DE1596899B2 - CHEMICAL RESISTANT GLASS FOR GLASS ELECTRODES WITH LOW ELECTRIC POTENTIAL PER PH UNIT AND A LINEAR DEPENDENCE BETWEEN POTENTIAL AND PH CHANGES - Google Patents

Description

2. Glass according to claim 1, characterized in that the glass consists in percent by weight

Weight percent

Silica 35 to 45

Lithium oxide or sodium oxide or potassium oxide .... 15 to 18

Cesium oxide 5 to 8

Barium Oxide 8 to 10

Lanthanum oxide 5 to 7

Zirconia 6 to 10

Niobium pentoxide

or vanadium pentoxide ... 3 to 6 triurane octoxide 5 to 10

3. Glass according to claim 1, characterized in that the glass consists in percent by weight

Weight percent

Silica 41.1

Lithium oxide 16.4

Cesium oxide 8.0

Barium oxide 9.5

Lanthanum oxide 5.0

Zirconium oxide 10.0

Niobium pentoxide 4.0

Triurano octoxide 6.0

The invention relates to a chemically resistant glass for glass electrodes with low electrical resistance, high electrical potential per pH unit and linear dependence between potential and pH changes, this glass being melted a mixture of silicon dioxide, lithium oxide or sodium oxide or potassium oxide, cesium oxide, Barium oxide, lanthanum oxide, zirconium oxide, an oxide of the pentavalent metals niobium pentoxide or vanadium pentoxide, and triuranoctoxide is obtained. There are various special glasses for glass electrodes known. For lithium silicate glass, according to P e r 1 e y (Anal. Chem., 21, 394, 559 [1949]) a high electrical potential reported. However, the disadvantage here is that its electrical resistance is high is; it is in the range from 10 to 100 ΜΩ. In Chemisches Zentralblatt, 1962, p. 4652, a Mg-free Glass for glass electrodes described with 30 percent by weight lithium oxide, 5 percent by weight barium oxide, -63 Weight percent silicon dioxide and 2 weight percent uranium dioxide, and also the electrical resistance and the electrical potential mentioned, nevertheless are no glasses for glass electrodes with sufficiently low electrical resistance and sufficiently high electrical potential per pH unit. Schmidt - Voss (»The raw materials zur Glaserzeugung ", 2nd edition, Leipzig, 1958, p. 315) teaches the use of sodium oxide, Potassium oxide, silicon dioxide and 2 to ^ percent by weight of triuranoctoxide for colored glass without devitrification, however, barium oxide, niobium pentoxide, lithium oxide, cesium oxide or lanthanum oxide are used not provided and their use for glass electrodes not suggested. In the British patent 793,866 will use 5 to 6 weight percent uranium trioxide and at least of a glass-forming oxide from the group vanadium pentoxide, tellurium dioxide, molybdenum trioxide, tungsten trioxide and diphosphorus pentoxide and the addition of up to 57 weight percent sodium oxide and also barium oxide, silicon dioxide and boron trioxide for glass masses as a source of radiation emanating from the Decay of atomic nuclei results, taught. However, this prior publication suggests no material for Glass electrodes. In the French patent 1 452 796 the use of niobium pentoxide, Vanadium pentoxide, zirconium dioxide, silicon dioxide and 5 to 10 percent by weight uranium dioxide in glass masses suggested for fiber optics. However, the French patent 1 452 796 does not mention cesium oxide, Lithium oxide, barium oxide and lanthanum oxide and their use for glass electrodes. The German patent specification 974 398 suggests glasses for high conductivity glass electrodes containing 72 percent by weight silicon dioxide, 20 to 22 weight percent sodium oxide, 6 to 8 weight percent calcium oxide, 2 to 6 weight percent Contain vanadium pentoxide and / or uranium dioxide and / or chromium trioxide. The amount of uranium dioxide however, it is less than 2 percent by weight, and German patent specification 974 398 does not see that Use of barium oxide, cesium oxide, lanthanum trioxide, niobium pentoxide and zirconium dioxide.

A disadvantage of these prior art teachings is that - although glass materials are made of Oxides are proposed, some of which are the oxides of which the present invention is concerned - the known glass materials do not meet all the requirements of the low electrical Resistance, high electrical potential per pH unit, high chemical resistance, good meet linear dependence between changes in electrical potential and pH changes. Glass electrodes for a pH sensor work in conjunction with a voltmeter. A glass electrode

With low electrical resistance can not only with voltmeters, which have a high impedance (Impedance), which is accurate, but expensive, but also with a voltmeter with low Impedance, which is cheaper, can be used. In addition, a glass electrode with low electrical resistance not only above room temperature, but also at a low temperature below room temperature can be used, whereas a glass electrode with a high electrical resistance can only be used at a temperature above room temperature. In addition, a glass electrode with a low electrical resistance is much more stable when measuring of pH values as a glass electrode with high electrical resistance.

However, when the electrical potential per pH unit of the glass electrode is low, measurement is without additional amplifier not possible, even if a glass electrode has a low electrical resistance Has.

Λ The object of the invention was to provide a glass electrode

To find T mass that has both a very low] electrical resistance and a high electrical resistance Potential per pH unit shows (over 58 mV / pH) a high chemical resistance, good linear dependence between the change in electrical potential and pH changes in a range between pH 1 and 10 has.

The subject of the invention "is based on chemically resistant glasses for glass electrodes with low electrical resistance, high electrical potential per pH unit and linear dependence between potential and pH changes, this glass being produced by melting a mixture of silicon dioxide, lithium oxide or sodium oxide or potassium oxide, cesium oxide, barium oxide, lanthanum oxide, zirconium oxide, an oxide of the pentavalent metals niobium pentoxide or vanadium pentoxide and triurane octoxide is obtained, and is characterized in that the glass consists of 30 to 50 percent by weight silicon dioxide, 15 to 22 percent by weight of lithium oxide or sodium oxide or potassium oxide, 4 to 10 Ge more ts {percent cesium oxide, 5 to 13 weight percent barium oxide, from 5 to 12 weight percent lanthanum oxide,! 3 to 16 percent by weight of zirconium oxide, 2 to 12 weight percent niobium pentoxide or vanadium pentoxide \ and 3 to 15 weight percent Triurane octoxide consists j glasses of the above composition, which anyway St.

'■ a low electrical resistance as well; have high electrical potential per pH unit, j make it possible to reduce the size of the obtained glass ^: electrode and can be used as an electrode! material can be used for a voltmeter with a low impedance as well as a voltmeter with a high impedance.
j The invention is described in detail below

! explained. The following table 1 gives the components : the glasses and their proportions in percent by weight.

Table 1

Components

Silicon dioxide, SiO ₂

Li ₂ O or Na ₂ O or K ₂ O

Cesium oxide, Cs ₂ O

Barium oxide, BaO

Lanthanum oxide, La ₂ O ₃

Zirconium oxide, ZrO ₂

Nb ₂ O ₅ or V ₂ O ₅

Triurano octoxide, U ₃ O ₈

Shares
in percent by weight

30 to 50
15 to 22
5 to 10
5th to 13th
5 to 12
3 to 16
3 to 12
3 to 15

The glasses of the present invention are produced by weighing, dry homogeneous mixing and then melting a suitable mixture in a platinum crucible which contains or produces the reagents mentioned in the examples, in the amounts indicated. The various constituents can be added to the batches in the form of their carbonates or nitrates, the cost, stability and ease of handling being the determining factors. The homogeneously mixed material is heated for 2 hours at about 1200 ⁰ C, an additional 1 hour at 130o ⁰ C and then rapidly cooled to obtain a glass block. The glass block, comminuted to a suitable size, is ^{melted at about 1150 °} C. in a platinum crucible. A glass tube electrode holder is made of lead silicate glass and has almost the same coefficient of thermal expansion as the glass electrode compounds. The glass electrode was only small in size for pH measurement in the gastrointestinal tract. The holding tube has an outer diameter of 2.5 ~ 3.0 mm, an inner diameter of 2.1 ~ 2.6 mm and a length of 4.0 mm. A small amount of molten glass is picked up by the glass holder and blown into a small hollow sphere 3.0 mm in outside diameter and 2.8 mm in inside diameter.

Various glasses were made and their electrical properties were determined.

The electrical resistance of a constant-size glass electrode was measured at 25 ° C using a platinum wire as an electrode and an aqueous 0.1 N KCl solution with an electric field of 2 V DC measured. The electrical potential was measured at 25 ° C by forming a cell, which consisted of a glass electrode and a standard electrode immersed in a given buffer solution immersed. The results are shown in Table 2.

Examples 1 to 6, 10 to 12, 14 to 17 and 28 to 31 are glasses with a composition according to the invention, while the other glasses are outside the aim of the invention.

Table 2
Composition (weight percent) and electrical properties

Components and
Electrical Properties 1 2 3 4th 5 6th Seigames
7th 8th 9 10 11th 12th 13th 14th SiO, 41.70
16.40 40.70
16.40 41.70
17.40 41.10
16.40 44.00
18.00 40.00
17.00 46.00
15.40 45.00
16.40 49.50
14.20 29.00
21.55 32.00
18.50 38.50
16.40 40.50
16.00 40.50
15.55 Li ₂ O

continuation

Components and
Electrical Properties 1 2 3 4th 5 6th Example
7th Ie
8th 9 10 ^: 11 12th 13th 14th KTa Γ) V O Cs, 0 7.50
5.00
8.00
3.00
7.00
10.00
13th
58.5 7.50
5.00
9.00
5.40
6.00
10.00
13th
58.9 7.50
6.00
8.00
5.40
6.00
6.00
18th
59.0 8.00
5.00
9.50
4.00
10.00
6.00
8th
59.1 5.00
6.50
8.50
4.50
6.50
7.00
5
58.4 5.40
6.00
9.50
4.00
8.50
9.60
11th
58.8 6.80
6.00
10.45
4.85
10.50
66
58.1 7.50
5.00
9.40
3.85
8.85
79
58.3 9.30
5.00
5.00
4.00
10.50
2.50
66
59.0 4.95
10.00
10.50
8.00
6.00
10.00
5
57.5 5.00
8.00
8.00
12.00
6.50
10.00
10
57.5 6.30
11.30
12.50
4.00
7.00
4.00
16
58.6 4.55
3.95
5.25
11.25
15.55
2.95
70
58.8 6.45
6.00
5.00
8.30
3.50
14.70
13th
57.8 La, O, BaO Nb, O, ZrO, u, o _a Electrical resistance
(ΜΩ-cm) at 25 ° C.
Electrical potential
(mV / pH) at 25 ° C ...

Table 2 (continued)

Components and
Electrical Properties

16 17th 18th 19th 20th Examples 22nd 23 24 25th 26th 15th 39.30 42.55 39.30 51.0 51.5 21 51.5 56.0 55.0 27.0 40.0 42.55 - - - 14.0 12.5 51.5 - 12.0 11.0 23.0 17.0 - 21.30 - - - - - - - 1.0 - - 15.05 - 15.05 21.30 - - 12.5 12.5 - - - - - 4.30 8.30 4.30 2.0 1.0 - - 3.5 - 5.0 7.0 8.30 7.00 7.00 7.00 14.0 13.5 - 12.5 5.5 8.0 10.5 5.0 7.00 8.55 8.55 8.55 3.5 13.5 14.5 .15.5 5.0 6.0 10.5 9.0 8.55 4.25 4.25 4.25 5.5 2.0 5.5 3.0 11.0 6.0 7.5 3.0 4.25 4.50 4.50 4.50 4.5 2.0 4.0 3.0 2.0 5.0 6.5 3.0 4.50 8.00 8.00 8.00 5.5 4.0 6.0 2.0 5.0 8.0 10.0 16.0 8.00 15th 20th 17th 2000 9200 6.0 15000 13,000 123,000 relieved 5.0 15th 55.8 58.0 57.7 56.0 53.0 5200 51.0 51.0 50.0 - 48.5 59.1 53.0

SiO ₂

Li ₂ O;

Na ₂ O

K ₂ O

Cs ₂ O; ....

La ₂ O ₃

Nb ₂ O ₅ .....: ■■

ZrO ₂

U ₃ O ₈ ;

Electrical resistance (ΜΩ-cm) at 25 ° C ...

Electrical potential
(mV / pH) at 25 ° C ....

Table 2 (continued)

Components and electrical
properties 28 Example
29 Ie
30th 31 SiO, 41.10
16.40
8.00
5.00
9.50
4.00
10.00
6.00
20th
59.0. 32.00
18.50
5.00
8.00
8.00
12.00
6.50
10.00
35
58.1 42.55
15.05
8.30
7.00
8.55
4.25
4.50
8.00
22nd
59.0 42.55 Li, 0 Na ₂ O 15.05
8.30
7.00
8.55
4.25
4.50
8.00
38
57.8 K ₂ O Cs, 0 La, O, BaO V ₂ O ₅ ZrO ', U ₁ Oo Electrical resistance
(ΜΩ cm) at 25 ° C
Electrical potential
(mV / pH) at 25 ^° C

It can be seen from Table 2 that the glasses falling within the scope of the invention unexpectedly too have an electrical resistance that is noticeably lower than that of glass electrode masses, which are outside the range according to the invention, without the electrical potential per pH unit

is reduced. The masses, which in the area of discovery fall show good linearity between electrical potential and pH in the pH range from 1 to 10. The chemical resistance of the masses falling within the scope of the invention proved to be high enough.

Claims (1)

Patent claims: 1. Chemically resistant glass for glass electrodes with low electrical resistance, high electrical potential per pH unit and linear dependency between potential and pH changes, which by melting a mixture of silicon dioxide, lithium oxide or sodium oxide or potassium oxide, cesium oxide, barium oxide, lanthanum oxide, zirconium oxide, one of the pentavalent oxides Metals, niobium pentoxide or vanadium pentoxide, and triurane octoxide is obtained, characterized in that the glass in percent by weight consists of Weight percent Silica 30 to 50 Lithium oxide or sodium oxide or potassium oxide .... 15 to 22 Cesium oxide 4 to 10 Barium Oxide 5 to 13 Lanthana 5 to 12 Zirconia 3 to 16 Niobium pentoxide or vanadium pentoxide ... 2 to 12 Triurane octoxide 3 to 15