The determination of magnesium in biological fluids and tissues by flame spectrophotometry.

A flame spectrophotometric method for estimating magnesium in biological fluids and tissues is described. It may be applied to the Zeiss spectrophotometer PMQ II with flame attachment. Interferences are small, and recoveries from plasma and urine and from ashed faeces, soft tissue, and bone are satisfactory. Calcium can be measured on the same dilutions of plasma and urine and faecal ash. Sodium, potassium, calcium, and magnesium can be estimated on the same dilutions of soft tissue and bone ash. The plasma magnesium concentration of normal subjects falls within a narrow range. Differences between mean normal values previously reported may be partly attributed to the magnesium salt used in preparation of standard solutions.