Waters ACQUITY UPC2, Overview And Maintenance Manual, Page: 78 / 84

74
Solvent considerations
In general, molecular spectra are sensitive to the solvent in which the
compounds are dissolved. The lambda max values for the same solute
dissolved in water, methanol, or liquid CO
2
can differ by as much as 5 to 10
nm. Each observed value is correct, as it reflects the interaction of the solute
with its solvent. Similar effects are observed in aqueous solution when either
ionic strength or pH is changed.
Noise (wet) <10 μ AU (254 nm, 2 Hz, 1 sec TC, 3.6 BW res,
10 mm analytical flow cell, flow rate 0.5 mL/min,
90:10 H2O:ACN
Important:
If you will be using the PDA detector in
an ACQUITY UPC
2
system (using CO
2
) where
water was used previously, purge all water from
the system before converting to CO
2
.
Optical resolution 1.2 nm (nominal), with 50- μ m slit
Order filter Fixed, 370 nm to 800 nm
Photodetector 512 element selective access photodiode array
Wavelength accuracy ±1.0 nm (tested with Erbium Perchlorate)
Wavelength calibration
filter
Erbium filter, used at startup or on-demand
Wavelength range 190 to 800 nm
Wavelength
repeatability
±0.1 nm
a. ASTM drift tests require a temperature change of less than 2 °C/hour (3.6 °F/hour) over a one
hour period. Larger ambient changes will result in larger drift. Better drift performance
depends on better control of temperature fluctuations. To realize the highest performance,
minimize the frequency and the amplitude of temperature changes to below 1 °C/hour
(1.8 °F/hour). Turbulences around one minute or less can be ignored.
Warning:
To avoid chemical hazards, always observe Good Laboratory
Practices when operating your system, handling solvents, or changing
tubing. See the Material Safety Data Sheets for the solvents you use.
Performance specifications: (Continued)
Item Specification