Described are an interface module for two-dimensional chromatography and a method of performing a chromatographic separation that may use the interface module. The interface module includes a valve module, a collection needle, a modifier module and a sample storage element. The valve module has a first port configured to receive an eluent from a first chromatography system, a second port configured to provide a fraction obtained from the eluent, a third port and a fourth port. The collection needle and the modifier module are in fluidic communication with the valve module at the third and fourth ports, respectively. The modifier module includes a source of a modifier solvent. The sample storage element is in fluidic communication with the valve module and is configured to receive a volume of the fraction for injection as a sample into a second chromatography system.

Methods for achieving complete sequence coverage of monoclonal antibodies by trypsin digestion and dual-column LC-MS system are provided. The disclosed method improves upon current techniques for standard peptide mapping.

A method for modulating analytes in a gaseous stream passing through a capillary, wherein the analytes are retained in a trapping zone of the capillary, or allowed to pass therethrough, based on certain conditions. The method includes, during a first time period, heating the trapping zone of the capillary to a first temperature to desorb analytes therewithin and allow the analytes to pass therethrough, and during a second time period, cooling the capillary to a second temperature that is sufficient to trap and focus the analytes within the trapping zone. During the first time period, the method also includes retaining heat at the capillary during to minimize the load on a cooling device thermally connected thereto, and during the second time period, selectively allowing thermal transfer toward the cooling device.

A method for simultaneous determination of nitrogen and oxygen isotope compositions of natural nitrate and nitrite, which quantitatively converts natural nitrate and nitrite into an organic ester and a nitro-compounds respectively, and then nitrate and nitrite δ.sup.18O and δ.sup.15N are simultaneously determined by adopting a gas chromatography/pyrolysis/gas chromatography/isotope ratio mass spectrometry coupling technology (GC/Py/GC/IRMS). According to the method for simultaneously determining the nitrogen and oxygen isotope compositions of the natural nitrate salt and nitrite salt, the small amount of sample does not result in the loss, acquisition, exchange and fractionation of nitrogen and oxygen.

The disclosure describes embodiments of an apparatus including a first gas chromatograph including a fluid inlet, a fluid outlet, and a first temperature control. A controller is coupled to the first temperature control and includes logic to apply a first temperature profile to the first temperature control to heat, cool, or both heat and cool the first gas chromatograph. Other embodiments are disclosed and claimed.

Described are an interface module for two-dimensional chromatography and a method of performing a chromatographic separation that may use the interface module. The interface module includes a valve module, a collection needle, a modifier module and a sample storage element. The valve module has a first port configured to receive an eluent from a first chromatography system, a second port configured to provide a fraction obtained from the eluent, a third port and a fourth port. The collection needle and the modifier module are in fluidic communication with the valve module at the third and fourth ports, respectively. The modifier module includes a source of a modifier solvent. The sample storage element is in fluidic communication with the valve module and is configured to receive a volume of the fraction for injection as a sample into a second chromatography system.

The disclosure describes a method for simultaneous determination of nitrogen and oxygen isotope compositions of natural nitrate and nitrite, which quantitatively converts natural nitrate and nitrite into an organic ester and a nitro-compounds respectively, and then nitrate and nitrite δ.sup.18O and δ.sup.15N are simultaneously determined by adopting a gas chromatography/pyrolysis/gas chromatography/isotope ratio mass spectrometry coupling technology (GC/Py/GC/IRMS). According to the method for simultaneously determining the nitrogen and oxygen isotope compositions of the natural nitrate salt and nitrite salt, the small amount of sample does not result in the loss, acquisition, exchange and fractionation of nitrogen and oxygen.

A fluid processing apparatus includes a first fluid processing unit and a second fluid processing unit. A fluid unit is fluidically coupled to the first fluid processing unit and includes a first buffering unit configured for buffering fluid, and/or a mask flow source configured for providing a mask fluid or a flow thereof. A first coupling point is fluidically coupled between the first fluid processing unit and the fluid unit. A modulation unit is configured, selectively, for withdrawing fluid from the first coupling point, or for transferring withdrawn fluid into the second fluid processing unit. The apparatus may be utilized for chromatography.

Methods for achieving complete sequence coverage of monoclonal antibodies by trypsin digestion and dual-column LC-MS system are provided. The disclosed method improves upon current techniques for standard peptide mapping.

The disclosure features methods that include obtaining a vibrational spectrum of a solution in a biological manufacturing system, analyzing the vibrational spectrum using a first chemometrics model to determine a value of a first quality attribute associated with the solution, analyzing the vibrational spectrum using a second chemometrics model to determine a value of a second quality attribute associated with the solution, and adjusting at least one parameter of a purification unit of the biological manufacturing system based on at least one of the values of the first and second quality attributes.