Unico 1200 User manual

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1200 SERIES
SPECTROPHOTOMETER
USER’S MANUAL
United Products & Instruments, Inc.
182 Ridge Road, Suite E Dayton, NJ 08810, USA
TEL: [phone] FAX: [phone]
www.unicosci.com [email protected]

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General Information
The spectrophotometer described in this manual is designed to be used by properly
trained personnel in a suitable equipped laboratory. For the correct and safe use of this
spectrophotometer it is essential for laboratory personnel to follow generally accepted
safe procedures in addition to the safety precautions called for in this manual.
The inside of the power supply unit is a hazardous area and its cover should not be
removed under any circumstances. ANY Servicing must be done by an authorized
person.
Some of the chemicals you use in the spectrophotometer may be corrosive, flammable,
radioactive, toxic, and/or potentially infective. Care should be taken to follow the normal
laboratory procedures for handling chemicals and samples. Please carefully read the
Safety, Electrical, Warning, Performance and Radio Interference instructions below.
Safety
This spectrophotometer has been designed and tested in accordance with EN 61326-1:
1997 Safety Requirements for Electrical Equipment for Measurement, Control, and
Laboratory Use standard (EMC Requirements). The spectrophotometer has been tested
and supplied in a safe condition.
Read the following before installing and using the instrument and its accessories.
Electrical
Before switching on the spectrophotometer, make sure it is set to the voltage of the
local power supply (see Installation section).
The main plug shall be inserted in a socket provided with a protective earth grounded
contact. The protective action must not be negated using an extension cord without a
protective conductor.
Warning
Any interruption of the protective conductor inside or outside the spectrophotometer or
disconnection of the protective earth terminal is likely to make the spectrophotometer
dangerous. Intentional interruption is prohibited. Whenever it is likely that the protection
has been impaired, the spectrophotometer shall be made inoperative and be secured
against any unintended operation.
The protection is likely to be impaired if, for example, the spectrophotometer
•Shows visible damage
•Fails to perform the intended measurements
•Has been subjected to prolonged storage under unfavorable conditions
•Has been subjected to severe transport stresses
Performance
Carry out performance checks with reference to wavelength and absorbance accuracy
to ensure that the spectrophotometer is working within its specification, especially when
making measurements of an important nature. Performance checks are detailed in this
manual.

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Radio Interference
For compliance with the EMC standards referred to in the EC Declaration of Conformity,
it is necessary that only shielded cables supplied by UNICO®are used when connecting
the instrument to computers and accessories.
Introduction
UNICO®1200/1201 Spectrophotometers are single beam, general purpose instruments
designed to meet the needs of the conventional laboratory. UNICO®1200/1201 is ideal
for various applications, such as: Clinical Chemistry, Biochemistry, Petrochemistry,
Environmental Protection, Food and Beverage Labs, Water and Waste Water Labs, and
other fields of quality control.
Featuring a digital display of photometric result, easy operation, and wavelength range
of 325 nm~1000 nm, UNICO®1200/1201 are ideal for measurements in the visible
wavelength region of the electromagnetic spectrum.
Working Principle
The spectrophotometer consists of five parts:
1) Light Source (Halogen Lamp) to supply the light;
2) A Monochromator to isolate the wavelength of interest and eliminate the unwanted
second order radiation;
3) A Sample Compartment to accommodate the sample solution;
4) A Detector to receive and convert the transmitted light to an electrical signal;
5) A Digital Display to show absorbance or transmittance. Figure-1 illustrates the
relationship between these parts.
Light Source Monochromator Sample Compartment Detector Digital Display
Figure-1 Block Diagram for the Spectrophotometer
In the spectrophotometer, light from the Halogen Lamp is focused on the entrance slit of
the Monochromator where the collimating mirror directs the beam onto the grating. The
grating disperses the light beam to produce the spectrum, a portion of which is focused
on the exit slit of the Monochromator by a collimating mirror. From here the beam is
passed to a Sample Compartment through one of the filters, which helps to eliminate
unwanted second order radiation from the diffraction grating. Upon leaving the Sample
Compartment, the beam is passed to the silicon photodiode Detector and causes the
Detector to produce an electrical signal that is shown on the Digital Display window.
Specifications
100%T
0 A

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Model 1200 Model 1201
Wavelength Range 325~1000 nm
Spectral Bandpass 5 nm
Wavelength Accuracy ± 2 nm
Wavelength Repeatability ± 1 nm
Stray Radiant Energy < 0.5%T at 340 and 400 nm
Photometric Range 0~125%T
0~2.0 Abs
0~1999C (0~1999 Factor)
Photometric Accuracy ± 1.0%T
Power Requirements 115/230 V ±10%, 60/50 Hz switchable
Sample Holder Single Test Tube/Cuvette 4-poisiton Cuvette Holder
Dimensions 415W x 320D x 175H (mm) (16-1/2 x13 x 6-3/4 inches)
Net Weight 6.5 kg (15 lbs)
Unpacking
Carefully unpack the contents and check the materials against the following packing list
to ensure that you have received everything in good condition.
Description Quantity
Model 1200 Model 1201
Spectrophotometer 1 1
Dust Cover 1 1
10 mm Optical Square Cuvette 2 2
Test Tubes (1/2 inch) Box of 12 -
V-type Tube Holder (8 to 25 mm) 1 (installed) -
10 mm Single Cuvette Holder 1 -
Black Block 1 1
4-position Cuvette Holder - 1 (installed)
Power Cord 1 1
User Manual 1 1
Installation
1. Place the instrument in a suitable location away from direct sunlight. To have the best
performance from your instrument, keep it as far as possible from any strong magnetic
or electrical fields or any electrical device that may generate high-frequency fields. Set
the unit up in an area that is free of dust, corrosive gases and strong vibrations.
2. Remove any obstructions or materials that could hinder the flow of air under and
around the instrument.
1200 and 1201 Spectrophotometer Operation Panel

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Mode Indicator: Show the current measurement mode (T--%Transmittance, A--
Absorbance, C--Concentration, and F--Factor) (refer to Figure-3).
LCD Display Mode 0A/100%T 0%T Print/Enter
Sample compartment Wavelength Knob
Figure-3 UNICO®1200 Spectrophotometer
MODE Button: There are four modes.
¾T mode is transmittance mode;
¾Amode is absorbance mode;
¾C mode is to measure unknown sample concentration through a standard solution;
¾Fmode is to measure unknown value with a previously determined factor.
∧(0A/100%T) Button: Adjust Digital Display reading to 100%T or 0.000A when blank
reference solution is in the Sample Compartment.
∨(0%T) Button: When in Tmode, put S-1200-111 into the Cuvette Holder to block the
optical light beam. Press ∨button to adjust the Digital Display reading to 00.0%T.
ENT (PRINT) Button: When pressed:
At Aand Tmodes, send the displayed results to printer;
At C mode, set the concentration value (refer to Concentration Mode in Basic
Operation section);
At Fmode, set the factor number and change to Cmode (refer to Factor Mode in Basic
Operation section); If you want to print the test results at C mode, push the MODE
button to the position when the LED light is off, then push the ENT button;
Sample Compartment: Accept 10 mm test tube or 10 mm square cuvette (with
different cuvette holders). The compartment can accept up to 50 mm pathlength

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cuvettes with optional holders.
WAVELENGTH Knob: Select desired wavelength in nanometers (nm).
Wavelength Readout Window: Display desired wavelength.
Basic Operation
Sample Preparation and Analysis
A. Spectrophotometer Warm-up and 0%T Check
1. Turn on the spectrophotometer by turning on the Power Switch (IO). Allow 15
minutes for the instrument to warm up.
2. Even through the 0%T is pre-set at UNICO®; it may shift due to unexpected
factors like temperature change. To check 0%T, simply insert the Black Block
(item number: S-1200-111, used to check the 0%T) into the Cuvette Holder and
close the lid. Select Tmode, the display should be 00.0%T. If not, press the 0%T
button to set 0%T.
3. Select either the T(Transmittance Mode) or A(Absorbance Mode) by pressing
the MODE button until the red light for T or Ais on.
4. Select the desired wavelength by turning the WAVELENGTH control knob.
5. Insert the blank cuvette into Sample Compartment and close the cover.
6. Set 0.000A or 100%T with the 0A/100%T (∧)button.
7. Remove the blank square cuvette or test tube. Set it aside in case that you may
need to adjust the 0A/100%T using ∧ button later (i.e. change the wavelength).
9. Rinse a second square cuvette with a small amount of the sample solution to be
tested. Fill the square cuvette half full and wipe it.
10. Put the sample cuvette in the Sample Compartment. Close the cover.
11. Read the Tor Afrom the Digital Display window. Remove the sample cuvette or
test tube.
Concentration Mode
Cis used for determining the concentration of unknown samples.
NOTE: This method should only be used when the relationship between Absorbance
and Concentration is known to be linear. The concentration of the Standard solution
used to calibrate the instrument should be higher than the most concentrated sample.
1. Select the desired wavelength by turning the wavelength control knob.
2. Using the MODE button, select Amode.
3. Insert the cuvette containing the blank solution.
4. Set 0.000A with the ∧button.
5. Using the MODE button, select Cmode.
6. Insert a cuvette containing a standard solution of known concentration in the Sample
Compartment and set the Digital Display window to be the value of the standard by
using the ∧and ∨buttons.
7. Press the ENT button.
NOTE: If the reading changes, the factor required is too high (i.e. >1999) to be
displayed. In this case, divide the concentration by 10; re-select the C mode by
successive presses on the MODE button, cycling through the F,T, and Amodes, and

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follow step 2 above to set the concentration of the standard to the reduced value.
8. With the standard concentration set, determine the concentration values of samples
with unknown concentration by inserting the sample cuvette into the Sample
Compartment and reading the value direct from the Digital Display.
9. To read the value of the multiplier used to convert Abs to Concentration, after
measuring all the samples, change the mode to F and read the multiplier from the
display. Keep a record of this value for future use.
Operational Note: if the MODE is changed to read For Aand the Concentration C
reading is “frozen”, re-start at step 1.
Factor Mode
This is a special mode for measuring concentration values of unknown samples using a
previously determined factor to convert absorbance readings to concentration.
1. After setting the wavelength, and setting zero Abs on the blank solution, using
the MODE button, select Fmode.
2. Insert a cuvette containing a sample.
3. Using the ∧and ∨buttons, set the Digital Display window to the desired value
of the multiplier.
4. Press the ENT button. The spectrophotometer switches to the Cmode.
Operational Note: If the Concentration of the sample is too high to be displayed, the
instrument will not switch to Cmode when the ENT button is pressed. Dilute the sample
and multiply the concentration reading by the dilution factor to obtain the original sample
concentration. If dilution is impossible or causes other problems, you may divide the
factor value by “10” or “100” and follow step 1 to 4 to enter the “new” factor value. You
need to calculate the sample concentration by multiplying readout with the multiple “10”
or “100”.
5. Read the concentration value of the sample direct from the display.
6. Insert a cuvette containing the next sample and read the result. Repeat until all
samples have been measured.
Operational Note: if the MODE is changed to read Aor Tand the Concentration C
reading is “frozen”, re-start at step 1.
Maintenance
Bulb Replacement
1. Replacement bulb pn#1200-505: 6V/10W G4 with horizontal filament.
2. Turn off and unplug the instrument.
3. Remove the lamp access door at the back of the instrument by removing the four set
screws pointed by arrows on the image below. Remove the black cover next to the
access door and set it aside.

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3. Loosen-up 2 lamp holding screws pointed by arrows on the image below. Remove
damaged bulb and insert the new bulb all the way in to the holder. Lightly tighten
the holding screws but not all the way.
4. Plug the power cord back and turn the instrument on. Set the wavelength to 340nm.
Avoid to stair directly on to the bulb. Use the bulb observation window to the right.
Make sure the projection of the light is aligned on the slit as shown by the arrow
below. If necessary – turn the instrument off, allow time for the bulb to cool off and
adjust the bulb by pulling or pushing it.
CAUTION: DO NOT HANDLE THE LAMP WITH BARE FINGERS. USE TISSUE OR
CLOTH WHEN HANDLING LAMP.

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5. Insert a test tube or an empty cuvette with cuvette holder, and blank the instrument.
If the energy is low, adjust the lamp by “pulling” or “pushing” it so that the light beam
is focused on the entrance slit of the monochromator. Since the lamp socket is pre-
aligned, there will be minimum, if any, adjustment required.
6. Tighten the lamp holding screws and re-install the access door.
Wavelength Calibration Check
Normally the UNICO®1200 Series spectrophotometer retains its wavelength calibration
indefinitely. However if the instrument receives a severe shock or is abused, use the
following methods to check wavelength calibration. Please note that this test requires
the UNICO®Didymium filter, item number S-90-9116, or the Holmium Oxide filter, item
number S-90-9115.
In the filter method, the didymium filter has two distinct absorbance peaks at 529 nm
and 807 nm. The Holmium filter has a distinct peak at 361 nm. When the instrument is
calibrated properly you will find minimum Transmittance (maximum Absorbance) at the
range ± 2 nm from these peaks. Note that the specific Transmittance values are not
important as you are only looking for the wavelength where the minimum Transmittance
(maximum Absorbance) occurs.
Note: If you calibration filter has a certified peak/valley curve attached, please use the
peaks on the curve to verify the instrument.

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Holmium Oxide Filter Method
1. Turn instrument on and allow it to warm up for 15 minutes.
2. Select the Amode.
3. Set the wavelength to 350 nm.
4. Make sure the Cuvette Adapter is empty and place it in the Sample Compartment.
Close the lid.
5. Set zero Absorbance by pressing the ∧button. Wait a few seconds when the display
flashes. The reading should be 0.000A. If not, repeat step 5.
6. Remove the Cuvette Adapter and insert the Holmium filter into it. Place it in the
Sample Compartment again and close the lid.
7. Record the Absorbance reading on the Digital Display window.
8. Advance the wavelength setting by 1 nm and repeat step 4 to 7.
9. Repeat step 8 until the wavelength setting reaches 370 nm.
10.Look for the maximum absorbance reading obtained, and this should be found within
359~363 nm. The wavelength accuracy of the 1200 is ± 2 nm.
Didymium Filter Method
1. Set the Wavelength to 800 nm.
2. Make sure the cuvette adapter is empty and place it in the Sample Compartment.
Close the lid.
3. Set zero Abs by pressing the ∧button. Wait a few seconds when the display flashes.
The reading should then be 0.000A. If not, repeat step 3.
4. Remove the cuvette adapter and insert the Didymium filter into it. Place it in the
Sample Compartment again and close the lid.
5. Record the Absorbance reading on the Digital Display window.
6. Advance the wavelength setting by 1nm and repeat step 2 to 5.
7. Repeat step 6 until the wavelength setting reaches 815 nm.
8. Look for the maximum absorbance reading obtained, and this should be found within
805~809 nm. The wavelength accuracy of the 1200 is ± 2 nm.
9. If a “middle” wavelength check is desired, set the wavelength to 522 nm (optional)
10.Make sure the Cuvette Adapter is empty and place it in the Sample Compartment.
Close the lid.
11.Set zero Abs by pressing the ∧button. Wait a few seconds when the display flashes.
The reading should be 0.000A. If not repeat step 11.
12.Remove the Cuvette Adapter and insert the Didymium filter into it. Place it in the
Sample Compartment and close the lid.
13.Record the absorbance reading on the Digital Display window.
14.Advance the wavelength setting by 1 nm and repeat step 10 to 13.
15.Repeat step 14 until the wavelength setting reaches 536 nm. Again, look for the
maximum absorbance reading. It should be within 527~531 nm.
Absorbance Accuracy Check
Specification: ± 1% at 1A
The absorbance accuracy should be checked against a set of neutral density filters
accurately calibrated to the NIST standards. Contact your UNICO®representative for
more information (800-588-9776 or 732-274-1155).

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Stray Light Check
Specification: Less than 0.5%T at 340 nm by ASTM E 387
The stray light should be checked against a set of filters accurately calibrated to the
NIST standards. Contact your UNICO®representative for more information (800-588-
9776 or 732-274-1155).
Troubleshooting
PROBLEM Possible Cause Solution
Instrument
Inoperative
(Power indicator
has no light)
Power cord not connected to outlet Plug instrument in
Dead Power outlet
Wrong voltage setting
Change to a different outlet
Internal fuse blown or defective electronic
component
Call an authorized service
engineer
Instrument can
not set 100%T
(0.000A)
No Cuvette Adapter in the Sample
Compartment
Cuvette Adapter must be in
Sample Compartment to open
sample holder shutter
Light beam blocked:
•Holder misaligned
•Shutter
Check sample holder
Lamp is old or defective Replace lamp
Lamp is off alignment Refer to Lamp Replacement
instructions in this manual
Defective electronic component Call an authorized service
engineer
%T can not be
set to 00.0%T
Sample holder Remove Cuvette Adapter or
test tube
Sample holder shutter May be stuck open Close
shutter
Defective electronic component Call an authorized service
engineer
Incorrect
Transmittance to
Absorbance
correlation
Bubbles or particles in solution Check sample preparation and
analytical procedure
Defective electronic component Call an authorized service
engineer
Digital Display
does not change
regardless of
sample
concentration
Concentration reading “frozen” Change MODE from C to F, T
or A and back to C Restart
measurement procedure
Wrong wavelength setting Check sample procedure and
wavelength setting
Insufficient sample volume Fill cuvette with more samples
Stray sample preparation vapors Prepare the sample away from
the instrument. Use proper
ventilation
Bubbles or particles in solution Check sample preparation and
analytical procedure
Defective electronic component or loose wiring Call an authorized service
engineer

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Instrument drift
and noise
No sufficient warm up time
Significant temperature change
Lamp not adjusted properly
Check lamp has been properly
installed or has moved during
transit
Refer to Lamp Replacement
instructions in this manual
Lamp old or defective Replace with a new lamp
Sample Holder Misaligned Refer to Lamp Replacement
instructions in this manual
Unstable power supply
Defective or dirty detector or defective
electronic component
Call an authorized service
engineer
Incorrect
readings
obtained
Insufficient sample volume Fill cuvette with more samples
Wrong wavelength setting
Failed to blank (0A/100%T)
Failed to set 0%T
Check analytical procedure
and wavelength setting Check
wavelength accuracy
according to procedure in this
manual
Stray sample preparation vapors Prepare sample away from
instrument. Use proper
ventilation
Bubbles or particles in solution Check sample preparation and
analytical procedure
Instrument out of electronic calibration Call an authorized service
engineer
UNICO Authorized Service Contact Information
UNICO
182 Ridge Road, Suite E,
Dayton, NJ 08810, USA
Tel.: [phone] or 732-274-1155
Fax: [phone]
Web: www.unicosci.com
E-mail: [email protected]