Determination calcium

Calcium, determination by x-ray emission spectrography, 222, 328 in biological samples, determination by monochromatic x-ray absorption-edge method, 299-301 in biological sections, determination by x-ray absorption-edge method, 293, 294... 

In patients on EDTA therapy, calcium cannot be determined by the Indirect colorimetric or fluorometrlc methods based on the chelation of a calcium - EDTA complex. However, In calcium determinations by atomic-absorption spectroscopy, the complexlng agent Is destroyed In the flame and the direct concentration of calcium can be determined. 

Two new chromogenic crown ether derivatives based on an identical design principle have been synthesized. The lipophilic KBC-002 shown in Figure 23 is a useful new chromo- ionophor for the highly selective calcium determination with cation exchange type optode53. 

Patients should be closely monitored with frequent serum phosphorus and calcium determinations, especially if phosphorus is given IV or if renal dysfunction is present. 

Kohman (3) determined that spinach interfered with growth and bone formation. Studies were conducted on 21-day-old rats for 21 or 28 days and body calcium determined. The diets furnished about 0.22% calcium supplied by calcium carbonate, calcium oxalate, 8.2% spinach, or 4.5% turnip greens. The supplements were added to a diet containing meat, peas, carrots, and sweet potatoes. 

Guil. J.L.. Torija. M.E.. Gimenez. J.J.. Rodriguez-Garcia. I., and Gimenez. A. Oxalic acid and calcium determination in wild edible plants. J. Agric. Food Chem., 44(7) 1821-1823. 1996. 

Samples were taken from each solution after incubation for calcium determination. Samples of the collagenase incubations were assayed for hydroxyproline. 

Selected entries from Methods in Enzymology [vol, page(s)] Cellular calcium determination, 238, 73, 146, 298 calibration,... 

Adults-500 mg to 1 g at intervals of 1 to 3 days, depending on response of patient or serum calcium determinations. 

Thus if 2 g soil were taken instead of 5 g, an additional factor of x 5/2 should be used. If the sample solution for calcium determination was diluted 5 ml solution plus 15 ml M ammonium ethanoate reagent before addition of 1 ml releasing agent, then an additional factor of x 4 will be necessary. 

Frequent urine and serum calcium determinations (breast cancer)... 

A. Moreno-Cid and M. C. Yebra, Continuous ultrasound-assisted extraction coupled to a flow injection-flame atomic absorption spectrometric system for calcium determination in seafood samples. Anal. Bioanal. Chem., 379(1), 2004, 77-82. 

Considering pressure, a threshold value is found above which the amount of dissolved C02 and (bi)carbonate, together with the dissolved calcium (determined also by L/S ratio) exceeds the calcium carbonate solubility product, such that precipitation can occur. 

Wess, T. J., Purslow, P. P., Sherratt, M. J., Ashworth, J. L., Shuttleworth, C. A., and Kielty, C. M. (1998a). Calcium determines the supramolecular organization of fibrillin-rich microfibrils./. Cell Biol. 141,829-837. 

Gailly, P., Boland, B., Himpens, B., Casteels, R., and Gillis, J.M., 1993, Critical evaluation of cytosolic calcium determination in resting muscle fibres from normal and dystrophic (mdx) mice, Cell Calcium, 14, pp 473 183. 

Wu LG, Betz WJ (1996) Nerve activity but not intracellular calcium determines the time course of endocytosis at the frog neuromuscular junction. Neuron 17 769-79 Zenisek D, Steyer JA, Feldman ME, Aimers W (2002) A membrane marker leaves synaptic vesicles in milliseconds after exocytosis in retinal bipolar cells. Neuron 35 1085-97 Zhou FM, Liang Y, Salas R, Zhang L, De Biasi M, Dani JA (2005) Corelease of dopamine and serotonin from striatal dopamine terminals. Neuron 46 65-74 Zucker RS, Regehr WG (2002) Short-term synaptic plasticity. Annu Rev Physiol 64 355—405... 

Note that instruments 1-4 were photometric devices with less then 0.01 absorbance accuracy evaluated against reference neutral filters at 546 nm and A = 1.000, traceable to INM. The bandwidth provided by the interference filters equipping the absorption photometers was within the range of 4-10 nm. Instrument 5 was a 10 nm bandwidth photometric device with less than 1.0% absorbance linearity, evaluated at 405 nm and 500 nm, against liquid absorbance RMs type 16.02 and 16.03 [5], Enzymatic colorimetric methods for determination of glucose and urea were used. The o-cresoftalein colorimetric method was used for calcium determination. 

Some analysts prefer to conduct calcium determinations in a nitrous oxide-acetylene flame to minimize the risk of interferences, and this is a sound practice. However, the element has a low ionization potential, so that an ionization buffer such as 5 mg ml-1 potassium must then be added. The AES determination in this flame is very sensitive, and gives a lower detection limit than flame AAS. However flame AAS is sufficiently sensitive to meet the needs of most environmental applications. Flame AFS is really only of academic interest for calcium determination. 

Calcium determinations in serum are valuable in the diagnosis of a number of pathologic conditions. Hypocalcemia (low serum calcium) is seen in hypopara-... 

Suitability for Calcium Determinations Dissolve 300 mg in 100 mL of water, add 10 mL of 1 N Sodium Hydroxide and 1.0 mL of a 1 200 calcium chloride solution, and dilute with water to 165 mL. The solution is red-pink. Add 1.0 mL of 0.05 M Disodium EDTA. The solution becomes deep blue. 

K. Ayajiki, M. Kindermann, M. Hecker, 1. Fleming and R. Busse, Intracellular pH and tyrosine phosphorylation but not calcium determine shear-stress induced nitric oxide production in native endothelial cells. Circ Res 78, 750-758 (1996). 

Knoll, E., Hafner, F.W., Dettmer, K. and Wisser, H. (1981). Evaluation of serum uric acid and calcium determinations with the Kodak Ektachem analyzer. J. Clin. Chem. Clin. Biochem. 19, 734. 

Because citrate, oxalate, and EDTA bind calcium and significantly reduce free calcium, heparin is the only acceptable anticoagulant for free calcium determinations. However, heparin, a polyanion, significantly lowers free calcium at the concentrations (30 to 100 U/mL or more) found in many conventional blood gas syringes (Table 49.3).8 - 02,495,496,56 addition, the use of hquid heparin should be avoided it can result in errors in free calcium because of dilution, as well as high and variable concentrations of heparin. 

A number of commercially available syringes containing lyophilized heparin are suitable for free calcium-determinations (1) electrolyte-balanced or calcium-titrated heparin... 

Patient preparation and the manner of specimen collection can significantly alter the results of total and free calcium determinations (see Box 49 4) l23o,469,498,5S9... 

Because of the dependence of free calcium on pH, it is recommended that pH be measured and reported with aU free calcium determinations. This will assist the laboratory and physician in identifying specimens in which inappropriate preanalytical handling has led to an in vitro change in pH. Correction of the free calcium to pH 7.4 may be inappropriate and confusing to the physician. 

Morgan BR, Artiss JD, Zak B. Calcium determination in serum with stable arsenazo III and triglycerides clearing. Clin Chem 1993 39 1608-12. 

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