SPECTRONIC® 20+ SERIES Spectrophotometers
Contents
1. A 1 Absorba nce Mod 3 e Seale 8 e e De e GR e o bw a a wu d ee A 1 Concentration MOGG cba eri Sept A A 1 Concentration Factor Check Feature A 2 Appendix Optical Diagram B 1 This page intentionally left blank vi Section 1 Introduction The SPECTRONIC 20 series of spectrophotometers summarizes the specifications for the two current is one of the most widely used laboratory models in SPECTRONIC 20 series instruments Over the years the series has been improved and now includes the SPECTRONIC 20 Operational procedures for the SPECTRONIC 20 and the SPECTRONIC 200 and 20D spectrophotometers are included in this manual This section describes these two latest instruments and their basic operating features The table below Table 1 Specifications for SPEQTRONIC 20 and SPECTRONIC 20 Spectrophotometers SPECTRONIC 20 SPECTRONIC 20D 340 t 950mm 2 5nm near 525nm Display Meter LED 5 mirrored scale T A C Factor linear T non linear A Wavelength Photometric range 0 to 100 T 0 to 100 T 0to2A 0 to 1 95A 0 to 1999C 0 1 to 1000 Factor Stray radiant energy 0 5 T from 340nm to 950nm Accessory output 1 0 VDC nominal at 100 T 1 0 VDC nominal at 100 T RS 232C serial I O port 100 115V 50 60Hz 220 240V 502. SPECTRONIC 20 SERIES Spectrophotometers gt Uw c OPERATOR S Thermo Spectronic MANUAL gt NOTE This operator s manual contains information and instructions for Thermo Spectronic s SPECTRONIC 20 and 20D spectrophotometers that were believed accurate at the time this manual was written However as part of Thermo Spectronic s on going program of product development the specifications and operating instructions for these spectrophotometers may be modified or changed as needed Thermo Spectronic reserves the right to change such operating instructions and specifications Under no circumstances shall Thermo Spectronic be obligated to notify purchasers of any future changes in either this operator s manual or any other instructions or specifications relating to the SPECTRONIC 20 series spectrophotometers nor shall Thermo Spectronic be liable in any way for its failure to notify purchasers of such changes FCC COMPLIANCE STATEMENT FOR U S A USERS This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause interference to radio communications It has been tested and found to comply with the limits for Class A computing device pursuant to Subpart J of Part 15 of FCC Rules which are designed to provide reasonable protection against such interference when operated in a commercial environment Operation of this equipment in a res
3. Thermo Spectronic is an ISO 9001 systems certified company THERMO SPECTRONIC North America 820 Linden Avenue Rochester NY 14625 USA Telephone 800 654 9955 or 585 248 4000 Fax 585 248 4014 E Mail info spectronic com Web Site www uvvis com THERMO SPECTRONIC Europe Middle East amp Africa Mercers Row Cambridge CB5 8HY UK Telephone Int 44 0 1223 446655 Fax Int 44 0 1223 446644 E Mail uv vis unicaminstruments com Web Site www uvvis com For Asia Pacific and Latin America sales offices contact Rochester New York USA Thermo Spectronic A Thermo Electron business
4. 4 1 high frequency fields and Table 4 2 on page 4 2 2 Ifyou are connecting the instrument to an The instrument should be installed in an area that is Accessory Printer computer or chart recorder free of dust corrosive gases and severe vibrations refer to Table 2 1 for information about cabling requirements In addition there should be no obstructions that could hinder the flow of air under and around the instrument Table2 Cabling requirements for SPECTRONIC 20 series of spectrophotometers DEVICE Analog 333174 Patch Cord 333174 Patch Cord 333174 Patch Cord Recorder Accessory Not available 333177 Serial Interface 333132 Serial Interface Printer Cable Cable Kit 335488 1601 included with Serial Printer 335488 Not available 333177 Serial Interface 333132 Serial Interface Cable Cable Kit 335243 Null Modem Cable OR 333132 Serial Interface Cable Kit Not available 333177 Serial Interface 333132 Serial Interface Cable Cable Kit 335243 Null Modem Cable 345002 111 Adapter Cable OR 333132 Serial Interface Cable Kit 2 1 Installation amp Operating Procedures If you are using either a SPECTRONIC 20 or 20D refer to Table 2 2 for information on filters and phototubes that must be installed for accurate results Table2 Phototube options SPECTRONIC 20 and 20D only Phototube Filter Range Cat No Cat No 340 to 600nm 332971 None
5. 60Hz 1625 W 41 3cm x 8 5 H 21 60m x 13 5 D 34 3cm Net 180 8 2kg When measured with appropriate accessory filter installed Accessory Filter Kit 333129 Introduction Environmental and electrical requirements The SPECTRONIC 20 series of spectrophotometers has been designed to operate under the environmental and electrical requirements listed below Line voltages Catalog Line voltage Frequency Current 333182 000 115VAC 60 Hz 0 9 Amp 333182 002 220 50 60 Hz 0 5 Amp 333182 004 240 50 60 Hz 0 5 Amp 333182 005 100 50 60 Hz 0 9 Amp 333183 000 115VAC 60Hz 1 0 Amp 333183 002 220 50 60Hz 0 5 Amp 333183 004 240 50 60Hz 0 5 Amp 333183 005 100 50 60Hz 1 0 Amp Operating environment The instrument meets the specifications on the previous page under the following conditions after a 30 minute warm up period Ambient temperature Relative humidity 50 F to 75 F 15 C to 24 C 20 to 80 76 F to 85 F 25 C to 29 C 20 to 70 86 F to 95 F 30 C to 35 C 20 to 60 96 F to 105 36 C to 40 C 20 to 50 Temperature should be maintained at 4 F 2 C Relative humidity should be maintained to 5 SPECTRONIC 20 series Storage environment 40 F to 140 F 40 C to 60 C Relative humidity not to exceed 60 Allow instrument to adjust to room temperature for 24 hours after taking it out of storage Altitude From below sea level to 2000
6. hydrochloric acid ACS grade Mix and make to volume with distilled water to obtain 1 hydrochloric acid solution 2 Ina 1 volumetric flask place 22 to 23gm cobalt chloride CoCL ACS grade Dissolve in the 1 hydrochloric acid Make to volume with 1 hydrochloric acid to obtain cobalt chloride stock solution To perform the cobalt solution check 1 Turn on the Power Switch Zero Control and allow the instrument to warm up for at least 15 minutes 2 Ifyou have SPECTRONIC 20D or 20D set the display mode to Transmittance 3 With the sample compartment empty and the cover closed adjust the Power Switch Zero Control until the meter or display reads 0 4 Set the Wavelength Control to 500nm 5 Set the Filter Lever to 340 599nm 6 Insert the glassware filled with distilled water into the sample compartment and use the Transmittance Absorbance Control to set the meter or display to 100 T 7 Replace the distilled water with the cobalt chloride solution 8 Insert the glassware filled with the cobalt chloride solution into the sample compartment 9 Read T on the meter or display 10 Repeat steps 4 through 9 at 505 510 515 and 520nm The instrument is in proper calibration when minimum transmittance maximum absorbance occurs between 505 and 515nm The specific transmittance or absorbance values are unimportant Wavelength calibration adjustment If the wavelength accuracy is out of tolerance re
7. meters 6562 feet For indoor use only Your instrument package includes SPECTRONIC 20 Cat No 333182 or SPECTRONIC 20D Cat No 333183 spectrophotometer SPECTRONIC 20 Series Spectrophotometers Operator s Manual Cat No 333182 10001 Box of 12 test tube cuvettes Cat No 331780 Dust cover Cat No 332961 149 Adapter Cat No 333178 1 16 Allen wrench Cat No 332260 174 for interchanging test tube adapters SPECTRONIC 20 series Introduction SPECTRONIC 20 spectrophotometer Cat meter spectrophotometer with a wavelength range of Nos 333182 000 333182 02 333182 04 333182 05 340nm to 95nm The nominal spectral slit width of or 333182 07 shown in Figure 1 1 is a single beam 20nm is constant over the entire range 98 eE CA Figure 8 SPECTRONIC 20 spectrophotometer KEY 1 Sample compartment Pilot lamp Wavelength control Transmittance Absorbance control 100 T 0A Power switch Zero control Filter lever Introduction The SPECTRONIC 20D spectrophotometer Cat Nos 333183 000 333183 02 333183 04 333183 05 or 333183 07 shown in Figure 1 2 is a single beam Figure 9 KEY 1 Sample compartment Digital readout Decrease Increase QUA amp 7 8 Mode indicators 9 Mode selection 10 11 Filter lever SPECTRONIC 200 spectrophotometer Print Wavelength control SPECTRONIC 20 series digital spectropho
8. required 600 to 950nm 332972 332918 400 to 700nm 332989 332992 Or use appropriate filter from Accessory Filter Kit Cat No 333128 Included with instrument 4 Plug the power cord into a grounded outlet with the appropriate voltage 5 Turn the Power Switch Zero Control clockwise and allow the instrument to warm up for at least 15 minutes Technique Successful use of your spectrophotometer depends on the consistent use of correct laboratory procedures and analytical techniques To minimize problems follow these simple rules Keep all solutions free of bubbles Make sure that all sample holders are at least half full Use the same cuvette for both sample and blank measurements Use square cuvettes Cat No 331709 with Holder Cat No 333176 for greater accuracy Make sure that the mark fiducial line on the test tube aligns with the mark on the adapter toward the front of the instrument During extended operation at a fixed wavelength check from time to time for 100 T drift Possible causes of drift are listed in Table 3 1 in the Maintenance section Use clean test tubes and do not touch the test tubes below the fiducial line 2 2 SPECTRONIC 20 series Sample Measurements Once your instrument has been set up properly and has warmed up for at least 15 minutes you can begin taking measurements SPECTRONIC 20 and 20 Notes To read the meter properly align the needle with its reflection in
9. series 10 Wipe the cell with a tissue and insert the cell into the sample compartment Align the guide marks and close the lid Read the appropriate value oT or A from the meter Remove the cell from the sample compartment and repeat steps 9 through 11 for any remaining sample solutions When all measurements are completed turn off the spectrophotometer by turning the Power Switch Zero Control counterclockwise until it clicks SPECTRONIC 20D and 20D Notes Flashing display A flashing display indicates that the reading is out of range and the 100 T 0A control must be adjusted This adjustment controls an optical occluder which regulates the amount of light passing through the sample In 7 mode A reading greater than 200 T will cause the display to flash Ifthe flashing reading is 1999 turn the 100 T 0A control clockwise until the display operates normally Ifthe flashing reading is 1999 turn the 100 T 0A control counterclockwise until the display operates normally In absorbance mode A reading greater than 2A will cause the display to flash Ifthe flashing reading is 1999 turn the 100 T 0A control counterclockwise until the display operates normally Ifthe flashing reading is 1999 turn the 100 T 0A control clockwise until the display operates normally It may require several complete turns of the 100 T control to return to the proper range 2 3 Installat
10. RONIC 20 spectrophotometer 1 6 Operating features of the SPECTRONIC 20D spectrophotometer 1 6 Section 2 Installation amp Operating Procedures 2 1 Environment PI Uh teh a 2 1 SaBlup nstallallon 3 27 55 3 944 ee gos 2 1 MT men 2 2 Sample Measurements 3s 2 4 9 x x RR UR EROR CRUS RUN ORG 2 2 Printing be Rois deca deed sd beng adda Septet ade 2 4 semiote operation v op D de taa Sedet gor piura 2 5 Section 5 Maintenance siste xd REIR EG NE WU 3 1 Lamp Replacement P ERA 550555455502 5955 O84 3 1 Cleaning the sample 3 2 Wavelength Calibration Check 3 2 Photometric linearity 3 3 Replacing PHOLOLUDES acie patent say tetas 3 4 Sevice Proc d re RUE ERAN ET RE Ru RD doces 3 6 TrOUDIGSTHODBPIG eo e ee dui de dab dg 3 6 Section 4 ACCeSSOTFIGS vo gc a e or eie a ne od v d 4 1 Appendix A Choosing a Readout Mode A 1 Transmittance Mode
11. d the concentration of the standard See page 2 4 for detailed instructions A 2 SPECTRONIC 20 series Concentration Factor Check Feature To verify that operating conditions do not vary between reagent batches or from day to day use the concentration factor check features as follows After the concentration mode has been set up with standard solutions press the MODE select control until the FACTOR LED lights and read and record the factor given on the digital display Every time new standard solutions are used for the same test such as for a new reagent batch or when setting up the instrument press the MODE select control until the FACTOR LED lights and note the factor on the digital display A change in the factor indicates a change in the slope of the standard curve due to variation in operating conditions It is recommended that a standard always be used to set the concentration mode The operator may choose however to set the blank to 000A then switch to the concentration mode L8 saajamojoydo saads 521425 QZ OINOWLOIdS 40f 1 jooudo HOLOALAGOLOHd INSWLSNPGV 1 96 001 Sulla dOLS 318viHvA 1931 H31N3O ONILVYD Uns se Nie cs 4 SN31 4 Ed SN31 X dONVHIN3 lt OAN NALSONNAL jeondo xipueddy ca 120100 SPECTRONIC is a registered trademark and GENESYS is a trademark of Thermo Spectronic
12. dards 333150 Quick reliable way to test and evaluate instrument performance 0 T wavelength accuracy stray radiant energy photometric accuracy requires Cuvette Holder Cat No 333176 and Adapter Cat No 333178 included with instrument Accessory Filter Kit 333129 Use for lowering stray light to lt 0 5 T and for validating wavelength accuracy includes four stray radiant energy 274 order filters and one didymium filter Accessory Printer 335488 RS 232 C Serial Interface Cable 333177 Connects SPECTRONIC 20D to Accessory Printer or computer Vernier Software 333 192 02 For using the SPECTRONIC 20D 20D with an IBM compatible computer includes standard curve wavelength scan and kinetics programs see Table 2 1 on page 2 1 for required cable RS 232C Cable 333132 Cable Kit to connect SPECTRONIC 20D or 20D to an IBM compatible computer or SPECTRONIC 20D to 335488 40 column printer SPECTRONIC 20 Series Service Manual 333182 10020 Includes optical diagrams circuit diagrams diagnostics troubleshooting schematics and assemblies SPECTRONIC 20 Series Service Manual 333175 10020 For SPECTRONIC 20 and 20D models includes optical diagrams circuit diagrams diagnostics troubleshooting schematics and assemblies Educational Manual 332909 10030 Booklet of lab experiments and basic spectrophotometry information 4 1 Accessories SPECTRONIC 20 series Glassware selection and sampling options To change adapte
13. dels also require replacement of the phototube see Table 2 2 Note The source lamp has a nominal life of 250 hours The operator may also perform routine checks for wavelength calibration and photometric accuracy Lamp Replacement The lamp gets very hot during operation Before removing the lamp turn off the instrument and allow the lamp to cool down for 10 minutes Turn off and unplug the instrument before removing the lamp door 3 Turn off and unplug the instrument 4 Tilt up the unit and set on its back 5 Loosen the thumbscrew on the lamp access door and open the door see Figure 1 3 6 Using finger pressure press the lamp socket toward the mounting bracket Figure 3 1 1 Do not touch the lamp with your fingers 7 avoid getting skin oils on the surface of the lamp use the Lamp Gripper supplied with the instrument to grip the lamp Push the lamp toward the lamp socket and rotate counterclockwise to remove it Maintenance Figure 3 Lamp replacement KEY 1 Lamp 2 Lamp socket 3 Mounting bracket 4 Lamp flange 5 Locating pins 6 Terminals 8 Install a new lamp by properly aligning the large openings in the lamp flange with the locating pins Press the lamp and the lamp socket toward each other and rotate the lamp clockwise until secure Do not touch the lamp with your fingers 9 Clean the lamp of fingerprints and oils close the door and tighten securely Thi
14. desires results in absorbance for direct correlation of concentration by Beer s Law A abc Results in percent transmittance may be converted to absorbance values by use of transmittance absorbance conversion tables or by the formula A log T Results in absorbance may be plotted against the concentration of known standards on rectilinear graph paper The best line is drawn through these points to construct a standard curve The concentration of unknowns may then be determined by locating on the standard curve the concentration value which corresponds to the absorbance of the unknown To eliminate T to A calculations each model of the instrument provides conversion of transmittance to absorbance The SPECTRONIC 20 has an absorbance scale marked with values corresponding to percent transmittance The operator may simply read the absorbance scale and use these values to construct a standard curve as described above The SPECTRONIC 20 offers precise electronic conversion of transmittance to absorbance When the absorbance mode is used the reference blank sets 0 000A and the results for standards and unknowns are obtained in absorbance Results in absorbance may be related to concentration by Beer s Law A abc if the absorptivity and pathlength are known or by constructions of a standard curve as described above Absorbance measurements are useful for kinetics studies and for reaction systems which do not obey Beer
15. e LED beside Concentration is lit Remove the standard solution and rinse and fill the cell with the sample solution of unknown concentration Wipe the cell with a tissue and insert the cell in the sample compartment Read the concentration of the sample directly from the display 2 4 SPECTRONIC 20 series 8 Remove the cell from the sample compartment and repeat steps 6 and 7 for each of the samples 9 When all measurements are completed turn off the spectrophotometer by turning the Power Switch counterclockwise until it clicks Concentration measurements using FACTOR mode Note Refer to Appendix A for more information about the FACTOR mode 1 Determine the factor value by following steps 1 through 4 of the procedure for Concentration mode above 2 Press the MODE control key until the LED beside factor 1s lit 3 Press the INCREASE or DECREASE key until the desired factor is displayed a value between 0 100 and 1000 4 Press the MODE control key to select the CONCENTRATION mode 5 Rinse and fill the cell with the sample solution of unknown concentration Wipe the cell with a tissue and insert the cell in the sample compartment 6 Read the concentration of the sample directly from the display 7 Remove the cell from the sample compartment and repeat steps 5 and 6 for each of the samples 8 When all measurements are completed turn off the spectrophotometer by turning the Power Switch counterclockwise un
16. er the instrument is still under warranty or it has expired If it is necessary to ship the instrument 1 Wrap the spectrophotometer in plastic then pack carefully in a crush resistant carton with at least three inches of shock absorbing material to prevent transit damage Table3 Operator s troubleshooting guide 1 Instrument does not function Dead power outlet Internal fuse blown Defective electronic component 2 Meter Display does not zero Lamp access door not tightly closed c Phototube defective 3 Readings are drifting or a Poor sampling technique incorrect Filter selection lever is in wrong position Fumes from sample Excessive line voltage variation e Wrong line voltage setting international models only Source lamp defective Phototube defective Possible Cause Power line cord not connected to outlet Sample compartment cover not closed Defective electronic component Defective electronic component 2 Include a detailed letter inside the shipping carton fastened to the instrument describing the trouble Please include the name and phone number of the person or department head most familiar with the problem This information enables service personnel to make required repairs promptly and at least expense 3 Inthe United States mark on the shipping container FIRST CLASS LETTER ENCLOSED First class postage is required only on the lette
17. es not apply to equipment and accessories that have been modified or tampered with in any way misused or damaged by accident neglect or conditions beyond Thermo Spectronic s control This warranty does not apply to lamps glassware and similar expendable components However such parts and components may be warranted by their manufacturer Thermo Spectronic is not responsible under this warranty for loss in operating performance due to environmental conditions THIS WARRANTY IS IN LIEU OF ALL WARRANTIES EXPRESSED IMPLIED OR STATUTORY INCLUDING BUT NOT LIMITED TO WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY OR OTHERWISE and states Thermo Spectronic s entire and exclusive liability and the Customer s exclusive remedy for any claim in connection with the sale or furnishing of services goods or parts their design suitability for use installation or operations Thermo Spectronic will in no event be liable for any direct indirect special or consequential damages whatsoever including loss of goodwill whether grounded in tort including negligence strict liability or contract and Thermo Spectronic s liability under no circumstances will exceed the contract price for the goods and or services for which liability is claimed Contents Section 1 Introduction 3 a dad 849 45 3635 5298 nes 1 1 Environmental and electrical requirements 1 2 Operating features of the SPECT
18. fer to the Service Procedure section on page 3 5 Customer recalibration is not recommended 3 3 Maintenance Photometric linearity check If the photometric linearity of the instrument is questionable first check your analytical procedure and technique see Techniques on page 2 2 If proper operation is still in doubt use the Photometric Accuracy Linearity Test from SPECTRONIC Standards Cat No 333150 to test and evaluate photometric performance of your instrument The alternate method below uses specially prepared potassium dichromate solutions 1 Turn on the Power Switch Zero Control and allow the instrument to warm up for at least 15 minutes 2 Make sure that the sample compartment is empty and the cover is closed then adjust the Power Switch Zero Control until the display reads 0 3 Ifyou have a SPECTRONIC 20D or 20D set the display mode to Absorbance 4 Prepare 0 01N sulfuric acid diluent by adding 0 3mL of concentrated sulfuric acid to about 500mL of deionized or distilled water in a clean 1L volumetric flask Fill to volume with deionized or distilled water 5 Prepare a stock solution of potassium dichromate by weighing 0 500g of potassium dichromate e g Fisher Certified A C S potassium dichromate formula weight 294 19 and dissolving it in about 400mL of 0 01N sulfuric acid solution in a 500mL volumetric flask Fill to volume with 0 01N sulfuric acid solution This is your stock 1 0g L potassi
19. ff the instrument and allow the area to cool down for 10 minutes 3 4 SPECTRONIC 20 series Turn off and unplug the instrument before removing the lamp door To change the phototube 1 2 3 4 Turn off and unplug the instrument Tilt up the unit and set on its back Loosen the thumbscrew on the lamp access door see Figure 1 3 Remove the phototube using the plastic straps as an aid see Figure 3 3 Do not touch the lamp with your fingers Install the new phototube If a filter is required insert it into the holder on the inside of the door see Figure 3 3 The tube and filter must be clean and free of fingerprints If necessary use a lint free tissue for cleaning Close the door and securely fasten the thumbscrew This is essential for proper operation SPECTRONIC 20 series Maintenance Figure 5 Lamp compartment for 20 and 20D models KEY 1 Phototube 3 Filter holder 2 Plastic straps 4 Lamp 3 5 Maintenance SPECTRONIC 20 series Service Procedure If the instrument develops a malfunction that cannot be corrected by operator maintenance it may be serviced by your local Thermo Spectronic service organization Ifyou are in the U S A contact Thermo Spectronic whether the instrument is still under warranty or it has expired Ifyou are outside the U S A contact the distributor from whom you purchased the instrument wheth
20. he filter to be used for the measurement Red is used for measurements from 600 to 950nm Black is used for measurements from 340 to 599nm Meter Readings are taken directly from the meter in either transmittance or absorbance Transmittance Absorbance Control This control sets the display to 100 T 0 0A when a cuvette containing a blank reference solution is inserted in the sample compartment It must be reset whenever the analytical wavelength has been changed When operating at a fixed wavelength for SPECTRONIC 20 series an extended period of time check the 100 T 0 0A readout and readjust if necessary Analog Output Jack This jack is used to connect an analog recorder to the instrument see Figure 1 3 The analog output signal level is fixed at approximately 1 VDC at 100 T This output is not adjustable The signals on each pin are listed below 1 Analog output 2 Analog ground 3 Analog ground 4 Analog output Operating features of the SPECTRONIC 20D spectrophotometer The main controls for routine operation are the Power Switch Zero Control Wavelength Control Filter Lever Transmittance Absorbance Control the MODE selector and Factor Adjust controls The accessory Analog Output Serial I O port is located on the underside of the instrument as shown in Figure 1 3 Power Switch Zero Control The ON OFF main power switch is operated by the Power Switch Zero Control knob The Zero Contro
21. idential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be required to correct the interference GENERAL SAFETY NOTES USED IN THIS MANUAL This symbol alerts you to important information about using the instrument Be sure to read and follow the associated instructions carefully This symbol alerts you to potential electrical hazards Be sure that only qualified persons perform the related procedures This symbol alerts you to hot surfaces Be sure to read and follow the associated instructions carefully Copyright O 2001 Thermo Spectronic All rights reserved SPECTRONIC is a registered trademark of Spectronic Instruments Inc All other brand and product names are trademarks or registered trademarks of their respective companies NEW PRODUCT WARRANTY Thermo Spectronic warranties the SPECTRONIC 20 series of spectrophotometers against defects in material and workmanship for a period of three 3 years from the date of delivery Related accessories are warranted against defects in material and workmanship for a period of one 1 year from the date of delivery This warranty covers all parts except those specified below and labor and applies only to equipment which has been installed and operated in accordance with the operator s instruction manual and which has been serviced only by authorized Thermo Spectronic dealers or service personnel This warranty do
22. ion amp Operating Procedures Change in wavelength It is important to insert the blank and reset the display to 100 T or 0 0A every time the wavelength is changed The basic steps for taking measurements are highlighted in bold text in the following instructions Tip Transmittance and Absorbance 1 Turn on the instrument by turning the Power Switch knob on the left side of instrument clockwise Allow the spectrophotometer to warm up for at least 15 minutes to stabilize 2 After the warmup period set the desired wavelength with the Wavelength Control Knob 3 Set the filter lever to the appropriate position for the selected wavelength not required for SPECTRONIC 20D 4 Adjust the display to 0 with the Zero Control knob on the front left side of the instrument Make sure that the sample compartment is empty and the cover is closed 5 Set the display mode to TRANSMITTANCE or ABSORBANCE by pressing the MODE control key until the appropriate LED is lit 6 Fill a clean cell with water or another blank solution and wipe the cell with a tissue to remove liquid droplets dust and fingerprints 7 Place the cell in the sample compartment and align the guide mark on the cell with the guide mark at the front of the sample compartment Press the cell firmly into the sample compartment and close the lid 8 Adjust the display to 10095 T or 0 0A with the Transmittance Absorbance Control knob on the right side of in
23. ion if necessary has spilled on them Refer to Figure 3 2 or Figure 3 3 Remove any liquid spilled on the lamp filter photodiode or phototube surfaces Lamp filter and phototube surfaces Clean with a soft cloth or the softest area of a cotton swab and glass cleaner Photodiode The photodiode is easily damaged cleaning should be performed by your Thermo Spectronic service organization Clean the photodiode only if liquid is spilled on it Use very light pressure with the softest area of a cotton swab dipped in high grade isopropyl alcohol Do not touch the wire connected to the detector 3 2 Wavelength Calibration Check Under normal operating conditions the SPECTRONIC 20 and 20D spectrophotometers should retain their wavelength accuracy indefinitely If the instrument is subjected to a severe shock or other abuse wavelength performance may be checked by one of three methods Cobalt solution check Didymium filter from the Accessory Filter Kit Cat No 333129 Wavelength Accuracy Test from SPECTRONIC Standards Cat No 333150 An explanation of the cobalt solution check follows Instructions on use of the didymium filter and SPECTRONIC Standards are found in the user s manual for each accessory SPECTRONIC 20 series Cobalt solution check To prepare a stock cobalt solution 1 Ina 1 liter volumetric flask place 200mL distilled water Slowly and cautiously add 10mL concentrated
24. l knob is used to set the display to a 0 readout when the sample compartment is empty and the adapter cover 1s closed SPECTRONIC 20 series Wavelength Control The Wavelength Control selects the desired analytical wavelength of the instrument The selected wavelength appears on the left side of the LED display The Filter Lever should be set to the proper filter for the wavelength setting Filter Lever This control selects the filter to be used for the measurement Red is used for measurements from 600 to 950nm Black is used for measurements from 340 to 599nm Digital Readout The Digital Readout displays wavelength and data readings The four LED status indicators next to the labels TRANSMITTANCE ABSORBANCE CONCENTRATION and FACTOR indicate the MODE currently active Transmittance Absorbance Control This control sets the display to 100 T 0 0A when a cuvette containing a blank reference solution is inserted in the sample compartment It must be reset whenever the analytical wavelength has been changed When operating at a fixed wavelength for an extended period of time check the 100 T 0 0A readout and readjust if necessary MODE Select This control selects the TRANSMITTANCE ABSORBANCE CONCENTRATION or FACTOR mode Introduction Factor Adjust Controls The push buttons labeled INCREASE and DECREASE are used in the CONCENTRATION and FACTOR modes To set a lower CONCENTRATION or FACTOR val
25. ndard adapter easily turn the adapter bottom end up and look into the barrel of the adapter Figure 4 1 illustrates the pre 1986 design which will not accommodate square cuvette This can be replaced with a current adapter Cat No 333178 to accommodate 1 2 square cuvettes 4 3 Accessories Figure 4 1 Standard adapter KEY 1 Spring found in pre 1986 adapters Accessories SPECTRONIC 20 series 4 4 Appendix A Choosing a Readout Mode Transmittance Mode All SPECTRONIC 20 series spectrophotometers measure the relative amount of light transmitted yielding results in transmittance The transmittance mode is useful for calibration stray radiant energy tests and filter studies Furthermore very low concentrations may be measured with greater sensitivity in the transmittance mode When the transmittance mode is used the reagent blank sets 100 T and the results for standard solutions and unknown samples are obtained as percent transmittance A standard curve may be constructed on semi logarithmic paper by plotting the percent transmittance on the logarithmic axis vs the concentration of known standard solutions on the linear axis The best line is drawn through these points The concentration of unknown samples may then be determined by locating the concentration value which corresponds to the percent transmittance of the unknown on the standard curves Absorbance Mode Usually the operator
26. pectrophotometers Command CONTROL X Reset the spectrophotometer to initial power up condition Set the spectrophotometer s baud rate to the rate used by a computer or an ASCII carriage return CR connected to the serial output port 2 5 Installation amp Operating Procedures Baud rate settings Data is sent to the printer or received from an external device at a rate of 1200 baud if the instrument is turned on with the PRINT line high at logic 1 greater than 2 0 VDC Other baud rates may be selected when the spectrophotometer is connected to a computer These rates include 110 300 1200 2400 4800 and 9600 baud If the spectrophotometer is turned on with the PRINT line low logic 0 less than 0 8 VDC it adjusts to the computer s baud rate upon receipt of either the letter E or a carriage return CR character from the computer 2 6 SPECTRONIC 20 series Note The PRINT line is normally high The PRINT line can be set low by pressing the PRINT button For SPECTRONIC 20D models you can set the PRINT line low by pressing the push button on the Serial Interface Cable Cat No 333177 while turning on the spectrophotometer Section 3 Because of the functional design and reliability of the SPECTRONIC 20 and 20D spectrophotometers routine customer maintenance has been reduced to replacement of the 6 0 volt 3 00 amperes source lamp Cat No 333385 SPECTRONIC 20 and 20D mo
27. r The carton is accepted at standard mail rates Troubleshooting Table 3 1 Operator s Troubleshooting Guide outlines some diagnostic techniques that may help you isolate the cause of a problem Plug in power line cord Try a different power outlet Refer to service manual or service center Refer to service manual or service center Close cover Close door and retighten thumbscrew Replace as required Refer to service manual or service center Eliminate bubbles or particles in solution Set 100 T on appropriate blank solution Set filter lever to proper position Remove sample immediately after analysis Check voltage and grounding Reset Line Voltage Selection Switch Replace with new lamp Replace as required Refer to service manual or service center SPECTRONIC 20 series Maintenance Table 3 1 continued Possible Cause 4 Cannot set 100 T 0 0 100 T not properly set Set 100 T with blank solution in the sample or display flashes compartment and cover closed Several turns of the 100 T control may be necessary Filter selection lever in wrong position Set filter lever to proper position c O T not properly set all models except Set 0 with the sample compartment empty and the SPECTRONIC 20D cover closed Occluder closed Install test tube in sample compartment Sample holder not fully inserted into adapter Insert full
28. rs loosen the small set screw on the inner wall of the adapter using the adapter wrench In addition to the standard test tube and adapter clipped to the bottom of the instrument see Figure supplied with the instrument several types of 1 3 glassware are available The sample adapter must match the glassware as shown in the chart below Table 4 Cell selection chart for SPECTRONIC 20 series of spectrophotometers PICTURE DESCRIPTION CATALOG PATHLENGTH ADAPTER ALSO NUMBER REQUIRES Square Cuvette 331709 10 mm 333178 333176 Optical Glass included with Cell Holder 45 mm tall instrument Cuvette 331701 11 66 mm 333178 Optical Glass included with 100 mm tall instrument Semi Micro Cuvette 331713 10 mm 333178 333176 included with Cell Holder instrument included with 331713 cuvettes 72 Test Tube 331780 0 459 333178 Optical Glass 11 7 mm included with 100 mm tall instrument 3 4 Test Tube 331781 0 657 332931 332932 Optical Glass 16 69 mm Light Shield 150 mm tall 1 Test Tube 331782 Optical Glass 0 880 332930 332932 Light Shield 150 mm tall 4 2 SPECTRONIC 20 series The design of the standard adapter provided with the instrument was changed in 1986 The current adapter Cat No 333178 accommodates diameter test tube or a 4 square cuvette Prior to 1986 the standard adapter Cat No 333127 accommodated only the diameter test tube To identify the sta
29. s Law and therefore have non linear standard plots Concentration Mode The SPECTRONIC 200 provides a more convenient readout the concentration mode which eliminates the necessity for constructing a standard curve The instrument electronically converts results in absorbance to concentration units by multiplying the absorbance value by the factor which is the inverse of the slope of the standard curve factor 1 ab Note that the concentration mode can be used only if the linearity of the standard curve has been verified for the test conditions used These test conditions include wavelength concentration range of interest cuvette pathlength and analytical procedure Furthermore the concentration mode may be used only if the standard curve has a positive slope 1 absorbance increases with concentration Choosing a Readout Mode When using entered standard solutions the 1 ab factor is used to convert absorbance to concentration according to the equation C f A Concentration Measurements using FACTOR mode on page 2 4 describes how to use the factor mode For more information on concentration measurements and other techniques contact Thermo Spectronic s Application Laboratory and request a list of available SpecTech Notes Note It is not actually necessary to know the 1 ab factor because this factor is introduced into the instrument when the concentration adjust control is used to set the digital display to rea
30. s is essential for proper operation Note Do not push on the lamp socket terminals This will inhibit the installation of a new lamp 3 1 SPECTRONIC 20 series Maintenance Cleaning the sample compartment In the event a test tube breaks in the sample compartment it is important to remove the glass and any spilled liquid as soon as possible Turn off and unplug the instrument before cleaning the sample compartment 1 Turn off and unplug the instrument 2 Use protective equipment safety goggles gloves lab coat etc 3 Using tweezers remove broken pieces of glass from the sample compartment 4 While supporting the instrument move it to the edge of the lab bench so that the lamp access door may be opened Figure 4 Location of photodiode 5 Loosen the lamp access door thumbscrew and KEY carefully open the door Spilled fluid may be 1 Photodiode present inside Make sure to clean up all liquid 2 Connection wire that was spilled 6 Reach inside the lamp compartment and remove any remaining glass 10 7 Tip the instrument back on the lab bench and 11 clean the sample compartment with appropriate cleaning solvent 8 Visually inspect the lamp photodiode or phototube and filters to determine if any liquid 3 Lamp 4 Filter Close the door and tighten the thumbscrew Check the calibration of the instrument using the procedures below or call your local Thermo Spectronic service organizat
31. strument 9 Remove the cell from the sample compartment and empty the water Rinse the cell twice with small volumes of the solution to be measured and fill it with the solution 10 Installation amp Operating Procedures Wipe the cell with a tissue and insert the cell into the sample compartment Align the guide marks and close the lid Read the appropriate value oT or A from the display Remove the cell from the sample compartment and repeat steps 10 through 12 for any remaining sample solutions When all measurements are completed turn off the spectrophotometer by turning the Power Switch counterclockwise until it clicks Concentration measurements using CONCENTRATION mode 1 Follow steps 1 through 9 of the Transmittance and Absorbance procedure using the absorbance mode Rinse the cell twice with small volumes of the standard solution of known concentration and fill the cell with the solution Wipe the cell with a tissue and insert the cell in the sample compartment Align the guide marks and close the lid Press the MODE control key until the LED beside concentration is lit Press the INCREASE or DECREASE key until the displayed value matches the concentration of the standard solution Note Limits are 0 to 1999 To determine the factor press the MODE control key until the LED beside the Factor is lit Read and record the factor value Press the MODE control key until th
32. the mirror It is important to insert the blank and reset the meter to 100 T every time the wavelength is changed Tip The basic steps for taking measurements are highlighted in bold text in the following instructions 1 Turn on the SPECTRONIC 20 by turning the Power Switch Zero Control knob on the left side of instrument clockwise Allow the spectrophotometer to warm up for at least 15 minutes to stabilize 2 After the warmup period set the desired wavelength with the Wavelength Control Knob 3 Setthe filter lever to the appropriate position for the selected wavelength not required for SPECTRONIC 20 4 Adjust the meter to 0 T with the Power Switch Zero Control knob on the front left side of instrument Make sure the sample compartment is empty and the cover is closed 5 Fillaclean cell with water or blank solution and wipe the cell with a tissue to remove liquid droplets dust and fingerprints 6 Place the cell in the sample compartment and align the guide mark on the cell with the guide mark at the front of the sample compartment Press the cell firmly into the sample compartment and close the lid 7 Adjust the meter to 10094 T with the Transmittance Absorbance Control knob on the front right side of instrument 8 Remove the cell from the sample compartment and empty the water 9 Rinse the cell twice with small volumes of the solution to be measured and fill it with the solution SPECTRONIC 20
33. til it clicks Printing SSPECTRONIC 20D and 20D only Normally the spectrophotometer is in the print mode when it 1s first turned on and operates at a rate of 1200 baud A range of other transmission rates from 110 to 9600 baud may also be accommodated SPECTRONIC 20 series Installation amp Operating Procedures To use the Accessory Printer Data format 1 Set the baud rate the Accessory Printer to Data from the instrument to a printer or other remote 1200 Refer to the Accessory Printer Operator s device is sent as shown in the following example Manual Cat No 335488 10001 2 Push the PRINT key for a printout 574NM 01 5 CH amp LF 3 DIGITS FOR CARRIAGE Remote operation SPECTRONIC 20D and WVL THEN NM RETURN AND LINE 20D only SPACE FEED DATA SIGN A T C OR F Command set BLANK OR SPACE An external device may send the commands listed in DATA 3 DIGITS PLUS A DECIMAL Table 2 4 to the SPECTRONIC 20D and 20D POINT spectrophotometer Table 2 3 lists conventions for serial I O data Table2 Serial I O data conventions Word length 8 data bits 1 stop bit most significant bit set to 0 Parity None Echo None Terminators Ignores all carriage return or line feed characters sent by external device except for CR in Auto Baud Rate mode Transmits ASCII CR LF after every data line Table 2 Commands for remote operation of SPECTRONIC 20D s
34. tometer with a wavelength range of 340nm to 950nm The nominal spectral slit width of 20nm is constant over the entire range 27 E e 46 SQ om Transmittance Absorbance control 100 T 0A Power switch Zero Control SPECTRONIC 20 series Introduction The main features on the underside of the instrument are shown in Figure 1 3 Figure 10 Bottom view of SPECTRONIC 20 or 20D KEY 1 Lamp access door with thumbscrew 2 Filter lever 3 Analog output jack Serial I O port 4 Line voltage switch under this plate international models only Introduction Operating features of the SPECTRONIC 20 spectrophotometer The main controls for routine operation are the Power Switch Zero Control Wavelength Control Filter Lever and Transmittance Absorbance Control Power Switch Zero Control The ON OFF main power switch is operated by the Power Switch Zero Control knob The Zero Control knob is used to set the display to a 0 readout when the sample compartment is empty and the adapter cover is closed Wavelength Control The Wavelength Control selects the desired analytical wavelength of the instrument The selected wavelength is indicated on the wavelength scale in the window next to the knob Red numbers indicate that the 600 950nm filter should be used black numbers indicate that the 340 599nm filter should be used All gradations are in 5 nm intervals Filter Lever This control selects t
35. ue press and hold down the DECREASE button until the desired value is displayed To set a higher value press and hold down the INCREASE button until the desired value is displayed Print This push button is used to send data to a serial printer connected to the output jack Analog Output Serial I O Port Analog Output This port is used to connect an analog recorder to the instrument The analog output signal level is approximately 1 VDC at 100 T This output is not adjustable Serial Port The Serial Input Output I O Port is used to connect the instrument to the Accessory Printer Cat No 335488 or to an external device enabling the instrument to accept and execute any one of six commands sent from the device in RS 232 C format The signals on each pin are listed below 1 Analog output 2 Clear to send CTS 3 Ground 4 Transmit data TXD 5 Receive data RXD 6 Print Refer to page 2 5 for remote operation and to Table 2 1 on page 2 1 for cabling requirements Introduction SPECTRONIC 20 series This page intentionally left blank Section 2 Installation amp Operating Procedures Environment Setup Installation Make sure that your spectrophotometer is placed as 1 Select the appropriate glassware and adapters far as possible from any strong magnetic or electrical For more information about glassware adapters fields or any electrical apparatus that may generate and cell holders refer to Table 4 1 on page
36. um dichromate solution 6 Measure 2 5mL of the stock 1 0g L potassium dichromate solution into a clean 100mL volumetric flask containing about 75mL 0 01N sulfuric acid solution Fill to volume with 0 01N sulfuric acid solution This is your 0 025g L potassium dichromate solution 7 Measure 5 0mL of the stock 1 0g L potassium dichromate solution into a clean 100mL volumetric flask containing about 75mL 0 01N sulfuric acid solution Fill to volume with 0 01N sulfuric acid solution This is your 0 05g L potassium dichromate solution 8 Setthe Wavelength Control to 350nm Set Filter Lever to 340 950nm 10 Fill a 10mm pathlength rectangular cuvette with 0 01N sulfuric acid solution and place it in the sample compartment Maintenance 11 Set the readout of the instrument to 0A 12 Fill the 10mm pathlength rectangular cuvette with 0 025g L potassium dichromate solution place it in the sample compartment and read the absorbance You should expect to read 0 248A 13 Fill the 10mm pathlength rectangular cuvette with 0 05g L potassium dichromate solution place it in the sample compartment and read the absorbance You should expect to read 0 496A Note Values should be within 0 02A of the expected absorbance values if the solutions have been prepared carefully Replacing phototubes SPECTRONIC 20 or 20D models only The lamp and surrounding metal parts get very hot during operation Before removing the phototube turn o
37. y Source lamp weak or burned out Replace with new lamp Wrong line voltage setting international models Reset Line Voltage Selection Switch only Phototube weak Replace as required Error in wavelength calibration Check calibration Defective electronic component Refer to service manual or service center k Incorrect phototube or filter installed Check Table 2 2 page 2 2 for correct phototube SPECTRONIC 20 20D only and filter and install a Loose lamp Tighten thumbscrew on lamp access door 5 Readings are not repeatable even though the 0 T and 100 T readings are set correctly Loose sample holder adapter Tighten set screw inside adapter c Poor analytical technique Clean or replace dirty test tubes remove bubbles etc See Techniques on page 2 2 Test tube position not repeating Always position fiducial line in exactly the same place when test tube is inserted into adapter Use square cuvettes Meter sticking SPECTRONIC 20 and 20 only Tap lightly for possible correction If problem persists refer to service center Maintenance SPECTRONIC 20 series This page intentionally left blank 3 8 Section 4 Accessories Table 4 Accessories available for SPECTRONIC 20 and 20 series of spectrophotometers Accessory Catalog Number Description Cell Holders and Sample See Table 4 2 on page 4 2 Compartment Adapters SPECTRONIC Stan
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