@article{okumura_seike_fujinaga_hirao_1997, 
  title={In situ Preconcentration Method for Iron(II) in Environmental Water Samples Using Solid Phase Extraction Followed by Spectrophotometric Determination.}, 
  volume={13}, 
  DOI={10.2116/analsci.13.231}, 
  publisher={Japan Society for Analytical Chemistry}, 
  author={OKUMURA and SEIKE and FUJINAGA and HIRAO}, 
  year={1997}
  }