4 Agilent ICP-MS Journal November 2010 - Issue 44 www.agilent.com/chem/icpms

Success Story:Medical Lab AchievesCertification for ICP-MS Method for TraceElements in UrineG.Deumer, B.Stockman, J.Casters,G.Cinar, C.Vanderstocken, V.HaufroidLaboratory of Industrial and EnvironmentalToxicology, Cliniques Universitaires SaintLuc, Brussels, Belgium

The InstitutionThe Laboratory of Industrial andEnvironmental Toxicology, CliniquesUniversitaires Saint Luc, Brussels, isspecialized in biological monitoringof occupational and environmentalexposure to chemical substances. Inrelation to its service activities, thelaboratory carries out over 20,000analyses of metals every year inseveral biological media includingwhole blood, plasma, urine andalternative matrices (e.g. water,intraarticular fluid). In this context,in June 2010, the laboratory wasawarded ISO 15189 accreditation(specific accreditation for MedicalLaboratories) for the analysis oftwenty metals in urine and alternativematrices by ICP-MS. At the same time,analytical methods are developedand validated for research activities,clinical and environmental studiesin close collaboration with theLouvain Centre for Toxicology andApplied Pharmacology.

Instrumentation for Metal AnalysisPrior to 2005, metals analyses werecarried out using six graphite furnaceatomic absorption spectrometers(GFAAS) and one flame atomicabsorption spectrometer (FAAS). Inorder to increase analytical sensitivityand sample throughput, a firstAgilent 7500ce ICP-MS was installedin the laboratory and was dedicated tometal analyses in urine and alternativematrices. Twenty two elements(beryllium, aluminum, vanadium,chromium, manganese, cobalt, nickel,copper, zinc, arsenic, selenium,molybdenum, cadmium, tin, antimony,tellurium, barium, platinum, thallium,lead, bismuth and uranium) are routinely monitored using the7500ce fitted with a Micro Mist nebulizer, following a 1:10 dilutionin 0.5% HCl / 1% HNO3 in no-gas orhelium mode (ISO 15189 accreditedmethod). All elements are analyzed

Laboratory of Industrial and Environmental Toxicology located in Brussels (Rosalind Frankin Tower ofClinical Biology)

in a single run. In 2008, a secondAgilent 7500cx ICP-MS was purchasedand dedicated to whole blood andplasma analyses. Typically we analyzeMn, Co, Cd, Hg, Tl and Pb in a singlerun in whole blood and Al, Cu, Zn,Se, B in plasma samples using aBabington and a Micro Mist nebulizer,respectively, following a 1:10 dilutionin a basic diluent: 1-butanol (2%w/v),EDTA (0.05%w/v), Triton X-100(0.05%w/v), NH4OH (1%w/v), internalstandards (Sc, Ge, Rh and Ir) andMilliQ water.

Occupational Exposure to HardlySoluble Indium CompoundsIndium (In) is a rare soft, silvery-white metal found primarily in oresof zinc, copper, and tin. Demand forindium has increased dramaticallyover the past 15 years, due largely tothe growth of the electronics market.Production of indium tin oxide (ITO)constitutes the leading end-use ofindium and accounts for most globalindium consumption. ITO thin-filmcoatings are used primarily for electrical conductive purposes in avariety of flat-panel devices mostcommonly liquid crystal displays(LCDs). Other end-uses include low-melting point solders and alloys,compounds, electrical componentsand semiconductors, and research.One of the most important indiumrefineries in the world is located inBelgium.

With reports of interstitial pneumoniacases in several indium-processingworkers worldwide, occupationalexposure to these compounds needed

to be investigated further. The firststep was to validate a method for thedetermination of indium levels inurine and plasma using our 7500cxICP-MS. The final goal of the pilotstudy was to assess whether theindium concentrations in urine andplasma could be used as exposurebiomarkers in a group of workersmanufacturing indium ingots andmainly exposed to hardly solubleindium compounds such as indiumtrioxide (In2O3) and indium hydroxide(In(OH)3). Twenty non-exposed controlswere also included in this pilot study.

Analytical ProtocolIndium stock solution at 1000 ppmwas used to prepare six pre-calibrationlevels from 10 ppb to 5 ppm. Then, a1:100 dilution of those pre-calibratorswas realized in a basic diluent solution. The basic diluent solutionwas prepared in a low-density polyethylene bottle by mixing 1-butanol (2%w/v), EDTA (0.05%w/v),Triton X-100 (0.05%w/v), NH4OH(1%w/v), internal standards andMilliQ water. Samples (urine andplasma) were prepared by a simple1:10 dilution in this basic diluentsolution and quantification of In wasrealized at m/z 115 in no gas mode(In is free of spectral overlaps) usingRh m/z103 as the internal standard.

Great care was taken to avoid externalcontamination of the samples. Allbiological samples were collected ina room separate from the indium-contaminated areas. Blood sampleswere collected by venipuncture using85.1160 needles and trace element

5www.agilent.com/chem/icpms Agilent ICP-MS Journal November 2010 - Issue 44

that the 7500cx ICP-MS has sufficientsensitivity to determine indium inthe urine and/or plasma of workersexposed to hardly soluble indiumcompounds (In2O3 or In(OH)3).Further investigation is needed toset a biological limit value for indiumin relation to the occupationalhealth implications of indium and itscompounds.

AcknowledgementsThe authors wish to thank two additional members of the ICP-MSteam: Franine Uwambayinema andTho Seminck. Acknowledgementalso goes to Professors DominiqueLison and Perrine Hoet for theircollaboration.

Further Informationwww.toxi.ucl.ac.be/mbi.htm(in French), Director: Professor Vincent Haufroid, mailto: vincent.haufroid@uclouvain.be

Louvain Centre for Toxicology andApplied Pharmacology (LTAP)www.uclouvain.be/ltap, Director: Professor Dominique Lison

Figure 2: Indium concentration in urine (g/g creatinine) and plasma (g/liter) in 12 workers exposed to hardly soluble indium compounds (In2O3 or In(OH)3)(mean of 5 different sampling times for each worker) and in 20 controls.

Indium concentration urine Indium concentration plasma

free tubes (S-Monovette TraceElement K2EDTA, Sarstedt, D-51588,Nmbrecht). Blood was centrifugedat 1800 g for 10 minutes and plasma was transferred to polyethylene tubesby means of disposable polyethylenepipettes. Spot urine samples werecollected into clean polypropylenecups. All samples were kept frozenat -20C prior to analysis.

ResultsThe linear range covered an equivalentsample concentration range from 1ppb to 500 ppb (Figure 1). The limitsof quantification (LOQ) of In werecalculated to be 0.05 and 0.08 ppb inurine and plasma, respectively.

Indium was found to be present inthe urine and plasma of all of theworkers exposed to the metal intheir workplace while no indiumwas determined above the LOQ inthe biological samples taken fromthe control group. Results obtainedin control plasma (n=20/ all