Provided herein are methods for multiplexed sample analysis by mass spectrometry. The methods may be performed without the need for chemical tagging. The methods also may include the analogous use of frequency modulation to multiplex mass spectrometric analysis, which may be referred to as frequency-modulated continuous flow analysis electrospray ionization mass spectrometry (FM-CFA-ESI-MS).

The present disclosure relates to methodologies, systems and apparatus for controlling pressure in a CO.sub.2-based chromatography system. A first CO.sub.2 pump operates in constant flow mode and delivers CO.sub.2 to a chromatography column, and liquid modifier is introduced to the chromatography column according to a gradient. A second CO.sub.2 pump is disposed downstream of the column and operates in constant pressure mode to introduce CO.sub.2 into a flow stream at an output of the column. Liquid modifier is also introduced into the flow stream at the output of the column according to a reverse gradient compared to the gradient entering the chromatography column.

A thermal modulator for a chromatographic system includes a cooler, a thermal valve, a thermal buffer, a heater, and a capillary. The thermal valve thermally-engages the cooler. The thermal buffer thermally-engages the thermal valve. The heater thermally-engages the thermal buffer. The capillary thermally-engages the heater and is configured to transport an analyte in a first direction.

The present disclosure relates generally to processes for separating chemical compounds via two-dimensional gas chromatography. Certain embodiments comprise rapid heating and cooling of the second dimension column by a unique arrangement of heating and cooling elements.

The present disclosure relates generally to processes for separating chemical compounds via two-dimensional gas chromatography. Certain embodiments comprise rapid heating and cooling of the second dimension column by a unique arrangement of heating and cooling elements.

The present disclosure relates generally to systems for separating chemical compounds via two-dimensional gas chromatography. Certain embodiments of the system are configured to rapidly heat and cool the second dimension column by a unique arrangement of heating and cooling elements.

The present disclosure relates generally to systems for separating chemical compounds via two-dimensional gas chromatography. Certain embodiments of the system are configured to rapidly heat and cool the second dimension column by a unique arrangement of heating and cooling elements.

Provided herein are methods for multiplexed sample analysis by mass spectrometry. The methods may be performed without the need for chemical tagging. The methods also may include the analogous use of frequency modulation to multiplex mass spectrometric analysis, which may be referred to as frequency-modulated continuous flow analysis electrospray ionization mass spectrometry (FM-CFA-ESI-MS).

The invention relates to a method and an apparatus for determining a chromatogram. The method includes a first step where a sample is inserted in two separation columns (2.1, 2.2, 2.3), wherein for each separation column (2.1, 2.2, 2.3), a corresponding part of the sample is inserted in the respective separation column (2.1, 2.2, 2.3) with a corresponding insertion device (3.1, 3.2, 3.3) which is controlled by a corresponding modulation function for generating a corresponding modulated part of the sample in the respective separation column (2.1, 2.2, 2.3), wherein the modulation functions with which the parts of the sample are modulated in the separation columns (2.1, 2.2, 2.3) differ from each other. Furthermore, the method includes a second step where each modulated part of the sample is guided through the respective separation column (2.1, 2.2, 2.3), a third step where a signal of each modulated part of the sample is measured with a same detector (4) after having passed the respective separation column (2.1, 2.2, 2.3), and a fourth step where for each separation column (2.1, 2.2, 2.3), a correlation of the signal and the modulation function with which the corresponding part of the sample is modulated in the respective separation column (2.1, 2.2, 2.3) is calculated in order to determine the chromatogram of the respective separation column (2.1, 2.2, 2.3).

An in-line electrolytic reagent concentrator device that circumvents the need for additional pumps and supplies of reagents to support operation of a carbonate or ammonia removal device. The device generates regenerant solutions as strong as, or even stronger, than commercially recommended regenerant solutions. The device may also regenerate eluent solutions so as to reduce the frequency of eluent maintenance and replacement in ion chromatography systems.