An impurity in water has an extinction coefficient of 3.45 × 103 M-1 cm-1 at 280 nm, its absorption maximum (A Closer Look, p. 564). Below 50 ppb, the impurity is not a problem for human health. Given that most spectrometers cannot detect absorbance's less than 0.0001 with good reliability, is measuring the absorbance of water at 280 nm a good way to detect concentrations of the impurity above the 50-ppb threshold?