Injecting a liquid borne sample into a field flow fractionator

A method comprising:

• flowing a mobile phase into a channel flow inlet port of a top plate of a field flow fractionation unit and out of a channel flow outlet port of the top plate, thereby filling with the mobile phase a separation channel, defined by a surface of the top plate, sidewalls of a spacer of the field flow fractionation unit, and a surface of a membrane of the field flow fractionation unit, thereby establishing a channel flow of the mobile phase along a length of the separation channel;
• sealing the channel flow inlet port and the channel flow outlet port, thereby stopping the channel flow;
• and
• in response to the sealing, injecting a liquid borne sample via a sample injection inlet port of the top plate into the separation channel and simultaneously withdrawing liquid contained within the separation channel via a sample injection outlet port of the top plate,
• wherein the spacer comprises;
• a separation channel cavity defining at least a portion of the separation channel,
• a sample injection inlet cavity configured to be in fluid contact with the separation channel and located beneath the sample injection inlet port,
• wherein the sample injection inlet cavity is configured to act as an injection inlet path, and
• a sample injection outlet cavity configured to be in fluid contact with the separation channel and located beneath the sample injection outlet port,
• wherein the sample injection outlet cavity is configured to act as an injection outlet path,
• wherein the sample injection inlet cavity is adjacent to a first sidewall of the separation channel cavity and the sample injection outlet cavity is adjacent to a second sidewall of the separation channel cavity, and
• wherein the first sidewall is opposite across a width of the separation channel cavity from the second sidewall, such that the injection inlet path and the injection outlet path are configured to define an injection channel that is essentially perpendicular to the length of the separation channel and that spans the width of the separation channel cavity,
• thereby forming a line of the liquid borne sample along the injection channel;
• and
• allowing particles within the line of the liquid borne sample to relax to at least one accumulation wall in a region of the injection channel under the influence of an applied cross field.

A method comprising:

• forming a sample injection inlet port in a top plate of a field flow fractionation unit,
• wherein the sample injection inlet port configured to allow a liquid borne sample to be injected into a separation channel defined by a surface of the top plate, sidewalls of a spacer of the field flow fractionation unit, and a surface of a membrane of the field flow fractionation unit;
• forming a sample injection outlet port in the top plate,
• wherein the sample injection outlet port is configured to allow liquid contained within the separation channel to be withdrawn;
• forming a separation channel cavity in the spacer,
• wherein the separation channel cavity defines at least a portion of the separation channel;
• forming a sample injection inlet cavity in the spacer,
• wherein the sample injection inlet cavity is configured to be in fluid contact with the separation channel and is configured to be located beneath the sample injection inlet port,
• wherein the sample injection inlet cavity is configured to act as an injection inlet path;
• and
• forming a sample injection outlet cavity,
• wherein the sample injection outlet cavity is configured to be in fluid contact with the separation channel and is configured to be located beneath the sample injection outlet port,
• wherein the sample injection outlet cavity is configured to act as an injection outlet path,
• wherein the sample injection inlet cavity is adjacent to a first sidewall of the separation channel cavity and the sample injection outlet cavity is adjacent to a second sidewall of the separation channel cavity, and
• wherein the first sidewall is opposite across a width of the separation channel cavity from the second sidewall, such that the injection inlet path and the injection outlet path are configured to define an injection channel that is essentially perpendicular to the length of the separation channel and that spans the width of the separation channel cavity.