Natural gypsum, in the form of small chippings, was obtained from British Gypsum
(East Leake, Leicestershire, UK). The material was prepared using a jaw crusher
fitted with hardened chromium steel jaws to provide a powder, nominally 3 mm
maximum diameter. The crushed material was dried at 30 °C in a calibrated drying
oven. After drying, the material was milled until the powder passed a calibrated
75 µm stainless steel sieve mesh.
This reference material is intended for use in the validation of new methods, and for
monitoring the performance of methods commonly used in laboratories to analyse
samples of gypsum for quality control and environmental monitoring purposes.
Certified Value
Mercury .................................. 1.35 ± 0.40 µg/kg
Assessed Values
Aluminium (as Al
2
O
3
) ....... 2.872 ± 0.056 g/100 g Silicon (as SiO
2
) ............ 10.93 ± 0.22 g/100 g
Calcium (as CaO) .............. 26.31 ± 0.36 g/100 g Sodium (as Na
2
O) ....... 0.183 ± 0.018 g/100 g
Iron (as Fe
2
O
3
)................. 1.150 ± 0.062 g/100 g Sulfur (as SO
3
) .............. 34.67 ± 0.60 g/100 g
Phosphorus (as P
2
O
5
) .. 0.0367 ± 0.0052 g/100 g Titanium (as TiO
2
) ... 0.1480 ± 0.0075 g/100 g
Potassium (as K
2
O) ......... 0.830 ± 0.024 g/100 g Loss on Ignition ............. 19.78 ± 0.71 g/100 g
Nickel ........................................ 9.5 ± 2.0 mg/kg Zinc ..................................... 19.3 ± 3.8 mg/kg
Vanadium ................................ 21.3 ± 3.2 mg/kg
Indicative Values
Magnesium (as MgO) ...................... 3.2 g/100 g Strontium (as SrO) ..................... 0.20 g/100 g
Manganese (as MnO) .................. 0.030 g/100 g
Arsenic .............................................. 2.4 mg/kg Copper ........................................... 5.0 mg/kg
Barium .............................................. 170 mg/kg Lead ............................................... 4.2 mg/kg
Chromium ........................................... 15 mg/kg Thallium ....................................... 0.18 mg/kg
Cobalt ................................................ 3.8 mg/kg
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