Indicator for calcium

Potential central nervous system indications for calcium channel antagonists... 

Calcium is titrated with EGTA (l,2-bis-(2-amminoethoxyethane N,N,N, N -tetracetic acid) in the presence of the zinc complex of zincon as indirect indicator for calcium. Theoretical titration curves are calculated by means of the computer program HALTAFALL in order to assess accuracy and precision. The method gives a relative precision of 0.00028 when applied to estuarine water of 0.05-0.35% salinity. 

Aberg, G., Jacks, G., Wickman, T. Hamilton, P. J. (1990). Strontium isotopes in trees as an indicator for calcium availability. Catena, 17, 1-11. 

The logarithm of the formation constant of calmagite with calcium is 6.1, a smaller value than with magnesium. The effect of this difference is that the conditional formation constant is not large enough at a pH of about 10 for calmagite to act as a sensitive indicator for calcium (Figure 11-8). Consequently, for a sharp end point in... 

What are some indications for calcium channel blocker use ... 

Figure 49-3 Metal loch romic indicators for calcium and chelators for calcium and magnesium.

Methods Based on Indicators for an Added Metal Ion When a good, direct indicator for the analyte is unavailable, a small amount of a metal ion for which a good indicator is available can be added. The metal ion must form a complex that is less stable than the analyte complex. For example, indicators for calcium ion are generally less satisfactory than those we have described for magnesium ion. Consequently, a small amount of magnesium chloride is often added to an EDTA solution that is to be used for the determination of calcium. In this case, Eriochrome Black T can be used in the titration. In the initial stages, magnesium... 

Measures to enhance elimination from the bloodstream by hemodialysis or multiple-dose activated charcoal have not been shown to be effective and are not indicated for calcium channel blocker... 

The dependence of RET on proximity has been used to develop indicators for calcium. One example used a pep-... 

One of the widely used indicators for calcium is Eriochrome Black T which is a sulfonated, o,o -dihydroxy azo dye that can be represented by the formula H2ln. The dissociation of the two protons can be represented by the equations ... 

Procardia XL. Procardia XL extended-release capsules, marketed by Pfizer Labs Division of Pfizer, Inc., contain nifedipine [21829-25-4] a calcium channel blocker of mol wt 346.3. The extended release tablet is formulated as a once-a-day controlled release capsule for oral adrninistration dehvering either 30, 60, or 90 mg nifedipine. Procardia XL is indicated for use in the management of vasospastic angina, chronic stable angina, and hypertension (see Cardiovascularagents). 

Calcichrome. This indicator, cyclotris-7-( l-azo-8-hydroxynaphthalene-3,6-disulphonic acid), is very selective for calcium. It is in fact not very suitable as an indicator for EDTA titrations because the colour change is not particularly sharp, but if EDTA is replaced by CDTA (see Section 2.26), then the indicator gives good results for calcium in the presence of large amounts of barium and small amounts of strontium.13... 

Notes. (1) The usefulness of the HHSNNA indicator for the titration of calcium depends upon the fact that the pH of the solution is sufficiently high to ensure the quantitative precipitation of the magnesium as hydroxide and that calcium forms a more stable complex with EDTA than does magnesium. The EDTA does not react with magnesium [present as Mg(OH)2] until all the free calcium and the calcium-indicator complex have been complexed by the EDTA. If the indicator is added before the potassium hydroxide, a satisfactory end-point is not obtained because magnesium salts form a lake with the indicator as the pH increases and the magnesium indicator-lake is co-precipitated with the magnesium hydroxide. 

The indicator calcichrome (see Section 10.48) is specific for calcium at pH 11-12 in the presence of barium. 

Calcium was present throughout at 0.5 mol m. NaCI and KCl were present at 10 mol m and ABA at 25 mmol m" where indicated. For excision treatment root tips (1 cm) were incubated in 0.5 mol m CaCl2. All measurements were taken after 24 h of the appropriate treatment. 

Figure 5.11 (Crisp Wilson, 1974b) shows the time-dependent variation of the concentration of soluble ions in setting and hardening cements. Note that the concentrations of aluminium, calcium and fluoride rise to maxima as they are released from the glass. After the maximum is reached the concentration of soluble ions decreases as they are precipitated. Note that this process is much more rapid for calcium than for aluminium and the sharp decline in soluble calcium corresponds to gelation. This indication is supported by information from infrared spectroscopy which showed that gelation (initial set) was caused by the precipitation of calcium polyacrylate. This finding was later confirmed by Nicholson et al. (1988b) who, using Fourier transform infrared spectroscopy (FTIR), found that calcium polyacrylate could be detected in the cement paste within one minute of mixing the cement. There was no evidence for the formation of any aluminium polyacrylate within nine minutes and substantial amounts are not formed for about one hour (Crisp et al, 1974).

The P-blockers propranolol and timolol are FDA-approved for migraine prophylaxis, but other drugs in the class are also as effective.46 Cautious dosage titration is advised for those patients who do not have other indications for P-blocker use. Rizatriptan interacts with propranolol and thus dosages must be titrated downward, or another triptan chosen for abortive therapy.36 Comorbid reactive airway disease is a relative contraindication to P-blocker prophylaxis, and patients with cardiac conduction disturbances should be closely monitored. Calcium channel antagonists are often used when patients cannot tolerate P-blockers. They are purported to beneficially... 

Hormone-replacement therapy is also indicated for the prevention of osteoporosis but is not recommended for longterm use. Alternatives such as bisphosphonates or raloxifene should be considered as first-line therapy for the prevention of osteoporosis, in addition to appropriate doses of calcium and vitamin D. 

Calcium can be used as an indicator for selective carbonate dissolution. Its concentration in the extracts is limited either by its content in the carbonate phase (at low pHs and/or low carbonate content of the soil) or by the acid capacity of the extracting solution (at higher pHs and/or higher carbonate content in the soil). The interplay of these factors is clearly shown in Fig. 4.2. 

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