ISO 16740 pdf download – ISO 16740 pdf Workplace air – Determination ofhexavalent chromium in airborneparticulate matter – Method by ion chromatography and spectrophotometric measurement using diphenyl carbazide.
If deswed, total hexavalent ciroinium can be measured directly using the sodiirn hydroxidefsodium carbonate extraction solution.
5 Reactions
Post-column derivatization involves reaction of hexavalent chromium with 1 ,5-diphenylcarbazide ID produce tflvalent chromium and daphenylcarbazone, These then combine to form a trivalent chromiumdiphenylcarbazorie complex containing the characteristic magenta chromagen (A1 = 540 nm). However, the exact mechanism of this reaction is not fully understood.
6 RequIrement
The measurement procedure shall comply with any relevant international, European or national standard which specifies performance requirements for procedures for rneasunng chemical agents In workplace air (e.g.
EN 482 (SI)
7 Reagents
During the analysis, use only reagents of recognised analytical grade. and only water as specified in 7.1
7.1 Water, complying with the requirements for ISO 3696 grade 2 water (electrical conductivity less than
0,1 mSm 1 and resistivity greater than 001 Mi-m at 25 C).
It is recommended that the water used be obtained from a water purification system that delivers ultrapure water having a resistivity greater than 0,18 MQ.m (usually expressed by manufacturers of water purification systems as IS Mt.cm).
7.2 SulfurIc acid (H2S04), concentrated, p 1.84 g.ml 1, mass fraction = 98%.
WARNING — Concentrated sulfuric acid Is corrosive and causes bums. Avoid exposur, by contact with the skin or eyes. Use suitable personal protective equipment (Including suitable gloves, face shield or safety spectacles, etc.) when working with concentrated or dilute sulfuric acid. Fumes produced when concentrated sulfuric acid is heated are irritant. Therefore, carry out procedures with sulfuric acid In a fume hood. Exercise great caution when dilutIng sulfuric acid with water, sInce this process Is very exothermlc. Do not add water to sulfuric acid, since It reacts violently when mixed In this manner. Prepare sulfuric acldlwater mixtures by adding sulfuric acid to water.
7.3 Nitric acid (HNO3), concentrated, p = 1.42 g.ml 1, mass fraction = 70%.
WARNING — Concentrated nitric acid Is corrosive and oxidizing, and nitric acid fumes are Irritant. Avoid exposure by contact with the skIn or eyes, or by InhalatIon of fumes. Use suItable personal protective equipment (including suitable gloves, face shield or safety spectacles, etc.) when working with the concentrated or dilute nitric acid, and carry out procedures with concentrated nitric acid in open vessels in a fume hood.
7.4 Nitric acid, diluted 1 to 10.
Carefully and slowly add 50 ml of concentrated nitric acid (7.3) to 450 ml of water (7.1) in a 1-litre polypropylene boule (8.2.3.1). Add the acid In small aliquots. Between additions, swirl to mix and run cold tap water over the side of the bottle to cool the contents, Do not allow tap water to contaminate the contents of the bottle. When addition of the concentrated nitric acid Is complete, swirl the bottle to mix the contents, allow to cool to room temperature, dose the bottle wilh its screw cap and mix thoroughly.
7.5 Ammonium sulfate I(NH4)2S04]. mass fraction of ammonium sulfate 99,5 %.
7.6 Ammonium hydroxide solution (NH4OH). concentrated, p 0.9 gmr1. mass tractIon 29% of ammonia (NH3).
WARNING — Concentrated amnionlum hydroxid. solution causes bums and Is Irritating to the respiratory system. Avoid exposure by contact with the skin or eyes, or by inhalation of the vapour. Use suitable personal protective equipment (including suitable gloves, face shield or safety spectacles, etc) when working with the concentrated ammonium hydroxide solution, Handle open vessels containing concentrated ammonlum hydroxide solution In a fume hood.
7.7 Sodium carbonate (N82CO3), anhydrous, mass fraction of sodium carbonate . 99,9 %.
7.8 Sodium hydroxide (NaOH). pellets, purity> 99,5%.
WARNING — Sodium hydroxide causes bums and is Irritating to the respiratory system. Avoid exposure by contact with the skIn or eyes, or by Inhalation of the dust. Use suitable personal protective equipment (including suitable gloves, face shield or safety spectacles, etc.) when working with the sodium hydroxide pellets or concentrated sodium hydroxide solutions.
7.9 1 ,5-Diphenylc.arbazide (C6H5 NH-NH)2C0. mass fraction of I ,5-diphenylcarbazide> 98 %.
7.10 Methanol (CH3OH). HPLC grade
7.11 PotassIum dlchromate (K2Cr2C)7), mass fraction of potassium d.chromate> 99.9 %.
7.12 ExtractIon solutions
7.12.1 Soluble hexavalent chromium extraction solution concentrate, animonium sulfate I(NH4).2S041. c= 0,5 molt 1lammonium hydroxide (NH4OH), = 0,5 md11.
Dissolve 66 g of ammonium sulfate (7.5) in approximately 500 ml of water (7.1). Quantitatwely transfer the solution into a 1-litre one-mark volumetric flask (82.2.2), add 32,5 ml of concentrated ammoniLxn hydroxide (7.6) and swirl to mix. Dilute to the mark with waler, stopper and mix thoroughly.
7.12.2 Soluble hexavalent chromium extraction solution, ammonium siifate I(NHthSO4J. (c -0.05 md.[’)lammonium hydroxide, pH 8.
Add 100 ml of soluble hexavalent chromium extraction solution concentrate (7.12.1) tO a 1-litre one.mark volumetric flask (82.2.2), dilute to the mark with water (7.1), stopper and mix thoroughly.
ISO 16740 pdf download – ISO 16740 pdf Workplace air – Determination ofhexavalent chromium in airborneparticulate matter – Method by ion chromatography and spectrophotometric measurement using diphenyl carbazide
