Multi-Mode-Electrode pro Manual 8.110.
Metrohm AG CH-9100 Herisau Switzerland Phone +41 71 353 85 85 Fax +41 71 353 89 01 info@metrohm.com www.metrohm.com Multi-Mode-Electrode pro 6.1246.120 Manual 8.110.8018EN 06.
Teachware Metrohm AG CH-9100 Herisau teachware@metrohm.com This documentation is protected by copyright. All rights reserved. Although all the information given in this documentation has been checked with great care, errors cannot be entirely excluded. Should you notice any mistakes please send us your comments using the address given above. Documentation in additional languages can be found on http://documents.metrohm.com.
■■■■■■■■■■■■■■■■■■■■■■ Table of contents Table of contents 1 Introduction 1 1.1 Instrument description ......................................................... 1 1.2 Intended use ......................................................................... 1 1.3 About the documentation ................................................... 2 1.3.1 Content and scope .................................................................. 2 1.3.2 Additional documentation ..........................................
■■■■■■■■■■■■■■■■■■■■■■ Table of contents 5.2.6 5.2.7 5.2.8 5.2.9 5.2.10 5.2.11 6 Technical specifications 45 7 Accessories 46 Index IV ■■■■■■■■ Mounting the capillary ........................................................... 35 Inserting the needle ............................................................... 37 Filling in mercury ................................................................... 39 Mounting the MME pro onto the measuring head ................. 41 Adjusting the needle valve ..
■■■■■■■■■■■■■■■■■■■■■■ Table of figures Table of figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 MME pro – Construction ................................................................... 5 Electrode stand ................................................................................. 7 MME pro – Mounting the capillary .................................................. 10 MME pro – Inserting the needle ....................
■■■■■■■■■■■■■■■■■■■■■■ 1 Introduction 1 Introduction 1.1 Instrument description The Multi-Mode electrode pro (MME pro) combines the most important polarographic and voltammetric mercury electrodes in one single construction: ■ ■ ■ 1.2 Dropping Mercury Electrode (DME) This is the classic mercury electrode. The mercury drops fall continuously from the capillary. Drop intervals are synchronized with the voltage steps of the measurement.
■■■■■■■■■■■■■■■■■■■■■■ 1.3 About the documentation 1.3 About the documentation Caution Please read through this documentation carefully before putting the instrument into operation. The documentation contains information and warnings which the user must follow in order to ensure safe operation of the instrument. 1.3.1 Content and scope This manual describes the construction, the installation, and the maintenance of the Multi-Mode electrode pro (MME pro).
■■■■■■■■■■■■■■■■■■■■■■ 1 Introduction Method Dialog text, parameter in the software File ▶ New Menu or menu item [Next] Button or key Warning This symbol draws attention to a possible life hazard or risk of injury. Warning This symbol draws attention to a possible hazard due to electrical current. Warning This symbol draws attention to a possible hazard due to heat or hot instrument parts. Warning This symbol draws attention to a possible biological hazard.
■■■■■■■■■■■■■■■■■■■■■■ 1.4 Safety instructions 1.4.2 Flammable solvents and chemicals Warning All relevant safety measures are to be observed when working with flammable solvents and chemicals. ■ ■ ■ ■ 1.4.3 Set up the instrument in a well-ventilated location (e.g. fume cupboard). Keep all sources of flame far from the workplace. Clean up spilled liquids and solids immediately. Follow the safety instructions of the chemical manufacturer.
■■■■■■■■■■■■■■■■■■■■■■ 2 Overview 2 Overview 2.1 Construction of the MME pro 1 1 12 2 8 3 7 13 4 9 10 14 5 11 15 6 Figure 1 MME pro – Construction 1 Needle holder (6.1247.140) 2 Needle (6.1247.020) 3 Thread For the needle holder (1-1). 4 Thread For the capillary retaining screw (1-6). 5 Silicone seal (6.1247.150) 6 Capillary retaining screw (6.1247.120) For the capillary. 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 2.2 Tools and auxiliary equipment 7 Screw cap (6.1247.110) For the mercury refill opening. 8 Connector For inert gas supply for controlling the needle valve. 9 Thread For the screw cap (1-7). 10 Contact pin Electrical contact with mercury. 11 Mercury reservoir 12 Connector For inert gas supply. 13 Quick connector For the WE cable. 14 Adapter (6.2112.130) For connecting the working electrode cable with the quick connector (1-13). 15 Glass capillary 6.1226.030 or 6.
■■■■■■■■■■■■■■■■■■■■■■ 2 Overview A Figure 2 B C Electrode stand A Position A For inserting or replacing the capillary. C Position C For replacing the needle. B Position B For filling in mercury or for storing the MME pro. Wrench The wrench supplied with the MME pro has two functions: ■ ■ One end is a screwdriver. You can use it to open and close the needle holder and the screw cap of the mercury refill opening. The other end is a torque wrench.
2.2 Tools and auxiliary equipment ■■■■■■■■■■■■■■■■■■■■■■ Mounting ring The mounting ring is used to pull the needle holder out of the electrode body. Adapter for working electrode connection The MME pro is fitted with a quick contact. Screw the adapter onto the working electrode cable once and leave it on. When inserting or removing the electrode from the instrument, you can simply plug the adapter onto the quick contact of the MME pro or pull it off. 8 ■■■■■■■■ 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use 3 Preparing the MME pro for use Caution When handling mercury please observe the relevant safety regulations (see also Mercury Handling Guideline 8.000.5054EN). In order to ensure that no mercury can escape into the environment, the following procedures must always be carried out in a dry drip pan (6.2711.030). Mercury which escapes into the drip pan must be completely collected.
■■■■■■■■■■■■■■■■■■■■■■ 3.1 Mounting the capillary Drip pan (6.2711.030) Electrode stand (6.2615.130) Wrench (6.1247.220) Silanized capillary (6.1226.050) or non-silanized capillary (6.1226.030) Scissors ■ ■ ■ ■ ■ 1 2 3 4 Figure 3 MME pro – Mounting the capillary Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. 1 Placing the MME pro into the electrode stand ■ 10 ■■■■■■■■ Place the electrode stand into the drip pan. 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use ■ Place the MME pro into the electrode stand. The capillary retaining screw is pointing upwards. 2 Loosening the capillary retaining screw ■ ■ Remove the transport locking stopper. Loosen the capillary retaining screw either by hand or with the wrench. The capillary retaining screw must sit loosely in the thread.
■■■■■■■■■■■■■■■■■■■■■■ 3.2 Inserting the needle 3.2 Inserting the needle Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. Inserting the needle To insert the needle you need the MME pro and the following accessories: ■ ■ ■ ■ ■ ■ 12 ■■■■■■■■ Drip pan (6.2711.030) Electrode stand (6.2615.130) Needle (6.1247.020) Mounting ring (6.1247.210) Wrench (6.1247.220) Scissors 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use 1 2 4 3 6 5 7 Figure 4 MME pro – Inserting the needle 1 Loosening the needle holder ■ ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. Use the wrench to loosen the needle holder, turn out the screw as far as it will go. 2 Screwing on the mounting ring ■ Screw the mounting ring onto the needle holder in clockwise direction. 3 Pulling out the needle holder ■ 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 3.3 Filling in or refilling mercury 4 Inserting the needle Note Do not touch the needle with bare hands! Each needle is individually wrapped. ■ ■ Cut open the wrapper of the new needle with the scissors and unwrap the white plastic part only. Do not yet completely remove the wrapper. Insert the needle into the hole of the membrane and press in as far as the white marking. Now, remove the wrapper.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use ■ ■ Mercury Mercury drop catcher (6.2406.000) 1 2 3 Figure 5 4 MME pro – Filling in mercury 1 Placing the MME pro into the electrode stand ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. The mercury refill opening is pointing upwards. 2 Opening the screw cap ■ Open the screw cap (1-7) at the mercury refill opening with the wrench and remove it.
3.4 Mounting the MME pro onto the measuring head ■■■■■■■■■■■■■■■■■■■■■■ 4 Closing the screw cap Insert the screw cap into the mercury refill opening and fasten it with the wrench as far as it will go. 3.4 Mounting the MME pro onto the measuring head Before you can adjust the needle valve and test the electrode function, you must mount the MME pro onto the measuring head of the instrument.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use Note If you use another software than 797 VA Computrace, then follow the instructions on adjusting the needle valve in the manual of your instrument. For adjusting the needle valve you need the wrench (6.1247.220) or a coin which will fit the slot of the screw. 1 Preparation ■ ■ ■ ■ Place an empty measuring vessel. Set the inert gas supply to 1.0 to 1.2 bar, in order to pressurize the electrode.
■■■■■■■■■■■■■■■■■■■■■■ 3.6 Testing the electrode function 3.6 Testing the electrode function Note If you use another software than 797 VA Computrace, then follow the instructions on adjusting the needle valve in the manual of your instrument. Preparing the test 1 ■ Fill 20 mL of water and a few drops of KCl-solution into the measuring vessel. DME test 1 ■ ■ In the 797 VA Computrace Software, open the Computrace Control with Utility ▶ Computrace Control.
■■■■■■■■■■■■■■■■■■■■■■ 3 Preparing the MME pro for use HMDE test 1 ■ ■ In the 797 VA Computrace Software, open the Computrace Control with Utility ▶ Computrace Control. Select the electrode type HMDE and switch on the electrode with [New drop]. At the tip of the capillary, a mercury drop is forming, which serves as the actual electrode. 2 6.1246.120 Multi-Mode-Electrode pro ■ Watch the drop formation. Drop formation is functioning properly when the old drop is knocked off and a new drop is formed.
■■■■■■■■■■■■■■■■■■■■■■ 4 Storing the MME pro If the MME pro is not used for measurements, we recommend to ways of storing it: ■ ■ short term storage (less than 1 week) long term storage (more than 1 week) Short term storage 1 You can leave the MME pro in the measuring stand. 2 Fill the measuring vessel with ultrapure water. 3 Store the reference electrode separately.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 5 Maintenance 5.1 Small maintenance Caution When handling mercury please observe the relevant safety regulations (see also Mercury Handling Guideline 8.000.5054EN). In order to ensure that no mercury can escape into the environment, the following procedures must always be carried out in a dry drip pan (6.2711.030). Mercury which escapes into the drip pan must be completely collected.
■■■■■■■■■■■■■■■■■■■■■■ 5.1 Small maintenance 5.1.2 Filling in or refilling mercury Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. Filling in mercury To carry out this procedure you need the MME pro and the following accessories: ■ ■ ■ ■ ■ ■ 1 Drip pan (6.2744.030) Electrode stand (6.2615.130) Wrench (6.1247.220) Syringe (6.2816.020) with needle (6.2816.030) Mercury Mercury drop catcher (6.2406.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance ■ Place the MME pro into the electrode stand. The mercury refill opening is pointing upwards. 2 Opening the screw cap ■ Open the screw cap (1-7) at the mercury refill opening with the wrench and remove it. 3 Filling in mercury Using the syringe, carefully fill in the mercury into the mercury reservoir. Note Only fill in mercury until it reaches the making max. fill.
■■■■■■■■■■■■■■■■■■■■■■ 5.1 Small maintenance Electrode stand (6.2615.130) Wrench (6.1247.220) Silanized capillary (6.1226.050) or non-silanized capillary (6.1226.030) Scissors ■ ■ ■ ■ 1 2 3 4 Figure 7 MME pro – Replacing the capillary 1 Loosening the needle holder ■ ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. Loosen the needle holder using the wrench turning it counterclockwise 1–2 rotations.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 2 Removing the old capillary Caution Do not touch the needle! ■ ■ ■ ■ Turn the MME pro in the electrode stand. Loosen the capillary retaining screw and lift it so far that you can see the lower end of the capillary, the end with the broad opening. Check whether there is still mercury in the opening. If there is mercury left in the capillary, then gently knock at the capillary, this will cause the mercury to flow back into the electrode body.
■■■■■■■■■■■■■■■■■■■■■■ 5.1 Small maintenance Note Do not apply the wrench a second time. See also the video Replace capillary in the multimedia guide Electrodes in Voltammetry. 5.1.4 Replacing the needle Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. Replacing the needle To replace the needle you need the MME pro and the following accessories: ■ ■ ■ ■ ■ ■ 26 ■■■■■■■■ Drip pan (6.2711.030) Electrode stand (6.2615.130) New needle (6.1247.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 1 2 4 3 6 5 7 Figure 8 MME pro – Replacing the needle 1 Loosening the needle holder ■ ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. Use the wrench to loosen the needle holder, turn out the screw as far as it will go. 2 Screwing on the mounting ring ■ Screw the mounting ring onto the needle holder in clockwise direction. 3 Pulling out the needle holder ■ 6.1246.
■■■■■■■■■■■■■■■■■■■■■■ 5.1 Small maintenance 4 Replacing the needle Note Do not touch the needle with bare hands! Each needle is individually wrapped. ■ ■ ■ Pull the old needle out of the membrane of the needle holder. Cut open the wrapper of the new needle with the scissors and unwrap the white plastic part only. Do not yet completely remove the wrapper. Insert the needle into the hole of the membrane and press in as far as the white marking. Now, remove the wrapper.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance Note If you use another software than 797 VA Computrace, then follow the instructions on adjusting the needle valve in the manual of your instrument. For adjusting the needle valve you need the wrench (6.1247.220) or a coin which will fit the slot of the screw. 1 Preparation ■ ■ ■ ■ Place an empty measuring vessel. Set the inert gas supply to 1.0 to 1.2 bar, in order to pressurize the electrode.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 5.2 Large maintenance Large maintenance consists of the following tasks: 1. Removing the MME pro from the measuring head (see Chapter 5.1.1, page 21). 2. Emptying the mercury reservoir (see Chapter 5.2.2, page 30). 3. Removing the capillary (see Chapter 5.2.3, page 31). 4. Removing the needle (see Chapter 5.2.4, page 33). 5. Cleaning the electrode body (see Chapter 5.2.5, page 34). 6. Mounting the capillary (see Chapter 5.2.6, page 35). 7.
■■■■■■■■■■■■■■■■■■■■■■ ■ ■ ■ ■ ■ 5 Maintenance Drip pan (6.2711.030) Electrode stand (6.2615.130) Wrench (6.1247.220) Mercury collection container Mercury drop catcher (6.2406.000) 1 Placing the MME pro into the electrode stand ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. The mercury refill opening is pointing upwards (see Figure (2-B), Page 7). 2 Opening the mercury reservoir ■ ■ ■ Use the wrench to remove the screw cap from the mercury refill opening.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 1 2 3 4 Figure 9 MME pro – Removing the capillary 1 Placing the MME pro into the electrode stand ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. The capillary retaining screw is pointing upwards. 2 Removing the capillary retaining screw Loosen the capillary retaining screw and remove it. 3 Removing the capillary Pull capillary and the seal out of the MME pro.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 5 Collecting the mercury Collect mercury adhering to the seal using the mercury drop catcher. Place the seal into the drip pan. 6 Disposing of the capillary Professionally dispose of the capillary. 5.2.4 Removing the needle Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. To remove the needle, you need the following accessories: Drip pan (6.2711.030) Mounting ring (6.1247.210) Wrench (6.1247.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 2 Screwing on the mounting ring Screw on the gray mounting ring and carefully pull the needle holder out of the MME pro. Hold the mounting ring tight and pull out the needle holder by carefully jiggling it from side to side. 3 Pulling out the needle holder Pull the needle out of the membrane of the needle holder. 4 Removing the needle Dispose of the needle. 5.2.
■■■■■■■■■■■■■■■■■■■■■■ 5.2.6 5 Maintenance Mounting the capillary Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan. There are two types of capillaries which can be mounted into the MME pro, depending on the application: ■ ■ Silanized capillaries (6.1226.050) are especially suitable for voltammetric determinations at the HMDE in acidic to slightly alkaline solutions which do not contain organic solvents. Non-silanized capillaries (6.1226.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 1 2 3 4 Figure 11 MME pro – Mounting the capillary 1 Placing the MME pro into the electrode stand ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. The thread for the capillary retaining screw is pointing upwards. 2 Inserting the silicone seal ■ ■ 36 ■■■■■■■■ Insert the silicone seal. Use the capillary retaining screw to push it into position. Place the capillary retaining screw loosely into the opening. 6.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 3 Inserting the capillary Caution Only hold the capillary by its sides! Do not exert pressure on the tip of the capillary! Each capillary is individually wrapped. ■ ■ ■ Cut open the plastic wrapper with the scissors at the marking and unwrap the capillary. Grab the capillary at its sides, insert it through the capillary retaining screw into the electrode body. Gently press it through the silicone seal.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance Electrode stand (6.2615.130) New needle (6.1247.020) Wrench (6.1247.220) Scissors ■ ■ ■ ■ 1 2 3 4 Figure 12 MME pro – Inserting the needle 1 Inserting a new needle Each needle is individually wrapped in a plastic wrapper. Note Do not touch the needle with bare hands! ■ ■ Cut open the wrapper of the new needle with the scissors and unwrap the white plastic part only. Do not yet completely remove the wrapper.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance 4 Fastening the needle holder ■ Use the wrench to tighten the needle holder by turning it clockwise until the black sealing ring becomes visible in the electrode body. See also the video Replace the needle in the multimedia guide Electrodes in Voltammetry. 5.2.8 Filling in mercury Caution In this procedure mercury is used. Always carry out the following steps in a dry drip pan.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 2 1 Figure 13 3 4 MME pro – Filling in mercury 1 Placing the MME pro into the electrode stand ■ ■ Place the electrode stand into the drip pan. Place the MME pro into the electrode stand. The mercury refill opening is pointing upwards. 2 Filling in mercury Using the syringe, carefully fill in the mercury into the mercury reservoir. Note Only fill in mercury until it reaches the making max. fill.
■■■■■■■■■■■■■■■■■■■■■■ 5.2.9 5 Maintenance Mounting the MME pro onto the measuring head Before you can adjust the needle valve and test the electrode function, you must mount the MME pro onto the measuring head of the instrument. Note Before you can mount the MME pro onto the measuring head of the instrument, you must place an empty measuring vessel into the measuring stand. If the measuring vessel is not empty, then liquid can enter through the capillary into the MME pro.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 5.2.10 Adjusting the needle valve Adjusting the needle valve Before you can adjust the needle valve, the following requirements must be fulfilled: ■ ■ ■ The MME pro is mounted onto the measuring head of the instrument and the inert gas supply is connected. An empty measuring vessel is placed beneath the MME pro. The instrument is connected to a PC on which the 797 VA Computrace software is installed and running.
■■■■■■■■■■■■■■■■■■■■■■ 5 Maintenance ■ Rotate the screw clockwise by another quarter rotation (90 – 100°). The MME pro is now ready for operation. 5.2.11 Testing the electrode function Note If you use another software than 797 VA Computrace, then follow the instructions on adjusting the needle valve in the manual of your instrument. Preparing the test 1 ■ Fill 20 mL of water and a few drops of KCl-solution into the measuring vessel.
■■■■■■■■■■■■■■■■■■■■■■ 5.2 Large maintenance 2 ■ Watch the drop formation. Drop formation is functioning properly when each impact of the knock-off mechanism removes an identically large drop from the capillary. HMDE test 1 ■ ■ In the 797 VA Computrace Software, open the Computrace Control with Utility ▶ Computrace Control. Select the electrode type HMDE and switch on the electrode with [New drop]. At the tip of the capillary, a mercury drop is forming, which serves as the actual electrode.
■■■■■■■■■■■■■■■■■■■■■■ 6 Technical specifications 6 Technical specifications Electrode types ■ ■ ■ Drop surface DME (Dripping Mercury Electrode) HMDE (Hanging Mercury Drop Electrode) SMDE (Static Mercury Drop Electrode) 0.15 - 0.60 mm2 (HMDE and SMDE) Glass capillary Non-silanized glass capillary (6.1226.030) For polarography at the DME or SMDE and voltammetry at the HMDE in alkaline solutions and in solvents. Inner diameter = 0.05 mm Silanized glass capillary (6.1226.
■■■■■■■■■■■■■■■■■■■■■■ 7.1 Scope of delivery 7 Accessories Note Subject to change without notice. 7.1 Scope of delivery 6.1246.120 Multi-Mode-Electrode pro Qty. 1 Order no. Description 6.1247.110 Screw cap for the mercury refill opening for MME pro Material: Material remark: Material 2: Material remark 2: 1 6.1247.120 Retaining screw for capillary for MME pro Material: Material remark: Material 2: Material remark 2: Material 3: Material remark 3: 1 6.1247.
■■■■■■■■■■■■■■■■■■■■■■ Qty. 1 7 Accessories Order no. Description 6.1247.150 Silicone seal, green 13.9 mm for MME pro Material: Height (mm): Outer diameter (mm): Hole diameter (mm): 1 6.1247.210 Assembly ring for needle holder for MME Material: Height (mm): Outer diameter (mm): Hole diameter (mm): 1 6.1247.220 6.2112.130 PVC 5 25 16 Wrench for MME Material: 1.0 Silicone 8.5 13.9 5.2 PETP Adapter plug contact 5.
■■■■■■■■■■■■■■■■■■■■■■ 7.2 Optional accessories Qty. 1 Order no. Description 6.2615.130 Electrode stand for MME pro Electrode stand for filling and storing the Multi-Mode Electrode pro. Material: PP Width (mm): 50 Height (mm): 50.5 Depth (mm): 74 7.2 Optional accessories 6.1246.120 Multi-Mode-Electrode pro Order no. Description 6.1226.030 Mercury drop capillary (non-silanized) for MME Non-silanized mercury drop capillary (10 pieces) Material: Glass Outer diameter (mm): 4.
■■■■■■■■■■■■■■■■■■■■■■ Index Index A Adapter Working electrode connection ............................................. 8 C Capillary Exchange ............................ 23 Insert .............................. 9, 35 Mount ............................ 9, 35 Remove .............................. 31 Replace .............................. 23 D DME Description ........................... 1 Test .............................. 18, 43 E Electrode Test .............................. 18, 43 Electrode stand .....