GB 14883.4-2016Examination of radioactive materials for foods -- Determination of promethium-147 (English PDF)

3.1 Reagents

3.1.1 two - (2-ethylhexyl) phosphoric acid (C16H35O4P). also known as double iso-octyl phosphate, chemically pure.

3.1.2 n-heptane (C7H16).

3.1.3 hydroxylamine hydrochloride (NH2OH · HCl).

3.1.4 anhydrous sodium acetate (C2H3NaO2).

3.1.5 Uranium reagent III (C22H18As2N4O14S2).

3.1.6 monochloroacetic acid (C2H3ClO2).

3.1.7 Uranium reagent I (C16H11AsN2Na2O11S2).

3.1.8 Ammonium thiocyanate (NH4SCN).

3.1.9 butanone (C4H8O).

3.1.10 absolute ethanol (C2H6O).

3.1.11 hexamethylenetetramine (C6H12N4).

3.1.12 nitric acid (HNO3).

3.1.13 sulfosalicylic acid (C7H6O6S · 2H2O).

3.1.14 ascorbic acid (C6H8O6).

3.1.15 2,4-dinitrophenol (C6H4N2O5).

3.2 Reagent preparation

3.2.1 hydroxylamine hydrochloride - sodium acetate buffer. 1L of water was added to hydroxylamine hydrochloride and 9g 10g of anhydrous sodium acetate, pH adjusted with nitric acid solution to 1.5.

3.2.2 a buffer acid - a mixture of uranium reagent III. the 1.00g dissolved uranium reagent III 120mL1mol/L sodium hydroxide solution.

In a 500mL water dissolve 100g acid, mixing the two, diluted with water to 1L.

3.2.3 eluent. Add 2.5g 300mL ammonium thiocyanate in methyl ethyl ketone was added 4mL of water and dissolved, stirring constantly added 3mL of concentrated nitric acid. Use the supernatant.

3.2.4 uranium reagent layer was I agent. Weigh 0.10g uranium reagent I, dissolved in 35mL saturated aqueous solution of hexamine, diluted with anhydrous ethanol to 100mL, mix, clarified and filtered. When using a volume of about 150mL prosper in the nebulizer.

3.3 Standard

147Pm standard solution. radioactive decay intensity of about 1 × 103/(min · mL).

3.4 Standard Solution

Neodymium, samarium standard solution. Weigh accurately spectroscopically pure neodymium oxide (Nd2O3) and samarium oxide (Sm2O3) each 1.0000g, was dissolved in a small amount of concentrated nitric Acid, with 0.5mol/L nitrate formulated into 1L, this solution per ml of stock standard solution containing 1.0mg of each Nd2O3 and Sm2O3. With shift Pipette accurately Pipette 10.0mL standard stock solution was diluted to 100mL with 0.5mol/L nitrate. This solution per milliliter and Nd2O3 Sm2O3 100µg of each standard solution.

5.2 Determination of counting efficiency

147Pm various amounts of standard solution (200 decays/min ~ 1500 decays/min) at five 50mL beaker was added thereto in 0.5mL neodymium, samarium standard solution. 5.4.13 analysis in accordance with the source system and under the same conditions were beta radioactivity measured in a sample. In computer processing or at the graph paper beta counting rate and the actual radioactivity of the sample drawing, the slope of the line is the counting efficiency 147Pm.

5.3 Sampling and pretreatment

Sampling and pretreatment according to the provisions of GB 14883.1.

5.4 Preparation of sample and assay

5.4.1 Weigh 5g ~ 10g (accurate to 0.001g) in 150mL food gray porcelain crucible, accurate added neodymium, samarium standard solution of 1.0mL.

Ash moistened with water after adding 5mL ~ 10mL 3mL of nitric acid and hydrogen peroxide, evaporated to dryness on a sand bath, 600 °C 30min ashing in a muffle furnace.

5.4.2 cooling to room temperature, 50mL of nitric acid was added, covered with a watch glass and heated to boiling, 5mL of hydrogen peroxide was added dropwise and then heated 15min. from Heart, and the supernatant was poured into a 200mL beaker. The residue was then 40mL of nitric acid and hydrogen peroxide heated 3mL leaching, centrifugation. With 20mL water the residue was washed by centrifugation. The combined supernatant was discarded residue.

5.4.3 added to the supernatant 4g ~ 6g oxalic acid (for a small amount of calcium-containing foods, such as found in oxalate precipitation too little calcium can be added to an appropriate carrier body). The solution was adjusted with ammonia to pH 1.5, water bath 20min, cooled and filtered. Precipitated together with the filter paper into 100mL porcelain crucible. carbon After the burning of high-temperature furnace at 600 °C 1h.

5.4.4 cooling to room temperature, 30mL of nitric acid was added and heated to boiling. 2mL ~ 3mL was added dropwise hydrogen peroxide, and heating continued for 15min, and filtered.

Successively washed with nitric acid and 10mL water. Insolubles were discarded and the filtrate was collected in the 150mL beaker.

5.4.5 To the filtrate was added 500mg of hydroxylamine hydrochloride and 450mg of anhydrous sodium acetate with aqueous ammonia solution was adjusted to pH 1.5.

5.4.6 The solution flow rate of 2mL/min through a chromatographic column (4.1) with hydroxylamine hydrochloride 20mLpH1.5 - the sodium acetate buffer solution to wash Fandi chromatographic column, discard the effluent. With 40mL2mol/L nitric acid to 1mL/min flow rate for rare earths. Effluent was collected in 100mL beaker.

5.4.7 with aqueous ammonia solution was adjusted to pH 9 to 10. Heated to boiling, cooled to room temperature. Medium speed quantitative filter paper with a pH9 ~ 10 Ammonia water.

5.4.8 precipitated together with the filter paper into 5mL crucible. After charring in a high temperature furnace burning 600 °C 20min. After cooling, 10 drops Glass Acid and 2 drops of hydrogen peroxide, sand bath steam until nearly dry. Cooled to room temperature.

5.4.9 instillation of 3 drops 0.1mol/L nitrate, an infrared lamp capillary apply the solution to the colored layer paper coating solution reticle. Then respectively 1 drop and 2 drops of 0.1mol/L nitric crucible washed, the washing liquid is also applied to the reticle. The upper end of the strip of glass hook put emphasis placed chromatography tube Immersed in the eluent containing a large dish.

5.4.10 downstream chromatography time is generally (depending on the room temperature and the degree may be closed barrel) is 40h ~ 80h.

5.4.11 Remove the paper dry. I significant uranium reagent layer agent to strip spray until the blue plaque layer up.

5.4.12 Cut neodymium and samarium two blue spots layer, add 15mL crucible (crucible I). Cut purple paper neodymium and samarium between locus coeruleus Section, into another crucible (crucible II), plus neodymium, samarium standard solution of 0.5mL, after charring two crucibles transferred into a high temperature furnace burning 600 °C 20min. Then cool, add 1mL of nitric acid and 2 drops to 3 drops of hydrogen peroxide on the sand bath steam until nearly dry, cool.

5.4.13 with about 10mL1mol/L nitric acid and 10mL water crucible II contents were transferred into a 50mL beaker. Adjusted with ammonia Solution to pH 9 to 10, heated to boiling, cooled to room temperature. In pad speed quantitative filter paper (phi20mm) removable funnel filtration, with Ammonia water washed pH9 ~ 10's. Remove the paper, dried under an infrared lamp, beta radioactivity measured with a low background beta measuring instrument.

5.5 Determination of the chemical recovery

5.5.1 The crucible I water contents were transferred to a graduated colorimetric tube, dilute with water to 10mL, shake.

5.5.2 Pipette 5mL solution is placed in a volume of 25mL colorimetric tube, add 0.2mL10% sulfosalicylic acid, 0.2mL freshly prepared 1 drop of 1% ascorbic acid and 2,4-dinitrophenol indicator. With 2mol/L sodium hydroxide solution to yellow, then 0.5mol/L hydrochloric acid and to colorless, diluted with water to 15mL, 5mL added a TCA buffer - III uranium reagent mixture. Diluted with water to 25mL, shake uniform. Sheng into 1cm cuvette in the spectrophotometer (lambda = 665nm) absorbance was measured.

5.5.3 isolated on the working curve neodymium, samarium micrograms recovered, divided by neodymium, samarium added in an amount, namely chemical yield of 147Pm.