title: Development of a sensor for calcium based on quartz crystal microbalance.
abstract: A new sensor for calcium based on a piezoelectric quartz crystal is presented. The selectivity depends on the ratio lipophilic salt/ionophore of the composition of the coating of the quartz crystal. A crystal coated with a THF solution of PVC (34.5% w/w), DOS (62.1% w/w) and 10,19-bis[(octadecylcarbamoyl) methoxyacetyl]-1,4,7,13,16-pentaoxa-10,19-diaza cycloheneicosane (3.4% w/w) and a salt/ionophore molar proportion of 60%, corresponding to a frequency decrease of the dry crystal of 6.0 kHz, showed a detection limit to calcium of 2.2 mg/L. Both a standard calcium chloride solution and a commercially balanced salt solution for tissue culture were analyzed subsequent to ion chromatographic separation. The results obtained with the sensor developed were compared with those obtained with a conductivity detector. Although the results from both detectors agreed for the standard solution, only the quartz crystal sensor was able to give reliable results for the tissue culture solution.
authors.affiliation: Department of Chemistry, University of Aveiro, Portugal. mtgomes@dq.ua.pt
authors.forename: M T
authors.initials: MT
authors.lastname: Gomes
authors.forename: K S
authors.initials: KS
authors.lastname: Tavares
authors.forename: J A
authors.initials: JA
authors.lastname: Oliveira
mesh_terms: D002118:Calcium / Q000032:analysis*; D002122:Calcium Chloride; D003470:Culture Media / Q000737:chemistry*; D046508:Culture Techniques; D004492:Edetic Acid; D004563:Electrochemistry / Q000379:methods; D011791:Quartz; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003470:Culture Media; D011791:Quartz; D004492:Edetic Acid; D002122:Calcium Chloride; D002118:Calcium