Ion selective electrode measurement of Ca2+ in chemical solutions used to extract calcium from plant tissue.
Jobin-Decor, M. P.; Joyce, D. C.; Hofman, P. J.;
Proceedings of the Australasian postharvest horticulture conference 'Science and technology for the fresh food revolution', Melbourne, Australia, 18-22 September, 1995. Year: 1996 Pages: 5-8 Ref: 6 ref.
1996
บทคัดย่อ
The performance of a Ca2+-selective electrode in various extractants (water, 2.5 M sodium chloride, 2% acetic acid and 5% hydrochloric acid) was investigated. Ca was measured in these extractants and in their 10-, 100- and 1000-fold dilutions. pH ranges for the various extractants were 5.9-6.1, 5.6-6.1, 2.6-4.2 and 0.6-3.5, respectively, with pH increasing with dilution. Strong linear relationships were obtained in all solutions between electrode signal (mV) and pCa over the ranges 3.9-2.4 (1.25x10-4-4.0x10-3 moles Ca2+/litre) and 4.2-3.1 (6.0x10-5-7.5x10-4 moles Ca2+/litre). For the various solutions, lines had similar slopes (28.5 mV/pCa) but different intercepts (mV). Intercepts for the pCa 3.9-2.4 range were -6.0, +3.1, -12.0 and -19.5 mV for water, sodium chloride, acetic acid and hydrochloric acid, respectively. In diluted sodium chloride and acid solutions the intercepts approached that in water (-6.0 mV). The results suggest that an ion-selective electrode could be used to measure Ca in
water-, sodium chloride- and acid-extracts of fruit tissues.