Practical soil analysis by laser induced breakdown spectroscopy employing subtarget supported micro mesh as a powder sample holder

A practicalalternativeofsamplepreparationtechniqueisproposedfordirectpowderanalysisusinglaser-in- ducedbreakdownspectroscopy(LIBS)insteadofthecommonlyadoptedtreatmentofpelletizingthepowder. Theresultedpelletisknowntosufferfromreducedsensitivityofemission.Besides,itmayalsogiverisetointer- feringeffectfromthebinderemission.Weintroduceinthisreportamorepracticaltechniqueofusingasubtarget supportedmicromesh(SSMM)powdersampleholder.TheLIBSspectrumofstandardsoilpowdermeasured with 13mJ1064nmNd:YAGlaserin0.65kPaambientairisshowntoexhibitthesharpemissionlinesofall themajorelementsinthesample.Acomparisonwiththeemissionspectrameasuredfromthepelletizedpowder, thespectrumobtainedusingtheSSMMsampleholdershowsdistinctlysuperiorspectralqualitymarkedbythe absenceofmatrixeffectfoundinpelletizedpowdersamples,andthemuchstrongerintensityduetothemore effectiveshockwaveplasmainducedthermalexcitationprocessproducedbythehardsubtargetinthesample holder.RepeatingthemeasurementonanumberofthestandardsoilsamplesofvariousPbcontentsisshown to yieldalinearcalibrationlinewithpracticallyzerointerceptandadetectionlimitoflessthan10ppm.We have thusdemonstratedtheviabilityoftheproposedpowdersampleholderforthedevelopmentofpractical andquantitativepowderanalysisinthe field.