I-5
Matec Applied Sciences
56 Hudson St., Northborough, MA 01532 Ph: (508) 393-0155 Fax: (508) 393-5476
www.matec.com
e-mail: [email protected]
This peak is likely due to non-ionic surfactant. Non-ionic surfactants can continuously adsorb and desorb
from the capillary wall as they travel down the fractionation capillary. This adsorption/desorption
retards the non-ionic surfactant from exiting the capillary.
16.
Can the marker be blended with the sample so that only one injection is made per sample?
Yes, in manual operation only. Simply add maker fluid to your samples, and make only the sample
injection (do not inject the marker).
17.
How long should the instrument be allowed to equilibrate (or warm up) at the beginning of the day
before starting sample analysis?
Approximately 30 to 45 minutes.
18.
Can the CHDF be turned off at the end of the day, or should it be left running overnight?
The CHDF can be operated in either mode. We prefer to turn it off at the end of the day.
19.
How much sample, and marker, should be Loaded into the injection valve?
100 microliters for manual operation. It is recommended that at least 400 microliters be drawn into the
syringe in order to minimize the chances of loading air bubbles into the injection valve. If using a
syringe filter make sure the filter is filled with sample before loading sample into the injection valve.
80-90 microliters is recommended for auto-sampler operation. This is set under System/Configure
Auto-Sampler.
20.
Are samples loaded directly into the fractionation capillary?
No. They are loaded into a sample loop (a piece of stainless steel tubing) which is connected to a vent. As
sample is pushed into the injection valve, the sample loop becomes filled with sample. Sample exits
from the sample loop vent as more sample is loaded. The sample loop becomes connected to the
pump, and the fractionation capillary upon switching to Inject.
21.
Can the CHDF software be run under Windows9X, NT, and 2000?
Yes, the CHDF2000 software can be run on any Windows operating system software.
22.
What solids concentration should be used for calibration standards?
Calibration standards should not be overly concentrated. Solids concentrations should be such that Raw
Data peak heights are 10 to 30 mAU’s for calibration standards and 20-60 for regular samples.
Calibration standards larger than 300 nm should be sonicated prior to use in order to break up
aggregates.
23.
How frequently should the CHDF capillary be calibrated?
Calibration shifts are related mainly to two factors: (i) changes in GR500 eluant composition; and (ii)
changes in ambient temperature (not important for the CHDF-2000). It is recommended that the
conductivity of the GR500 eluant be monitored; replace the eluant if the conductivity is outside its
normal range. Calibration standards can be run prior to regular sample analysis in order to confirm
calibration accuracy. These “control” standards may be added to the calibration curve if re-calibration
is deemed necessary.
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