Spectrometric determination of silicon in food and biological samples: an interlaboratory trial

Accuracy and precision of silicon determination in biological matrices (ser um, urine, water, beer and spinach) by spectrometric techniques (when neces sary after acid destruction) were assessed by means of a collaborative inte rlaboratory trial. The trial was set up in accordance with ISO 5725-2 (1994 ). The relative overall repeatability standard deviation was acceptable. It varied between 4% for spinach powder (mean content: 176 mg kg(-1)) and 11% for serum (mean content: 5.33 mg L-1). On the other hand, the relative ove rall between-laboratory standard deviation was found to vary from a satisfa ctorily 15% for spinach after destruction (mean content: 3.32 mg L-1) to an unacceptable 107% for spinach powder (mean content: 176 mg kg(-1)). The ov erall conclusion of the trial was that silicon determination in biological matrices can properly be performed by spectrometric techniques. However, wh en sample pretreatment (i.e., acid destruction) is needed prior to silicon determination problems still remain.