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High Precision in Spectro-Optics




Optical Reference Materials
for UV/VIS Spectroscopy
PRODUCT CATALOGUE WITH HANDLING GUIDELINES



TRACEABLE

 MADE IN GERMANY



RELIABLE AND SAFE MEASUREMENT
RESULTS IN OPTICAL ANALYTICS
For over 100 years Hellma has been the world‘s leading supplier of UV|VIS|NIR spectroscopy cuvettes
for laboratory analytics and is now also a solution specialist in process analytical technology for a wide
range of applications in research and industry. Products and services of the Hellma Analytics and Hellma
Solutions brands provide the basis for precise and reliable measurement results in laboratory and
process and thus safe and high-quality end products in the chemical, pharmaceutical, life science, food
and beverage, cosmetics, environment, energy, technology and research industries. Eight Hellma sales
subsidiaries worldwide and over 200 international points of sales are available to customers for direct
contact. Hellma is valued worldwide for its high performance, consulting competence and well-proven
products. 100% Made in Germany.

RELIABIILLITY

CONTINUITY

TRUST

fwww.hellma.com

2

 Traceable to
NIST, PTB
DAkkS
accredited calibration
laboratory*
ACCREDITED*
ACCORDING TO
DIN EN ISO/
IEC 17025
30 YEARS
GUARANTEE
with regular recalibration
COMPLIANT
with the most important
Pharmacopeias

* Accredited calibration laboratory by
DAkkS according to DIN EN ISO/IEC
17025. The accreditation is valid only for
the scope listed in the annex of the accreditation
certificate D-K-18752-01-00.



Benefit from from
over 100 years
Experience.
Where you see this
icon you will find useful
information to make
EXPERTS
TIP: your processes safer
and more effective.
3

 CONTENTS

1. INTRODUCTION .......................................................................................6
1.1 Hellma Analytics calibration laboratory: Accredited* acc. to DIN EN ISO/IEC 17025 ............................................... 7
1.2 Certified test equipment .............................................................................................................................................. 8
1.3 Glass filter applications ............................................................................................................................................... 8
1.4 Liquid filter applications .............................................................................................................................................. 8
1.5 DAkkS calibration certificate* .................................................................................................................................... 10
1.6 Warranty – 30 years manufacturer’s warranty on all Hellma Analytics reference materials ................................. 13
2. GLASS FILTERS ....................................................................................14
2.1 Checking wavelength accuracy .................................................................................................................................. 14
2.1.1 Holmium glass filter .................................................................................................................................................. 14
2.1.2 Didymium glass filter ................................................................................................................................................. 15
2.2 Checking the photometric accuracy .......................................................................................................................... 16
2.2.1 Neutral density glass filter ........................................................................................................................................ 16
2.3 Glass filter sets........................................................................................................................................................... 17
3. LIQUID FILTERS ....................................................................................18
3.1 Checking the wavelength accuracy ........................................................................................................................... 18
3.1.1 Holmium liquid filter .................................................................................................................................................. 18
3.1.2 Didymium liquid filter ................................................................................................................................................. 19
3.1.3 HoDi liquid filter ......................................................................................................................................................... 20
3.1.4 Rare earth (Cerium) liquid filter ................................................................................................................................ 21
3.2 Checking the photometric accuracy .......................................................................................................................... 22
3.2.1 Potassium dichromate liquid filters for checking the photometric accuracy acc. to USP <857> (and Ph. Eur.) ....22
3.2.2 Nicotinic acid (Niacin) liquid filters for checking the photometric accuracy acc. to Ph. Eur. and USP <857> ....... 24
3.3 Checking for stray light .............................................................................................................................................. 25
3.3.1 Checking for stray light – measurement acc. to Ph. Eur. and USP <857> procedure B .......................................... 25
3.3.2 Checking for stray light – measurement acc. to USP <857> procedure A ............................................................... 27
3.4 Checking the spectral resolution............................................................................................................................... 29
3.5 Liquid filter sets ......................................................................................................................................................... 30
3.5.1 Basis filter set for Ph. Eur. conformity ...................................................................................................................... 30
3.5.2 Basis filter set for USP <857> conformity ................................................................................................................. 31


4

 CONTENTS



4. REFERENCE PLATES.............................................................................32
4.1 Checking the photometric accuracy .......................................................................................................................... 32
4.2 Checking the photometric accuracy and wavelength accuracy ............................................................................... 33
5. RECERTIFICATION .................................................................................34

6. PRODUCT OVERVIEW ............................................................................36

7. FAQ .......................................................................................................42

8. GLOSSARY ............................................................................................44

9. LITERATURE REFERENCES ...................................................................45

10. GENERAL USAGE GUIDELINES ..............................................................46
10.1 General usage guidelines for glass filters ................................................................................................................ 46
10.2 Calibration with glass filters (wavelength accuracy and photometric accuracy)..................................................... 47
10.3 General usage guidelines for liquid filters ................................................................................................................ 52
10.4 Calibration with liquid filter (wavelength accuracy and photometric accuracy) ...................................................... 53
10.5 Calibration with liquid filters (stray light and spectral resolution) ........................................................................... 60
10.6 General usage guidelines for reference plates ......................................................................................................... 66
10.7 Calibration of reference plates .................................................................................................................................. 67






* Accredited calibration laboratory by DAkkS according to DIN EN ISO/IEC 17025.
The accreditation is valid only for the scope listed in the annex of the accreditation certificate D-K-18752-01-00.


5

 1. INTRODUCTION

Dear Readers,
Although checking measuring equipment to ensure that results
are accurate has long been common practice for analytical
balances, it still tends to take something of a backseat where
spectrophotometers are concerned. Spectrophotometers are
important instruments that play a major role in health care,
life sciences, environmental analysis and processes such as
production control and ensuring product quality. Over the last
two years, many laboratories have become considerably more
aware of the need to check their spectrophotometers, making
it all the more important to know that these precision tools are
also subject to mandatory checks under DIN EN ISO 9001. The
standard clearly stipulates that measuring equipment must be
calibrated or verified, either at regular intervals or before use,
using measurement standards that can be traced back to international
or national standards. For an overview of the measurement
standards for UV-Vis spectrophotometers, please
refer to our reference materials in this brochure. An increasing
number of laboratories are turning to this easy method for ensuring
high standards of work, not only to satisfy requirements
in time for their next audit, but also to be safe in the knowledge
that they are taking accurate measurements and thus
basing their actions and responses on correct results. We are
delighted that our products are helping to achieve this. Details
of our product range, as well as usage guidelines, helpful
tips and recommendations, are all included in this handbook.
ENJOY READING!





FOR YOUR INFORMATION
Proven reliability completely documented.
The Hellma Analytics calibration laboratory is the
only calibration laboratory in Germany accredited
for the calibration of UV/Vis reference materials.
The calibration laboratory is accredited by DAkkS
according to DIN EN ISO/IEC 17025. The accreditation
is valid only for the scope listed in the annex of
the accreditation certificate D-K-18752-01-00.

6

 1. INTRODUCTION


1.1 Hellma Analytics calibration laboratory:
Accredited* according to DIN EN ISO/IEC
17025
The Hellma calibration laboratory is accredited* by DAkkS
according to DIN EN ISO/IEC 17025. The DIN EN ISO / IEC
17025 standard requires a comprehensive QM system that
seamlessly connects to other systems such as ISO 9001.
By achieving this accreditation*, we demonstrate proof-of-expertise
in the calibration activities for the optical measurement
variable radiometry. The accreditation* authorizes us
to issue internationally recognized DAkkS* calibration certificates
and is the key to the high quality of the measurements
, the international comparability and confidence in the
work of the calibration laboratory and the transparency of the
results.

TRACEABLE
DIN EN ISO/IEC 17025
* The accreditation is valid only for the scope listed in the annex of the
accreditation certificate D-K-18752-01-00

»
With the UV/Vis reference materials
from Hellma Analytics, we create the
basis for reliable measurements for
our customers.
Birgit Kehl,
Compliance Manager
Calibration Laboratory


7

 1. INTRODUCTION



1.2 Traceable test equipment 1.3 Glass filter applications
Quality assurance and quality control regulations, such as 666 at the beginning of the article number identifies our
ISO 9001, GLP, GMP and Pharmacopeias, require companies glass filters. Glass filters are reference materials made of
to verify the consistently accurate performance of any spec- glass manufactured specifically for calibration. They are,
trophotometer in use. The two most important factors for ob- above all, extremely robust. All glass filters measured by
taining precise spectrophotometer data are the photometric Hellma Analytics are traceable to NIST primary standards.
accuracy (absorbance accuracy) and wavelength accuracy of Glass filters are suitable for checking the following parathe
spectrophotometer, which should be tested on a regular meters of your spectrophotometer:
basis.
O Wavelength accuracy
The production of the optical reference materials in the O Photometric accuracy (absorbance)
Hellma Analytics calibration laboratory, which is accred- O Photometric linearity (Vis range)
ited by the DAkkS according to DIN EN ISO/IEC 17025, is
based on the regulatory codes issued by NIST (National
Institute of Standards and Technology), ASTM (American 1.4 Liquid filter applications
Society for Testing and Materials) and Pharmacopeias (Ph.
Eur., USP). The accreditation is valid only for the scope list- 667 at the beginning of the article number identifies our
ed in the annex of the accreditation certificate D-K-18752- liquid filters. Liquid filters are liquid reference materials that
01-00. All measurement results can be traced back to NIST are manufactured in compliance with Pharmacopeias and/or
(photometric accuracy) or to PTB (Physikalisch-Technische NIST standards and inserted into quartz glass cuvettes un-
Bundesanstalt) (wavelength accuracy) standard reference der controlled conditions. The cuvettes are then permanently
materials (Photometric accuracy: NIST SRM® 930e, NIST sealed to become airtight. Liquid filters have the distinct ad-
SRM® 1930. Hellma 666S300; wavelength accuracy: Hellma vantage of equating to real measurement conditions. Hellma
667005). Analytics liquid filters are suitable for checking the following
parameters of your spectrophotometer:
O Wavelength accuracy
O Photometric accuracy (absorbance)
FOR YOUR INFORMATION O Photometric linearity in the UV range
O Stray light levels
The UV/Vis reference materials from Hellma
Analytics comply with the requirements stipulated by O Spectral resolution
quality management systems and Pharmacopeias,
meeting the highest quality requirements and ensur- You should regularly check your UV/Vis spectrophotometer
ing the international comparability of measurement for all of these parameters, especially photometric and waveresults.
length accuracy, while observing the relevant requirements
in your device handbook. Thanks to their ease of use and long
service life, Hellma Analytics reference materials provide an
excellent aid for all routine checks.
Choose between filter glass-based optical reference
materials, so called glass filters, and
liquid-based optical reference materials, so
called liquid filters:



8

 1. INTRODUCTION











HELLMA ANALYTICS REFERENCE MATERIALS IN ACCORDANCE
WITH THE MOST IMPORTANT REGULATIONS

MATERIAL CHECKING OF RANGE Ph. Eur. USP <857> ASTM
GLASS FILTERS
Holmium glass Wavelength accuracy UV/Vis × × ×
Didymium glass Wavelength accuracy UV/Vis × (×)
Neutral density
Photometric accuracy / linearity Vis
glass × × ×
LIQUID FILTERS
Holmium
Wavelength accuracy UV/Vis
(solution) × × ×
Rare Earth
Wavelength accuracy UV
(Cerium-solution) × ×
Didymium
Wavelength accuracy UV/Vis
(solution) × ×
Potassium dichro-
Photometric accuracy / linearity UV/Vis (×)
mate (solution) × ×
Nicotinic acid
Photometric accuracy / linearity UV
(Niacin-solution) × ×
Toluene in hexane
Spectral resolution UV
(solution) × ×
Potassium chloride
Stray light UV
(solution) × × ×
Potassium iodide
Stray light UV
(solution) × × ×
Sodium iodide
Stray light UV
(solution) × × ×
Sodium nitrite
Stray light UV
(solution) × × ×
Acetone
Stray light UV (×)
(high purity) × ×
(×) Not explicitly listed, but can be used according to the corresponding pharmacopoeia.
9

 1. INTRODUCTION




1.5 DAkkS calibration certificate* materials are only considered to be calibrated if they have
been issued with a DAkkS calibration certificate and bear a
After careful production, reference materials are measured calibration mark. Using the measurement values documentin
the Hellma Analytics calibration laboratory, which is ac- ed in the calibration certificate, users can check and calibrate
credited by DAkkS according to DIN EN ISO/IEC 17025, us- their spectrophotometers accordingly.
ing a high-performance UV-Vis/NIR spectrophotometer. The * Accredited calibration laboratory by DAkkS according to DIN EN ISO/IEC 17025.
accreditation is valid only for the scope listed in the annex The accreditation is valid only for the scope listed in the annex of the accreditation
certificate D-K-18752-01-00.
of the accreditation certificate D-K-18752-01-00. Reference




1


2 9
1 0
1 1

3


4

5
1 Reference to the accreditation*
2 Name and address of issuing
calibration laboratory
3 Description of calibrated item
4 Clear details of measured 6
calibration item
5 Customer
6 Date of calibration measurement
7 Internal document reference,
including date of issue and revision
status
8 Date of issue of calibration
certificate
9 Calibration certificate
serial number 8
10 Hellma registration number at 7
DAkkS*
11 Year and month of calibration
12
12 Approval by authorized person
10

 1. INTRODUCTION



IMPORTANT INFORMATION
18605
Only if the DAkkS calibration cer-
D-K- tificate* has been issued and the
18752-01-00 calibration mark has been affixed,
do the reference materials become
2023-11 traceable reference materials.
* Accredited calibration laboratory by DAkkS according to DIN EN ISO/IEC 17025.
The accreditation is valid only for the scope listed in the annex of the accreditation
certificate D-K-18752-01-00.





1

2



3


4



5

1 Description of calibrated item
2 Measurement method including
naming the reference
3 Measurement conditions
6 (device settings)
4 Type of device used to carry out
measurements
5 Type, serial number and validity
of calibrated NIST/PTB reference
standards used to regularly check
reference photometers; details of
additional checking methods
6 Ambient conditions during
measurement
11

 1. INTRODUCTION




1.5 DAkkS Calibration Certificate* 3 Notes on initial measurements of filters used to determine optical density.
Initial measurements are not taken for filters used to determine
wavelength accuracy.
1 Measurement value and smallest attributed measurement uncertainty
that can be specified. This value only refers to Hellma Analytics mea- 4 Calibration certificates shall not contain recommended recalibration
surements and applies solely to the company’s specific measurement intervals (according to DIN EN ISO/IEC 17025). Exceptions may be made
conditions. In justified cases, calibration certificates may also show if requested by the customer or required by legislation.
measurement results that do not fall within the calibration laboratory’s 5 Provision of the filters by the customer or by Hellma in the case of new
scope of accreditation*. These must be clearly labeled as such on the filters.
calibration certificate.
* Accredited calibration laboratory by DAkkS according to DIN EN ISO/IEC 17025. The accreditation
2 Notes on determining expanded measurement uncertainty. is valid only for the scope listed in the annex of the accreditation certificate D-K-18752-01-00.









1




2




3

5

4

1 Measured value and assigned
measurement uncertainty
2 Note on measurement uncertainty
3 Information
4 Recalibration interval
5 Providing the filters
12

 1. INTRODUCTION




1.6 Warranty – 30-year manufacturer’s warranty on all Hellma Analytics reference materials
We’re confident of our quality and you can be confident of Reference materials sent in for recalibration are carefully
reliable measurement results! All Hellma Analytics refer- cleaned and recalibrated before being sent back with a new
ence materials come with a 30-year warranty, provided that calibration certificate and calibration mark. Damaged filters
they are regularly recalibrated – at least every two years – at and filters that deviate significantly from nominal values are
the Hellma Analytics calibration laboratory. usually replaced in consultation with the customer.

Details of recalibration can
be found on pages 34 and 35.


All our reference materials come with a
30-year warranty, provided that they are
regularly recalibrated (at least every two
years) at the Hellma Analytics calibration
laboratory. 30

YEARS
WARRANTY





13

 2. GLASS FILTER
Wavelength Accuracy
2.1 Checking wavelength accuracy 2.1.1 Holmium glass filter
APPLICATION PRODUCT DESCRIPTION
To measure wavelength accuracy, the filter absorbs the light The holmium glass filter 666-F1 has a range of narrow,
beam of the spectrophotometer to a greater extent at cer- well-defined peaks in the UV and visible range, making holtain
wavelengths creating absorbance peaks. Ideally, any mium an excellent choice for checking the wavelength scale
reference materials used to determine wavelength accuracy of spectrophotometers. In comparison to filters that use
should have narrow, well-defined peaks at a variety of wave- holmium solution, the holmium glass filter has a somewhat
lengths in the UV and visible range. weaker spectrum with fewer peaks. In the low UV range in
particular, the absorbance behavior of the glass matrix is superimposed
on the holmium peaks. The main advantage of
using a glass filter over a liquid filter is that it is more robust.


NOTE
The positions of holmium peaks may vary slightly
depending on the glass batch used. This is why
Hellma Analytics measures each holmium glass
filter individually.
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of a holmium glass filter

ARTICLE NO. 666F1-339
APPLICATION Checking the wavelength accuracy in the UV and Vis range (270 nm to 640 nm)
CONTENT Holmium glass filter with metal frame
Wavelengths: 279, 361, 453, 536, 638 nm
STANDARD MEASUREMENT
Slit width: 1 nm
Wavelengths: 279; 287; 361; 418; 445; 453; 460; 536; 638 nm
POSSIBLE MEASUREMENTS
Slit width: 1-2 nm (0.1-0.9 nm only on request)
14

 2. GLASS FILTER




2.1.2 Didymium glass filter
PRODUCT DESCRIPTION
The didymium glass filter 666-F7W is made from material
NOTE
specially manufactured by Schott AG. Like holmium glass,
didymium glass has a variety of characteristic peaks in the The positions of didymium glass peaks may vary
ultraviolet and visible range and is therefore typically used for slightly depending on the glass batch used. This
checking wavelength accuracy. However, its peaks are not as is why Hellma Analytics measures each didymium
narrow as those of holmium glass filters. glass filter individually.
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of a didymium glass filter

ARTICLE NO. 666F7W-323
APPLICATION Checking the wavelength accuracy in the UV and Vis range (320 nm to 880 nm)
CONTENT Didymium glass filter with metal frame
Wavelengths: 329, 472, 512, 681, 875 nm
STANDARD MEASUREMENT
Slit width: 1 nm
Wavelengths with 1 nm slit width: 329; 430; 472; 482; 512; 681; 875 nm
POSSIBLE MEASUREMENTS
Wavelengths with 2 nm slit width: 430; 472; 482; 512; 875 nm
15

 2. GLASS FILTER

Photometric Accuracy
2.2 Checking the photometric accuracy 2.2.1 Neutral density glass filter
APPLICATION PRODUCT DESCRIPTION
To measure photometric accuracy (absorbance), the filter Hellma Analytics neutral density glass filters are made from
reduces the light beam from the spectrophotometer. An ab- filter materials produced by Schott AG, which are selected on
sorbance value (Abs) can be deduced from the light extinction account of their homogeneity and stability. Thanks to a relacaused
by the filter. tively constant transmittance within the wavelength range of
405 nm to 890 nm, they have been used to check photometric
accuracy and linearity in the visible wavelength range (over
405 nm) for decades. Please note, the thickness of the filter is
set at the manufacturing so that the specified nominal optical
NOTE density (values from 0.04 to 3.0 Abs) is obtained at 546.1 nm.
If you have several neutral density glass filters with This results in slightly increasing absorbances at shorter
different nominal absorbances, you can check the wavelengths.
linearity of your absorbance scale by plotting the
absorbance values measured for each wavelength
against the measurement values on the calibration
certificate in a diagram.

) )
) )
) )
) )
) )
) )
) )
) )
) )
) )
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of a neutral glass filter with a slit width of 1 nm

666F390-25, 666F2-39, 666F201-39, 666F3-38, 666F204-37, 666F4-37, 666F202-36, 666F203-36,
ARTICLE NO.
666F301-361, 666F303-361
APPLICATION Checking the photometric accuracy in the Vis range (405 – 890 nm)
Neutral density glass filters:
CONTENT F390 (0.04 Abs); F2 (0.25 Abs); F201 (0.3 Abs); F3 (0.5 Abs); F204 (0.7 Abs); F4 (1.0 Abs); F202 (1.5 Abs);
F203 (2.0 Abs); F301 (2.5 Abs); F303 (3.0 Abs)
Wavelengths: 440, 465, 546.1, 590, 635 nm
STANDARD MEASUREMENT
Slit width: 1 nm
All wavelengths from 405 to 890 nm possible.
Over 890 nm is also possible with Hellma Analytics calibration certificate (since the accredited* range ends
POSSIBLE MEASUREMENTS
at 890 nm).
Slit widths: all up to 5 nm
* Accredited calibration laboratory by DAkkS according to DIN EN ISO/IEC 17025.The accreditation is valid only for the scope listed in the annex of the accreditation certificate D-K-18752-01-00
16

 2. GLASS FILTER

Sets
2.3 Glass filter sets
Specifically created to meet customer requirements, Hellma
Analytics glass filter sets consist of existing individual filters
suitable for standard or custom validation procedures.
To ensure that filters can be easily identified, the set number is
engraved on each filter frame. The absorbance/peak position
values measured for each filter can be found on the calibration
certificate provided



Handling instructions for glass
filters can be found on the pages
46 to 51.






FILTER-SET CONTENT WAVELENGTH nm ARTICLE NO.
Glass filter sets for checking photometric accuracy, photometric linearity and wavelength accuracy
Glass filter set: F0, F1, F2, F3, F4 A: 440; 465; 546.1; 590; 635
666-S000 666S000
(Abs: 0.25, 0.5, 1.0) W: 279; 361; 453; 536; 638
Glass filter set: F2, F3, F4
666-S002 A: 440; 465; 546.1; 590; 635 666S002
(Abs: 0.25, 0.5, 1.0)
Glass filter set: F0, F201, F202, F203
666-S004 A: 440; 465; 546.1; 590; 635 666S004
(Abs: 0.3, 1.5, 2.0)
Glass filter set: F0, F1, F3, F4 A: 440; 465; 546.1; 590; 635
666-S005 666S005
(Abs: 0.5, 1.0) W: 279; 361; 453; 536; 638
Glass filter set: F0, F2, F3, F4
666-S006 A: 440; 465; 546.1; 590; 635 666S006
(Abs: 0.25, 0.5, 1.0)
Glass filter set: F1, F390, F2, F3, F4 A: 440; 465; 546.1; 590, 635
666-S010 666S010
(Abs: 0.04, 0.25, 0.5, 1.0) W: 279; 361: 453; 536; 638
Glass filter set: F2, F4, F203
666-S200 A: 440; 465; 546.1; 590; 635 666S200
(Abs: 0.25, 1.0, 2.0)
Glass filter set: F390, F301, F303
666-S300 A: 440; 465; 546.1; 590; 635 666S300
(Abs: 0.04, 2.5, 3.0)
17

 3. LIQUID FILTERS
Wavelength Accuracy
3.1 Checking wavelength accuracy 3.1.1 Holmium liquid filter
APPLICATION PRODUCT DESCRIPTION
To measure wavelength accuracy, the filter reduces the light The holmium liquid filter consists of a solution of holmium
beam of the spectrophotometer to a greater extent at certain oxide dissolved in perchloric acid. This filter is ideally suited
wavelengths (peaks). Ideally, any standards used to deter- to checking the wavelength accuracy of spectrophotometers
mine wavelength accuracy should have narrow, well-defined in the UV and visible range. It has a spectrum with a variety of
peaks at a variety of wavelengths in the UV and visible range. characteristic, very well-defined peaks in the range between
240 nm and 650 nm. This filter is recommended in both the
Ph. Eur. and USP for checking wavelength accuracy in the
240 – 650 nm range.
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of holmium oxide dissolved in perchloric acid at a slit width of 1 nm

ARTICLE NO. 667005
APPLICATION Checking the wavelength accuracy according to Ph. Eur. in the UV and Vis range
CONTENT Holmium oxide in perchloric acid
Wavelengths: 241, 287, 361, 451, 485, 536, 640 nm
STANDARD MEASUREMENT
Slit width: 1 nm
Wavelengths: 241, 250, 278, 287, 333, 345, 361, 386, 416, 451, 468, 485, 536, 640 nm
POSSIBLE MEASUREMENTS
Slit width: 1-2 nm (0.1- 0.9 nm only on request), above peaks become indistinct

ARTICLE NO. 667005USP
APPLICATION Checking the wavelength accuracy according to USP <857> in the UV and Vis range
CONTENT Holmium oxide in perchloric acid
Wavelengths: 241, 250, 278, 287, 333, 345, 361, 386, 416, 451, 468, 485, 536, 640 nm
STANDARD MEASUREMENT
Slit width: 1 nm
POSSIBLE MEASUREMENTS Slit width: 1-2 nm

18

 3. LIQUID FILTERS




3.1.2 Didymium liquid filter
NOTE ON WAVELENGTH MEASUREMENT
ACCORDING TO Ph. Eur. PRODUCT DESCRIPTION
The didymium liquid filter consists of praseodymium and
The Ph. Eur. requires that all measurements be neodymium, dissolved in perchloric acid. This filter is ideally
measured against the corresponding solvent as a ref- suited for checking the wavelength accuracy of spectrophoerence
for background correction. This means that to
tometers in the UV and visible range. It has a spectrum with a
check the wavelength accuracy using holmium oxide
variety of characteristic, very well-defined peaks in the range
in perchloric acid (UV5), perchloric acid (UV14), the
between 320 nm and 870 nm. This filter is recommended in
corresponding solvent, must be used as a reference.
both Ph. Eur. and USP <857> for checking wavelength accuracy
above 640 nm.
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of didymium dissolved in perchloric acid at a slit width of 1 nm

ARTICLE NO. 667025
APPLICATION Checking the wavelength accuracy in the UV and Vis range
CONTENT Didymium in perchloric acid
Wavelengths: 329, 469, 575, 740, 864 nm
STANDARD MEASUREMENT
Slit width: 1 nm
Wavelengths: 329, 354, 444, 469, 482, 512, 522, 575, 732, 740, 794, 801, 864 nm
POSSIBLE MEASUREMENTS
Slit width: 1-2 nm (0.1- 0.9 nm only on request), above peaks become indistinct

ARTICLE NO. 667025EPUSP
APPLICATION Checking the wavelength accuracy according to Ph. Eur. and USP <857>
CONTENT Didymium in perchloric acid
Wavelengths: 512, 732, 740, 794, 801, 864 nm
STANDARD MEASUREMENT
Slit width: 1 nm
POSSIBLE MEASUREMENTS Slit width: 1-2 nm

19

 3. LIQUID FILTERS

Wavelength Accuracy
3.1.3 HoDi liquid filter
PRODUCT DESCRIPTION
Checking the UV-Vis wavelength accuracy
The HoDi liquid filter consists of a solution of holmium oxide
and didymium (praseodymium and neodymium) in perchlo- Broad wavelength spectrum from 240 – 870 nm
ric acid. This filter features an especially broad wavelength
spectrum and is therefore ideally suited to checking the Two filters in one: Holmium + Didymium = HoDi
wavelength accuracy of spectrophotometers in the UV and
visible range. It has a broad spectrum with a variety of characteristic
, very well-defined peaks in the range between 241
nm and 864 nm. Depending on the performance of the spectrophotometer
used, up to 22 peaks can be detected at a slit
width of 1 nm.
$EVRUEDQFH
:DYHOHQJWK QP
Typical spectrum of HoDi filter measured at a slit width of 1 nm

ARTICLE NO. 667045
APPLICATION Checking the wavelength accuracy in the UV and Vis range
CONTENT Holmium oxide and didymium in perchloric acid
Wavelengths: 241, 354, 444, 575, 641, 740, 864 nm
STANDARD MEASUREMENT
Slit width: 1 nm
Wavelengths: 241, 278, 287, 333, 347, 354, 361, 416, 444, 451, 468, 482, 512, 522, 537,
POSSIBLE MEASUREMENTS 575, 641, 732, 740, 794, 801, 864 nm
Slit width: 1 nm (0.1-2 nm only on request)

ARTICLE NO. 667045EPUSP
APPLICATION Checking the wavelength accuracy according to Ph. Eur. and USP <857>
CONTENT Holmium oxide and didymium in perchloric acid
Wavelengths: 241, 287, 361, 451, 482, 512, 537, 641, 732, 740, 794, 801, 864 nm
STANDARD MEASUREMENT
Slit width: 1 nm
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 3. LIQUID FILTERS




3.1.4 Rare Earth (cerium) liquid filter
PRODUCT DESCRIPTION
The rare earth liquid filter consists of cerium dissolved in per- Specially developed for checking wavelength
accuracy in the low UV range
chloric acid. This filter is ideally suited for checking the wavelength
accuracy of spectrophotometers in the low UV range. Wavelength spectrum from 200 – 260 nm
It has a spectrum with five characteristic peaks in the range
from 200 nm to 260 nm. This filter is recommended in both
Ph. Eur. and USP <857> for checking wavelength accuracy in
the 200 – 260 nm range.
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Typical spectrum of a rare earth filter measured at a slit width of 1 nm

ARTICLE NO. 667035
APPLICATION Checking the wavelength accuracy in the low UV range according to Ph. Eur. and USP <857>
CONTENT Cerium in perchloric acid
Wavelengths: 201, 211, 222, 239, 252 nm
STANDARD MEASUREMENT
Slit width: 1 nm
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 3. LIQUID FILTERS

Photometric Accuracy
3.2 Checking the photometric accuracy 3.2.1 Potassium dichromate liquid filter for