Partial modulation via pulsed flow modulator for comprehensive two-dimensional liquid or gas chromatography with multiple modulation periods
This invention is a method and device for use with multi-dimensional chromatography that utilizes partial modulation with multiple secondary retention times. An analyte-bearing sample is subjected to a first dimension of chromatography. Thereafter the separated analyte-bearing sample is diluted with a modulated second carrier such at the analyte-bearing sample is not stopped or its temperature altered. The secondary retention time period at which the modulator cycles is variable among multiple secondary retention time periods to prevent loss of resolution with less complex and/or low boiling point compounds and to prevent loss of data with more complex and/or higher boiling point compounds. The partially modulated analyte-bearing sample then feeds into a secondary column where the analyte-bearing sample is further separated.
1. A method of chromatographically separating a sample, said sample containing an analyte, said sample being in a first carrier, comprising:
separating said sample in a primary column;
modulating a second carrier continuously to cycle for a first period at a first fixed rate of time among a primary flow rate and a secondary flow rate and to cycle for a second period at a second fixed rate of time among said primary flow rate and said secondary flow rate, said second carrier primary flow rate and second carrier secondary flow rate being unequal;
continuously introducing said modulated second carrier to said separated sample-bearing first carrier, thereby partially modulating said separated sample-bearing first carrier; and
further separating said partially modulated separated sample-bearing first carrier in a secondary column.
2. The method of claim 1 , in which said partial modulation comprises:
positive pulse mode, wherein said primary flow rate of said second carrier is provided for a longer period of time than said secondary flow rate of said second carrier.
3. The method of claim 1 , in which said partial modulation comprises:
negative pulse mode, wherein said primary flow rate of said second carrier is provided for a shorter period of time than said secondary flow rate of said second carrier.
4. The method of claim 1 , wherein said primary flow rate of said second carrier is sufficient to prevent upstream commingling of said second carrier with said sample-bearing first carrier.
5. A method for chromatographically separating components of a sample, said sample containing an analyte, said sample being in a first carrier, comprising:
injecting said sample-bearing first carrier into a primary column, such that the sample-bearing first carrier migrates through said primary column;
said sample bearing first carrier at least partially separated in said first column;
said at least partially-separated sample transmitted to a three-way connector first entrance port;
providing a primary flow rate of a second carrier through a second entrance port of said three-way connector sufficient to prevent upstream commingling of said second carrier with said sample-bearing first carrier;
providing a secondary flow rate of said second carrier through said three-way connector second entrance port sufficient to distinguishably dilute said separated sample-bearing first carrier;
modulating said second carrier continuously to cycle for a first period at a first fixed rate of time among a primary flow rate and a secondary flow rate and to cycle for a second period at a second fixed rate of time among said primary flow rate and said secondary flow rate, said second carrier primary flow rate and second carrier secondary flow rate being unequal;
continuously introducing said modulated second carrier to said separated sample-bearing first carrier, producing a partially modulated sample-bearing first carrier with each modulation of said second carrier; and
feeding said partially modulated sample-bearing first carrier through an exit port of said three-way connector into a secondary column, wherein said sample undergoes further separation.
6. The method of claim 5 , in which said partial modulation comprises:
positive pulse mode, wherein said primary flow rate of said second carrier is provided for a longer period of time than said secondary flow rate of said second carrier.
7. The method of claim 5 , in which said partial modulation comprises:
negative pulse mode, wherein said primary flow rate of said second carrier is provided for a shorter period of time than said secondary flow rate of said second carrier.