Protocol for the Preparation of Samples for Trace Element Analysis06/06/10A. General Laboratory Guidelines Ensure the fume cupboard is on (it should be on all the time, even when room is not in use). Change gloves every time you touch something potentially contaminating, e.g. tupperware, benchtop. Ensure pipettes are regularly calibrated. Ensure pipettes are used in the correct manner, i.e. vertically. Follow the guidelines for disposal of acid waste and other materials.. !pen "i#estionGeneral $ules%Platinum &rucibles must only be handled 'ith platinum(tipped ton#s.Al'ays place platinum(tipped ton#s face up. Ashin# of Sample1. Remove the platinum crucibles from the perchloric acid beaer ! rinse with "# $ater.%. &lace crucibles onto blue paper in the right order and place %'mg of sample into each crucible." (eep a record of which sample is in which letter crucible and record the e)act weights using *dp.+ae ,R- the blan... +ove the crucibles to the fume cupboard, place on blue paper./. &ut 1ml of concentrated sulphuric acid (012 w3w) into a glass beaer.*. &ipette 1''ul of sulphuric acid into each crucible." "ispose of the pipette in the ha4adous waste bo)." "ispose of the acid accordingly ! into the sin in the fume cupboard with water running.5. &lace all crucibles on a hot plate (1*'C for . hrs).6. 7nce dry (i.e. no more vapour), remove the crucibles and place on the surface on blue paper."issol)in# refractory silicates in the Ash1. &lace the crucibles in a mu8e furnace overnight at *''C." (eep the crucibles in the right order.%. 9he resultant samples should be a dry residue... &our *ml of hydro:ouric acid (/'2 w3w) into a plastic beaer." $ipe bottom of acid ;ars before placing on surface." $ipe acid ;ar rim and lid with a tissue before putting acids bac in cupboard./. &our .ml of perchloric acid (5'2 w3w) into a glass beaer." $ipe acid ;ar rim and lid with a tissue and put acids bac in cupboard." $hen disposing the perchloric acid, pply acid all over inside of the crucibles." Ensure all the material in the crucible is washed into the mi)ture by the acid.%. &lace crucibles on a hot plate for 1*mins at 1*'C... >dd the solutions to 1'ml volumetric :ass using the wooden stand and a pply acid to the inside of the crucible, and remember to catch the drop hanging underneath." #f any acid goes on outside of crucible, wash o@ with a tissue to mae sure it doesn-t drop into the :as." $ash the crucible out with acid .A." Rinse drops on