Flameless atomic absorption spectroscopy of plasma chromium.

A flameless atomic absorption spectroscopy method has been developed for the measurement of chromium. Background correction has been modified by recording non-atomic absorption separately from atomic absorption on a double-pen recorder. This was achieved by using the prime spectral line of uranium (358.5 nm, within 0.6 nm of that of chromium--357.9 nm) and was possible only because of the absence of uranium from the plasma samples. Masking of the analytical signal at atomisation by non-atomic absorption was thus eliminated and gave the method a sensitivity of 3 pg and a detection limit of 150 pg/ml. Postprandrial plasma chromium values were measured in 32 insulin-treated diabetics (1.65 +/- 0.15 ng/ml), in 53 non-insulin treated diabetics (2.0 +/- 0.16 ng/ml), and in 144 control non-diabetics (2.00 +/- 0.14 ng/ml). The difference between the mean plasma chromium level of the insulin-treated diabetics and both the non-insulin treated diabetics and the control groups was statistically significant (P < 0.05).