Thermo Varioskan User Manual

Varioskan

User Manual

Rev. 2.0

Analyze •

Detect •

Measure •

Control™

Varioskan™

User Manual

Rev. 2.0

Copyright © 2005 Thermo Electron Corporation. All rights reserved. First edition printed in 2004. Printed in Finland. Reproduction of the accompanying user documentation in whole or in part is prohibited.

The Varioskan has a national and an international patent pending.

“Varioskan” is a trademark of Thermo Electron. “Microtiter” and “SkanIt” are registered trademarks of Thermo Electron.

All other trademarks and registered trademarks are the property of their respective holders.

Thermo Electron reserves the right to change its products and services at any time to incorporate technological developments. This manual is subject to change without prior notice as part of a continuous product development. Although this manual has been prepared with every precaution to ensure accuracy, Thermo Electron assumes no liability for any errors or omissions, nor for any damages resulting from the application or use of this information. This manual supersedes all previous editions.

Thermo Electron shall not be liable for any damages whatsoever arising out of the use or inability to use this product.

Thermo Electron Microplate Instrumentation Business products are fully guaranteed against defective parts and materials, including defects caused by poor workmanship, for a period of one year from the date of delivery. Thermo will repair or replace defective parts or materials during the term of warranty at no extra charge for materials and labor provided that the products were used and maintained in accordance with Thermo’s instructions. The warranty is invalid if products have been misused or abused. For the warranty to be effective, the product must have been purchased either directly from Thermo or from an authorized Thermo distributor. The guarantee is not transferable to a third party without prior written approval from Thermo. This guarantee is subject to the following exclusions:

● Any defects caused by normal wear and tear.

● Defects caused by fire, lightning, flood, earthquake, explosion, sabotage, war, riot, or any other occurrence

of the type listed above.

● Refurbished products that are subject to different warranty conditions.

THIS WARRANTY IS IN LIEU OF ALL OTHER EXPRESSED OR IMPLIED WARRANTIES, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. The seller is not liable for any loss or damage arising out of or in connection with the use of the product or other indirect damages. These warranty terms and conditions can be obtained from your local Thermo dealer.

Consumables are not included in the warranty.

Thermo Electron Corporation Varioskan™ User Manual 3

About This User Manual

This User Manual has been written for the actual user (e.g., laboratory technician) and provides information on the Varioskan, including the installation and operating instructions.

Read the manual in its entirety before operating the instrument.

This User Manual has been designed to give you the information you need to:

● Review safety precautions

● Install the Varioskan

● Use the Varioskan in daily use and research

● Perform basic cleaning and maintenance procedures

● Troubleshoot the instrument performance

This User Manual also describes all the features and specifications of the Varioskan instrument. Refer to Chapter 6: “Technical Specifications”.

In Chapter 8: “Troubleshooting Guide” you will find explanations of all error and warning messages and a problem-solving guide. The user should be familiar with the contents of Chapter 5: “Maintenance”.

For ordering information, refer to Chapter 9: “Ordering Information”.

For software-related issues, refer to the SkanIt Software for Varioskan User Manual (Cat. no. N02723). Both the user and software manuals can be found in PDF format on the SkanIt Software installation CD.

For the latest information on products and services, visit our worldwide websites on the Internet at:

http://www.thermo.com

In an effort to produce useful and appropriate documentation, we appreciate your comments on this User Manual to your local Thermo representative.

ho uses this

user manual

How to use this

user manual

For more

information

About This User Manual

Safety symbols and markings

4 Varioskan™ User Manual Thermo Electron Corporation

These symbols are intended to draw your attention to particularly important information and alert you to the presence of hazards as indicated.

The following symbols and markings appear on the type label and the instrument itself.

Power ON ▲

Power OFF ▲

Serial number ▲

Catalog number ▲

Date of manufacture ▲

Consult instructions for use ▲

Risk of radiation injury ▲

A black label with the following text (Figure 2–3):

CAUTION: WARNING: DISCONNECT SUPPLY BEFORE SERVICING and AVERTISSEMENT: COUPER L'ALIMENTATION AVANT L'ENTRETIEN ET LE DEPANNAGE. ▲

Safety symbols

and markings

Safety symbols and

markings used on

the Varioskan

About This User Manual

Safety symbols and markings

Thermo Electron Corporation Varioskan™ User Manual 5

The following symbols and markings appear in this User Manual.

Warning Risk of electric shock. ▲

Warning Biohazard risk. ▲

Warning Hot surface, risk of burns. ▲

Warning Risk of injury to the user(s). ▲

Warning Risk of ultraviolet radiation injury. ▲

Caution Risk of damage to the instrument, other equipment or loss of

performance or function in a specific application. ▲

Note Marks a hint, important information that is useful in the optimum operation of the system, or an item of interest. ▲

arning and other

markings used in

the documentation

About This User Manual

Instrument safety and guidelines for use

6 Varioskan™ User Manual Thermo Electron Corporation

1. Always follow basic safety precautions when using the Varioskan to

reduce the risk of injury, biohazardous contamination, fire, or electrical shock.

2. Read this User Manual in its entirety prior to operating the

instrument. Failure to read, understand, and follow the instructions in the manual may result in damage to the instrument, injury to laboratory and operating personnel or poor instrument performance.

3. Observe all “Warning”, “Caution”, and “Note” statements as well as

safety symbols and markings on the instrument and in the documentation.

4. Never open any other covers of the Varioskan than the dispenser

sliding cover (Figure 2–2) or measurement chamber door (Figure 2–2) while the instrument is plugged into a power source.

5. Never open the measurement chamber door while the instrument is

busy (when the LED indicator is orange).

6. You can push in the tray manually only when the instrument is

switched off.

7. Never force a microplate into the instrument.

8. The Varioskan is intended for laboratory research use only. Observe

proper laboratory safety precautions, such as wearing protective clothing and following approved laboratory safety procedures.

9. Preventative maintenance instructions should be followed closely to

keep the instrument in the best condition for maximum reliability. A poorly maintained instrument will not give the best results.

Instrument safety

and guidelines

for use

Thermo Electron Corporation Varioskan™ User Manual 7

Contents

Who uses this user manual ................................................................3

How to use this user manual ............................................................. 3

For more information .......................................................................3

Safety symbols and markings.............................................................4

Safety symbols and markings used on the Varioskan ......................4

Warning and other markings used in the documentation ...............5

Instrument safety and guidelines for use............................................ 6

Introduction to the Varioskan.................................................................... 15

Introduction.................................................................................... 15

Intended use.................................................................................... 15

Advantages of using Varioskan ........................................................ 16

Functional Description ............................................................................... 17

Instrument layout............................................................................17

Front view....................................................................................17

Back view..................................................................................... 17

Internal view ................................................................................ 18

Measurement techniques................................................................. 19

Fluorescence intensity ..................................................................19

Time-resolved fluorescence........................................................... 19

Photometry .................................................................................. 20

Optical system................................................................................. 21

Principle of the optical system...................................................... 21

Excitation optics........................................................................ 22

Measurement optics .................................................................. 23

Emission reading module .......................................................... 24

Photometric measurement module............................................ 24

Dispenser option............................................................................. 25

Incubator ........................................................................................27

Control switches .............................................................................27

Track mechanism............................................................................ 28

Tray options.................................................................................... 29

Tray composition......................................................................... 30

Universal tray with adapters .........................................................31

Robotic tray ................................................................................. 33

How to change the location of the holder for the tip priming

vessel ......................................................................................... 34

How to remove or replace the robotic tray adapter.................... 35

Installation .................................................................................................... 37

Installation checklist........................................................................37

What to do upon delivery ...............................................................38

Chapter 1

Chapter 2

Chapter 3

Contents

8 Varioskan™ User Manual Thermo Electron Corporation

How to unpack ............................................................................ 38

Checking delivery for completeness.............................................. 38

Checking for damage during transport ......................................... 38

Environmental requirements ........................................................39

Things to avoid ............................................................................39

Technical prerequisites................................................................. 39

Setups before you put the instrument into operation....................... 40

How to release the transport lock ................................................. 40

How to install the tray ................................................................. 43

How to setup the optional dispenser ............................................45

Installation of SkanIt Software .....................................................47

How to ensure startup.................................................................. 47

Operational check ........................................................................... 48

Automatic runtime calibration ..................................................... 49

Routine Operation ........................................................................................51

Do’s and Don’ts of the Varioskan ...................................................51

Do ...............................................................................................51

Don’t ........................................................................................... 52

Switching on ...................................................................................53

Loading the microplate ................................................................54

Fluorometric measurement..............................................................55

Fluorometric spectrum scanning .....................................................57

Photometric measurement............................................................... 58

Photometric spectrum scanning ......................................................58

Other functions............................................................................... 59

Orbital shaking ............................................................................59

Incubating.................................................................................... 60

Dispensing ................................................................................... 61

Priming..................................................................................... 61

Tip priming ..............................................................................62

Dispenser washing..................................................................... 62

Dispensing and measurement....................................................62

Helpful hints.............................................................................63

Chemical resistance of the dispenser..........................................63

Shutdown .......................................................................................66

Emergency situations ......................................................................67

Maintenance .................................................................................................69

Maintenance checklist ..................................................................... 69

Regular and preventive maintenance ............................................... 70

How to clean the measurement chamber......................................71

How to clean the tray................................................................... 72

How to clean the reagent basin and dispensing area .....................73

Routine maintenance of the optional dispenser ............................ 73

Daily maintenance .......................................................................73

Weekly maintenance .................................................................... 74

Weak detergent or 10% bleach.................................................. 74

Weak base and acid in sequence ................................................... 74

Chapter 4

Chapter 5

Contents

Thermo Electron Corporation Varioskan™ User Manual 9

Periodic maintenance ......................................................................75

Replacing the aspirate tube assembly or the complete dispensing

tube assembly............................................................................... 75

Replacing a dispensing tip ............................................................ 76

Replacing a dispenser syringe .......................................................77

Replacing the 3-port valve............................................................... 78

Disposal of materials ....................................................................... 79

Decontamination procedure............................................................ 79

How to refit the transport lock.....................................................81

Maintaining a system log................................................................. 83

How to pack for service...................................................................83

Service contracts..............................................................................84

Disposal of the instrument .............................................................. 84

Technical Specifications ........................................................................... 85

General specifications......................................................................85

Performance specifications ..............................................................86

Safety specifications...................................................................... 88

In conformity with the requirements...............................................89

Frequently Asked Questions...................................................................... 91

Troubleshooting Guide ............................................................................... 95

Error and warning codes .................................................................95

Service request protocol................................................................... 99

Certificate of Decontamination....................................................... 99

Ordering Information................................................................................. 101

List of spare parts and accessories ..................................................101

Upgrade kits.................................................................................. 102

References .................................................................................................. 103

Useful web links............................................................................ 103

Literature ......................................................................................105

Fluorescence intensity ................................................................105

Time-resolved fluorescence......................................................... 105

Photometry ................................................................................ 106

System Log .................................................................................................. 107

Varioskan Brief User’s Guide.................................................................. 109

Certificate of Decontamination............................................................... 111

Varioskan Feedback Form........................................................................ 113

Chapter 6

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Appendix A

Appendix B

Appendix C

Appendix D

Contents

10 Varioskan™ User Manual Thermo Electron Corporation

Glossary........................................................................................................115

Index .............................................................................................................117

Notes.............................................................................................................121

Figures

Thermo Electron Corporation Varioskan™ User Manual 11

Figures

Figure 1–1. Varioskan spectral scanning multimode reader ........................ 15

Figure 2–2. Varioskan front view .................................................................. 17

Figure 2–3. Varioskan back view................................................................... 17

Figure 2–4. Close-up of the computer and mains supply connectors .......... 18

Figure 2–5. Varioskan internal view.............................................................. 18

Figure 2–6. Varioskan optics ......................................................................... 21

Figure 2–7. Excitation optics ......................................................................... 22

Figure 2–8. Principle of the double monochromator..................................... 23

Figure 2–9. Measurement optics .................................................................. 23

Figure 2–10. Emission optics......................................................................... 24

Figure 2–11. Photometric measurement module.......................................... 25

Figure 2–12. Varioskan dispensing system................................................... 26

Figure 2–13. Dispensing tip options: 0.40 mm, and 0.25 mm ...................... 26

Figure 2–14. Varioskan incubator cross-section........................................... 27

Figure 2–15. Control switches....................................................................... 28

Figure 2–16. Part of the Varioskan track mechanism ................................... 29

Figure 2–17. Assembly picture of the universal tray .................................... 30

Figure 2–18. Robotic tray fitted with adapter for plate w/o lid, #126 ......... 33

Figure 2–19. Changing the location of the tip priming vessel holder .......... 34

Figure 2–20. Removing or replacing the adapter for plate w/o lid, #126 .... 35

Figure 3–21. Transport lock and transport lock tag present......................... 40

Figure 3–22. Dispenser sliding cover and measurement chamber door

opened ............................................................................................................. 41

Figure 3–23. Front cover removed................................................................. 41

Figure 3–24.

Transport lock fastened (screws 1 – 4 shown)........................ 42

Figure 3–25. Releasing the transport lock (screws 1 – 4 shown)................. 42

Figure 3–26. Transport lock in its horizontal storage position (screws 3 and

4 shown) .......................................................................................................... 43

Figure 3–27. Tray holder................................................................................ 44

Figure 3–28. Fastening the tray frame to the tray holder............................. 45

Figure 3–29. Close-up of the positioning lever when the tray is out ........... 45

Figure 3–30. Varioskan with the dispenser sliding cover open.................... 46

Figure 3–31. Protective cap removed from the dispensing tip 5 – 1000 µl

(0.40 mm) ......................................................................................................... 47

Figure 3–32. Dispenser assembly ................................................................. 47

Figure 3–33. Connecting the mains supply cable ......................................... 48

Figure 4–34. Microplate loaded .................................................................... 54

Figure 4–35. Dynamic range selection.......................................................... 55

Figure 4–36. Structure of the TRF measurement cycle................................. 57

Figures

12 Varioskan™ User Manual Thermo Electron Corporation

Figure 4–37. ON-OFF period time and total shaking time............................. 59

Figure 4–38. Speed & diameter combinations for different plate formats ..60

Figure 5–39. Front cover removed .................................................................71

Figure 5–40. Internal view of the measurement chamber ............................ 72

Figure 5–41. Replacing the dispensing tip (A)............................................... 76

Figure 5–42. Replacing the dispensing tip (B)............................................... 76

Figure 5–43. Dispenser assembly..................................................................77

Figure 5–44. Replacing the dispenser syringe ..............................................78

Figure 5–45. 3-port valve replacement..........................................................79

Figure 5–46. Transport lock released (A) and fastened (B) (screws 1 – 4

shown)..............................................................................................................82

Tables

Thermo Electron Corporation Varioskan™ User Manual 13

Tables

Table 2–1. Compatibility of the universal tray and plate-specific adapters 32

Table 2–2. Compatibility of the robotic tray and plate-specific adapter...... 33

Table 3–3. Installation checklist.................................................................... 37

Table 4–4. LED indicator................................................................................ 53

Table 4–5. Compatibility chart of solvents suitable with the plastic

materials used in the dispenser...................................................................... 64

Table 5–6. Maintenance checklist ................................................................ 69

Table 5–7. Example of a system log.............................................................. 83

Table 6–8. Technical specifications .............................................................. 85

Table 6–9. Fluorometry .................................................................................. 86

Table 6–10. Photometry................................................................................. 87

Table 6–11. Incubator .................................................................................... 87

Table 6–12. Shaker ........................................................................................ 88

Table 6–13. Dispenser ................................................................................... 88

Table 7–14. Tray vs. plate-specific adapter .................................................. 92

Table 8–15. Error codes reported .................................................................. 95

Table 8–16. Warning codes reported............................................................ 98

Table 9–17. Instrument catalog numbers.................................................... 101

Table 9–18. Codes for spare parts and accessories ................................... 101

Table 9–19. Codes for upgrade kits............................................................. 102

Tables

14 Varioskan™ User Manual Thermo Electron Corporation

Thermo Electron Corporation Varioskan™ User Manual 15

Chapter 1

Introduction to the Varioskan

The Thermo Electron Varioskan (Figure 1–1) is an advanced spectral scanning multimode reader. The Varioskan is used to measure fluorescence intensity, time-resolved fluorescence (TRF) and absorbance in end point, kinetic and spectral measurements in the UV/Vis range from appropriate microplate formats. In fluorometric measurements appropriate 6- to 1536-well plates can be used, and correspondingly appropriate 6- to 384-well plates in photometric measurements. Incubation can be carried out in a controlled incubation temperature. The instrument also allows shaking and reagent dispensing. The instrument is run on SkanIt Software 2.2 (or greater), which controls all the instrument functions and provides data processing as well as reporting functions.

Figure 1–1. Varioskan spectral scanning multimode reader

The Varioskan spectral scanning multimode reader is intended for professional laboratory research use by trained personnel, who understand the nature of fluorometry and photometry. The Varioskan is used to measure fluorescence intensity and time-resolved fluorescence (TRF) from appropriate 6- to 1536-well plate formats or absorbance from appropriate 6- to 384-well plate formats mentioned in the manual. It also has incubation, shaking and reagent dispensing capabilities.

Use for self-testing is excluded.

For validation of the entire system, it is recommended that Good Laboratory Practices (GLP) are followed to guarantee reliable analyses.

Refer to Chapter 6: “Technical Specifications”.

Introduction

Intended use

Introduction to the Varioskan

Advantages of using Varioskan

16 Varioskan™ User Manual Thermo Electron Corporation

The Varioskan provides several advantages relating mainly to the principle of operation in that it:

● Supports applications requiring measurement in the UV/Vis/NIR

wavelength range

● Allows optimization of the measurement wavelengths according to

the application needs

● Allows use of freely selectable wavelengths and spectral scanning

● Enables measurement of multiple labels from the same well

● Allows optimization of the assays to different plate formats

depending on the throughput requirements

● Enables precise incubation of temperature-critical assays due to the

unique design of the universal tray

● Enables fast kinetic measurements due to simultaneous

measurement and dispensing

● Enables automation due to robot compatibility

● Is controlled by SkanIt Software that provides features required to

make comprehensive calculations and reports

● Ensures high-quality performance due to automatic runtime

calibration and operational checks, including safety features

Advantages of

using Varioskan

Thermo Electron Corporation Varioskan™ User Manual 17

Chapter 2

Functional Description

This section shows the front, internal and back views of the Varioskan instrument.

Figure 2–2. Varioskan front view

Figure 2–3. Varioskan back view

Instrument

layout

Front view

Back view

ON/OFF switch

Power, busy and

Dispenser sliding cover

Measurement chamber door

Front cover

Cooling-fan outlet

Serial connector

Warning marking

USB connector

ON/OFF switch

Mains power supply connector

Type label

Indentation for lifting Varioskan

Functional Description

Instrument layout

18 Varioskan™ User Manual Thermo Electron Corporation

Figure 2–4. Close-up of the computer and mains supply connectors

Figure 2–5. Varioskan internal view

Internal view

Dispensing head positioner (dispensing head in positioner while dispensing; blind plug present when no dispensing)

USB connector

Ethernet connector (not in use)

Serial connector

Mains power supply connector

Dispenser sliding cover

Plate In/Out switch

Dispensing head holder

Dispensing head positioner

(dispensing head in positioner

while dispensing; blind plug

present when no dispensing)

Prime/Empty switch (opt., with dispenser)

Dispensing head (opt.)

Dispenser (opt.)

Reagent bottle holder

Reagent basin

Measurement chamber door

Blind plug

Dispensing head holder

Reagent bottle holder

Dispensing head (opt.)

Blind plug

Functional Description

Measurement techniques

Thermo Electron Corporation Varioskan™ User Manual 19

This section describes the relevant measurement techniques, including fluorescence intensity, time-resolved fluorescence and photometry.

Fluorescence is the phenomenon in which absorption of excitation light of a given wavelength by a fluorescent molecule is followed by the emission of light at longer wavelengths. Fluorescence intensity of the emitted light (RFU) at selected excitation and emission wavelengths is proportional to the concentration of the fluorescent molecule being investigated.

Fluorescent molecules have two characteristic spectra: an excitation spectrum which shows the wavelength-dependent amount of light absorbed and an emission spectrum which shows the wavelengthdependent amount of light emitted. No two compounds have exactly the same fluorescence spectra, thus, making fluorometry a highly specific analytical technique.

One of the major advantages of fluorescence detection is high sensitivity. This is important as relatively small changes in, for example, ion concentration in living cells can have significant physiological effects. In addition of fluorescence being a versatile tool in cell biology, biochemistry and molecular biology, it is also a powerful technique for studying molecular interactions in analytical chemistry, physiology, photochemistry, and environmental science.

Fluorescence resonance energy transfer (FRET) is a fluorescence intensity based measurement technique. Two labels are required for FRET measurements: donor (fluorescent), and acceptor (either fluorescent or non-fluorescent). The emission spectrum of the donor needs to overlap with the absorption spectrum of the acceptor to allow the energy transfer to happen.

FRET allows homogeneous assay formats to be used in the detection of biological interactions. The change in the intensity of the generated FRET signal can be related to specific biological events, such as enzyme-mediated cleavage of DNA or protein substrates, protein-DNA interactions and protein-peptide interactions.

Time-resolved fluorescence (TRF) is a special form of fluorescence intensity where fluorescence lifetime of the signal is remarkably longer than in fluorescence intensity. TRF uses lanthanide labels which have similar excitation and emission spectra as fluorescence intensity labels. Every TRF label has a unique fluorescence lifetime parameter τ (tau) which reflects the duration of fluorescence emission after excitation has been switched off. In TRF measurements the lanthanide label is excited with a light flash and the resulting emission is detected after a labelspecific delay time.

Typical biological samples have a fluorescence background with a very short lifetime, which has an effect on fluorescence intensity

Measurement

techniques

Fluorescence

intensity

Time-resolved

fluorescence

Functional Description

Measurement techniques

20 Varioskan™ User Manual Thermo Electron Corporation

measurements. In TRF technology this biological background has decayed before the TRF signal is measured, giving improved assay performance.

Time-resolved fluorescence labels can well be used for resonance energy transfer applications as fluorescence intensity labels. This time-resolved fluorescence energy transfer technology is known as TR-FRET.

When a beam of light enters a sample, part of the light is absorbed by the sample and the rest is transmitted (passes through the sample).

Absorbance (A) is defined by Equation 1:

A = log (Io/I) Equation 1

where: Io = intensity of incident light

I = intensity of transmitted light

The absorbance is linearly related to the concentration of the absorbing compound by Bouguer-Lambert-Beer’s Law (Equation 2).

A = εC d Equation 2

where: A = absorbance

ε = molar absorption coefficient [l/(mol*cm)]

C = concentration [mol/l]

d = pathlength [cm].

Photometry

Functional Description

Optical system

Thermo Electron Corporation Varioskan™ User Manual 21

The Varioskan employs fluorometric and photometric measurement techniques. Fluorometric measurements are made from the top of the well and photometric measurements are made through the well.

The principle of the Varioskan optical measurement modules is shown in the following block diagram (Figure 2–6). Each submodule is described separately in the subsequent lower-level block diagrams (Figure 2–7 through Figure 2–11).

Figure 2–6. Varioskan optics

The Varioskan optical unit consists of four subunits (Figure 2–6):

● The excitation optics produces light of selected wavelength for

fluorometric measurement and also for photometric measurement.

Refer to “Excitation optics” on page 22.

● The measurement optics produces a high-definition optical beam

for fluorometric and photometric measurements. The excitation

light reference detector is incorporated into the measurement

optics. Refer to “Measurement optics” on page 23.

● The emission optics carries out the reading of a selected wavelength

for fluorometry. Refer to “Emission reading module” on page 24.

● The photometric measurement module measures light-beam

intensity passing through the well. Refer to “Photometric

measurement module” on page 24.

Optical system

Principle of the

optical system

Excitation optics

Emission optics

Measurement optics

Excitation / emission optical module

Photometric measurement module

Fluorescence excitation

Fluorescence emission

Photometric beam through the plate

Functional Description

Optical system

22 Varioskan™ User Manual Thermo Electron Corporation

The excitation optics (Figure 2–7) consists of the light source and the wavelength selection devices.

Warning Do not open the optical covers under any circumstances. There is a risk of ultraviolet radiation injury. Only authorized service personnel has permission to open the optical covers. ▲

Xenon flash module

Diffraction order selection filters

1. Monochromat or

2. Monochromator

Bandwidth selector

Excitation light

Figure 2–7. Excitation optics

Light source:

A xenon flash lamp is used as the light source. The lamp provides a wide spectral range needed for photometry and fluorometry. The lamp is pulsed at a 100 Hz rate and activated only when measuring. A short light pulse enables accurate TRF measurements.

One measurement consists of 1 to 1000 flash pulses according to the measurement quality and measurement speed requirements.

Diffraction order selection filters:

Excitation diffraction order filters, i.e., cut-off filters, are used to block unwanted harmonic transmission of monochromators. The correct diffraction order filter is selected automatically.

Monochromators:

The monochromator is based on the diffraction grating. A grooved surface of the grating diffracts the different colors into different angles and a bandpass wavelength is selected by rotating the grating (Figure 2–8). The final pickup of the desired wavelength band is made by an entrance/exit slit combination.

Two monochromators are serially connected for high spectral quality and this essentially minimizes leakage of undesired wavelengths, i.e., stray light.

Excitation optics

Functional Description

Optical system

Thermo Electron Corporation Varioskan™ User Manual 23

Figure 2–8. Principle of the double monochromator

Bandwidth selector:

The bandwidth is set by means of the monochromator slit width. A selection of two bandwidths, 5 nm and 12 nm, is made by controlling the slits.

The measurement optics module (Figure 2–9) is the front surface mirror optics system to generate a wavelength-independent, highdefinition beam for fluorometric measurement and for photometric measurement. Simultaneously the measurement optics collects emission light, which is fed to the emission reading channel.

Figure 2–9. Measurement optics

Measurement optics

Reference sensor

Excitati on light

Emission light

Functional Description

Optical system

24 Varioskan™ User Manual Thermo Electron Corporation

The excitation beam intensity is measured by the reference sensor before the measurement beam enters the well. The reference sensor value is used to correct the result level to compensate for long-term and short-term flash intensity fluctuations.

The emission optics (Figure 2–10) is basically similar to the excitation optics. Refer to “Excitation optics” on page 22.

Warning Do not open the optical covers under any circumstances. There is a risk of ultraviolet radiation injury. Only authorized service personnel has permission to open the optical covers. ▲

Figure 2–10. Emission optics

Emission monochromators:

Two diffraction grating monochromators are connected serially as in the excitation optics to gain high stray-light rejection. The monochromator bandwidth is 12 nm.

Emission diffraction order filters:

Emission diffraction order filters are used to block unwanted harmonic transmission from the monochromators.

Emission detector:

Emission light is converted into electrical signals by the photomultiplier tube (PMT). The dynamic range is adjusted automatically (AutoRange default) or manually according to the measurement situations. The manual dynamic range setting has three selections: Low; Medium, and High range (Figure 4–35).

Photometric measurement is carried out by using the excitation optics module as the photometric measurement light source.

The photometric measurement module (Figure 2–11) is just underneath the fluorometric measurement position.

Emission reading module

Photometric

measurement module

Diffractio n order selecti on filters

3. Monochromator

4. Monochromat or

Photomultiplier tube (PMT)

Emission light from the well

Functional Description

Dispenser option

Thermo Electron Corporation Varioskan™ User Manual 25

Measurement optics

Reference sensor

Excitat ion light

Photometer module

Figure 2–11. Photometric measurement module

The optional dispenser (Figure 2–5) is located in the instrument housing (Figure 2–2) under the dispenser sliding cover (Figure 2–5). The dispenser is intended for accurate dispensing, in the range of 1 to 1000 µl with increments of 1 µl. The dispenser consists of a pump with a valve, a syringe (1.0 ml), tubing and a dispensing head (Figure 2–12).

The instrument supports simultaneous dispensing and reading, enabling fast signal monitoring from the very start of the reaction. The dispenser is located close to the measurement position in order to achieve a low dead volume and minimal reagent consumption. This is important when using expensive reagents. Optimal design of the reagent bottle holder (Figure 2–5) also aids utilization of all the reagent. The combination of a special dispensing tip (Figure 2–12) and the tip priming feature ensures that even very small volumes can be dispensed accurately.

Dispenser option

Functional Description

Dispenser option

26 Varioskan™ User Manual Thermo Electron Corporation

Figure 2–12. Varioskan dispensing system

There are two different dispensing tip options: the black dispensing tip

0.40 (∅ 0.40 mm), and the transparent dispensing tip 0.25 (∅

0.25 mm) (Fig. 4.12). Dispensing tip 0.25 (Cat. no. N03081) is intended for small volumes in the range of 1 to 20 µl. Dispensing tip

0.40 (Cat. no. N03080) is recommended for volumes > 5 µl, since the dispensing is then more rapid.

Figure 2–13. Dispensing tip options: 0.40 mm, and 0.25 mm

Refer to “How to setup the optional dispenser” on page 45.

Complete dispensing tube

assembly, i.e., output tubing

3-port valve

Dispenser syringe (1.0 ml) and plunger

Aspirate tube assembly, i.e., input tubing (incl. tubing and end weight)

Dispensing tip (2 options:

0.40 mm, and 0.25 mm)

Plunger lock screw

Functional Description

Incubator

Thermo Electron Corporation Varioskan™ User Manual 27

The accurate incubator is useful for temperature-critical applications, for example, certain enzyme assays and cell-based applications.

The universal tray is specially designed for precise and uniform temperature control. The incubator consists of two main parts: a fixed upper heater (Figure 2–14), and a moving universal tray (Figure 2–14). The microplate (Figure 2–14) is surrounded by temperature-controlled heaters with the exception of a narrow space between the upper heater and the universal tray and the reading windows (Figure 2–14). The tray and the upper heater together form the isothermal chamber.

Note that incubation can be carried out with the Varioskan universal tray and a correct adapter. Refer to “Universal tray with adapters” on page 31. The upper element is slightly warmer than the lower element to avoid condensation on the plate lid.

On the other hand, heating can be carried out with all trays and adapters, e.g., the robotic tray, by using only the upper heater element located in the ceiling of the measurement chamber to minimize condensation in the plate lid.

Figure 2–14. Varioskan incubator cross-section

There are two rocker switches in all: one Plate In/Out rocker switch for driving the plate carrier in or out (Plate In/Out function) (Figure 2–15), and one Prime/Empty rocker switch for priming and emptying the dispenser tubing (Prime/Empty function) (Figure 2–15). Note that the Prime/Empty switch is only present if there is a dispenser fitted. The Prime function requires a microplate to be loaded and this is automatically checked before priming. The Empty function does not require a microplate to be present. The Prime/Empty switch has an additional function as a washing option of the dispenser. Refer to “Dispenser washing” on page 62.

Incubator

Control switches

Upper heater (slightly tilted)

Universal tray frame

96-well adapter for

plate without lid, #2

Microplate

Bottom reading hole

Thermo Varioskan User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual