LWCC-M-10
MicroLWCC (WPI #
LWCC-M-10
) is a new fiber optic, low volume flow cell for UV/
VIS/NIR absorbance analysis.
Based on WPI’s established
liquid core waveguide tech-
nology, the analyte solution
functions as the core of a fluid
filled light waveguide. Wetted
parts in the sample cell light
path are PEEK, fused silica and
Teflon. Optical fibers are used
to transport light to and from
the sample cell. The cell can be
used in biochemistry for DNA,
RNA and protein quantification,
colorimetric nutrient and trace
metal analysis, drug discovery
and dissolution testing, process
control and HPLC analysis.
ASSeMbLy
Light source and detector can be connected to the
LWCC-M-10
via two SMA-termi-
nated fiber optic cables with a core diameter of 600µm. The fiber optic connections
are interchangeable in that either connector can be used to connect to the light
source or to the spectrometer.
As with the fiber optic connectors, the liquid ports are also interchangeable. It makes
no difference which port is set-up as inflow and which port serves as the outflow.
However, if an in-line filter is to be installed, it should be connected on the input side
of the liquid flow path. Use standard HPLC type 10-32 coned PEEK 1/16
th
tubing fit-
tings (WPI #
800827
) to make connections to the pump and waste receptacle.
OpeRATINg INSTRUCTIONS
The following procedures can be used to verify the transmission, noise and refractive
index of your
LWCC-M
.
Transmission Verification
1. Connect one 600
m
m diameter fiber optic assembly to a light source and one
600
m
m diameter fiber optic assembly to the detector.
2. Use an SMA bulkhead adapter (WPI #
13395
) to butt-couple the fibers. This is the
reference for the measurement of transmission.
3. Remove the SMA bulkhead adapter and insert the
LWCC-M
.
4. Record the percent transmission. Values for the 254nm, 280nm and 550nm
should exceed 40%.
Noise Determination
Noise is determined using the ASTME685-93 standard as reapproved in 2000. Use
methanol as the solvent at a flow rate of 1.0mL/min. Using the WPI test setup, noise
values are below 35uAU. See www.astm.org/Standards/E685.htm to obtain a copy of
the standards document.
Refractive Index
The refractive index between methanol and cyclohexane is measured using a flow
rate of 3.0mL/min. Because of the immiscibility of the solvents, ethanol is used be-
tween the solvents to prevent unwanted interaction between methanol and clyclohex-
ane. An RI value between zero and seven is acceptable at the 280nm wavelength.
MAINTeNANCe
Cleaning
With normal use, the
LWCC-M-10
will rarely need cleaning. If measurement results
diminish, clean your
LWCC-M-10
. Use the cleaning kit for liquid waveguides (WPI
#
501609
).
1. Connect the exit tubing (for example, silicon or equivalent) from the fluid output
of the
LWCC-M-10
to a waste container.
2. Rinse the cell thoroughly using Ultra Pure water. Obtain a new reference intensity
and take a baseline absorbance reading.
3. Inject 1cc “Cleaning Solution 1” into the
LWCC-M-10
fluid input port.
4. Inject 1cc “Methanol Solution 2” into the fluid input port of the
LWCC-M-10
.
5. Inject 1cc “HCl Solution 3” into the fluid input port of the
LWCC-M-10
.
6. Flush out the cleaning solutions with distilled, Ultra Pure, reverse osmosis or
equivalent quality water and take an absorbance reading.
7. Repeat these cleaning cycles until a stable absorbance signal can be obtained.
8. If the UV readings are still low after cleaning, swab the fiber optic surfaces of the
sample cell with a fiber optic Q-tip dipped in isopropyl alcohol.
Storage
To store the instrument, clean the
LWCC-M-10
, and then seal the fluid input and
output ports using either the caps provided or an alternative.
SpeCIfICATIONS
LWCC-M-10
Optical pathlength
10mm
Internal volume
2.4
m
L
Wavelength Range
200–1000nm
Fiber Connection
(SMA) 600µm
Transmission at 254nm*
> 40%
Liquid Connection
10-32 coned port for 1/16
th
tubing
Maximum Pressure
1000 PSI
Refractive Index at 280nm**
< 7 mAU
Wetted materials
PEEK, Fused Silica, Teflon
* Reference: Two 600µm fibers, butt-coupled
** Measured using ASTM E 685 - 93
WPI U.S. Patents: 5,444,807; 5,570,447; 5,604,587; 6,603,556; 6,385,380.
Light Input
600
µ
m S
MA
Light Output
600
µ
m S
MA
Fluid Input
800827 Connector
Fluid Output
800827 Connector
1.00"
1.3
8”
Fig. 1–LWCC-M-10 showing connections.
