CZ301714B6 - Casing for carbon paste for electrochemical measurements - Google Patents

Abstract

The present invention relates to a casing for a carbon paste electrode comprising a piston (1) and a hollow shaped body (3), wherein the piston cylindrical section (4) reaches into a cylindrical cavity (2) inside the body (3). The piston (1) is provided in its upper portion with a threaded section (5). A rotary head (6) moves the piston (1) in the thread. A lower smooth cylindrical portion (7) of the body (3) matches the shape of the piston (1), too, and the complete piston (1) is supported in the body (3) by a threaded insert, i.e. upper threaded part (8). In a first structural embodiment the lower portion of the shaped body (3) is provided with a thread for en exchangeable end piece (10) with a circular opening (9), while in a second structural embodiment said shaped body (3) is terminated directly by the circular opening (9) of a defined diameter. A filling tool (11) and a cleaning tool (12) having the shape corresponding to the shape of the cylindrical cavity (2) representing a filling opening of a given diameter can be used as accessories for filling and cleaning the second structural embodiment of the casing, wherein said filling tool (11) and cleaning tool (12) upper section is provided in both the cases with a shaped bracket (13).

Description

Housing for carbon paste for electrochemical measurements

Technical field

Said technical solution relates to the construction of a housing for carbon paste, respectively. for a carbon paste electrode which serves as an electrode material especially for electrochemical measurements.

BACKGROUND OF THE INVENTION

Modern electroanalysis utilizes a variety of detection systems with a number of new electrode types of various designs. Carbon paste has also become a widespread electrode material, see Adams R. N .: Anal. Chem. 30 (1958) 1576. It is a common name for a mixture of spectroscopic and carbon (graphite) powder with a suitable liquid binder, e.g., paraffin or silicone oil, see Kalcher K., Kauffmann J. -M., Wang J., Svancara I. ., Vyřás K., Neuhold C.,

YangZ .: Electroanalysis 7 (1995) 5; Švancara I., Vytřás K., ZimaJ., Bárek J .: Crít. Roar. Anal. Chem. 31 (2001) 311. Carbon pastes are typically prepared by laboratory mixing of the respective components in a mortar, see Svancara I., Schachl K .: Chem. Listy 93 (1999) 490. As the name suggests, carbon paste is a soft, not very compact material that is incorporated into a suitable electrode body shell. This configuration is then usable for measurement and is referred to as carbon paste electrode (CPE).

Carbon pastes are appreciated primarily because their composition and thus the physicochemical and electrochemical properties are chosen by the user himself. It is possible to choose the type of graphite, the binder used, their mutual ratio, but it is possible to incorporate into the paste another component, the so-called modifier, which in many cases fundamentally influences the resulting behavior of the resulting heterogeneous mixture, see Kalcher K „Kauffmann J.-M., WangJ ., Svancara I., Vyras K., Neuhold C., YangZ .: Electroana30 lysis 7 (1995) 5; Švancara I., Vytřás K., Zima J., Bárek J .: Crít. Roar. Anal. Chem. 31 (2001) 311.

Conventional glass tubes, small syringe bodies and the like are often used as carbon paste shells. and specially designed borehole plastic plugs, see Adams R.N .: Electrochemistry at Solid Electrodes, p. 281, M. Dekker, New York 1969, where electrical contact is solved by inserting a precious metal wire into the paste fill. These are very simple constructions, however, they do not allow a prompt change of the surface of the electrode material, which is necessary for some measurements, see Švancara I., Schachl K .: Chem. Letters 93 (1999) 490.

Sleeves with rotary pistons solve this fundamental problem. The present technical solution is based on the original design of Monien et al., See Monien H., Specker H., Zinke K .: Fresenius Z. Anal. Chem. 225 (1967) 342, but brings a number of new features and improvements over this.

SUMMARY OF THE INVENTION

The present application is based on a carbon paste electrode housing comprising a piston and a molded body with a cavity wherein the piston (1) extending into the cylindrical cavity (2) within the molded electrode body (3) consists of a lower smooth cylindrical section (4) and an upper special threaded section (5) adjoining the rotatable head (6), wherein the lower smooth cylindrical part (7) and the upper special threaded part (8) of the cylindrical cavity (2) also correspond to the shape of the piston (1); a circular opening (9) of a defined diameter is formed by a lower part of the shaped body (3).

- 1 GB 301714 B6

The lower part of the cylindrical cavity (2) is further provided with a replaceable terminal (10) with a circular hole (9) of a defined diameter.

DETAILED DESCRIPTION OF THE INVENTION

An example of a design for a carbon paste electrode housing of the present application is an arrangement comprising a piston and a molded cavity body, wherein the piston 1 extending into the cylindrical cavity 2 within the molded electrode body 3 consists of a lower smooth cylindrical section 14 and an upper threaded section 5. the lower smooth cylindrical part 7 and the upper special threaded part 8 of the cylindrical cavity 2 also correspond to the shape of the piston 1 and where a circular hole 9 of a defined diameter is further formed in the lower part of the shaped body 3. The lower portion of the cylindrical cavity 2 may further be provided with a replaceable terminal 10 having a circular opening 9 of a predetermined diameter. A filler 11 may also be used to fill and clean the carbon paste electrode housing. and a cleaner 12, the shape of which also corresponds to the shape of the cylindrical cavity 2 and whose upper part is provided with a shaped grip 13.

The basic design element of the carbon paste housing is a specially shaped, hollow plastic body along its entire length. The wider upper part, for a comfortable grip with rounded edges and regularly grooved on the perimeter, has a tight brass insert in which the piston is screwed. The lower part of the body is narrower, without creasing and its diameter is chosen so that the sleeve can be inserted into the holes of standardized electrode cell heads of commercial manufacturers.

At the top, smooth end of the piston shaft, a plastic head with rounded edges is pressed, fixed with a small, transversely inserted screw ("worm"). The upper part of the shank is hollow because a hole for the lead-in cable with plug (“banana” type) is drilled in it. A thread is cut in the central part of the shaft. Position in the body of the screwed-in piston, resp. its end, smooth portions, defines the capacity of the cavity for filling the carbon paste. In the "SLIM" variant, the size of the cavity is also defined by the diameter of the hole drilled in the body.

In the “THICK” type, the lower part of the body is terminated by another tapered threaded part, which serves for screwing in the exchangeable terminals. These hollow end pieces, identical in shape and size, have a hole of different diameter in the center of the front wall (underneath). In the “SLIM” type, the working surface of the electrode is given directly by the body structure, which is available in two different modifications 35 with a cavity of appropriate diameter (see Table 1).

Specification and description of paste filling aids:

Copies or small laboratory spoons can be used to fill the carbon paste into the cavities of both types. The required paste packing is achieved with a standard glass rod (0 = 5 mm) for the "THICK" version and a specially designed filling and cleaning tool for the "SLIM" version. Both are designed as shafts of appropriate diameter, firmly fitted into ergonomically shaped handles of identical shape and size. The filler 11 has a shorter shank and its length corresponds to the maximum capacity of the cavity in the housing body. The cleaner rod 12 then allows the hole to be emptied along the entire length of the housing body (i.e., including a threaded insert for screwing in the piston).

Assembly, disassembly, filling, emptying, cleaning, use and maintenance:

The piston 1 is inserted into the threaded insert in the housing and screwed into the initial position (approx. 3 turns of the thread). Carbon paste prepared according to recommended procedures (see eg Švancara I.,

Schachl K .: Chem. Sheets 93 (1999) 490) are introduced into the cavity in the housing body in small portions. During dosing, the paste must be packed thoroughly with the filling tools described above. After filling the cavity, the “SLIM” type is ready for use. In the “THICK” variant, after filling it is necessary to screw the replacement end piece JLO with the required diameter of the end hole 9.

-2GB JU1714 B6

The assembled, paste-filled and attached to the measuring device (using the socket in the piston head) is ready for use. The working surface of the carbon paste is obtained by squeezing out a small amount of paste from the container (about 0.5 to 1 mm thick), followed by wiping and smoothing, for example using wet filter paper, see Švancara I., Vytřás K., Renger F., Smyth MR: Coll. Ved. Ex. SKK. ChemickotechnoL, Pardubice 56 (1992/93) 21. In the same way, the surface of the carbon paste is renewed during the measurement itself if the nature of the experiment so requires.

In the period between measurements, it is recommended to store the filled shells in a container with distilled water and their end parts with carbon paste filling should be fully submerged, see Švancara I., Vytřás K., Zima J., Bárek J ,; Crit. Roar. Anal. Chem. 31 (2001) 311; Svancara I., Schachl K .: Chem. Listy 93 (1999) 490. With the “THICK” option, it is not recommended to expose the upper body to strongly aggressive solutions of the more concentrated acid and hydroxide type due to the material used for the housing (see Table 1).

When emptying the sleeves, the contents of the container are first displaced by the piston. In the "THICK" variant, the exchangeable end is then removed. Remnants of paste that stick in the cavity are removed with a cleaning agent 12 in combination with a small roll of pulp or tissue paper. The coil is forced through the cleaned cavity and can be replaced as needed, even repeatedly. In a similar manner, the cavity and threads of the exchangeable tip 10 of the "THICK" type are also cleaned, including the end hole 9. The cleaning rolls can be moistened with a suitable solvent, such as acetone. In no case can chlorinated solvents etch the plastics from which the cases are made (see Table 1).

BRIEF DESCRIPTION OF THE DRAWINGS

1 is an example of constructional variations of the housing for the carbon paste electrode of the present application. The piston 1 extending into the cylindrical cavity 2 within the shaped body 3 of the electrode consists of a lower smooth cylindrical section 4 and an upper special threaded section 5 adjoining the rotating head 6, the piston I also corresponding to the lower smooth cylindrical part 7 and the upper threaded part 8 of the cylindrical cavity 2 and further in the lower part of the shaped body 3 a circular hole 9 of a defined diameter is formed. The lower part of the cylindrical cavity 2 is provided with a replaceable end piece 10 with a circular hole 9 of a defined diameter, as required.

As an accessory for filling and cleaning the carbon paste electrode housing, a filler 11 and a cleaner 12 may also be used, the shape of which also corresponds to the shape of the cylindrical cavity 2 and whose upper part is provided with a shaped grip 13 shown in Fig. 2.

Fields of application

Said carbon paste electrode housing assemblies are particularly useful for a variety of electrochemical measurements in which the electrode measuring cell is arranged as a batch, i.e. non-flowable, and with standardized instrumentation dimensions from commercial manufacturers. Thus, the main fields of application of the present patent application are electroanalytical chemistry, electrochemistry and environmental chemistry.

-3GB 301714 B6

Table 1

Specifications and dimensions * of individual parts and components: Variant type THICK type SLIM ^B Electrode body - material Silon * Teflon * - total length ^c 105 mm 120 mm - wider part: length / diameter 32/24 mm 42/15 mm - narrower part: length / diameter 58/14 mm 80/8 - threaded part ^D : thread length / diameter 15/10 mm - - filling hole: length / diameter 20/6 mm 3 mm Threaded insert (pressed into the body) - material brass brass - length / outside / inside diameter (thread) Rotary piston with thread and head ^E 30/12/8 mm 40/6/4 mm - total length 125 mm 140 mm Head: - material Silon * Bakelite * - length / diameter // number of grooves (0) [in mm] Piston shaft: 20/22 // 12 (2) 20/14 // 14 (1) - material stainless steel stainless steel - length of thread without thread / with thread / for head fixation (without thread) 80/22/23 mm 83/35/22 - Diameter of threadless / threaded / head fixation 6/8/5 mm 2; Additional terminals ^T 4 pieces - material Teflon * - - length / outside diameter / inside diameter 20/14/10 mm threaded cavities - end hole diameter 1, 2, 3, 5mm - Filling Aids and Cleaning ^e (filler; cleaner): - 2 pcs shaft: material // length / working diameter steel // 40; 130 parts / 2.3, 2 mm Handle: Material // Length / Diameter Bakelit // mane parts / hole length of the shaft recess 70/16/30 mm Complete housing assembly - total length 155 mm 170 mm - total weight ^J 70 g 40 g - maximum capacity of carbon paste ^H 0,6 cm ³ 0.1; 0.2 cm ³

Legend: A) according to Fig. 1; B) modifications “2” and “3”; C) without additional end piece for "THICK" type;

D) for type "THICK" only; E) head with socket for electrical plug (banana) fixed by pressing on the end of the shaft with a banana cavity and behind it fixed by a transverse screw (Worm); F) possibility of exchange by type of measurement; (G) only for 'SLIM' type; (H) with the piston screwed into the position corresponding to the maximum carbon paste charge; I) Including screwed end piece for “THICK” type; J) without filling.

Claims (2)

PATENT CLAIMS 1. A carbon paste electrode housing comprising a piston and a molded body with a cavity, characterized in that the piston (1) extending into the cylindrical cavity (2) within the molded electrode body (3) consists of a lower smooth cylindrical section (4) and an upper special threaded section (5) adjoining the swivel head (6), the lower smooth cylindrical part (7) and the upper threaded part (8) of the cylindrical cavity (2) also corresponding to the piston (1). a circular opening (9) of a defined diameter is formed at the bottom of the shaped body (3). Carbon paste electrode housing according to claim 1, characterized in that the lower part of the cylindrical cavity (2) is provided with a replaceable terminal (10) with a circular hole (9) of a defined diameter.