Micro-capillary tubes, ideal for spotting TLC plates or chromatography paper, thanks to the small volume of liquid contained within each narrow bore tube. The liquid to be spotted is drawn up into the glass tube by capillary action and will be drawn back out by touching the end onto a TLC plate or chromatography paper. Supplied in packs of 100 glass tubes, each 75mm long with a volume of 75 microlitres, or a bulk pack of 1000 tubes. Bulk pack of 1000 tubes.