© ISO 2017 Leather — Chemical determination of chromium(VI) content in leather — Part 1 Colorimetric method Cuir — Détermination chimique de la teneur en chrome(VI) du cuir — Partie 1 Méthode colorimé[.]
INTERNATIONAL STANDARD ISO 17075-1 IULTCS/IUC 18-1 First edition 2017-02 Leather — Chemical determination of chromium(VI) content in leather — Part 1: Colorimetric method Cuir — Détermination chimique de la teneur en chrome(VI) du cuir — Partie 1: Méthode colorimétrique Reference numbers ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) © ISO 2017 ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Contents Page Foreword iv Scope Normative references Terms and definitions Principle Chemicals Apparatus and materials Procedure 7.1 7.3 7.4 7.5 7.2 7.6 Prep aratio n o analytical s o lutio n D eterminatio n o the recovery rate 7.6.1 I nfluence o the matrix 7.6.2 I nfluence o the S PE material ( Calculation and expression of results 8.1 8.3 8.2 Sampling and preparation of samples f Determination of chromium(VI) in the solution obtained from the extraction procedure Blank solution Calibration f f f 6.9) Calculation of chromium(VI) content 7.6.1) Expression of results Recovery rate (acco rding to Test report Annex A (informative) Solid phase extraction (SPE) material Annex B (informative) Accuracy Annex C (informative) Comparison between the colorimetric method (ISO 17075-1) and the ionic chromatography method (ISO 17075-2) 11 © ISO 2017 – All rights reserved iii ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html ISO 17075-1 was prepared by the Chemical Test Commission o f the International Union o f Leather Technologists and Chemists Societies (IUC Commission, IULTCS) in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 289, Leather, the secretariat of which is held by UNI, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement) IULTCS, originally formed in 1897, is a world-wide organization o f pro fessional leather societies to urther the advancement o f leather science and technology IULTCS has three Commissions, which f are responsible for establishing international methods for the sampling and testing of leather ISO recognizes IULTCS as an international standardizing body for the preparation o f test methods for leather This first edition o f ISO 17075-1, together with ISO 17075-2, cancels and replaces ISO 17075:2007, which has been technically revised The main changes compared to ISO 17075:2007 are as follows: — the sample preparation has been revised; — mechanical shaking in 7.1, 7.2 and 7.3 has been revised A list of all parts in the ISO 17075 series can be found on the ISO website iv © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) INTERNATIONAL STANDARD Leather — Chemical determination of chromium(VI) content in leather — Part 1: Colorimetric method Scope T h i s c ument s p e ci fie s a me tho d for de term i n i ng ch rom iu m( VI ) i n s olution s le ache d from le ather u nder defi ne d cond ition s T he me tho d de s crib e d i s s u itab le to qua nti fy the ch rom ium( VI ) content i n leathers down to mg/kg T h i s c ument i s appl ic able to a l l le ather typ e s T he re s u lts ob ta i ne d from th i s me tho d a re s tric tly dep endent on the e xtrac tion cond ition s Re s u lts ob ta i ne d by u s i ng o ther e xtrac tion pro ce du re s (e xtrac tion s olution, pH , e xtrac tion ti me, e tc ) are no t comp arab le with the re s u lts pro duce d b y the pro ce du re de s crib e d i n th i s c u ment If a leather sample is tested with both this document and ISO 17075-2, the results obtained with ISO 17075-2 are considered as the reference The advantage of the method described in ISO 17075-2 is f f f Annex C) and the results are comparable between both methods ff that there are no i nter erence s no t s how s ign i fic ant d i rom the colou r o the extrac t Never thele s s , i nterlab orator y tria l s erence s (s e e Normative references T he fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 2418, Leather — Chemical, physical and mechanical and fastness tests — Sampling location ISO 3696, Water for analytical laboratory use — Specification and test methods ISO 4044:2017, Leather — Chemical tests — Preparation of chemical test samples ISO 4684, Leather — Chemical tests — Determination of volatile matter Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at http://www.iso org/obp — IEC Electropedia: available at http://www.electropedia org/ 3.1 chromium(VI) content amount of chromium(VI) in leather determined after extraction with an aqueous salt solution at pH 7,0 to 8,0 N o te to entr y: T he ch ro m iu m( VI ) content i s rep or te d a s ch ro m iu m( VI ) i n m i l l igra m s p er ki lo gra m (m g/ kg) , e x pre s s e d a s the d r y m a s s o f the s a mp le © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Principle Extractable chromium(VI) is leached from the sample in phosphate buffer at pH 7,0 to 8,0 and co- extracted coloured substances which influence the detection are removed by solid phase extraction i f necessary The chromium(VI) in solution oxidizes 1,5-diphenylcarbazide to 1,5-diphenylcarbazone to give a red/violet complex with chromium which can be quantified photometrically at 540 nm Chemicals All reagents used shall have at least analytical grade purity 5.1 Extraction solution Dissolve 22,8 g dipotassium hydrogenphosphate, K2 HPO ⋅3H O, in 000 ml water, adjusted to pH 8,0 ± 0,1 with phosphoric acid (5.3) Degas this solution with either argon or nitrogen (5.6) or ultrasonic bath Standard practice is to make up a fresh solution each day However, the solution can be kept for up to one week in a refrigerator at (4 ± 3) °C but shall be warmed to room temperature and degassed prior to use 5.2 Diphenylcarbazide (DPC) solution Dissolve 1,0 g 1,5-diphenylcarbazide, CO(NHNHC 6H ) , in 100 ml acetone, (CH ) CO, and acidified with one drop of glacial acetic acid, CH COOH The solution should be kept in a brown glass bottle The shel f li fe is up to 14 days at °C 5.3 Phosphoric acid solution 700 ml o-phosphoric acid, ρ = 1,71 g/ml, made up to 000 ml with deionised water (5.7) First add approximately 200 ml o f deionised water (5.7 ) to a 000 ml volumetric flask, then add the 700 ml of o-phosphoric acid and dilute to the mark with deionised water 5.4 Chromium(VI) stock solution Dissolve 2,829 g potassium dichromate (K2 Cr2 O ) (5.8 ) in water in a volumetric flask and make up to 000 ml with water One millilitre of this solution contains mg of chromium A stock solution at this concentration level of hexavalent chromium is an alternative available commercially 5.5 Chromium(VI) standard solution Pipette ml of solution (5.4) into a 000 ml volumetric flask and make up to the mark with extraction solution (5.1) One millilitre of this solution contains μg of chromium The solution can be kept for up to one week in a refrigerator at (4 ± 3) °C but shall be warmed to room temperature prior to use A stock solution at this concentration level of hexavalent chromium is an alternative available commercially 5.6 Argon or nitrogen, oxygen-free Preference should be given to argon as an inert gas instead of nitrogen because argon has a higher specific mass than air © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) 5.7 Distilled or deionised water, Grade quality as s p ecified in I S O 5.8 Potassium dichromate (K2 Cr2 O ), dried for (16 ± 2) h at (102 ± 2) °C 5.9 Methanol , HPLC grade Apparatus and materials Us ua l lab orator y e qu ipment and , i n p ar tic u la r, the Suitable mechanical orbital shaker, (100 ± 10) 6.1 fol lowi ng C o n i c a l f l a s M e V o m l u b r a m e n t r e i c , o f cap acity ml, with s to p p er f i k Aeration tube and 6.3 −1 l f l t e a s r f l o w m e t e r , s uitab le fo r a flow rate o f (5 ± ) ml/min , , 45 μm p o re s ize [p o lytetrafluo ro ethylene (PTFE ) o r p o lyamide 6 ] k s , o f cap acity ml, 0 ml and 0 ml 6.6 Pipettes , various nominal volumes 6.7 Spectrophotometer or 6.8 Photometric cell , quartz, 40 mm length o r any o ther s uitab le cell length f i l t e r p h o t o m e t e r , wavelength 540 nm Glass or , e.g reversed phase (RP) C18 or a suitable activated magnesium silicate, see Annex A for examples of SPE materials 6.9 p o l y p r o p y l e n e c a r t r i d g e s f i l l e d w i t h a s u i t a b l e s o l i d p h a s e e x t r a c t i o n ( S P E ) m a t e r i a l 6.10 Solid phase extraction (SPE) system , with vacuum device o r s o lvent- res is tant medical syringe 6.11 Sharp cutting tool or blade , suitable for cutting the leather into mm to mm pieces 6.12 Analytical balance , capable of weighing to the nearest 0,1 mg Procedure 7.1 Sampling and preparation of samples If possible, sample in accordance with ISO 2418 If sampling in accordance with ISO 2418 is not possible f test report 6.11 ISO 4044:2017, 6.3 (e g le athers rom fi n i she d pro duc ts l i ke sho e s , garments) , de tai l s ab out s ampl i ng sh a l l b e given i n the P rep a re the le ather s a mple b y c utti ng ( ) i nto s ma l l pie ce s accord i ng to the me tho d s p e ci fie d i n 7.2 Preparation of analytical solution Weigh (6.12 degassed solution (5.1 ) approxi mately (2 ± ,1) g o f le ather pie ce s to the ne are s t , 01 6.2 ) i nto a m l ic a l fla sk ( © ISO 2017 – All rights reserved g P ip e tte 10 ml of ) D i s place ox ygen b y p as s i ng ox ygen- fre e a rgon ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) (or nitrogen) (5.6 tube (6.3 ) i nto the fla sk for m i n with a volu me flow o f (5 ± 10) m l/m i n Remove the aeration ) , add the le ather pie ce s a nd clo s e the fl as k with a s topp er Re cord the ex trac t volu me a s S ke the ic a l fla sk with the le ather pie ce s (100 ± 10) to extract the chromium(VI) for 6.1) at h ± m i n on a me cha n ic a l orbita l sha ker ( −1 S ke the fla s k i n a s mo o th ci rc u la r movement to ke ep the le ather pie ce s the fla sk and avoid s ki ng fa s ter V0 from ad heri ng to the wa l l o f tha n s p e ci fie d I mme diately a fter comple ti ng h o f extrac tion, fi lter the content o f the conical flask th rough a membrane fi lter into a glas s or plas tic ves s el with l id C he ck the pH o f the s olution T he pH o f the s olution shal l b e between 7,0 and 8,0 If the pH of the solution is not within this range, start the complete procedure again C on s ider u s i ng a s ma l ler s ample mas s i f the pH i s no t b e twe en 7, and , I n th i s c a s e, the qua nti fic ation limit will be increased 7.3 Determination of chromium(VI) in the solution obtained from the extraction procedure I f the le ather s ample i s coloure d, it i s l i kely s ome colou re d s ub s tance s , e g dye s , wi l l have b e en co extrac te d T he s e c an i n fluence the de te c tion o f ch rom ium( VI ) T he e xtrac te d colora nts c a n b e remove d 7.2) through a cartridge containing a suitable solid phase extraction material (6.9), see Annex A for examples f Pre-treat the SPE cartridges (6.9 6.9 5.9), b) afterwards with ml distilled water (5.7) and f f 5.1) 6.9) during or after the pre-treatment f From the solution obtained in 7.2, take 10 ml (V1 (6.9 6.10) Collect the eluate in a 25 ml volumetric 6.5) Flush the cartridge with 10 ml extraction solution (5.1 V2 ) with extraction solution (5.1 S1 Pipette (6.6) 10 ml (V3 ) of solution S1 f 5.1) Add 0,5 ml of phosphoric acid solution (5.3) and afterwards f 5.2 V4) with extraction solution (5.1) and mix well by p as s i ng the ex trac tion s olution ( ) i n the a) flu sh the c ar tridge ( c) d i re c tly a ter wa rd s with 10 m l o ol lowi ng way: ) fi rs t with m l me thanol ( e xtrac tion s olution ( D o no t d r y the c ar tridge s ( ) and tran s er th i s qua ntitatively th rough the c a r tridge ) on an S PE s ys tem with a vac uu m device or s yri nge ( fl as k ( ) i nto the m l fla sk M a ke up the fl as k to volu me ( ) M a rk th i s s olution a s i nto a m l volu me tric fla sk D i lute the s olution to 3/4 o the fl as k’s volu me with ex trac tion s olution ( 0, ml o d iphenylca rb a z ide s olution ( L e t s ta nd for ) M a ke up the flas k to volu me ( at le a s t m i n ± m i n M e as u re the ab s orb a nce o f the s olution at n m i n a m m cel l (6.8) against the blank solution (7.4) Record the absorbance obtained as A1 For each run, pipette another 10 ml aliquot of solution S1 f f f A2 i nto a m l volu me tric fla sk a nd tre at it as de s c rib e d ab ove, ab s orb ance o but without the add ition o the d iphenylc a rb a z ide s olution ( 5.2 ) M e a s ure the th i s s olution i n the s ame way a s b e ore a nd re cord it a s 7.4 Blank solution Fi l l a m l volu me tric fl as k th re e quar ters acid (5.3 solution (5.1 fu l l 5.1), add 0,5 ml of phosphoric 5.2) and make up to the mark with extraction with ex trac tion s olution ( ) and , m l o f d iphenylc arb a z ide s olution ( ) a nd m i x wel l P rep are th i s s olution da i ly a nd s tore it i n the da rk Tre at the bla n k s olution i n the s ame way as the ana lytic a l s olution, e xclud i ng the s ol id ph as e e xtrac tion © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) 7.5 Calibration Prepare calibrating solutions from the standard solution (5.5) The chromium concentration in these solutions should cover the expected range of measurements Prepare the calibration solutions in 25 ml volumetric flasks (6.5) Plot a suitable calibration curve by using at least six standards, within the range 0,5 ml to 15 ml o f standard solution (5.5) Pipette the given volumes of standard solution (5.5) into 25 ml volumetric flasks Add 0,5 ml o f phosphoric acid (5.3 ) and 0,5 ml diphenylcarbazide solution (5.2 ) to each flask Make up to volume with extraction solution (5.1), mix well and allow to stand for (15 ± 5) Measure the absorbance of the solutions in the same photometric cell (6.8) as the samples at 540 nm against the blank obtained in 7.4 Plot the chromium(VI) concentrations in micrograms per millilitre (μg/ml) against the absorbance measured Plot the chromium(VI) concentration on the x-axis and the absorbance on the y-axis In interlaboratory tests, the 40 mm cell (6.8) proved to be most suitable The standard solutions described above are intended for analysis using a 40 mm cell In some cases, however, it may be suitable to use higher or lower cell path length Care shall be taken to ensure that the calibration range used is within the linear measuring range of the spectrophotometer 7.6 Determination of the recovery rate I n f l u e n c e o f t h e m a t r i x The determination o f the recovery rate is important to provide in formation about possible matrix e ffects which can influence the results Spike a 10 ml aliquot of the solution obtained in 7.2 with a suitable volume of chromium(VI) solution to increase the chromium concentration by up to 10 mg/kg Select the concentration o f the spiking solution in that way that the final volume o f the spiked solution is maximum 11 ml Treat this solution in the same way as the sample (recording the absorbance as A1s and A 2s) (See 7.3.) The absorbance of the solution shall be within the range of the calibration curve, otherwise repeat the procedure using a smaller aliquot The recovery rate shall be greater than 80 % NOTE If the added chromium(VI) is not detected, this is an indication that the leather contains reducing agents In some cases, i f the recovery rate according to 7.6.2 is greater than 90 %, and a fter intensive considerations, this leads to the conclusion that this leather has no chromium(VI) content (below detection limit) NOTE The recovery rate is an indicator o f whether the procedure works or whether matrix e ffects are a ffecting the results Normally, the recovery rate is greater than 80 % I n f l u e n c e o f t h e S P E m a t e r i a l ( 6.9) Pipette a volume of solution (5.5) which corresponds to the chromium(VI) content of the leather into a 100 ml volumetric flask and make up to volume with extraction solution (5.1) Treat this solution in the same way as the leather extract Determine the content in this solution in the same way as that o f the leather extract and compare with the calculated content In cases where no chromium(VI) was detected in the leather sample, the concentration of the solution shall be μg/100 ml The recovery rate shall be greater than 90 % I f the recovery rate is equal to or lower than 90 %, the SPE material is not suitable for this procedure and shall be substituted © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Calculation and expression of results 8.1 Calculation of chromium(VI) content w Cr ( VI ) ( A1 = where A2 ) ⋅ V0 ⋅ V4 ⋅ V2 V1 ⋅ V3 ⋅ m ⋅ F (1) − is the mass fraction, expressed in milligrams per kilogram (mg/kg), of extractable chromium(VI) in leather; is the absorbance of sample solution with DPC; is the absorbance of sample solution without DPC; is the gradient of calibration curve ( y/x is the mass of the leather sample taken, expressed in grams (g); is the extract volume of the initial sample, expressed in millilitres (ml); is the aliquot taken from the extract volume of the initial sample, expressed in millilitres (ml); is the total eluate (S1) volume, after passage through the SPE column, to which the aliquot V1 was made up, expressed in millilitres (ml); is the aliquot taken from solution S1 , expressed in millilitres (ml); f f S1 , expressed in millilitres (ml) wCr(VI) A1 A2 F ) , expre s s e d i n m i l l i l itre s p er m icro gram (m l/μg) ; m V0 V1 V2 V3 V4 i s the fi na l ma ke -up volu me o the a l iquo t rom Re s u lt b a s e d on d r y matter: w Cr ( VI ) where D D= - = dry i s the 100 100 − (2) w Cr ( VI ) ⋅ D fac tor for convers ion to d r y matter: (3) w where w is the mass fraction of the volatile matter determined using ISO 4684, expressed as a percentage 8.2 Recovery rate (according to 7.6.1) η = where ( A1 s − A s ) − ( A1 − A ) ⋅ 100 ρ ⋅ F (4) η i s the re cover y rate, expre s s ed i n p ercent (%) ; ρ is the mas s concentration o f chromium( VI ) s piked, expres sed in micrograms per millilitre (μg/ml) ; F i s the grad ient o f c a l ibration c u r ve, expre s s e d i n m i l l i l itre s p er m ic ro gram (m l/μg) ; A1s is the absorbance of solution after adding chromium(VI) and DPC; © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) A 2s A1 A2 is the absorbance of solution after adding chromium(VI), but without adding DPC; is the absorbance of sample solution with DPC; is the absorbance of sample solution without DPC 8.3 Expression of results The chromium(VI) content is given in milligrams per kilogram (mg/kg) rounded to the nearest 0,1 mg T he content i s b as e d on d r y matter T he vol ati le matter, de term i ne d accord i ng to I S O 4, i s given i n p ercent (%) rou nde d to the ne are s t ,1 % The extraction matrix for leather is complex (for example due to coloration) and results below be considered mg/kg In the case of levels of chromium(VI) being detected above mg/kg, the UV/VIS spectrum of the test solution should be compared with a standard solution (5.5) to determine whether the positive result is due to interfering substances mg/ kg show a la rge vari ation a nd have l i m ite d rel iabi l ity; there fore the l i m it o f quanti fic ation shou ld Test report The test report shall include the following information: a) the chromium(VI) content(s) obtained from 8.1 to the nearest 0,1 mg/kg; b) a reference to this document, i.e ISO 17075-1:2017; c) a description of the sample tested and details about sampling (7.1 f d) the cell length used, if not 40 mm; ), i ne ce s s a r y; e) the volati le matter o f the le ather i n p ercent (%) to the ne a re s t ,1 %; f) the re cover y rate i n p ercent (%) i f lower than % or h igher tha n % ; g) de ta i l s o f a ny deviation s © ISO 2017 – All rights reserved from the pro ce du re ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Annex A (informative) Solid phase extraction (SPE) material I f coloured substances, e.g dyes, are co-extracted in the extraction process in remove these potentially inter fering substances from the extraction solution 7.2 , it is necessary to Experience has shown that various types o f solid phase extraction materials packed in small columns can e fficiently remove the coloured substances The amount o f extracted coloured substances from leather can di ffer depending on the dye application and fixation process It is important that the co-extracted dye is removed by the SPE column material Examples of suitable SPE materials 1) : — in interlaboratory trials, cartridges with g RP (C18) material and Dionex cartridges (Dionex OnGuard® RP) have been tested; — other suitable cartridges are supplied by Waters (WATERS Sep-Pak® Plus tC18); — also suitable SPE material is a cartridge with activated magnesium silicate, e.g Florisil® In order to remove the coloured substances, in some cases it is advisable to use more than g of SPE material or other phases In any case, the recovery rate has to be tested very care fully Activated charcoal proved to be unsuitable for the decolourization of the extracts 1) Dionex OnGuard® RP, WATERS Sep-Pak® Plus tC18 and Florisil® are examples of suitable products available commercially This in formation is given for the convenience o f the users o f this document and does not constitute an endorsement by ISO o f these products © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Annex B (informative) Accuracy Re s u lts ob tai ne d Tables B.1 and B.2 from two s ep arate i nterlab orator y tria l s c arrie d out in 07 a re i l lu s trate d in Table B.1 — Precision data from trial for two types of leathers Values in milligrams per kilogram (mg/kg) Chromium(VI) content a a b Repeatability b 7,04 7,83 Reproducibility b 1,58 1,11 3,22 3,54 M e a n va lue s P % , fac to r , Table B.2 — Results of trial for one type of leather Laboratory 1001a 1002a 1006a 1007a 1008a 1009a 1010a 501a 504a 505a 507a 508a 512a 2892a 2893a 2894a Chromium(VI) content 19,40 20,60 21,80 19,00 25,00 19,20 16,80 20,90 22,00 15,20 24,10 20,60 18,70 18,40 16,40 19,40 mg/kg 18,70 21,30 22,20 18,00 24,30 17,80 13,60 20,60 20,00 14,70 23,40 19,50 15,40 19,00 16,40 19,30 Mean value 19,3 21,7 21,8 21,0 24,9 18,3 13,7 18,1 19,00 16,2 25,7 21,1 16,5 — — 18,9 mg/kg 19,13 21,20 21,93 19,33 24,73 18,43 14,70 19,87 20,33 15,37 24,40 20,40 16,87 18,70 16,40 19,20 M e a n va lue : 19, m g/ kg Unce r ta i nty: , m g/ kg Ta ki ng i nto account the data d i s playe d i n as mg/kg for the mean value © ISO 2017 – All rights reserved Figure B.1 , the l i m it o f quanti fic ation o f the me tho d i s defi ne d ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Key X f Y measurements uncertainties associated to the mean value mean values o F 10 i g u r e B — the interlab o rato ry tes ts (2 0 to 0 ) G r a p h i c a l d e t e r m i n a t i o n o f t h e q u a n t i f i c a t i o n l i m i t o f t h e C r ( V I ) t e s t m e t h o d © ISO 2017 – All rights reserved ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) Annex C (informative) Comparison between the colorimetric method (ISO 17075-1) and the ionic chromatography method (ISO 17075-2) The data in Table C.1 participating laboratories One cut leather sample with an unknown amount of chromium(VI) was have b e en ob tai ne d in an i nterlab orator y tri a l (S ep temb er 01 ) with 13 ana lys e d Table C.1 — Interlaboratory results from a leather sample using the colorimetric method (ISO 17075-1) and the ionic chromatography method (ISO 17075-2) Colorimetric method (ISO 17075-1) Standard deviation mg/kg 3,71 0,93 Mean © ISO 2017 – All rights reserved Ionic chromatography method (ISO 17075-2) Standard deviation mg/kg 2,56 1,17 Mean 11 ISO 17075-1:2017(E) IULTCS/IUC 18-1:2017(E) ICS 59.140.30 Price based on 11 pages © ISO 2017 – All rights reserved