Ocean Optics LPC-500CM - Manual (Page 21)

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Chapter 4
Maintenance
Overview
Thorough and consistent cleaning routines are essential for maintaining the instrument and ensuring
optimal operation.
Tips to Avoid Contamination
The following information about contamination has been collected during the development and testing of
the LWCC:
 Most syringe filters contain some contaminants that absorb UV (probably the plastic mold release
agent). The first few milliliters of solution coming from a new filter will have some absorption in
the UV range due to the mold release agent.
 The first two loads of solution from most new plastic syringes often have some contamination
that absorbs UV. In addition, when plastic syringes are used to transfer organic solvents, the
rubbery gasket material in the plunger absorbs some of the chemical. If the syringe is later used to
transfer aqueous solution, the chemical will slowly leach out. Since most organic solvents have an
absorbance in the UV range, the liquid initially released from the syringe might be found to have
a different spectrum than the last of the liquid in the syringe, the latter having been contaminated
by the chemical in the plunger. Some commonly used organic solvents with relatively low UV
absorption that are suitable for UV detection in conventional spectrometers might not be
problem-free when used in the LWCC.
 A beaker of freshly filtered water sitting overnight in open air will probably have an increased
absorbance in the UV range because of dust from the air or growth of microorganisms.
 Some plastic tubing release a substance that absorbs UV. In lab tests, silicone tubing used in a
peristaltic pump constantly released a contaminant even after a week of washing.
 A bubble in the LWCC will result in unstable readings. Additional liquid circulating through the
device will usually push the bubble out. If the bubble doesn’t clear easily, try introducing a larger
bubble followed by liquid. This will usually pick up a small bubble that may cling and cause
problems.