AMINO-ACID DETERMINATION IN BIOLOGICAL-FLUIDS BY AUTOMATED ION-EXCHANGE CHROMATOGRAPHY - PERFORMANCE OF HITACHI L-8500A

The Hitachi L-8500A is a newly available apparatus for amino acid (AA) analysis that allows automatic on-line mixing of the ninhydrin reagen t. The within-run precision (human plasma pools at three different con centrations) showed CVs <3.8% except for the lowest concentration of c itrulline (4.4%), Tyr (4.5%), and a-aminobutyric acid (7.6%), and for the intermediate concentration of Asp (8.7%). Between-run precision (C V) was <3.1% for 17 AAs and <8.0% for 24 of 25 AAs (CV Asp = 12.0%). F or retention times, within-run precision was <0.4% and between-run pre cision <.1.8%. Excellent relations were found between the results from the Hitachi L-8500A and the widely used Beckman 6300 analyzer (0.929 less than or equal to r less than or equal to 0.999). The detection wa s still linear at 5 mu mol/L except for Pro and hydroxyproline (20 mu mol/L). The upper limit was at least 2500 mu mol/L for 13 AAs and at l east 1000 mu mol/L for 27 of 29 AAs (anserine = 500, Val = 600 mu mol/ L). Values from 100 human plasma samples agreed with previously publis hed data. We conclude that the results obtained with the Hitachi L-850 0A are satisfactory when compared with those of other AA analyzers uti lizing the same method. Furthermore, the Hitachi L-8500A displays seve ral advantages including programming flexibility, microsample capacity , low noise plotting, ammonia filtering, and manual repacking of the a nalytical column.