Determination of Trace Elements in Hair by ICP-MS

1 Determination of Trace Elements in Hair by ICP-MSToshihiro YamashitaApplication NoteClinicalAgilent TechnologiesInnovating the HP WayAbstractHuman hair samples were analyzed using an 4500 ICP-MS system. Sample preparation was by microwave digestion. A Japanese standardreference material (NIES Human Hair) was also analyzed. For 11 Elements including Hg, excellent agreement with the certifiedvalues were obtained, and the sensitivity of the 4500 ICP-MS enabled avery short acquisition time (24 seconds/sample) to be used. A recoverytest was performed to check the effect on the sample preparation andmeasurement methodology. The pre-digestion spike gave recoveries in the range of - 109%.1trace levels normally found in thebody, to the high levels resultingfrom industrial exposure.

2 Sincemedical treatment regimes forhospital patients depend on theanalytical results reported, theanalysis of biomedical samples is critical. Therefore, the need for fast and reliable analyticalmethods and instrumentation ICP-MS is a fast, sensitiveanalytical tool with the capabilityof multielement analysis. In addi-tion, sample consumption is verylow (in this case <1 mL of samplesolution). These characteristicsrepresent major advantages in afield where human life is directlyinvolved. Hair is a good index of exposureto Elements and easily levels of Trace Elements inhair also depend on race, age and gender of the patient. Thisapplication note describes thedetermination of several Trace Elements in hair by the 4500 PreparationSamples analyzed were comprisedof a Japanese standard referencematerial, NIES Human Hair,and a bulk sample of Japanesehair randomly obtained at aJapanese hairdressing salon.

3 The samples were digested byweighing g of each sample into a microwave digestion vesselwith 5 mL of nitric acid (TamaChemicals, Tokyo, Japan). Theywere placed in a microwave sample preparation system, MDS-2000 (CEM . Matthews, NC),and digested. The conditions formicrowave system are shown inTable digestion, the samples werediluted to 50 mL with DI water(Nihon Millipore, Tokyo, Japan).Parameters for 4500 ICP-MS aregiven in Table to quantitative measurement,a fast qualitative measurement forNIES was performed toselect internal standard elementsused for analysis. The spectrumobtained for NIES is shownin Fig. 1. Co, In and Tl were selected as the internal standardelements since these elementswere not present in the Determination of toxic Elements such as Hg, Pb and Cd inhumans has been a critical issuein the field of clinical chemistryfrom the toxicology viewpoint.

4 In addition, since recent biomedical research has shownthat some Elements at Trace levelhave specific functions in the biochemistry of living organisms,the Determination of Trace elementconcentrations in human beinghas also become a major issue inthe field of nutritional study. As a result, the analysis of toxicelements and also many Trace Elements in biological samples isrequired. The analyte concentrationrange is large, ranging from the2 Stage1234 Power (W)378378378378 Pressure (psi)204085130 Hold (min)5555 Table 1 Conditions for Microwave DigesterPlasma gas flow L/minAux. gas flow L/minCarrier gas flow L/minRF Power1300 WNebulizerPEEK, Babington - typeSpray chamberGlass, double passSpray chamber temp1 CICP torch injectorQuartz, mm Sample uptake rate mL/minSampler coneNickelSkimmer coneNickelSampling depth8 mmPoints/mass3 Integration secTotal acquisition time/replicate8 secReplicates3 Total acquisition time/sample24 secTable 2.

5 4500 ICP-MS Operating ParametersResultsQuantitative results and the certified values for NIES aregiven in Table 3. The 11 analytesvalues obtained were in excellentagreement for all the elementsthat had certified values. (There isno certified value for As.) Sincemicrowave digestion was used,even the results for volatile Elements such as Hg and Zn showgood agreement. Using normalopen vessel digestion with nitricacid, recoveries for these elementswould be poor due to losses byvaporization during the digestionstage. Also of note was the goodprecision obtained on the analyzed three sigma detection limitsfor the analytes measured werecalculated using the data obtainedfrom the reagent blank (which hadalso been through the digestionstep), and are also given in Table 3.

6 The detection limits areexpressed in the hair as received,and demonstrate the excellentsensitivity of the 4500 ICP-MS ,even though the total sample measurement time was only 21 sec. for three recovery test was performedusing a bulk sample of Japanesehair. A multielement spike wasadded to portions of the sampleboth before and after digestion, toassess the validity of the results are given in Table can be seen, both sets ofresults were excellent: the recoveries of the pre-digest spikedsample were - 109%, and therecoveries of the post-digestspiked sample were - 105%.These results show there was nocontamination or loss of analytesduring sample preparation andalso that the presence of samplematrix has no effect on the preparation and measurementmethodology.

7 3 NiCuZnSrCdSnBaIHgPbNaMgAlCrMn Qualitative spectrum of hair (NIES )ConclusionThe 4500 ICP-MS has been shownto give excellent results for thedetermination of Trace level met-als in hair. In combination withmicrowave digestion, precise,accurate determinations forvolatile Elements including As, Hgand Zn, can be obtained. Sincethe 4500 ICP-MS has excellentsensitivity, multielement data can be obtained with very short acquisition times. Threereplicates for 12 Elements wereperformed in only 24 seconds, far outperforming the samplethroughput available from eventhe latest multielement GFAA systems, and delivering the highsample throughput needed bybusy clinical labs with fast sampleturnaround (ug/g) (ug/g)Al27220+/-6240* + + + + Fe56219+/-5225+ + + + + Zn66171+/-4169+ + + * + + + + + * * : Not certified, information value only - : Not certifiedTable 3 Quantitative results.

8 NIES in hairSpiked volumeRecovery (%)(ug/g)(ug/g) 4 Recovery testAgilent TechnologiesInnovating the HP Way5 Agilent Technologies shall not be liable forerrors contained herein or for incidental orconsequential damages in connection with thefurnishing, performance or use of this , descriptions and specifications inthis publication are subject to change our website 2000 Agilent Technologies, 4/2000 Publication number 5965-5258E