Spectral Sensors by Carl Zeiss

AddiMet TM
On-line Polymer and Additives Analysis

INTRODUCTION
AddiMet™ is a complete and flexible approach tothe on-line analysis of polymers and additives.
It is modular in design allowing the system to be
optimally configured for the application. UV options
provide the high sensitivity for the measurement of
low level antioxidants e.g. Irganox, Irgafos andBHT (this cannot be done in the NIR). The NIR
option allows the determination of bulk compositionand prediction of physical properties of the polymer
matrix. Several of these options can be costeffectively combined into a single system.

Reference Channel
Carl Zeiss Spectrometer

Optical FiberMCS 551 UV Spectrometer

Optical Probe

THE ANALYSER
The System consist of a Carl Zeiss MCS 500
photodiode array UV/visible spectrophotometer whichis interfaced to the process via optical probes andoptical fibers. A PC running a dedicated software
package written in LabVIEW  controls thespectrophotometer. Charm Works Partial Least
Squares (PLS) tools are embedded in this applicationin order to predict the additive concentrations. The MCS
500 Carl Zeiss modular spectrometer is the heart of
the analyser system. The unique design of thespectrometer ensures reliable measurements in theharshest industrial environments. The analysis is madedirectly in the process stream (melt) using opticalprobes. These operate at up to 10,000 psi (660 bar)and over 250° C and can be installed within a processrheometer or a flow cell. A fiber optic connection
between the probes and the spectrometer enhances
the flexibility of the system.
THE BENEFITS♦ Analysis time greatly reduced♦ Tighter control of blending process is achieved♦ Reduced wastage♦ Customised installation

Application Note 10 / 00

Extruder or Flow Cell
Dicon Multiplexer

Figure 1: On-line analyser

Vankel 7000 with Auto Temp

Hellma Ultra-Mini Probes

Figure 2:

MCS 500 series

Spectral Sensors by Carl Zeiss
THE SYSTEM
ProbesMaximum operating temperature
Operating pressure
Optical fiber
Spectrophotometer
Computer
Digital interface

THE SOFTWARE

Polymer Melt Probes mounted in a melt measurement
platform (Rheometric Scientific).
250°C
in excess of 10,000 psi.
600 µm silica core
Carl Zeiss MCS UV seriesat least a Pentium 166 MHz PC with 24 Mbytes ofRAM running Window NTthe computer is equipped with a National Instrumentsinterface card, enabling the performance of thesystem to be monitored by the process control
system and to generate local alarms.

AddiMetTM software controls the spectrometer, analyses
the data and communicates with process control system(all industrial communication protocols supported).
AddiMetTM uses the PLS (Partial Least Squares)
algorithm to predict in real time the concentrations ofantioxidants (simultaneous multicomponent analysis) or
the physical properties of the polymer.
The PLS calibration set is obtained from liquid
chromatographic analysis on samples removed from theextruder. About 30 samples, evenly covering theconcentration range, are required. The exact number ofsamples depends on the number of additives to be analysed
and the quality of the reference analytical data. The model
can be upgraded and optimised by adding new training
samples at anytime.The use of PLS enables simultaneouson-line analysis of multiple additives. Thus further reducing
analysis time.The composition of the polyethylene melt is
inferred in real time rather than waiting several hours for offline chromatographic analysis. The measurement periodis typically 10 seconds. The software on the associated
PC processes the spectra on demand and passes theadditive concentrations to the process control system.

AddiMet™ software is licenced exclusively to Carl Zeissby Process Analysis and Automation LtdCarl Zeiss
Spektralsensorik

D-07740 Jena
Phone:++49 (03641)64 2838
Fax:++49 (03641)64 2485
E-Mail:info.spektralsensorik@zeiss.de
Internet:
http:// www.zeiss.de/spectral

Spectral Sensors by Carl Zeiss

In-line Analysis of the concentration offlavoured mineral waters
INTRODUCTION

For a few years now mineral waters have been flavoured
with additives in order to modify the taste.
These additives, the likes of ”Lemon” for Mineral
Waters, are dissolved in alcohol and are added to themineral water in strongly diluted form (approx. 1:1000).
The desired concentration is determined by subjective”tasting” and then released to the filling facilities. An
evaluation of samples taken before and during the filling
process can provide objective measures of theconcentration of the additives in the final product.
Chemical tests on production samples represented
another approach to the problem.
In-line monitoring of the current concentration of theadditives in the production stream by means ofimmersion probes or flow-though cells provides thepossibility of direct process control. Thus it is possible
to increase the continuity of the concentration in the final Figure 1: In-line monitoringproducts.

THE METHOD
The concentrated flavour additives dissolved in alcohol
generate typical absorbance in the UV spectral range.
The example shows a real sample (mineral water‘lemon’) and a dilution series of this sample. (Figure 2)
A tolerance window is specified to enable the processcontrol adjustment of the added concentration.

Figure 2: Sample

Application Note 2 /99

Spectral Sensors by Carl Zeiss

THE SYSTEM
The diode-array spectrometer system MCS551UV based on the established Zeiss MCS polychromator technology
provides spectral information in the UV range with a resolution of 0.8 nm / pixel.
The system is controlled by a PC, different interface types (RS422, 4-20 mA loops or trigger I/O ports) can be applied.
Systems can be cascaded and controlled via one host PC to take measurements in different streams.
THE SOFTWAREThe DM1 software (LabView generated) runs under Windows NT. The process monitoring programme provides a results
display of up to 4 measuring channels. The concentration of the additives in the stream can be displayed as digital
readouts of the current values and/or in form of trend charts. Storage of the results and data transfer via an analog
output are possible.
Digitally controlled devices like e.g. valves or shutters used to switch product or reference streams can be included inthe automated signal processing.

THE BENEFITS♦ Fast and continuous measurement♦ Short analysis and response time
♦ Established and proved system and method♦ High reliability, low maintenance♦ Easy to use software♦ Detailed spectral information available at high speed♦ Fibre optics allow flexibility in installation and location of the system

SYSTEM SPECIFICATIONS
Wavelength range
Wavelength resolution
Wavelength reproducibility
PC interface
Distance between PC and system
Analog output (4-20 mA)
Optical fibres
Housing

Carl Zeiss
Spectral Sensors

200-620 nm (optional 190-1020nm and/or 900-1700 nm)
0.8 nm/diode (2.4 nm Rayleigh)< 0.005 nm
RS 422up to 80m with standard cable
up to 2500m with waveguide transmission
4 channels (standard)quartz, 600 µm core, SMA connector
Max. distance 10 m
19” rack19” protective housing

D-07740 Jena
Telefon:(03641)64 33 85
Telefax:(03641)64 33 11
E-Mail:info.spektralsensorik@zeiss.de
Internet:
http:\\www.zeiss.de