Self-cleaning and base line stabilizing device of automatic nutritive salt analyzer

Abstract

A self-cleaning and base line stabilizing device of an automatic nutritive salt analyzer comprises a reaction assembly used for mixing a sample liquid sample, air and a corresponding reaction reagent to complete a chromogenic reaction; the light splitting detector is connected with the output end of the reaction assembly through a first connecting pipe; the cleaning assembly at least comprises a change-over valve, a second connecting pipe and a first peristaltic pump, the change-over valve is arranged on the first connecting pipe and located between the reaction assembly and the light splitting detector, one end of the second connecting pipe is connected with the change-over valve, the other end of the second connecting pipe can be connected with a reagent bottle filled with hydrochloric acid, and the second connecting pipe is sleeved with the first peristaltic pump. According to the method, pollution caused by adsorption of the flow cell can be actively prevented, the whole process only needs short time, baseline drift caused by adsorption of the chromogenic complex is prevented, the working efficiency is remarkably improved, and finally synchronous improvement of the determination efficiency and the data stability is achieved.

Description

Technical Field

[0001] This utility model relates to the field of nutrient analysis, specifically a self-cleaning and baseline stabilization device for an automatic nutrient analyzer. Background Technology

[0002] Marine essential nutrients (mainly including nitrates, nitrites, ammonium salts, phosphates, and silicates) are crucial material foundations for marine ecosystems. Phytoplankton, by absorbing nutrients and inorganic carbon, constitute primary producers in the marine food chain, and accurate determination of their concentrations is of great significance for studying marine biogeochemical processes and ecological environment evolution. Improving the quality of nutrient data and enhancing the comparability and traceability of results obtained from different analytical methods and equipment have become key issues in current marine chemical observation.

[0003] Currently, marine chemical observation in my country still mainly relies on a combination of sampling from research vessels and laboratory analysis. Traditionally, the national standard spectrophotometric method is used to manually measure the collected seawater samples. This method is cumbersome and inefficient, making it difficult to meet the high-throughput analysis needs of large batches of samples. In contrast, automated nutrient analyzers based on segmented continuous flow analysis (SCFA) technology have advantages such as high automation, good repeatability, and high throughput, and are also the technology commonly used in mature commercial nutrient analyzers. With the widespread application of flow analysis technology and the global prevalence of automated nutrient analyzers in laboratories, using automated nutrient analyzers for nutrient analysis during research voyages has become routine. The working principle of this type of instrument is as follows: water samples are introduced into the flow path through an autosampler, a peristaltic pump propels the sample forward, and an air pump injects uniform air bubbles, dividing the sample flow into regular, uniform liquid segments; each liquid segment is mixed with reagents in sequence, a colorimetric reaction is completed in the reaction coil, and finally, the absorbance is measured in the flow detection cell. Although automated nutrient analyzers based on SCFA technology have achieved efficient and automated analysis of seawater nutrients, in actual cruise applications, especially when dealing with large batches of seawater samples with complex matrices, their flow-through detection cells are susceptible to adsorption and contamination by colorimetric reaction products (such as the red azo dye generated in nitrite determination and the phosphomolybdic blue compound formed in phosphate determination). As the number of samples accumulates, contaminants gradually adhere to the inner wall of the detection cell, causing continuous baseline drift and a sustained increase in the baseline signal, which seriously affects the accuracy of the data and batch-to-batch consistency.

[0004] Therefore, there is an urgent need to develop a self-cleaning and baseline stabilization device for an automated nutrient analyzer. Utility Model Content

[0005] The purpose of the present utility model is to provide a self-cleaning and baseline stabilization device for a nutrient automatic analyzer, which can effectively solve the problem of baseline drift caused by the adsorption of specific chromogenic complexes in bubble interval flow analysis, improve the sample determination efficiency and the data stability of batch samples, so as to solve the existing technical defects and unachievable technical requirements.

[0006] To achieve the above purpose, the present utility model provides the following technical solutions: A self-cleaning and baseline stabilization device for a nutrient automatic analyzer, comprising:

[0007] A reaction component, which is used to mix a sample liquid sample, air and corresponding reaction reagents to complete a chromogenic reaction;

[0008] A spectrophotometric detector, which is connected to the output end of the reaction component through a first connecting pipe;

[0009] A cleaning component, which at least includes a switching valve, a second connecting pipe and a first peristaltic pump. The switching valve is arranged on the first connecting pipe, between the reaction component and the spectrophotometric detector. One end of the second connecting pipe is connected to the switching valve, and the other end can be connected to a reagent bottle containing hydrochloric acid. The first peristaltic pump is sleeved outside the second connecting pipe and is located between the switching valve and the reagent bottle containing hydrochloric acid during use;

[0010] The switching valve can switch the connection between the first connecting pipe and the reaction component or the cleaning component to complete the cleaning of the spectrophotometric detector.

[0011] In this application, it needs to be further explained that the "corresponding" reaction reagents in the previous description (for chromogenic reactions with different nutrients) can be understood as reaction reagents that can be adapted to different nutrients and carry out chromogenic reactions;

[0012] And the "one" in the previous description of "through a first connecting pipe" represents one kind or one category, rather than one, that is, it does not represent the quantity, but represents the type;

[0013] Moreover, the content that the switching valve is arranged on the first connecting pipe mentioned above indicates that the two are interconnected, that is, the switching valve divides the first connecting pipe into two parts. One part is connected to the output end of the chemical reaction device, and the other part is connected to the input end of the spectrophotometric detector. Therefore, the switching valve can control the on-off between the chemical reaction device and the spectrophotometric detector;

[0014] In addition, the end of the first connecting tube furthest from the spectrophotometer, as described above, is connected to a reagent bottle containing hydrochloric acid. However, it can also be connected to a container containing ultrapure water. This is because hydrochloric acid alone is not sufficient for the cleaning process; ultrapure water is also needed to rinse away the hydrochloric acid used for cleaning. This cleaning method is existing technology, but it is explained here to avoid ambiguity regarding the connection relationship of the first connecting tube.

[0015] Preferably, the reaction assembly includes a chemical reaction device, a third connecting pipe, and a second peristaltic pump;

[0016] The output end of the chemical reaction device is connected to the first connecting tube, and its input end is connected to the third connecting tube. It is used to receive and mix the sample liquid, air and corresponding reaction reagents to complete the colorimetric reaction.

[0017] The end of the third connecting tube furthest from the chemical reaction equipment can be connected to a reagent bottle containing reaction reagents and a container containing sample liquid.

[0018] The second peristaltic pump is sleeved outside the third connecting tube. In use, it is located between the chemical reaction equipment and the reagent bottle containing the reaction reagents, and is used to drive the liquids to move towards the chemical reaction equipment in the third connecting tube.

[0019] In this application, it is necessary to further explain that the location of the second peristaltic pump is not only between the chemical reaction equipment and the reagent bottle containing the reaction reagent, but also between the chemical reaction equipment and the container containing the sample liquid. Since the reagent bottle containing the reaction reagent and the container containing the sample liquid are located on the same side of the second peristaltic pump and on opposite sides of the chemical reaction equipment, the above description uses one side as a representative.

[0020] Preferably, the second peristaltic pump is a multi-channel peristaltic pump;

[0021] The third connecting pipe includes a first inlet pipe and a second inlet pipe. One end of the first inlet pipe is connected to the input end of the chemical reaction equipment, and the other end is connected to a reagent bottle containing the reaction reagent, for conveying the reaction reagent to the chemical reaction equipment. One end of the second inlet pipe is connected to the input end of the chemical reaction equipment, and the other end is connected to a container containing the sample liquid, for conveying the sample liquid segment to the chemical reaction equipment.

[0022] The first inlet pipe and the second inlet pipe are both fitted inside the second peristaltic pump, and they are located in different channels of the second peristaltic pump.

[0023] In this application, it should be explained that the sample liquid segment mentioned above refers to the sample liquid and air. This term is commonly used in the field of nutrient automatic analyzers of segmented continuous flow analysis (SCFA) technology, and will not be elaborated here.

[0024] Preferably, the chemical reaction apparatus includes at least:

[0025] The reaction device has its output end connected to the first connecting pipe, serving as the site for the color reaction, and the liquid after the color reaction is input into the first connecting pipe;

[0026] The fourth connecting tube has at least three interfaces, one of which is connected to the first liquid inlet tube, one of which is connected to the second liquid inlet tube, and one of which is connected to the end of the reaction vessel away from the first connecting tube, for receiving sample liquid, air and corresponding reaction reagents.

[0027] Preferably, it also includes a fifth connecting tube, which is connected to the output end of the spectrophotometer and is used to discharge the detected liquid and used hydrochloric acid from the spectrophotometer.

[0028] Preferably, the reaction element is spiral-shaped, and the fourth connecting pipe is a T-shaped pipe.

[0029] Preferably, the system also includes a controller, which is electrically connected to the switching valve, the first peristaltic pump, and the second peristaltic pump, respectively, and the switching valve is a solenoid valve.

[0030] Preferably, the first connecting tube, the second connecting tube, and the third connecting tube are all flexible tubes, and the fourth connecting tube and the reaction element are all transparent glass tubes.

[0031] In this application, it should be further explained that, because this application involves chemical reactions and solutions required for chemical reactions, as well as hydrochloric acid solutions used for cleaning, all pipelines are made of corrosion-resistant materials.

[0032] Preferably, the hydrochloric acid in the second connecting tube is a 1 mol / L hydrochloric acid solution.

[0033] Preferably, the chemical reaction apparatus has multiple reaction elements and a fourth connecting pipe evenly distributed in it, and the number of spectrophotometers and the number of channels on the first peristaltic pump are the same as the number of reaction elements.

[0034] Compared with the prior art, the beneficial effects of this utility model are:

[0035] 1. This application improves upon existing commercial nutrient automatic analyzers to effectively solve the problems of baseline drift and measurement interruption caused by the adsorption of chromogenic complexes when measuring large batches of complex matrix seawater samples. The utility model device is simple and does not require modification of the main functions of existing commercial instruments. It only requires switching to the functional components of this utility model after measuring a certain number of samples to actively prevent contamination caused by adsorption in the flow cell. The entire process takes only a short time. This application not only prevents baseline drift caused by the adsorption of chromogenic complexes, but also significantly improves work efficiency, ultimately achieving a simultaneous improvement in measurement efficiency and data stability. Attached Figure Description

[0036] Figure 1 This is a partial structural schematic diagram of the present invention;

[0037] Figure 2 This is a schematic diagram of another part of the structure of this utility model;

[0038] Figure 3 This is a schematic diagram of another part of the structure of this utility model;

[0039] Figure 4 This is a schematic diagram of the overall structure of this utility model;

[0040] In the diagram: 1. Reaction component; 2. Spectrophotometer; 3. First connecting pipe; 4. Switching valve; 5. Second connecting pipe; 6. First peristaltic pump; 7. Chemical reaction equipment; 8. Third connecting pipe; 9. Second peristaltic pump; 10. First inlet pipe; 11. Second inlet pipe; 12. Reaction element; 13. Fourth connecting pipe; 14. Fifth connecting pipe. Detailed Implementation

[0041] The following will refer to the appendix in the embodiments of this utility model. Figure 1-4 The technical solutions in the embodiments of this utility model are clearly and completely described herein. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0042] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0043] Please see Figure 1-4 Embodiments of this utility model:

[0044] Example 1:

[0045] like Figure 1 As shown: A self-cleaning and baseline stabilization device for an automated nutrient analyzer, comprising:

[0046] Reaction component 1, which is used to mix the sample liquid, air and corresponding reaction reagents to complete the colorimetric reaction;

[0047] Spectrophotometer 2, wherein the spectrophotometer 2 is connected to the output end of reaction component 1 via a first connecting tube 3;

[0048] The cleaning assembly includes at least a switching valve 4, a second connecting pipe 5, and a first peristaltic pump 6. The switching valve 4 is disposed on the first connecting pipe 3 and located between the reaction assembly 1 and the spectrophotometer 2. One end of the second connecting pipe 5 is connected to the switching valve 4, and the other end can be connected to a reagent bottle containing hydrochloric acid. The first peristaltic pump 6 is sleeved outside the second connecting pipe 5 and, in use, is located between the switching valve 4 and the reagent bottle containing hydrochloric acid to drive the hydrochloric acid to move towards the switching valve 4 within the second connecting pipe 5.

[0049] The switching valve 4 can switch the first connecting pipe 3 to the reaction component 1 or to the cleaning component.

[0050] In this embodiment, the first peristaltic pump 6 mainly serves as the power source for hydrochloric acid and ultrapure water, enabling them to enter the spectrophotometer sequentially.

[0051] like Figure 2 As shown: The reaction assembly 1 includes a chemical reaction device 7, a third connecting pipe 8, and a second peristaltic pump 9;

[0052] The output end of the chemical reaction device 7 is connected to the first connecting pipe 3, and its input end is connected to the third connecting pipe 8. It is used to receive and mix the sample liquid, air and corresponding reaction reagents to complete the colorimetric reaction.

[0053] The end of the third connecting tube 8 that is away from the chemical reaction device 7 can be connected to a reagent bottle containing reaction reagents and a container containing sample liquid.

[0054] The second peristaltic pump 9 is mounted outside the third connecting pipe 8. In use, it is located between the chemical reaction equipment 7 and the reagent bottle containing the reaction reagents, and is used to drive each liquid to move towards the chemical reaction equipment 7 in the third connecting pipe 8.

[0055] The second peristaltic pump 9 is a multi-channel peristaltic pump;

[0056] The third connecting pipe 8 includes a first inlet pipe 10 and a second inlet pipe 11. One end of the first inlet pipe 10 is connected to the input end of the chemical reaction device 7, and the other end is connected to a reagent bottle containing reaction reagents, for conveying reaction reagents to the chemical reaction device 7. One end of the second inlet pipe 11 is connected to the input end of the chemical reaction device 7, and the other end is connected to a container containing sample liquid, for conveying sample liquid segment to the chemical reaction device 7.

[0057] The first inlet pipe 10 and the second inlet pipe 11 are both fitted inside the second peristaltic pump 9, and the two are located in different channels of the second peristaltic pump 9.

[0058] In this embodiment, the end of the first liquid inlet pipe 10 that is away from the chemical reaction device 7 is mainly able to be connected to the polytetrafluoroethylene tube on the reagent bottle.

[0059] like Figure 3 As shown: The chemical reaction equipment 7 is equipped with at least the following:

[0060] The reaction element 12, the output end of which is connected to the first connecting pipe 3, serves as the site for the color reaction, and the liquid after the color reaction is input into the first connecting pipe 3;

[0061] The fourth connecting tube 13 has at least three interfaces, one of which is connected to the first liquid inlet tube 10, one of which is connected to the second liquid inlet tube 11, and one of which is connected to the end of the reaction vessel 12 away from the first connecting tube 3, for receiving sample liquid, air and corresponding reaction reagents.

[0062] like Figure 3 and 4 As shown: It also includes a fifth connecting tube 14, which is connected to the output end of the spectrophotometer 2 and is used to discharge the detected liquid and used hydrochloric acid from the spectrophotometer 2.

[0063] like Figure 3 As shown: the reaction element 12 is spiral-shaped, and the fourth connecting pipe 13 is a three-way pipe.

[0064] It also includes a controller, which is electrically connected to the switching valve 4, the first peristaltic pump 6 and the second peristaltic pump 9 respectively, and the switching valve 4 is a solenoid valve.

[0065] The first connecting tube 3, the second connecting tube 5 and the third connecting tube 8 are all silicone tubes, and the fourth connecting tube 13 and the reaction element 12 are all transparent glass tubes.

[0066] In this embodiment, the switching valve is made of polyetheretherketone (PEEK) and is specifically a two-position electromagnetic three-way selector valve.

[0067] The hydrochloric acid in the second connecting tube 5 is a 1 mol / L hydrochloric acid solution.

[0068] In this embodiment, concentrated hydrochloric acid is diluted with ultrapure water to prepare a 1 mol / L hydrochloric acid solution for cleaning.

[0069] like Figure 4 As shown: The chemical reaction device 7 has a plurality of reaction elements 12 and a fourth connecting pipe 13 evenly distributed in it. The number of spectrophotometers 2 and the number of channels on the first peristaltic pump 6 are the same as the number of reaction elements 12.

[0070] In this embodiment, the first peristaltic pump 6 has a four-channel peristaltic pump, while the corresponding second peristaltic pump 9 has an eight-channel peristaltic pump.

[0071] The specific operation in this embodiment is as follows:

[0072] Step 1: When the automatic nutrient analyzer is running normally, the first peristaltic pump 6 stops running. At this time, the switching valve 4 is in the left and right connected state, that is, the colorimetric reaction solution enters the spectrophotometer 2 normally for absorbance measurement.

[0073] Step 2: After the instrument has been running for a long time (such as continuously measuring 60 seawater samples), pause the operation of the second peristaltic pump 9 and start the operation of the first peristaltic pump 6. At the same time, switch the switching valve 4 to allow the cleaning solution: 1 mol / L hydrochloric acid solution to continuously enter the spectrophotometer detector 2. Run for about 5 minutes to effectively clean the colorimetric reaction products adhering to the inside of the detector.

[0074] Step 3: Replace the 1 mol / L hydrochloric acid solution with ultrapure water and continue to clean the spectrophotometer for about 5 minutes to remove any hydrochloric acid solution residue from the previous step.

[0075] Step 4: The first peristaltic pump 6 stops running, and the switching valve 4 is switched back to its original position. The second peristaltic pump 9 is then turned on, and the nutrient salt color reaction solution can return to normal and continue to enter the detector for absorbance measurement.

[0076] In this embodiment, the time from the start of cleaning to the resumption of normal analysis and detection is approximately 20 minutes.

[0077] Comparative Example 1: This comparative example uses a nutrient salt automatic analyzer, which is relatively common in the prior art.

[0078] Its standard operating procedures include:

[0079] Step 1: Power on and warm up, start the control software and pre-establish the analysis method, and set the basic parameters of the instrument;

[0080] Step 2: Rinse the entire tubing (including reagent tubing, sample tubing and the entire reaction tubing) with ultrapure water, hydrochloric acid solution and ultrapure water in sequence for 20-30 minutes each. This cleans the tubing and also ensures the stability of the instrument baseline.

[0081] Step 3: Place the carrier and reagent tubing into the corresponding solution, and run the program until the flow path is stable, the bubbles are uniform, the instrument baseline is stable, and the blank is reasonable;

[0082] Step 4: Place the sample tube on the autosampler, set the analysis sequence, start the analysis sequence, and update the sample midway. Finally, complete the sample measurement. The instrument will automatically record the signal results and calculate the sample concentration.

[0083] Step 5: After the sample measurement is completed, run the tubing cleaning procedure again, flushing the entire tubing with ultrapure water, 1 mol / L hydrochloric acid solution, and ultrapure water in sequence to maintain the instrument's condition.

[0084] In this comparative example, the time from the start of cleaning to the resumption of normal analysis and testing is approximately 1-2 hours.

[0085] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0086] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A device for self-cleaning and baseline stabilization of a nutrient salt autoanalyzer, characterized by, The utility model relates to a kind of automatic cleaning device for spectrophotometer, including: Reaction component (1), the reaction component (1) is used to mix sample liquid sample, air and corresponding reaction reagent, complete color reaction; Spectrophotometric detector (2), the spectrophotometric detector (2) is connected with the output end of reaction component (1) by a first connecting pipe (3); Washing component, the washing component at least includes switching valve (4), second connecting pipe (5) and first peristaltic pump (6), the switching valve (4) is arranged on first connecting pipe (3), between reaction component (1) and spectrophotometric detector (2), the second connecting pipe (5) one end is connected with switching valve (4), the other end can be connected with reagent bottle of hydrochloric acid, the first peristaltic pump (6) is set in second connecting pipe (5) outside, when using, between switching valve (4) and reagent bottle of hydrochloric acid; The switching valve (4) can switch first connecting pipe (3) and reaction component (1) or with washing component communication.

2. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 1, characterized in that, The reaction component (1) includes chemical reaction equipment (7), third connecting pipe (8) and second peristaltic pump (9); The output end of the chemical reaction equipment (7) is connected with first connecting pipe (3), and its input end is connected with third connecting pipe (8), for receiving and mixing sample liquid sample, air and corresponding reaction reagent, complete color reaction; The third connecting pipe (8) can be connected with reagent bottle of reaction reagent and container of sample liquid sample on the end away from chemical reaction equipment (7); The second peristaltic pump (9) is set in third connecting pipe (8) outside, when using, between chemical reaction equipment (7) and reagent bottle of reaction reagent, for driving each liquid to move in third connecting pipe (8) to chemical reaction equipment (7).

3. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 2, characterized in that, The second peristaltic pump (9) is multi-channel peristaltic pump; The third connecting pipe (8) includes first liquid inlet pipe (10) and second liquid inlet pipe (11), one end of the first liquid inlet pipe (10) is connected with the input end of chemical reaction equipment (7), and the other end is connected with reagent bottle of reaction reagent, for delivering reaction reagent to chemical reaction equipment (7), one end of the second liquid inlet pipe (11) is connected with the input end of chemical reaction equipment (7), and the other end is connected with container of sample liquid sample, for delivering sample liquid section to chemical reaction equipment (7); The first liquid inlet pipe (10) and the second liquid inlet pipe (11) are all set in second peristaltic pump (9), and they are located in different channels of second peristaltic pump (9).

4. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 3, wherein At least the following are provided in the chemical reaction equipment (7): Reaction piece (12), the output end of the reaction piece (12) is connected with first connecting pipe (3), as the place of color reaction, input liquid after color reaction to first connecting pipe (3); Fourth connecting pipe (13), at least three interfaces are provided on the fourth connecting pipe (13), wherein, one interface is connected with the first liquid inlet pipe (10), one interface is connected with the second liquid inlet pipe (11), and one interface is connected with the end of reaction piece (12) away from first connecting pipe (3), for receiving sample liquid sample, air and corresponding reaction reagent.

5. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 1, 2, 3 or 4, characterized in that, A fifth connecting pipe (14) is further included, which is connected with the output end of the spectrometer (2) and used for discharging the detected liquid and used hydrochloric acid out of the spectrometer (2).

6. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 4, wherein The reaction piece (12) is in a spiral shape, and the fourth connecting pipe (13) is a tee pipe.

7. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 5, wherein A controller is further included, which is electrically connected with the switching valve (4), the first peristaltic pump (6) and the second peristaltic pump (9), respectively, and the switching valve (4) is an electromagnetic valve.

8. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 4 or 6, wherein The first connecting pipe (3), the second connecting pipe (5) and the third connecting pipe (8) are all hoses, and the fourth connecting pipe (13) and the reaction piece (12) are both transparent glass pipes.

9. The self-cleaning and baseline stabilizing device for a nutrient salt autoanalyzer according to claim 4 or 6, wherein A plurality of reaction pieces (12) and fourth connecting pipes (13) are uniformly distributed in the chemical reaction device (7), and the number of the spectrometer (2) and the number of the channels on the first peristaltic pump (6) are both the same as the number of the reaction pieces (12).

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