Report from SIMS XVIII

The eighteenth meeting on Secondary Ion Mass Spectrometry, SIMS XVIII, was held last week in Riva del Garda, Italy. The meeting has been held biannually starting in 1977. As Nicolas Winograd pointed out in the opening lecture, it is a testament to the importance and vibrancy of the field that such a specialized meeting has continued to thrive. SIMS XVIII attracted nearly 400 participants divided roughly equally between Asia, the Americas, and Europe, with Asia being the somewhat largest third and the Americas the smallest.

I was pleased to see an increase in the number of papers that utilized multivariate analysis (MVA) in general and PLS_Toolbox and MIA_Toolbox in particular. In her talk, “Critical Issues in Multivariate Analysis of ToF SIMS Spectra, Images and Depth Profiles,” Bonnie Tyler noted that the number of publications in SIMS utilizing MVA is currently exponentiating, a trend which started about 10 years ago. Interestingly, I first taught a course utilizing SIMS data in 2001 at the Sanibel Island ASMS Meeting. That said, I still saw plenty of presentations and posters with 8-12 images at different AMUs that all looked the same: instances where PCA would result in a drastic reduction in the number of images to review plus some corresponding noise reduction.

Interesting talks where our software was used included:

• “ToF-SIMS Technique for Nano-Surface Analysis of Biosensors and Tissues” by Tae Geol Lee, Ji-Won Park, Sojeong Yun, Heesang Song, Hyegeun Min, Hyun Jo Jung, Taek Dong Chung, Ki-Chul Hwang, Hark Kyun Kim, Dae Won Moon and Daehee Hwang
• “Development of ToF-SIMS Enzyme Screening Assays” by Robyn Goacher, Elizabeth Edwards, Charles Mims and Emma Master
• “Evaluation of white radish sprouts growth influenced by magnetic fields using TOF-SIMS and MCR” by Satoka Aoyagi, Katsushi Kuroda, Ruka Takama, Kazuhiko Fukushima, Isao Kayano, Seiichi Mochizuki and Akira Yano
• “Multivariate Image Analysis of Chemical Heterogeneities Observed in Microarray Printed Polymers” by David Scurr, Andrew Hook, Daniel Anderson, Robert Langer, Morgan Alexander and Martyn Davies

I presented “Deconvolving SIMS Images using Multivariate Curve Resolution with Contrast Constraints,” by myself and Willem Windig. The talk demonstrated how in MCR contrast can be maximized in either the estimated spectra or concentrations/images. The solutions for each of these cases will give an indication of the range of solutions in the given MCR problem which all fit the data equally well. In many instances, one of the two solutions will be preferred, or both may be interpretable to illustrate different features of the data.

SIMS XVIII also included another installment of our “Chemometrics in SIMS” course. I was happy to present this course to another eager group of future chemometricians!

The SIMS XVIII conference was a great success. The technical program was very interesting and went off without a hitch. Riva del Garda is a beautiful location, perhaps the most scenic conference venue I have experienced. Congratulations to the organizers! I’m already looking forward to SIMS XIX in Jeju Island, Korea in 2013.

BMW