How is the carryover test calculated for the SystemsQT project for the Alliance 2695? - WKB91577

ENVIRONMENT

• Alliance HPLC System
• 2695 Separations Module
• Waters SystemsQT

ANSWER

The injector carryover test determines the presence of sample carryover from one injection to the next. Two (2) pre-blank injections are performed to determine whether the system is clean enough to measure injector carryover. These injections are followed by three (3) caffeine calibration injections at a concentration of 0.4 μg/mL with an injection volume of 10.0 μL, which corresponds to 0.01% of the challenge injection. The challenge injection is made at a concentration of 4.0 mg/mL with an injection volume of 10.0 μL, followed by three (3) post-blank injections. The test passes if the % injector carryover is
< or = 0.01%, or the peak is missing for PostBlank1.

ADDITIONAL INFORMATION

This same test methodology is applied to nearly all Waters qualification products across Empower, MassLynx, UNIFI, and waters_connect and all LC and LCMS product lines. While the concentrations, injection volumes, and specs vary, the same process applies. The prechallenge standard injections are used to create a calibration upon which the postchallenge blanks are quantitated. Its important to understand that the challenge injection is not used in the calculation. The high concentration of the challenge injections makes it above the linear dynamic range of the detector, meaning its area cannot be accurately quantitated. So the spec is only calculated based upon the prechallenge standard areas.