PendoTECH UV-VIS-NIR User manual

PendoTECH UV-VIS-NIR Photometer for UV
Absorbance and Turbidity Measurements User’s Manual
Revision 3
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Document Title: UV-VIS-NIR Photometer P-Version User’s Manual
PENDOTECH® UV-VIS-NIR
PHOTOMETER FOR UV
ABSORBANCE AND TURBIDITY
MEASUREMENTS
USER’S MANUAL
PendoTECH
www.pendotech.com

PendoTECH UV-VIS-NIR Photometer for UV
Absorbance and Turbidity Measurements User’s Manual
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Disclaimer
All rights reserved. No part of this publication may be reproduced, stored in an electronic retrieval
system, or transmitted, in any form or by any means, whether electronic, mechanical, by photocopying,
or otherwise, without the written consent of PendoTECH.
The information in this User Guide is believed to be accurate and reliable for use and operation of the
monitor, however, PendoTECH assumes no responsibility for the use of this product except for what is
covered in the Limited Warranty and Terms and Condition of Sale.
NOTE: “NOTE” is used to notify the user of installation or operation information which is important but
not hazard related.
Safety Guidelines
Warning potential shock hazard. Do not submerge this product. Protect the product
before cleaning with any liquids by covering openings that expose the internal
components.
Each prospective user must test the measurement unit for its proposed application to determine its
suitability for the purpose intended prior to incorporating the sensor to any process or application. The
measurement unit is not intended for use as a component in life support. The sensor is not designed for
any application in which the failure of the product could result in property damage, personal injury, or
death. Proper safeguards must be put into place for the process in which the unit is used.
This device has left our facility after careful testing of all the photometer’s functions and safety features.
The functioning and operational safety of the product can only be ensured if the user observes the usual
safety precautions as well as the specific safety guidelines stated in these operating guidelines:
Before connecting the device to the electrical
supply, ensure that the operating voltage
stated on the power supply corresponds to
the voltage supplied to the unit.
The functioning and operational safety of the
instrument can only be maintained under the
conditions specified in the specifications
section of this manual.
If the instrument is moved from warm
surroundings, condensate may form and
interfere with the functioning of this
instrument. In this event, wait until the
temperature of the photometer equilibrates
to the new temperature before putting it back
into operation.
If there is any reason to assume that the
product can no longer be employed without
risk, it must be set aside and appropriately
marked to prevent further use.
The safety of the user may be endangered if
the instrument:
•is visibly damaged
•no longer operates as specified
•has been damaged in transport
If you are in doubt, the product should be
sent back to the factory.
The operator of this product must ensure that
the following laws and guidelines are
observed when using this product around
dangerous substances:
•EEC Directives
•National Fire Protection Association
•Safety data sheets of the chemical
manufacturer
Maintenance, and repair work must only be
carried out by PendoTECH

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Absorbance and Turbidity Measurements User’s Manual
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Optical Safety
WARNING: The photometer can emit light from ≈200 – 1100nm . Hazardous UV and IR radiation
are emitted from the unit. Never directly stare into the source/return ports on the photometer or
the fiber optic cables, as this can cause eye damage. The viewer-related risk is dependent on how
the users install and use the product.
Ensure that both ends of the fiber optic cables (photometer and flow cell connections) are
properly secured (firmly hand tight) before powering on the photometer.
The photometer should always be powered off when handling the fiber optic cables. If you must
handle the fibers when the unit is powered on, protective eyewear must be worn.
In the event of product failure, do not attempt to open the unit or replace the LED. There are no
user-serviceable parts.
This warning label shown below can be found on both the photometer and the fiber optic cables
ends. Users should take precautions and safety measures for both UV and IR radiation:

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Absorbance and Turbidity Measurements User’s Manual
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Notice of Confidentiality
The information contained within this document is confidential and proprietary to PendoTECH and may
be covered under existing US patents or patents pending. This information shall not be reproduced or
further disclosed, in whole or in part, to anyone other than employees of the company purchasing the
product without prior written consent from PendoTECH.

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Absorbance and Turbidity Measurements User’s Manual
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Contents
Section 1: Introduction and Unpacking ......................................................................................................... 6
Section 2: Hardware Installation ................................................................................................................... 8
Section 4: Glossary and Definitions ............................................................................................................. 16
Section 5: Instrument Controls ................................................................................................................... 17
Section 6: Absorbance Operations ..............................................................................................................19
Section 7: System Specifications ................................................................................................................. 20
Section 8: Appendix..................................................................................................................................... 21

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Section 1: Introduction and Unpacking
PendoTECH’s UV-VIS-NIR Photometer is a measuring and monitoring device that allows users to
make in-line absorbance and turbidity measurements from bioprocess fluid streams. The photometer also
acts as a transmitter with a 4-20mA output scaled 0-3 AU. The absorbance measurements are made by a
collimated beam of light which passes through a sample with a defined path length. The absorbance is
determined as the ratio of the light applied from the source to what passed through the sample. At
wavelengths below 400nm, the photometer can be used to measure the UV absorbance of a liquid
solution to identify the absence or presence of a molecule of interest. At wavelengths greater than
400nm, the photometer can be used to measure turbidity as an indication of filter performance or to
measure unclarified material. The photometer also comes in a dual wavelength version, which allows
users to make two measurements of different wavelengths (from 255 to 1000nm) simultaneously in the
same sample.
The combination of the UV-VIS-NIR photometer and the PendoTECH Single Use Flow Cells allow
the measurements to be made in-line. The flow cells contain a special silica glass lens and compartments
to insert optical couplers which attach to the fiber optic cables from the photometer. The flow cells can
also be used with PendoTECH’s Flow Cell Stand with integral couplers in place of the optical couplers to
connect the fiber optic cables. The flow cell stand is optional for UV absorbance applications, but it is
highly recommended for turbidity applications because it blocks out ambient light that would otherwise
affect the readings. Although they are designed for single use, the flow cells may be repeatedly cleaned
and re-used.
Identify the following components:

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Absorbance and Turbidity Measurements User’s Manual
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3. Optical Couplers/Flow Cell Holders (Varies per flow cell used and configuration type)
Optional Flow Cell Stand
4. Example Flow Cells:
Single Use Flow Cell, 1cm path length
Adjustable Path Length Flow Cell,
coupler removed
Adjustable Path Length Flow Cell,
coupler inserted

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Absorbance and Turbidity Measurements User’s Manual
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Section 2: Hardware Installation
Please follow the outlined sections below as a guideline for installing the photometer and associated
accessories. These guidelines apply for specific application installations or in the case of OEM component
installation onto a suitable panel.
2.1 Environmental
It is strongly recommended that the photometer be installed in a clean, dry area where ambient
temperature does not exceed 115F/46C. Systems mounted in enclosures can be purged with clean, dry,
oil-free air (or nitrogen) to dissipate heat within the enclosure.
2.2 Physical
For permanent installations, bolt the photometer, back panel, or enclosure (as appropriate) in place using
mounting screws. The location should be secure, rigid, and strong enough to support the weight of the
installed system.
For laboratory use, ensure that there is sufficient space on the bench or tabletop to accommodate the
hardware supplied.
For all systems, run the fiber optic cable(s) through conduit or other appropriate protective measures as
desired. Refer to Section 2.3 below for optical component installation instructions.
Run required electrical wiring for instrument power and output signals (4-20mA). Review Section 2.4
below prior to making electrical connections.
2.3 Optical
DO NOT SUPPLY POWER TO THE UNIT UNTIL TOLD TO DO SO IN THE
INSTRUMENT SETUP AND INITIALIZATION PROCEDURE IN SECTION 6.

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Photometer, front view
Complete system setup showing measure unit/photometer, flow cell stand/holder, and fiber optic cables
1. Remove the protective caps from the SMA-905 connectors on the fiber optic cables and the
photometer.
2. Clean the fiber ends with spectroscopic-grade isopropyl alcohol (IPA, also known as 2-propanol)
or methanol using a lint-free cotton swab or non-abrasive task wipe. Spectroscopic grade acetone
can also be used, but separation of cotton from the swab might occur as the binding agent
dissolves.
3. Properly mount the flow cell stand/holder (if applicable to system). The flow cell stand can be set
directly flat on a lab bench, or should be properly wall/panel-mounted. Proper mounting of the
flow cell stand facilitates the pass through of bubbles/air pockets in the fluid stream, which if
trapped in the flow cell, can degrade system performance.
SPEC-FCH-L Panel Mounting
SPEC-FCH-S Panel Mounting

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4. Connect the flow cell with optical couplers or flow cell stand to the photometer with the fiber
optic cables. It does not matter which fiber connects to the source and return.
NOTE: Ensure that both ends of the fiber optic cables (photometer and flow cell connections) are
properly secured (firmly hand tight) before powering on the photometer.
5. Power on the unit. Refer to section 2.4 below.
6. Press the tare button (or perform dry contact closure over Tare/Zero +/- pins). This initiates the
calibration and taring routine. The status light will turn green.
a. Note: For best results, the unit should be tared/calibrated with the process background
fluid in the flow cell if possible. If not possible, then a tare/calibration with air in the flow
cell may be used instead.
7. Wait at least 10 seconds for the taring and calibration routine to complete. The status light will
turn back blue.
a. Note: In a panel mount installation, the status LED is not visible. It is recommended to
integrate a 10s indication display on the user interface that the unit is not ready for use
(do not change fluid sate in the flow cells light path).
8. The unit is now ready for operation.
NOTE:The fiber optic cables must be secured so they are not free to
move around, be stepped on, leaned against, or otherwise damaged
during normal operations. The minimum bend radius for fibers
supplied with the UV-VIS-NIR Photometer is 8” (20.3cm).
NOTE: Only hand tighten SMA-905 connections. Never use a wrench,
pliers, or other tool. Over-tightening the SMA-905 connections may
result in damage to the connector and the fiber optic cable,
drastically reducing or prohibiting light transmission and requiring the
replacement of the fiber optic cables.

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2.4 Electrical
Panel mount version
Lab version
NOTE: DO NOT power up the unit during installation. Ensure that all
electrical connections are made with un-energized wires. It is
recommended that an ON/OFF switch be employed for panel
mounting.

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1. Connect the power and ground to the system.
For laboratory systems, a 24VDC power supply is provided (wall adapter with plug blades for global
use).
For panel-mounted systems, a 13-position terminal block connector is provided. Use a small flathead
screwdriver to loosen the screw and insert a NON-ENGERGIZED 12-48VDC lead (with the end stripped
so that the metal wire is exposed) to position 12, and tighten the screw to secure the lead. Repeat
the same procedure for the securing the grounding lead to position 13.
2. Connect the 4-20mA output. For single channel units, only pins 1 and 2 are used. For dual
channel units, pins 1 and 2 correspond to the photometer’s first wavelength (lower) and pins 3
and 4 correspond to the second wavelength (higher).
For panel-mounted systems, a terminal strip is provided for electrical connectivity.
For lab version systems, a cable that connects to the Signal I/O terminal on the back of the
photometer may be purchased. The cable that has flying leads that can be used to connect to the
desired output and alarms (PN: PDKT-UV2-FL). The leads are as follows:
Yellow: Alarm-Out (-)
Orange: Alarm-Out (+)
Violet: Current Loop 2 (-) (If dual wavelength unit, higher wavelength value)
Green: Current Loop 2 (+) (If dual wavelength unit, higher wavelength value)
Brown: Current Loop 1 (-)
Blue: Current Loop 1 (+)
PendoTECH also has other pre-configured cables for connections to the PendoTECH PressureMAT®
Plus monitors, PendoTECH Control Systems, and other PendoTECH products.

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Absorbance and Turbidity Measurements User’s Manual
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Section 3: Introduction to Absorbance Monitoring
3.1 Theory of Operation
Absorbance measures how much of an incident light is absorbed when it passes through a material. The
intensity of light decreases exponentially with distance as light passes through the material, so
transmittance can be determined by measuring the intensity of both the incident and transmitted light.
The value for transmittance can then be used to calculate the absorbance of the sample.
The Beer-Lambert Law relates how absorbance is related to the concentration and the distance the light
must travel through the sample (path length):
A= εcl
Where A is absorbance, ε is the extinction coefficient, c is the concentration of the solution (in mol/L),
and l is the path length traveled by light through the sample (in cm).
3.2 LED-Based Absorbance
Light emitting diode (LED)-based photometers are a good choice when qualitative measurements are
desired. Additionally, through the use of calibration standards and environmental control, an LED-based
photometer is capable of quantitative determination of analyte concentration. When making quantitative
measurements, it is critical that the LED-based photometer is accurately correlated to standard
laboratory methods and solutions.
The LED provides a specific wavelength (or wavelengths for dual channel models) range for
measurement, selected to coincide with analyte-specific molecular absorbance. The LED is located
internal to the photometer and is specific to the application. Therefore, the UV-VIS-NIR photometer is a
dedicated instrument for monitoring only one or two specific analytes of interest.
Shown below are three example LED spectrum profiles graphs, for typical LED light source wavelengths
260/280/880nm (Figures 1-3).
Definitions
•CWL (Center Wavelength): The wavelength of an optical source that is considered its’ middle. The
wavelength of the peak of the spectral density curve.
oWatch-Out: If measurements are attempted on a shoulder/slope of the molecule’s
absorption profile, the absorption measurement can change dramatically over the span
of a few nanometers. Absorbance may never saturate as a portion of the LED’s output is
outside of the molecule’s absorbance profile. Minute photometer unit-to-unit absorption
variations exist due to CWL tolerance.
•FWHM (Full Width Half Maximum): A measure of the range of light the LED generates. The width
of an optical signal at half its maximum intensity

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oWatch-Out: If the light source FWHM width is wider than the molecule’s absorption peak,
that will produce false, low absorption values.
Figure 1 LED wavelength spectrum example for 260nm UV-VIS-NIR photometer.
Figure 2 LED wavelength spectrum example for 280nm UV-VIS-NIR photometer.

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Figure 3 LED wavelength spectrum example for 880nm UV-VIS-NIR photometer.
In brief, the photometer works as follows: The measuring system is in the detector block of the
photometer. Light is provided by an LED, which produces a stable light output at a narrow wavelength
range. The reference signal is measured directly from the light source by the reference detector, and light
that passes through the sample is measured by the measure detector. The reference channel is used in
order to cancel variations from light source intensity fluctuations, spectral change due to window fouling,
or suspended particles in the process stream.
Figure 4Optical diagram of photometer and flow cell sample interface
The remainder of this manual provides the user with the necessary tools to operate the photometer and
meet the measurement requirements.

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Section 4: Glossary and Definitions
Dynamic Range: Dynamic range refers to the range of concentrations an instrument can read, from the
minimum to the maximum detectable concentration. The minimum detectable concentration is
determined by the signal-to-noise ratio. The maximum detectable concentration is determined by the
compound’s chemistry and by factors such as instrument sensitivity ranges, optical pathlength, etc.
Linearity: Absorbance intensity is typically directly proportional (linear) to concentration. There are,
however, many factors that affect this linear relationship. For example, stray light, turbidity, variation in
chemical composition of the background, etc. can affect the linearity of the absorbance response.
Measure Detector: A detector that measures the intensity of light after it has contacted the sample. The
system is designed in such a way that only absorbing wavelengths of light are measured by the measure
detector.
Measure LED: The measure LED is the light emitting diode (LED) used to select the
measurement wavelength.
Measure Wavelength: The wavelength, or range of wavelengths, of light that are absorbed by the
analyte(s) of interest.
Process Background: The liquid or gas used to transport or sustain the analyte of interest in the process.
This includes all the chemical constituents found in the process except the analyte of interest.
Reference LED: The reference LED is the light emitting diode (LED) used to select the reference
wavelength to be measured by the reference detector. The center wavelength selected is a wavelength at
which the analyte of interest does not absorb and is used to cancel variations from such effects as light
source intensity fluctuations or spectral change due to window fouling or suspended particles in the
process stream. Reference LED is an optional feature but is required for through media referencing.
Sensitivity: The ability of the photometer to detect a given level of analyte based on the molecular
absorbance of the analyte. The actual limits of detection depend on the properties of the analyte
measured and the process conditions.
Specificity: The ability of the analyzer to monitor one specific analyte in a mixture of
background materials without interference from the background materials.

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Absorbance and Turbidity Measurements User’s Manual
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Section 5: Instrument Controls
5.1 Zero
The zero button/contacts will set one (or both channels for dual wavelength model) to zero absorbance
(0.00AU or 4.00mA).
NOTE: For best results, the unit should be tared/calibrated with the
process background fluid in the flow cell if possible. If not possible,
then a tare/calibration with air in the flow cell may be used instead.

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5.2 Indicator LED
The indicator LED located on the top of the unit illuminates BLUE when the unit is making normal
measurements, and RED when there is an issue with either the photometer or the flow cell.
5.3 Alarms
The photometer’s indicator LED will glow RED, indicating an alarm condition. For panel mounted units, 2
dedicated alarm contact pins will close during an alarm. The alarm will activate if:
Alarm Activator
Cause
Solution
The measurement detector is
saturated at 100%
Photometer outputting negative
absorbance values due to bad
tare
Re-tare flow cell with background
solution or air
The reference detector is
saturated at 100%
Extreme amount of ambient
light entering flow cell/measure
detector
Use flow cell holder to block
ambient light from entering flow
cell; ensure fiber optic cable
connections are firmly hand tight
The reference light and dark
signals are too close to each
other
LED is dead
Send back to PendoTECH for
repair
See Figure 1 for
Indicator LED

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Section 6: Absorbance Operations
This procedure assumes that the hardware has been installed correctly and is ready for operation. For
panel-mounted systems, this procedure is valid once electrical connectivity is established.
DO NOT power the unit until directed to do so in this procedure.
1. Ensure that the fiber optic connections to the photometer and the corresponding optical flow cell
couplers are hand tight. See Section 2.3 for instructions
a. Insert single use flow cell into the flow cell stand/holder (if applicable). Replace the stand’s
cover, and tighten the cover’s screw firmly to securely hold the flow ce..
2. Ensure that both the power and the analog output connections are wired correctly. See Section 2.4 for
instructions.
3. Provide power to the unit.
4. Zero (tare) the unit.
I. For best results, the unit should be tared/calibrated with the process background fluid in the flow
cell if possible. If not possible, then a tare/calibration with air in the flow cell may be used
instead.
NOTE: The 4-20mA output is correlated to absorbance intensity in AU
(absorbance units). To convert absorbance intensity to relevant
engineering units, the 4-20mA output must be scaled using an
external device. The photometer cannot be set to relevant
engineering units, and has a fixed range of 0.00-3.00AU = 4mA -
20mA.
NOTE: Please reference Section 2 for hardware installation
instructions (environmental specifications, physical mounting, optical
connectivity, and electrical connectivity).

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Section 7: System Specifications
This section provides detailed specifications for the UV-VIS-NIR Photometer system purchased. In
addition, this section may contain application specific notes on operability, functionality, etc.
7.1 Optical Configuration
The optical configuration listed is for a complete analyzer system. The detectors and light emitting diode
(LED) are internal to the photometer housing.
Optical Method
Absorbance
Light Source
LED
Reference Selection
Internal Source Reference
7.2 Photometer Specifications
Configuration
Internal Source Reference
Optical Connectivity
SMA-905
Mechanical
4” (10.2cm) W x 4” (10.2cm) L x 2.5” (6.4cm) H
Weight: ~1.5lbs.
Power Requirement
24VDC nominal, 2.7W max power
Output
4-20mA (Active/sourcing) spanned 0-3AU
Analog Loop Resistance
500 ohms at 24VDC
Operating Temperature
41to 122°F (5 to 50C)
Storage Temperature
-4 to 122°F (-20 to 50C)
Measurement Range
0.00-3.00AU
Response Time
1 second
Accuracy*
0-2AU: ±1%FS (±0.03AU) ; 2-3AU: ±2%FS (±0.06AU)
Precision/Repeatability
±0.5% full scale (±0.015AU)
LED Lifetime
> 5 years
Available Wavelengths
240-1000 nm
Regulatory
RoHS3, REACH, CE
*Accuracy is dependent on system arrangement and proper tare
When converting the 4-20mA output to Absorbance Units (AU):
Let x= 4-20mA output
4
16 × 3.000 =