Concurrent solvent recondensation large sample volume splitless injection

Abstract

Concurrent solvent recondensation large sample volume splitless injectionConcurrent Solvent Recondensation Large Sample Volume (CRS-LV) splitless injection overcomes the limitation of the maximum sample volume to 1 -2 lL valid for classical splitless injection. It is based on control of the evaporation rate in the vaporizing chamber, utilization of a strong pressure increase in the injector resulting from solvent evaporation, and greatly accelerated transfer of the sample vapors from the injector into the inlet of an uncoated precolumn by recondensation of the solvent. The sample vapors are transferred into the column as rapidly as they are formed in the injector (concurrent transfer). 20 -50 lL of liquid sample is injected with liquid band formation. The sample liquid is received by a small packing of deactivated glass wool positioned slightly above the column entrance at the bottom of the vaporizing chamber. Solvent evaporation strongly increases the pressure in the injector (auto pressure surge), provided the septum purge outlet is closed and the accessible volumes around the vaporizing chamber are small, driving the first vapors into the precolumn. Transfer continues to be fast because of recondensation of the solvent, obtained by keeping the oven temperature below the pressure-corrected solvent boiling point. The uncoated precolumn must have sufficient capacity to retain most of the sample as a liquid. The experimental data show virtually complete absence of discrimination of volatile or high boiling components as well as high reproducibility.

Problemas en el análisis de metilsiloxanos volátiles (VMS): origen y soluciones

“…44 En comparación con la inyección PTV-LVI, la ventaja más importante de esta técnica consiste en que la muestra inyectada se transfiere completamente a la columna cromatográfica, sin la eliminación del disolvente mediante una válvula split, con lo cual esta técnica resulta ideal para el análisis de estos compuestos volátiles. Además, la técnica CSR-LVI permite inyectar un mayor volumen de extracto (30 -50 µL) 62 que la técnica PTV-LVI (hasta 15 µL), 55 y en consecuencia se puede alcanzar un mayor incremento en sensibilidad. Así, con la aplicación de la CSR-LVI en el análisis de VMS en suelos y fangos se inyectaronEvitar las pérdidas por volatilización es el otro aspecto importante a tener en cuenta en el análisis de VMS.…”

Injector‐internal thermal desorption from edible oils. Part 2: Chromatographic optimization for the analysis of migrants from food packaging material

“…With n-butyl acetate, recondensation must be expected when the oven temperature during splitless transfer is below about 1108C. Partial solvent recondensation has two advantages: early eluted compounds are reconcentrated by solvent trapping and the large volume of solvent vapor generated does not overload the vaporizing chamber thanks to recondensation sucking vapors into the inlet of the precolumn [16]. For instance, at 2508C injector temperature and 200 kPa inlet pressure, 1 lL of butyl acetate forms 115 lL vapor.…”

Large volume splitless injection with concurrent solvent recondensation: Keeping the sample in place in the hot vaporizing chamber

“…In 2002, Magni and Porzano [14] described a technique applying concurrent solvent recondensation (CSR): the vapors are transferred into the oven-thermostatted column inlet at the rate of their formation, making use of recondensation in an uncoated precolumn kept below the solvent boiling point. An injector with a minimum accessible volume around the vaporizing chamber is a prerequisite in order to create a strong auto pressure pulse, i.e.…”