Off-line automated sample preparation--experience in a clinical drug investigation unit.

The authors describe an evaluation of the Du Pont Prep. off-line automatic centrifugal sample processing system, used in the authors' Drug Investigation Unit over the past two years. In comparison to liquid-liquid extraction, the authors found that assay precision has generally been improved, absolute recovery was quantitative, reliability has been good and the use of the system has resulted in notable labour saving. However, the cost per test based on a seven-year amortization of capital cost shows that the system is more expensive. Assays for urinary opiates, serum tricyclic antidepressants, serum isoxicam, serum valproate, serum metoclopramide and serum pindolol are presented and the merits of the method are compared with those for manual liquid-liquid extraction procedures.

The blunder-rate in a clinical biochemistry service.

We describe a study undertaken to investigate the frequency and type of mistake detected in a large biochemistry laboratory. Blunders were recorded over three non-consecutive 3-week periods. The returns to the external quality assessment schemes during a 12-month period were also monitored. Despite changes in laboratory practice, the nature of the errors found has not altered substantially from those described by earlier investigators. The detected blunder rate was 0.3%.