Standardless semiquantitative analysis of metals using single-shot laser ablation inductively coupled plasma time-of-flight mass spectrometry

A method has been developed that allows the accurate, standardless measurem ent of the elemental composition of metal samples from single laser ablatio n (LA) pulses. This technique provides a fast, low-sample-consumption means for the characterization of samples having a range of matrixes. The method directly compares adjusted elemental signals with the total mass spectrome tric signal to produce relative percent composition information. Three math ematical techniques were used to determine the accuracy and precision of si ngle-shot LA measurement. Comparison of the techniques showed that a linear regression calculation, which plots individual elemental signals as a func tion of the summed signal for all elements in the sample on a point-by-poin t basis during a laser ablation transient proved superior. The simultaneous extraction capability of time-of-flight mass spectrometry permits the samp ling of all analytes from any temporal position within the transient laser ablation pulse, thereby reducing quantitation error. A typical concentratio n dynamic range of 3 orders of magnitude, from 0.1 to 100%, was achieved. H owever, by measuring low-abundance isotopes for matrix elements, the dynami c range of the technique was extended to 4 orders of magnitude. The new tec hnique is largely immune to sample matrix effects commonly experienced in l aser ablation, By performing a complete elemental analysis from a single ab lation pulse, high spatial resolution should be achieved.