Use Of Column Research Articles

Determination of nitrate in seawater: Nitrate to nitrite reduction with copper-cadmium alloy

Determination of nitrate in seawater first requires its reduction to nitrite. Construction of a reductor column for use during continuous flow analysis at sea is described. Novel use is made of an alloy of cadmium and copper ( 50 50 w w ) crushed to between 500 and 350 μm. Its performance is similar to that of the cadmium wire type of reductor but offers advantages of easier preparation and control of reductor volume.

Evaluation of HPLC column performance for clinical studies.

Several C18 HPLC columns, varying in column length as well as packing material diameter, were used to separate mixtures of biochemical compounds in standards and in various physiological fluids. The column performances were compared both qualitatively and quantitatively. Factors investigated included efficiency, resolution, selectivity, column effect on peak height, temperature effects, cost per analysis, and analysis times. Column lifetime was also examined. The results were used to evaluate the suitability of the various columns for use in the chromatographic analysis of physiological samples.

Vibration characteristics of self-expanding stayed columns for use in space

Abstract The type of stayed column considered was developed by the ASTRO Research Corporation for NASA to evaluate, and is designed to be deployed in space after forming a light, compact package in the Space Shuttle. It consists of a core with three identical stay frames equally spaced around it. Each stay frame has a central compressed spoke which pretensions stays which radiate from its end to the core. Three pretensioned battens connect the ends of the spokes. NASA performed vibration tests on a model of such a column and compared their results with approximate theoretical predictions. The present paper gives exact theoretical results, including natural frequencies and mode types not given in the NASA results. A substitute column method is used to achieve economy and a much deeper understanding of the modes. Approximations which give even greater economy and convenience are evaluated. A proposed design is analyzed alongside the NASA model. The proposed design is better than the NASA model because recent developments were implemented in the design method, and also because it has a graphite epoxy core whereas the NASA model had an aluminium one, due to temporary availability problems.

Refined design of self-expanding stayed column for use in space

Abstract The type of stayed column considered was developed by the ASTRO Research Corporation for NASA to evaluate, and is designed to be deployed in space after forming a light, compact package in the Space Shuttle. It consists of a core with three identical stay frames equally spaced around it. Each stay frame has a central compressed spoke with pretension stays which radiate from its end to the core. Three pretensioned battens connect the ends of the spokes. This paper refines, extends and discusses the original design method to give significantly lighter and compacter packages for the Space Shuttle; a better understanding of how such columns behave, many more results than hitherto, and arguments for simplifying construction, packaging and deployment by omitting the battens.

A micromethod for the measurement of estrogen receptors using high pressure liquid chromatography

Adequate sample size has been one of the difficulties encountered in routine determination of estrogen receptors in prostatic disease. The recent commercial availability of protein analysis columns for use with high pressure liquid chromatography (HPLC) equipment has made the achievement of a considerable reduction in sample size feasible. We present a method for determination of ER which includes the use of 16 alpha-125-iodo-estradiol ( [125I]-E2) of 1600 Ci/mmol specific activity, the use of G-25 column chromatography, followed by fractionation by HPLC and finally relation of the fmol specifically bound to mg protein measured in the HPLC peak. Data obtained upon determination of ER in the immature rat uterine model system are given to show consistent recoveries, ligand specificity, saturability, inhibition, and commonly accepted KD and n values for this system. Also, in a pilot study on 13 samples from human prostatectomies, the utility of the HPLC technique for ER measurement in that tissue using single point analysis is demonstrated. For comparison, all receptor determinations reported were also made using conventional methods.

Removal of specific antibody in vivo by whole blood immunoadsorption: preliminary results in dogs.

Effective immunoadsorption for removal of anti-red cell antibodies from plasma using affinity columns has been demonstrated. However, the requirement of a continuous-flow centrifuge to separate plasma increases the cost and complexity of the procedure. We have adapted red cell antigen immunoadsorption columns for use with whole blood. Effective and specific removal of anti-red cell antibodies was achieved in actively immunized dogs.

Design and use of short microbore columns in liquid chromatography

Abstract The various aspects of design and performance of short microbore columns for use in liquid chromatography are discussed. The basic hydrodynamic factors important in column design are considered. Consideration is given to instrumental time constant and solute band broadening due to the injection system, the column and the detector. The design and construction of a chromatographic system using commercially available components permitting the use of short microbore columns is described and experimental details for operation in isocratic and gradient elution modes are given. It is shown that a column 25 cm in length with 1 mm internal diameter can be packed with a 10-μm particle diameter silica gel to the limiting plate height of 20 μm to achieve 50,000 plates per meter. Examples of the use of the system for separations of compounds of pharmaceutical interest are given and advantages of the system are discussed.

Use of specfic retention volumes in the evalution of various types of columns for use in the trace determination of ethylene glycol by gas chromatography

Abstract Various types of column packings were evaluated for use in the gas chromatography determination of ppm concentrations of ethylene glycol in aqueous systems. The columns were evaluated by determining specific retention volumes and observing peak shapes for progressively smaller concentrations of ethylene glycol in water injected on to the column. An increase in the specific retention volume, accompanied by significant peak tailing, was taken to indicate that quantitative analysis would not be feasible below a certain concentration range, because of chemisorptive effects. The most desirable column for quantitative analysis at trace levels (10 ppm or more injected on to the column) was selected on the of comparative evaluation. Acid- washedd and silane-treated diatomaceous supports coated with Carbowax 20M, uncoated porous polymers (Chromosorb 101 and 102), and Chromosorb 102 coated with Carbowax 20M were considered unsatisfactory, Super-Pak 20 M coated with Carbowax 20M was marginally successful, while Chromatosorb 101 coated with Carbowax 20M was clearly the column packing of choice. these results are discussed in terms of column support adsorption effects.

On-Line Identification of Gas Chromatographic Fractions by a Raman Multichannel Spectrometer

A Raman multichannel system is described which is feasible for the on-line identification of fractions separated by gas chromatographic columns. In Raman multichannel systems, the sensor, i.e., the laser focus, is small enough and the possible recording times are short enough to avoid any affliction of the separation process, even with capillary columns in use. At the measurements described, capillary columns with a length of 15 m and an inner diameter of 0.25 mm were employed. The detection limit was at about 1 to 10 nl of one fraction corresponding to about 1 to 10% of the total amount of sample suited for capillary columns.

Mode of operation and performance characteristics of microbore columns for use in liquid chromatography

The production and operating characteristics of microbore columns are described and details of the modification of the LDC UV monitor to give the necessary low dead volume detection cell for use with such columns are given. A method of connecting the Valco high-pressure sampling valve to microbore columns to provide the necessary small sample volume is described and a system given that permits the operation of the Waters Assoc. 6000 pump over the flow-rate range of 2 to I00 ,ul/min. The effect on column performance of column radius and particle diameter of the packing is examined in detail and height equivalent to a theoretical plate curves and reduced plate height curves are included; the effect of coiling the column on efficiency is also reported. Examples of the use of microbore columns for high-speed and high- efficiency separations are given and include results obtained from reversed-phase columns. The construction and performance of a column having 750,000 plates is described.

Nickel gas chromatographic columns: an alternative to glass for biological samples

Nickel tubing may be substituted for glass in the fabrication of gas chromatographic columns for use with samples of biological interest. Comparisons of separations of mixtures of steroids, narcotic alkaloids, phenothiazines, and amphetamines on stainless stell, glass, and nickel packed columns showed little or no observable sample decomposition on glass or nickel as contrasted to complete loss of certain compounds on stainless steel. The nickel columns are easily prepared, durable, economical, and not subject to breakage.

Equipment

Three new microparticulate columns for use in high‐performance liquid chromatography (HPLC) have been added to the range manufactured by Reeve Angel Scientific Ltd, Springfield Mill, Maidstone. The stationary phases are derived from Partisil‐10 (a microparticulate silica‐gel adsorbent with a nominal particle diameter of 10 µm) by the addition of chemically bonded functional groups.

Simple, efficient reduction column for use in the automated determination of nitrate in water

Simple, efficient reduction column for use in the automated determination of nitrate in water

Molecular-sieve chromatography of amylose and dextran over porous glass

Porous glass of 370 A average pore diameter is useful for fractionating amylose and dextran of weight-average molecular weights ranging from 2 × 105 to 2 × 104 and at flow-rates of 2.4–2.9 ml/h,cm2 at room temperatures. Amylose and dextran in methyl sulfoxide-water (95:5) or 4 M guanidine hydrochloride as solvents exhibit the same calibration curve; hence, commercially available dextran fractions may serve to calibrate the column for use with amylose. Polystyrene fractions in tetrahydrofuran exhibit a different calibration curve. Thus the universal calibration concept does not apply to all three polymers in our column.

A study of extraction columns for aqueous polymer two-phase systems

Abstract The design and performance of two types of columns for use with aqueous polymer two-phase systems is described. In one of the columns the lower phase is stationary and the upper phase is mobile, while in the other column the two phases move towards each other. Studies on the separation of nucleic acids, proteins and particles showed that the columns function efficiently.

Improved Open Tubular Gas Chromatographic Columns for Use at 250 C and Above

A procedure for the construction of open tubular gas chromatographic columns suitable for use at elevated temperatures has been developed. The use of a quarternary phosphonium halide, benzyltriphenylphosphonium chloride, aids in coating the wall of a tube with substrate and causes it to adhere firmly. This technique produces a stable column that is easily reproduced. Differential thermal analysis was used to study the temperature stability of various GC substrates. Combining the proper substrate with the phosphonium halide results in columns that are usable to 250°C and above.

A mirror electron microscope using magnetic lenses

The principle of mirror electron microscopy is explained and the geometrical optics of the objective stage of such a microscope are discussed. The construction of an electron optical column for use as a mirror electron microscope is described. Magnifications of up to a few thousand are attainable and direct observation of the form of surface magnetic fields is possible.

An ion-exchange column for use with atomic-absorption analysis

An ion-exchange column for use with atomic-absorption analysis

Rejuvenation of Gas Liquid Chromatography Columns in situ

Atkinson and Tuey1 mention the in situ reconditioning of chromatographic columns. An in situ treatment of columns in use in this laboratory has been regularly utilized for some years. Our experience of this technique may be of interest to others.

Surface Modification of Capilary Columns for Use in Gas Chromatography.

Surface Modification of Capilary Columns for Use in Gas Chromatography.