Arsenic speciation by capillary gas-liquid chromatography

Specific environmentally significant arsenic compounds are determined by capillary gas-liquid chromatography. Inorganic (arsenite, arsenate) and organic (monomethylarsonate, dimethylarsinate) arsenicals are measured as the corresponding methylthioglycolate derivatives, which are simultaneously separated on wide-bore borosilicate glass and fused-silica columns under conditions of temperature programming. Inorganic arsenate and arsenite cannot be differentiated by the derivatization technique. Flame-ionization and electron-capture detection are evaluated. A simple and rapid sample preparation procedure is used for water, urine, blood, and tissue.     

Glass electrode measurements of sodium in albumin solutions

Measurements of the sodium level of albumin solutions and their ultrafiltrates were made with commercially available sodium-sensitive glass electrodes. The potential of the electrode was found to vary considerably with the depth of immersion. The potentials of albumin solutions which were allowed to remain at room temperature or higher for any length of time were found to increase, and in time gave unrealistic levels of sodium activity. An albumin solution stored in a refrigerator for a month did not show this effect. The sodium levels of albumin solutions as determined by the electrode were lower than the flame photometric values for the same solutions.     

Detection of Refractive Index Change of Liquids by Diffractive Element talrd Sensor

Refractive index change of liquids was detected using a temperature compensated prism cavity together with a diffractive optical element fabricated by electron beam lithography. Small changes of refractive index could be detected from image data of the sensor.     

Determination of calcium in biological material The use of calcein as an indicator in the edta titration

The EDTA titration of calcium using the change in fluorescence of Calcein indicator under ultraviolet illumination at the end-point was very satisfactory for essentially pure calcium chloride solutions. In order to use this method for biological samples, it was found best to separate the calcium by an oxalate precipitation at a pH of 4.7, convert the calcium oxalate to calcium carbonate, and dissolve the calcium carbonate in hydrochloric acid.     

Isolation of thorium in biological samples

A scheme for the isolation of subpicogram to microgram amounts of thorium from bone and soft tissue samples is described. Thorium is first collected by co-precipitation with iron(III) hydroxide and then adsorbed by a cation-exchange resin column from a concentrated hydrochloric acid solution of the precipitate. A double precipitation is necessary for bone samples whereas a single precipitation suffices for liver samples. The thorium is eluted from the column with an ammonium carbonate solution which is then evaporated to dryness to effect the isolation. Good recoveries of thorium from bone samples are obtained.     

Magnesium in biological samples by spectrophotometric measurement of the 8-quinolinolate extract

Conditions for the simple, rapid and sensitive determination of magnesium in biological samples have been determined. Commercially available solvents and reagents are used without further purification. Magnesium is separated and converted to a form which may be measured spectrophotometrically in a single extraction as the 8-quinolinolate in 1,1,2-trichloroethane. The extraction of other 8-quinolinolates is prevented by the addition of tartrate and cyanide to the buffer solution. Adequate sensitivity is obtained (absorbance of 0.4 for 20 μg of magnesium), and even greater sensitivity is possible by reducing the volumes of both aqueous and organic phases.     

Behaviour of dilute solutions of mercury

It is shown that loss of radioactivity from labelled mercury(II) solutions is due to reduction of some mercury(II) by reductants adventitiously introduced, followed by disproportionation of mercury(I) and loss of metallic mercury in the gas phase. The loss can be prevented by addition of a small excess of an oxidant such as permanganate.