AOAC-RI ERP Book - FAOM METHOD.pdf

480 M ASTOVSKA ET AL . J OURNAL OF AOAC I NTERNATIONAL V OL . 98, N O . 2, 2015

VWDQGDUGV WKDW HQFORVH WKH DQDO\WH VLJQDO LQ WKH VDPSOH FRXOG EH used to interpolate the analyte concentration. ( 3 ) The third step was a test of the solvent evaporation where participants determined absolute recoveries of both PAHs and & 3$+V LQ WZR HYDSRUDWLRQ H[SHULPHQWV ZLWK WKUHH UHSOLFDWHV HDFK a JHQWOH HYDSRUDWLRQ RI P/ RI D 3$+ & 3$+ solution in ethyl acetate and reconstitution in isooctane and ( b JHQWOH HYDSRUDWLRQ RI P/ RI D 3$+ & 3$+ VROXWLRQ LQ KH[DQH±GLFKORURPHWKDQH Y Y DQG UHFRQVWLWXWLRQ LQ LVRRFWDQH 7KH DEVROXWH UHFRYHULHV RI DOO DQDO\WHV LQFOXGLQJ naphthalene, and & QDSKWKDOHQH KDG WR EH DERYH ( 4 ) The fourth step was the determination of the elution SUR¿OHV RI 3$+V DQG IDW RQ VLOLFD JHO 63( FROXPQV FKRVHQ IRU WKH 3$+ DQDO\VLV E\ WKH ODERUDWRU\ 7KH VLOLFD JHO FROXPQV FRXOG EH SUHSDUHG LQ KRXVH XVLQJ WKH SURFHGXUH GHVFULEHG LQ WKH PHWKRG or could be obtained commercially from different vendors. The HOXWLRQ YROXPH RI P/ KH[DQH±GLFKORURPHWKDQH Y Y VSHFL¿HG LQ WKH ,&7 PHWKRG ZDV RSWLPL]HG IRU WKH DQDO\VLV RI 3$+V 3&%V DQG 3%'(V XVLQJ WKH LQ KRXVH SUHSDUHG VLOLFD JHO PLQLFROXPQV IRU ZKLFK WKH VLOLFD JHO GHDFWLYDWLRQ ZDWHU DGGHG DQG VWRUDJH DUH FRQWUROOHG E\ WKH ODERUDWRU\ )RU FRPPHUFLDOO\ DYDLODEOH VLOLFD JHO 63( FDUWULGJHV KRZHYHU WKH GHDFWLYDWLRQ DQG VWRUDJH FDQ YDU\ SRWHQWLDOO\ UHVXOWLQJ in different amounts of water in the silica thus potentially different retention characteristics. Therefore, it is important WR WHVW WKH HOXWLRQ SUR¿OHV RI 3$+V DQG IDW DQG GHWHUPLQH WKH optimum volume of the elution solvent to ensure adequate DQDO\WH UHFRYHULHV DQG IDW FOHDQXS 7KH 3$+ HOXWLRQ SUR¿OH ZDV GHWHUPLQHG E\ DSSO\LQJ P/ RI D 3$+ LQ KH[DQH VROXWLRQ WR WKH VLOLFD FDUWULGJH FROOHFWLQJ IUDFWLRQV RI KH[DQH±GLFKORURPHWKDQH Y Y HOXWLQJ IURP WKH FDUWULGJH H[FKDQJLQJ WKH IUDFWLRQV WR P/ LVRRFWDQH DQG DQDO\]LQJ WKHP E\ *& 06 7KH IDW HOXWLRQ SUR¿OH ZDV FKHFNHG JUDYLPHWULFDOO\ E\ DSSO\LQJ P/ RI KH[DQH FRQWDLQLQJ PJ RI IDW SXUH ¿VK RLO RQWR WKH VLOLFD FDUWULGJH FROOHFWLQJ WKH RSWLPXP HOXWLRQ IUDFWLRQ GHWHUPLQHG IRU 3$+V DQG WKUHH FRQVHFXWLYH P/ IUDFWLRQV DQG HYDSRUDWLQJ them to dryness. ( 5 7KH ¿IWK VWHS ZDV D UHDJHQW SURFHGXUH EODQN WHVW ZKHUH SDUWLFLSDQWV GHWHUPLQHG FRQFHQWUDWLRQV RI WKH WDUJHW 3$+V LQ WKUHH UHSOLFDWHV RI UHDJHQW SURFHGXUH EODQN WKDW ZDV SUHSDUHG WKH VDPH ZD\ DV WKH VDPSOHV H[FHSW WKDW P/ RI ZDWHU ZDV used instead of the sample. The concentrations of all analytes LQ WKH UHDJHQW EODQNV KDG WR EH EHORZ WKH FRQFHQWUDWLRQV LQ WKH lowest calibration level standard. For naphthalene, levels below WKH VHFRQG ORZHVW FDOLEUDWLRQ VWDQGDUG HTXLYDOHQW WR QJ J RI naphthalene in the sample) were still acceptable if the source of contamination could not be eliminated, such as by selection of D VLOLFD JHO 63( FROXPQ IURP D GLIIHUHQW YHQGRU RU SUHSDUDWLRQ RI VLOLFD JHO FROXPQV LQ KRXVH KHDWLQJ RI JODVVZDUH DGGLWLRQ RI D K\GURFDUERQ WUDS WR WKH QLWURJHQ OLQHV XVHG IRU VROYHQW evaporation, etc. ( 6 7KH VL[WK VWHS ZDV D ORZ OHYHO VSLNH WHVW ZKHUH FROODERUDWRUV SUHSDUHG DQG DQDO\]HG VHYHQ VSLNHG VDPSOHV XVLQJ EODQN VKULPS PDWUL[ DQG D PL[HG 3$+ VSLNLQJ VROXWLRQ that were both supplied to them. The samples were spiked at PAH concentrations equivalent to the second lowest calibration OHYHO —J NJ IRU %D3 ZKLFK LV D ¿WQHVV IRU SXUSRVH /24 requirement established for the study) to test instrument sensitivity and method precision. The shrimp matrix had to EH VWRUHG LQ D IUHH]HU VHW WR PDLQWDLQ DW OHDVW ± “ ƒ& 7KH

PL[HG 3$+ VSLNLQJ VROXWLRQ ZDV WR EH VWRUHG LQ D UHIULJHUDWRU VHW WR PDLQWDLQ “ ƒ& ( 7 ) The seventh step was the analysis of practice samples. Three practice samples were supplied to the participants. Two of the three samples were shrimp blank matrix already VSLNHG ZLWK WZR GLIIHUHQW PL[HG 3$+ VROXWLRQV %D3 OHYHOV RI ± —J NJ RWKHU 3$+V DW ± —J NJ 7KH WKLUG VDPSOH ZDV WKH 1DWLRQDO ,QVWLWXWH RI 6WDQGDUGV DQG 7HFKQRORJ\ 6WDQGDUG 5HIHUHQFH 0DWHULDO E ZKLFK LV D PXVVHO PDWUL[ ZLWK FHUWL¿HG FRQFHQWUDWLRQV RI LQFXUUHG 3$+V DQG RWKHU RUJDQLF FRQWDPLQDQWV $OO SUDFWLFH VDPSOHV ZHUH VKLSSHG IUR]HQ RQ GU\ LFH DQG KDG WR EH VWRUHG LQ D IUHH]HU VHW WR PDLQWDLQ DW OHDVW ± “ ƒ& The method uses a mixture of isotopically labeled & 3$+ VXUURJDWH VWDQGDUGV WKDW ZHUH DGGHG DW —J NJ WR WKH VDPSOHV SULRU WR WKH H[WUDFWLRQ SURFHVV 4XDQWL¿FDWLRQ ZDV EDVHG RQ FDOLEUDWLRQ RI DQDO\WH VLJQDOV SHDN DUHDV RU KHLJKWV GLYLGHG E\ VLJQDOV RI UHVSHFWLYH & ODEHOHG LQWHUQDO VWDQGDUGV SORWWHG YHUVXV DQDO\WH FRQFHQWUDWLRQV (LJKW FRQFHQWUDWLRQ OHYHOV ZHUH XVHG IRU WKH FDOLEUDWLRQ FRUUHVSRQGLQJ WR DQG —J NJ IRU %D3 DQG RWKHU ORZHU OHYHO 3$+V DQG WR DQG —J NJ IRU KLJKHU OHYHO 3$+V H[FHSW IRU QDSKWKDOHQH WKDW ZDV SUHVHQW DW OHYHOV FRUUHVSRQGLQJ WR DQG —J NJ 9DOXHV RI U 2 had WR EH RU JUHDWHU DQG EDFN FDOFXODWHG FRQFHQWUDWLRQV RI WKH FDOLEUDWLRQ VWDQGDUGV VKRXOG QRW H[FHHG “ RI WKHRUHWLFDO )RU lower concentration levels, a limited calibration curve (without WKH WKUHH KLJKHU HQG FRQFHQWUDWLRQ SRLQWV ZDV XVHG IRU EHWWHU DFFXUDF\ ,Q DGGLWLRQ WR UHSRUWLQJ U 2 YDOXHV EDFN FDOFXODWHG calibration standard concentrations, and analyte concentrations, the collaborators were also required to report ion ratios as a PHDQV RI YHULI\LQJ LGHQWL¿FDWLRQ RI WKH DQDO\WH SHDNV $ VROYHQW LVRRFWDQH EODQN ZDV LQMHFWHG EHIRUH DQG DIWHU HDFK FDOLEUDWLRQ VHW 5HDJHQW SURFHGXUDO EODQNV ZHUH DQDO\]HG ZLWK HDFK VHW RI VDPSOHV 'XULQJ KRPRJHQL]DWLRQ SRUWLRQV of the blank mussel and oyster matrixes were spiked with '03 ZKLFK VHUYHG DV D KRPRJHQL]DWLRQ FKHFN RI WKH VDPSOH SURFHVVLQJ VWHS Participants supplied PAH and & 3$+ VLJQDOV SHDN DUHDV RU KHLJKWV LQ WHVW VDPSOHV FDOLEUDWLRQ VWDQGDUGV DQG EODQNV DQG RWKHU SDUDPHWHUV DV GHVFULEHG DERYH LQ 4XDOLW\ $VVXUDQFH LQ ([FHO IRUPV FUHDWHG E\ WKH 6WXG\ 'LUHFWRUV 7KH\ DOVR KDG WR SURYLGH GHWDLOV DERXW WKHLU *& DQG 06 LQVWUXPHQWV DQG PHWKRG conditions, evaporation equipment and conditions, and silica JHO 63( FDUWULGJH DQG RSWLPXP HOXWLRQ YROXPH 3DUWLFLSDQWV were asked to record all observations and any potential method GHYLDWLRQV LQYHVWLJDWH DQ\ SRWHQWLDO XQUHDVRQDEOH UHVXOWV FDXVHG E\ H J LQFRUUHFW FDOFXODWLRQV DQG DULWKPHWLF HUURUV XVH RI ZURQJ XQLWV WUDQVSRVLWLRQ HUURUV LQFRUUHFW VWDQGDUG preparation or contamination), and have all the results and Quality Assurance Data Reporting