Abstract: In a reference electrode comprising an enclosure containing a half-cell electrode, a half-cell electrolyte, and a reference junction positioned in an outlet for the electrolyte, the half-cell electrode being connectable to an external measuring means, the improvement which comprises a removable and replaceable reference junction comprising a removable encasing body encasing a porous member, said porous member being in length only up to about one half the length of the encasing body, fixedly inserted through said outlet.

Abstract: Improved reference electrode of the double junction type wherein the half-cell junction is characterized in that the mathematical quotient of its liquid flow rate divided by its ionic electrical conductance under defined test conditions is less than about 0.12 ml.multidot.hr.sup.-1 .multidot.mho.sup.-1.

Abstract: Spurious a.c. noise signals impressed upon an electrochemical reference electrode 3 with separate half-cell and junction electrolytes are reduced by a low impedance bypass circuit including a capacitor 25 connected in series between the electrode lead wire 15 and an inert electronic conductor, such as a graphite rod 27, immersed in the junction electrolyte solution.

Abstract: A glass composition for use in pH-responsive glass electrodes, and a glass electrode having a pH-responsive membrane of such glass, which composition consists essentially of (in mole percent on the oxide basis):a. from about 30 to about 37 mole percent Li.sub.2 O;b. from 0 to about 4 mole percent of at least one oxide selected from the group consisting of Cs.sub.2 O and Rb.sub.2 O;c. from about 2 to about 12 mole percent of at least one oxide selected from the group consisting of La.sub.2 O.sub.3 and Pr.sub.2 O.sub.3 ;d. from about 2 to about 10 mole percent of at least one oxide selected from the group consisting of Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 ;e. from 0 to about 4 mole percent UO.sub.2 ; andf. the balance SiO.sub.2 ;with the proviso that there is present in the composition at least about 2 mole percent of at least one oxide selected from the group consisting of Pr.sub.2 O.sub.3 and Nb.sub.2 O.sub.5.

Abstract: An analyzer for electrophoretic samples includes a sensor of extremities, more particularly valleys, in the output from the detector. The analysis of electrophoretic samples includes integration of the area under each of the fractions of the multicomponent output. In order to integrate each of the components, it is necessary to detect valleys in the output. The detector output is first applied to a non-linear processor such as a logarithmic amplifier and a differentiator. The logarithmic amplifier changes the shape of the output to make the detection less dependent upon relative component amplitude. A threshold comparator produces a pulse when the slope of the analyzer output, as represented by the output of the differentiator, exceeds a threshold. The threshold is changed after the detection of the first valley. Noise suppression circuitry prevents the detector from responding to closely occurring extremities in the analyzer output.

Abstract: A test sample for testing a recording fluorometer/densitometer has multiple tracks with features that generate detector outputs indicating performance parameters. In the normal mode of operation the instrument scans the optical absorbance or fluorescence characteristics of electrophoretic samples in a plurality of tracks on a thin agarose film plate. In order to correctly record the optical characteristics of these electrophoretic samples, the instrument must respond linearly and with the correct range, resolution and alignment. A test sample is scanned in the same manner as a normal sample. The resulting instrument output provides easily analyzed information on fluorometric and densitometric performance parameters including linearity, range, spatial resolution, slit and scan path alignments, scan speed and excitation uniformities, response time, noise, electrical and optical offsets, integration accuracies, automatic gain and zeroing accuracies.