• British Pharmacopoeia Volume IV
  • Appendices
  • Appendix I A. General Reagents

Magnesium Oxide R1
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Magnesium Oxide R1 MgO  =  40.31

Use a grade of commerce that complies with the following tests.

Arsenic Dissolve 0.5  g in a mixture of 5  ml of water and 5  ml of 7m hydrochloric acid . The resulting solution complies with the limit test for arsenic , Appendix VII (2  ppm).

Heavy metals Dissolve 0.75  g in a mixture of 3  ml of water and 7  ml of 7m hydrochloric acid . Add 0.05  ml of phenolphthalein solution and sufficient 13.5m ammonia to produce a pink colour. Neutralise the excess ammonia by adding glacial acetic acid , add 0.5  ml in excess, dilute to 15  ml with water and filter if necessary. 12  ml of the solution complies with limit test A for heavy metals , Appendix VII (10  ppm). Use a mixture of 5  ml of lead standard solution (1 ppm Pb) and 5  ml of water to prepare the standard.

Iron Dissolve 0.2  g in 6  ml of 2m hydrochloric acid and dilute to 10  ml with water. The resulting solution complies with the limit test for iron , Appendix VII (50 ppm).