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Live injection
The MicroSAM has a two-stage injection system. Using a micro injection valve, a defined quantity of sample is first brought up to the carrier gas pressure. This eliminates the pressure-dependent error in the dosing quantity present with conventional systems. In the second stage, the sample is transferred to the column by a valveless micro injection system (live dosing). The result is an "active" injection.
The injection volume can be varied time-controlled, and exactly matched to the column requirements.
Valveless live column switching
Because of the high dead volume of conventional valves, only the valveless version can be considered for a miniaturized system. In this case, the generation of differences in flow using several electronic pressure regulators at appropriate positions of the column setup causes a change in the flow directions. (The system operates according to the Wheatstone principle, but pneumatically.) The functions "Cut" and "Backflushing" can then be implemented free of dead volume.
The column system
The column system consists of two or three capillary columns connected in sequence. Micro TCDs or micro live circuits are installed in sequence ("inline") upstream and downstream of the individual columns. Three electronic pressure regulators supply the columns with carrier gas and carry out the switching functions (injection, backflushing and cut).
By using narrow-bore capillary columns, the separation at high resolution is carried out within a much shorter time, approx. factor 2 to 3 compared to standard capillary columns.
Electronic pressure regulators
A high pressure stability together with rapid changing rates in the hPa range are required for precise and fast switching. This is achieved in the electronic pressure regulators by means of a piezo actuator.
Detector
The micro TCDs (based on silicon wafer technology) work on the principle of continuous measurement of the different thermal conductivities of the carrier gas and the components to be measured.
The measurement can be carried out without falsification by avoiding catalytic effects on the heating wires and maintaining a constant flow velocity. This permits consistent in-line detection, i.e. without qualitative or quantitative losses of substances.
Application modules
The standardized application modules all contain live injection and live switching. The modules D01 to D03 have four detectors and three separating columns, D04 to D08, D10 and D11 have three detectors and two separating columns, and D09 has three detectors and three separating columns.
The application modules are suitable for separation of the components described below.
|
Detector |
Column 1 |
Detector |
Column 2 |
Detector |
Circuit |
Column 3 |
Detector |
|
|---|---|---|---|---|---|---|---|---|
|
D01 |
||||||||
|
Injection |
TCD |
Sil5 C3, C4, C5, C6+ |
TCD |
PoraPLOT/Porabond Q CO2, C2, H2O |
TCD |
Live |
Molecular filter H2, (Ar+O2), N2, C1, CO |
TCD |
|
D02 |
||||||||
|
Injection |
TCD |
Sil5 C5+ |
TCD |
SilicaPLOT C2, C3, C4 (saturated, unsaturated), C5+ |
TCD |
Live |
Molecular filter H2, (Ar+O2), N2, C1, CO |
TCD |
|
D03 |
||||||||
|
Injection |
TCD |
Sil5 C5+ |
TCD |
Wax Volatile pole components such as alcohol, ether, ketones, aldehydes, C7+ |
TCD |
Live |
ALOX C1, C2, C3, C4 (saturated, unsaturated) |
TCD |
|
D09 |
||||||||
|
Injection |
- |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
Live |
Porabond Q All components except molecular filter components |
TCD |
Application modules D01 to D03 and D09
|
Detector |
Column 1 |
Detector |
Circuit |
Column 2 |
Detector |
|
|---|---|---|---|---|---|---|
|
D04 |
||||||
|
Injection |
TCD |
Wax Volatile pole components such as alcohol, ether, ketones, aldehydes, C7+ |
TCD |
Live |
SilicaPLOT C2, C3, C4, C5, C6 (saturated, unsaturated) |
TCD |
|
D05 |
||||||
|
Injection |
TCD |
Wax Polar aromatic and aliphatic hydrocarbons |
TCD |
Live |
Wax Polar aromatic and aliphatic hydrocarbons |
TCD |
|
D06 |
||||||
|
Injection |
TCD |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
Live |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
|
D07 |
||||||
|
Injection |
TCD |
Wax Polar aromatic and aliphatic hydrocarbons |
TCD |
Live |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
|
D08 |
||||||
|
Injection |
TCD |
Porabond Q All components except molecular filter components |
TCD |
Live |
Molecular filter H2, (Ar+O2), N2, C1, CO |
TCD |
|
D10 |
||||||
|
Injection |
TCD |
Sil5 Non-polar aromatic and aliphatic hydrocarbons |
TCD |
Live |
Wax Polar aromatic and aliphatic hydrocarbons |
TCD |
|
D11 |
||||||
|
Injection |
TCD |
RTX-5+ Non-polar aromatic and aliphatic hydrocarbons and medium-pole components such as chlorosilane |
TCD |
Live |
SilicaPLOT C2, C3, C4, C5, C6 (saturated, unsaturated) |
TCD |
Application modules D04 to D08, D10 and D11
Application
Various solution concepts are available:
- Adjustmentwithoutmethod development (on request)
- Run-out ex factory
The application modules are standardized. The functionality of the MicroSAM is proven with a specified carrier gas, exact setting of the oven temperature and the carrier gas inlet pressures, and with a standard calibration gas. The measured components and switching functions (live injection, backflushing, cut) are saved. - Commissioning on site
All application modules are standardized, i.e. the analytical hardware is defined and cannot be changed. The specific settings are carried out on site during commissioning.
- Run-out ex factory
- Adjustmentwithmethod development
Non-standardized applications require specific method development:
An optimum solution is elaborated on the basis of an existing specification and a selected calibration gas or with application of a customer sample.