Abstract: Described are a fraction collector and a method of fraction collection for a liquid chromatography system. The method includes diverting a liquid chromatography system flow from a waste channel to a collection tube at a start of a fraction collection window and collecting the system flow dispensed from the collection tube during the fraction collection window. At the end of the window, the system flow is diverted to the waste channel and a flow of a wash solvent is provided to the collection tube to dispense liquid remaining in the collection tube at the end of the window from the collection tube. The method can increase the amount of the collected fraction and can reduce or eliminate cross-contamination of a subsequently collected fraction. The method is useful for analytical scale applications where the collected fractions may have volumes defined by a limited number of drops dispensed from the collection tube.

Abstract: A method of preparing a liquid mixture for use in a liquid chromatography system is provided. The mixture comprises one or more acids, one or more bases, one or more salts, and one or more solvents, and the method comprises the steps of: i) calculating pH and/or salt concentration at a particular time t from a user-determined gradient function; and ii) based on the values obtained in step (i), calculating percent acid, percent base, percent salt and percent solvent in the liquid mixture at time t. A liquid chromatography system incorporating such method is also provided.

Abstract: A liquid chromatography system includes an autosampler with an injector valve by which a sample at low pressure within a sample loop is introduced into a high-pressure solvent mixture stream. A solvent delivery system includes a pump in fluidic communication with the injector valve of the autosampler to deliver the solvent mixture stream thereto. The solvent delivery system further comprises a processor that calculates a number of strokes of the pump needed to deliver the solvent mixture stream to the injector valve of the autosampler. The processor counts strokes of the pump during delivery of the solvent mixture stream. In response to a stroke count equaling the calculated number of strokes, the processor signals the autosampler to switch the injector valve to introduce the sample to the solvent mixture stream during a pump transfer period within which the pump performs pressure control to compensate for a drop in pressure.

Abstract: A liquid chromatography system includes an autosampler that prepares a sample for introduction to a solvent stream and a solvent delivery system that delivers a solvent stream to the autosampler. Delivery of the solvent stream occurs in parallel with the autosampler's pre-injection operations. The autosampler starts pre-injection operations to make the sample ready for injection into the mixture stream, and the solvent delivery system starts delivery of a solvent stream to the autosampler. The start of the solvent stream delivery is coordinated with the start of the pre-injection operations such that the solvent stream arrives at the autosampler approximately coincident with when the autosampler completes the pre-injection operations, making the sample ready for injection.

Abstract: Described are a fraction collector and a method of fraction collection for a liquid chromatography system. The method includes diverting a liquid chromatography system flow from a waste channel to a collection tube at a start of a fraction collection window and collecting the system flow dispensed from the collection tube during the fraction collection window. At the end of the window, the system flow is diverted to the waste channel and a flow of a wash solvent is provided to the collection tube to dispense liquid remaining in the collection tube at the end of the window from the collection tube. The method can increase the amount of the collected fraction and can reduce or eliminate cross-contamination of a subsequently collected fraction. The method is useful for analytical scale applications where the collected fractions may have volumes defined by a limited number of drops dispensed from the collection tube.

Abstract: A method of preparing a liquid mixture for use in a liquid chromatography system is provided. The mixture comprises one or more acids, one or more bases, one or more salts, and one or more solvents, and the method comprises the steps of: i) calculating pH and/or salt concentration at a particular time t from a user-determined gradient function; and ii) based on the values obtained in step (i), calculating percent acid, percent base, percent salt and percent solvent in the liquid mixture at time t. A liquid chromatography system incorporating such method is also provided.

Abstract: A liquid chromatography system includes an autosampler that prepares a sample for introduction to a solvent stream and a solvent delivery system that delivers a solvent stream to the autosampler. Delivery of the solvent stream occurs in parallel with the autosampler's pre-injection operations. The autosampler starts pre-injection operations to make the sample ready for injection into the mixture stream, and the solvent delivery system starts delivery of a solvent stream to the autosampler. The start of the solvent stream delivery is coordinated with the start of the pre-injection operations such that the solvent stream arrives at the autosampler approximately coincident with when the autosampler completes the pre-injection operations, making the sample ready for injection.

Abstract: A liquid chromatography system includes an autosampler with an injector valve by which a sample at low pressure within a sample loop is introduced into a high-pressure solvent mixture stream. A solvent delivery system includes a pump in fluidic communication with the injector valve of the autosampler to deliver the solvent mixture stream thereto. The solvent delivery system further comprises a processor that calculates a number of strokes of the pump needed to deliver the solvent mixture stream to the injector valve of the autosampler. The processor counts strokes of the pump during delivery of the solvent mixture stream. In response to a stroke count equaling the calculated number of strokes, the processor signals the autosampler to switch the injector valve to introduce the sample to the solvent mixture stream during a pump transfer period within which the pump performs pressure control to compensate for a drop in pressure.

Abstract: Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream, to enhance chromatographic performance related to retention time and reproducibility. The preferred embodiment coordinates the injection run with active pressure control of a binary solvent delivery system to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. An additional benefit that enhances reproducibility is accomplished by forcing a consistent timing relationship between the injection run, the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery.

Abstract: Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream, to enhance chromatographic performance related to retention time and reproducibility. The preferred embodiment coordinates the injection run with active pressure control of a binary solvent delivery system to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. An additional benefit that enhances reproducibility is accomplished by forcing a consistent timing relationship between the injection run, the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery.

Abstract: Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream to enhance chromatographic performance related to retention time and reproducibility. The injection event is coordinated with active pressure control of a binary solvent delivery system to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. Consistent timing with the injection event of the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery generates reproducible results.

Abstract: Systems, devices, and methods to mitigate the pressure disturbance associated with the injection of low-pressure analyte samples into a high-pressure HPLC fluid stream (52), to enhance chromatographic performance related to retention time and reproducibility. The preferred embodiment coordinates the injection run with active pressure control of a binary solvent delivery system (30) to virtually eliminate the customary pressure drop when the low-pressure loop is brought on line. An additional benefit that enhances reproducibility is accomplished by forcing a consistent timing relationship between the injection run, the mechanical position of the delivery pump pistons, and the start and subsequent gradient delivery.