Dedicated Quench-flow instrument

Four-syringe microvolume quench-flow - QFM-400

• Down to 10 µl per data point for each reactant
• An entire kinetics from millisecond to seconds use only a few 100 µL of reactants.

This instrument is based on the SFM-400 hardware.

It uses a microvolume mounting on the top of the body of the SFM-400.

It uses modified software to take advantage of the special abilities of the MPS-60 controller.

A QFM-400 instrument can be purchased as such (quench-flow only) and modified later to give a SFM-400/S instrument (stopped-flow). The reverse is also true.

Performances

The QFM-400 instrument is designed to exploit the outstanding microvolume specification and extreme precision of the drive by the MPS-60.

In optimal conditions, this instrument allows quench-flow reactions to be measured with minimal volumes of a 10 µL per shot for the reacting solutions, using minimal total quantities of a few tens of microliters for each of the reacting solutions.

The aging times that can be obtained range from a few milliseconds to many seconds (in continuous, interrupted or the new pulsed flow mode) with only one aging line

Description

Schematic diagram of the QFM-400

The QFM-400 instrument consists of two reagent syringes (S1 and S2), one syringe used for (optional) delay line washing (S3) and one syringe for the quench solution (S4).

Standard volume of the syringes is 1.9 mL.

Four independently programmable motors (M1 - M4) are used to actuate S1, S2, S3, and S4.

Motor drive rates are independent, so variable mixing ratios can be obtained by simply programming the drive sequence.

The S3 syringe may or may not be used (depending on the operational mode).

S1 and S2 are set with two-position dual-dual flow valves (V1 & V2) permitting syringe filling and storage line purge or filling.

Flow lines are easily replaceable PEEK or TEFZEL tubing whose length and diameters may be adapted to the operational mode and aging time.

The lines L1 and L2 may be used as solution micro-reservoirs for expensive solutions (L1 and L2 volumes may be varied from a few 10 µL to 200 µL).

S1 + S2 mixture is allowed to age in the delay line, DL. Volume of the delay line is fixed, but can be changed by easily replacing the DL. Its volume can be as low as a few µL.

Aging in DL can be set by varying the mean flow rate of S1 + S2

S1 and S2 flow rate can be adjusted from 0.001 mL/s to 5 mL/s (depending on motor programming and syringe size). The maximum flow rate obtainable is also dependent on flow line diameters.

Reaction product is mixed with the quenching solution in the mixer M2.

Final mixture is accumulated in the exit line EL.

Collection of the reaction product out of EL is made by purging its content through the exit purge port.

Principle of operation

The operational modes described here are just a few examples among the possible uses.

1. Classical quench-flow mode
   • This mode is the simplest to use and will be the preferred mode when 200 µL to 1 mL of the S1 and S2 solutions are available.
   • This uses only S1, S2 and S4
   • The reactants are set in S1 and S2
   • Aging is obtained in continuous-flow, in interrupted flow, or in pulsed flow mode.
   • The solutions in S1 and S2 are used for washing old (or aged) solution solution out of the delay line.
   • Due to the small volumes of mixer, flow lines and delay line, a QFM-400 operating in this mode will require significantly less volume than SFM-400/Q or SFM-300/Q.
2. Volume optimized quench-flow mode
   • The principle is to fill S1 and S2 with inexpensive buffer and use flow lines L1 and L2 as reagents accumulators.
   • The reagents are introduced via the 3-way valves V1 and V2. During the shots, these solutions are then pushed through the mixer and delay line by the buffer contained in S1 and S2.
   • The sample economy is further improved by using S3 filled to push the aged mixture out of the delay line at the end of the driving sequence.

In all modes S3 can be used to push the aged mixture out of the delay line at the end of the driving sequence and thus allows collection of all the reactants used. It can also be used to wash the delay line before the actual shot and S1 + S2 mixing.

Collection of the final mixture

The QFM-400 does not have an exit electrovalve. This is another source of sample economy.

After the last mixer, the final solution is accumulated downstream of the last mixer in an exit line (EL) whose length and diameter may modified.

At low total flow rates, this line may be used for temporary storage of the final solution, provided its volume is larger than the total volume to be collected.

At the end of the flow, the line contents are collected in a tube (e.g. an Eppendorf tube) by flushing air manually through the line vial the purge port.

Final mixture is accumulated in the exit line EL. It is collected by purging the line manually through the Exit Purge Port without any dead volume after the last mixer.

TOP