Bandwise Sample Applicationby Spray-On Technique

for Planar Chromatography

LINOMAT 5

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The LINOMAT Spray-On Technique

With the Linomat samples are sprayed onto the chromato-graphic layer in the form of narrow bands. This techniqueallows larger sample volumes to be applied than by contacttransfer (spotting). While the solvent is almost completelyevaporated in the process, the sample is concentrated on thelayer surface into a narrow band of selectable length.Even of samples dissolved in rather polar solvents such asmethanol or water compact and narrow zones are formed.

Starting zones sprayed on as narrow bands ensure the highestresolution attainable with any given planar chromatographicsystem.

All types of planar chromatography benefit from such opti-mized resolution: chromatography on conventional or HPTLClayers for qualitative or quantitative analyses, as well as pre-parative separations.

In quantitative planar chromatographic analysis sample appli-cation by the Linomat spray-on technique offers further advan-tages:

• Because the sample is distributed uniformly over the entirelength of the band, densitometric evaluation can be doneby aliquot scanning, i.e. by measuring only the center slice.This technique ensures best quantitative accuracy.

• For multilevel calibration different volumes of the samestandard solution can be applied to generate differentstandard levels. Labour time usually required to prepareseveral solutions of different concentrations, can thus bedramatically reduced.The frequently used method ofstandard addition can be simplified by over-spraying thealready applied sample with standard.

• In certain cases even pre-chromatographic derivatizationcan be performed by over-spraying samples with a reagentsolution.

All over the world, the CAMAG Linomat spray-on techniquehas become a synonym for quality in planar chromatographicanalysis. By the way, the same technique is also featured bythe CAMAG Automatic TLC Sampler.

Separation of a test dye mixture on HPTLCsilica gel; always CAMAG Test Dye III (fromleft) diluted 1:1 with hexane, toluene, ormethanol respectively, contact spotting2 µL each, bandwise spray-on applicationof 6 µL as 10 mm bands with Linomat 5;development with toluene. It is seen thatthe result for contact spotting is stronglydependent on the solvent of the sample,whereas for bandwise spray-on applicationthis is not the case. Furthermore, theseparation is significantly improved for thelatter.

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The Linomat 5

Operation under winCATSThe Linomat 5 is controlled by winCATS Planar Chromatography Manager. Platedimensions, number and distance of tracks, names of samples and volumes to beapplied onto each track are conveniently programmed and saved in winCATS.All information is then available for later densitometric evaluation. Only changingthe sample (cleaning, filling and inserting the syringe) has to be done manually.

The CAMAG Linomat 5 can be IQ/OQ qualified and then used in a GMP/GLPenvironment.

Operation in stand-alone modeTo meet the needs of users who are using the spray-on technique only occasion-ally, the Linomat 5 is also offered as a stand-alone instrument. Up to ten methodscan be entered from the keypad on the instrument panel or downloaded to theinstrument from a computer running a licensed winCATS program.

When the instrument is operating under winCATS Planar ChromatographyManager, the display shows the status of the instrument or the progressof the current application In stand-alone mode the keypad is usedto enter sample application parameters or to select a methodalready stored.

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The self-adjusting object support enablesapplication onto objects of variable thick-ness (up to 4 mm) without any adjustmentto the spray nozzle. This makes changingbetween conventional TLC and HPTLClayers, on glass plates and sheets, prepara-tive layers and very thin objects such asmembranes easy. The support accommo-dates objects up to 20 x 20 cm.

The sample liquid is sprayed onto the layerfrom the tip of the syringe needle.The stage movement is controlled so thatthe sample is uniformly distributed overthe entire length of the band.

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LINOMAT 5 and winCATS

Using the Linomat 5under winCATS – PlanarChromatography Manager

Like all other computer controlled CAMAGinstruments the Linomat 5 communicateswith winCATS via a software interfacecalled “EquiLink”.

From the tab ”General”principal settings for theinstrument are accessibleas well as manual opera-tion and method down-load to the instrument.

In the tab ”Sequence” all parametersrelevant to the actual sample application, suchas designation, volume and position are en-tered.

The system proposes a corresponding layout.Before sample application begins the user isprompted to confirm that the syringe containsthe correct sample.