopy Using the l'Vov Platform

Abstract

A method was developed for aluminium determination in dialysis fluids by graphite-tube furnace atomic absorption spectroscopy utilizing the L'vov platform.

Results are reported for various kinds of dialysis fluids.

In all cases accuracy and precision of the analytical procedure were ascertained.     

Determination of Vanadium with Chlorosubstituted Hydroxamic Acids for Photometric and Atomic Absorption Spectrophotometric Determination

Abstract

The eight newly synthesized chlorosubstituted hydroxamic acids are described for the extraction and spectrophotometric determination of vanadium. The sensitive and selective reagent, N-m-Chlorophenylpalmito hydroxamic acid, (m-CPPHA), which gives violet coloured vanadium complex was extracted with chloroform from 6M HCl. The violet coloured complex thus obtained has a maximum absorbance at 520 nm and molar absorptivity 4.9 ± 10³1mol^?1cm^?1. The Beer's law obeyed in the region 0.50-12.0ppm. Effects of acidity, reagent concentration, diverse ions have also been investigated. A comparison has been made with atomic absorption spectrophotometric method. Vanadium has been determined in the environment, e.g. plant, soil, rock, etc.     

Anionic and Nonionic Detergent Determination by Flameless Atomic Absorption Spectrophotometry

Abstract

Procedures for the determination of anionic and nonionic detergents in natural waters are described. Flameless atomic absorption spectrophotometry enables reduction of the sample volume and of the number of steps in the procedure. Sensitivities are better than 10 μg.1^?1 and relative standard deviations are of the order of 5%.     

Rapid Scheme of Silicate Analysis Based on The Lithium Metaborate Fusion Followed By Atomic Absorption Spectrometry I. Determination of Silica

Abstract

A method for the rapid determination of silica in silicates is given based on the superior lithium metaborate fusion with a view to the development of a total atomic absorption scheme of silicate analysis using this fusion. Interferences usually associated with solutions of this nature are studied. Results are given for several standard silicate samples.     

High-Performance Liquid Chromatographic Determination of Progesterone

Abstract

A practical, rapid, reliable and isocratic reversed-phase HPLC method is described for the determination of progesterone; a method important for determining in cows (1) early pregnancy, (2) reproductive disorders, and (3) timing of artificial insemination. The method is reproducible with a detection limit of 0.5 ng/peak (400 pg/μl) at 254 nm (0.005 AUFS); down by nearly 10-fold from other methods and using simple 254 nm detection. Radioimmunoassay of all eluting fractions demonstrated specificity.     

DIFFERENTIAL SENSITIVITY TO INACTIVATION OF NUR AND NUR+ STRAINS OF ESCHERICHIA COLI AT SIX SELECTED WAVELENGTHS IN THE UVA,UVB AND UVC RANGES*

The radiation response of stationary-phase cells of Escherichia coli strains RT4 (nur⁺) and RT2 (nur) was measured at 6 selected wavelengths between 254 and 405 ran. The relative response of the nur⁺. and nur strains was almost the same at 254 and 290 nm. However, the differential sensitivity of the RT4 and RT2 strains (ratio of the initial F₃₇ values of the nur⁺ to the nur strains) was 2.7 at 313 nm, 3.2 at 334 nm, 3.1 at 365 nm, and 2.3 at 405 nm. Thus, the fluence enhancing effect of the nur genotype extends over the wavelength range of approximately 300 to 420 nm. The substantial effect of nur at 313 nm strongly suggests that the increased sensitivity of the nur strain is the consequence of a repair deficiency that reduces the efficiency of mending DNA lesions produced by UVA (320–400 nm) and UVB (290–320 nm), but not UVC (200–290 nm) radiation.     

Oxygen-independent inactivation of Haemophilus influenzae transforming DNA by monochromatic radiation: action spectrum, effect of histitine and repair.

Abstract— The action spectrum for the oxygen-independent inactivation of native transforming DNA from Haemophilus influenzae with near-UV radiation revealed a shoulder beginning at 334 and extending to 460 nm. The presence of 0.2 M histidine during irradiation produced a small increase in inactivation at 254, 290 and 313 nm, a large increase at 334 nm and a decrease in inactivation at 365, 405 and 460 nm. Photoreactivation did not reverse the DNA damage produced at pH 7.0 at 334, 365, 405 and 460 nm, but did reactivate the DNA after irradiation at 254, 290 and 313 nm. The inactivation of DNA irradiated at 254, 290 and 313 nm was considerably greater when the transforming ability was assayed in an excision-defective mutant compared with the wild type, although DNA irradiated at 334, 365, 405 and 460 nm showed smaller differences. These results suggest that the oxygen-independent inactivation of H. influenzae DNA at pH 7 by irradiation at 334, 365, 405 and 460 nm is caused by lesions other than pyrimidine dimers.     

Safety Evaluation of Far-UV-C Irradiation to Epithelial Basal Cells in the Corneal Limbus

Basal cells in the corneal limbus play an important role in the turnover cycle because they are the source of all cells that constitute the corneal epithelium. We examined the penetration depth of ultraviolet (UV) light in the corneal limbus and assessed the safety of Far-UV-C on stem cells in the basal area of the corneal limbus. Rats were irradiated with UV at peaks of 207, 222, 235, 254 and 311 nm while under anesthesia. The UV penetration depth in the rat corneal limbal epithelium was wavelength dependent: 311 nm UV-B and 254 nm UV-C reached the basal cells of the epithelium, and 235 nm radiation reached the middle area; however, 207 and 222 nm UV-C reached only the superficial layer of the epithelium. Porcine cornea, which is similar to the human eye in size and structure, were irradiated with 222 and 254 nm UV-C. As in rats, 222 nm UV-C reached only the superficial layer of the porcine corneal limbal epithelium. These results indicate that Far-UV-C, such as radiation of wavelengths of 207 and 222 nm, could not reach corneal epithelial stem cells, i.e. the cells remained intact. It is unlikely that the turnover of the corneal epithelium is obstructed or disrupted by exposure to Far-UV-C.     

Determination of Tellurium by Electrothermal Atomic Absorption Spectroscopy: Isolation of Tellurium from Potential Interferences

Abstract

The determination of tellurium at nanogram levels using electrothermal atomic absorption spectroscopy is examined. Severe interferences are observed in the presence of many elements but can be overcome by the use of a sequential extraction scheme.     

Quantitation of Alkyl Sulfonates Using UV Detector Sensitive “Ion-Pair” Reagents in Reversed-Phase Liquid Chromatography

Abstract

Amplification of detector response by means of detector-sensitive ion-pairing reagents demonstrates good sensitivity, linearity, and precision for the quantitation of alkylsulfonate ions by means of ultraviolet absorbance detection at 254 nm.     

Liquid Chromatographic Analysis of Pentazocine and Tripelennamine in Combination

Abstract

A reverse phase and normal phase liquid chromatographic procedure is described for the separation of pentazocine and tripelennamine. The isocratic methods use dual wavelength detection at 254, 280, and 313 nm.     

A Sensitive Indirect Method for the Determination of Titanium by Atomic Absorption Spectrophotometry Using an Air-Acetylene Flame

Abstract

The enhancement of the atomic absorption signal of iron in a fuel-rich air-acetylene flame by small amounts of titanium makes possible the determination of titanium at concentrations of 0.01 to l0ppm. The optimisation of working conditions for the determination of titanium by this indirect method are reported.