Mixed gas sample introduction

Calibration techniques for laser ablation-atomization-ionization-excitation-detection 

The existence of reference materials and appropriate calibration procedures are two essential issues to be considered in quantifying the components of a sample. Quantitation has been substantially improved by the commercial availability of an increasing number of certified solid reference materials, especially for low concentration levels. Recently [42], NIST archival leaf standards were used as matrix-matched standards for reliable quantitative elemental analysis of Spanish moss samples. LA-ICP-MS was used with mixing standards in order to produce at least three data points for each calibration curve the results thus obtained were compared with those provided by microwave digestion ICP-MS/AES. Standard addition was also examined and found to be an effective method in the absence of matrix-matched standards. 

An alternative calibration technique was developed and successfully applied to techniques hyphenated to LA [43-48]. In addition, an increasing number of matrix-independent calibration procedures using external reference materials and/or internal standardization procedures is being developed [49-51]. 

Although laser ablation usually dispenses with the need for sample preparation in the analysis of rocks, the use of a major element of the sample as internal standard requires the prior knowledge of its concentration also, the addition of an internal standard element to a rock sample is difficult. Fusion of the sample with Li,B407 allows the use of Li and B as internal standards. Linear calibration graphs (constructed from standard reference geological materials) have thus been obtained for Al, Ca, Fe, K, Mg, Na, Si and Ti, and relative standard deviations of 1-2% n = 12) achieved. 

---