Calcium interferences

The effect of calcium interference is somewhat different. At its concentration in seawater, 0.010 M, calcium ion had no effect upon chemiluminescence analysis of a 6 x 10 8 M Crm solution in the absence of bromide ion. The... 

Experience at Barringer Research Laboratory demonstrated that the most effective method to reduce stray light is to combine several reduction procedures. The lead/calcium selectivity of the instrumentation as received was 160, but this has been increased to greater than 1,000,000 with the manufacturer s modifications. The actual steps included replacement of the calcium 393.3 nm line with the 315.9 nm line, replacement of the lead 405.8 nm line with the 220.3 nm line, installation of an interference filter mask over the lead photomultiplier, and computer correction of the residual calcium interference. The stray light reduction obtained by installation of interference filters is presented for three common concomitants in Table II. In many cases the stray light levels were less than or equivalent to the detection limit. The interference filters and the photomultiplier masks (which reduce the entrance angle to the photomultiplier to include only the receiver mirror) improved the detection limits for many elements in the array by decreasing the system band pass. 

Hallberg, L. (1998). Does calcium interfere with iron absorption Am. J. Clin. Nutr. 68, 3-4. 

Special software was introduced into EEPROM of the Microlyte 6, thus it is called Microlyte Mg, to compensate for calcium interference, the influence of ionic strength and to compensate for liquid junction potential changes, known to influence the quantitative reports on ionized magnesium [3]. 

Zettner and Seligson (Z3) conducted an extensive study of calcium interferences deriving from serum constituents and other substances. In the air-acetylene flame, no effect was seen from excess concentrations of the ions of potassium, ammonium, magnesium, chloride, bicarbonate, and hydroxide. Phosphate, sulfate, oxalate, and EDTA acted as strong anionic depressors. Sodium caused a small but distinct depression of... 

Spector, J., Mutual interferences in elimination of calcium interference in flame photometry. And. Chem. 27, 1452-1455 (1955). 

The level of calcium in the cell is low, about 0.1 //M compared with approximately 1.3 mM outside the cell. The intracellular concentration is kept low by the activity of transport systems which transport calcium out of the cell and sequester it in the mitochondria and endoplasmic reticulum. The plasma membrane thus houses a Ca2+ transporting ATPase, as does the endoplasmic reticulum and nucleus. Calcium may also be stored in the mitochondria, and the intracellular protein calmodulin will bind calcium. Interference with any of these processes may be caused by toxic compounds and can alter calcium homeostasis. This can allow an influx of Ca2+, inhibition of export of Ca2+ out of the cell, or a release of Ca2+ from compartments within the cell. The result of each of these will be a rise of intracellular Ca2+ which can cause a variety of damaging events. 

Problems are sometimes encountered in the use of chelates due to the chelate metal being replaced by other metals in the soil. Sometimes calcium interferes with the utilization of zinc chelates, but this is seldom a major problem because zinc chelates are many times more stable against hydrolysis than are calcium chelates. 

Unfortunately, no lead sensors have been developed to date that meet all of these criteria. The system that has been used most extensively to quantitate lead levels in vivo is the fluorescent sensor Indo-1 (Fig. 24) (443 45). Although originally developed as a calcium dye (446) log iCfc[Ca(II)] = 6.6, Indo-1 (2-[4-[bis(carboxymethyl)amino]-3-[2-[2-[bis(carboxymethyl)amino]-5-methyl-phenoxy]ethoxy]phenyl]-lH-indole-6-carboxylic acid) binds lead quite tightly (log ffo[Pb(II)] = 10.5 and exhibits a very different fluorescence emission spectrum when bound to lead than when free in solution or bound to calcium (Fig. 24). As a result, Indo-1 can be used to determine whether lead is present in cells, even in the presence of excess calcium, provided that the fluorescence spectrum is deconvoluted to account for calcium interference and all of the possible equilibria are taken into consideration (443, 445). The main drawback of the Indo-1 detection system is that the dye is almost completely quenched when bound to lead (Fig. 24, spectrum b), making it difficult to quantitate the amount of free lead present. 

Just how the calcium alters the effects of adrenaline and dobutamine is not known, but since they are both beta-receptor agonists a reasonable suggestion is that calcium interferes with the signal transduction through the beta-adrenergic receptor complex. The clinical importance of these findings is uncertain. 

Xylidyl blue (Magon) Magnesium forms a colored complex with sulfonated Magon in a strongly basic medium. The absorbance maximum of the complex is at 548 nm. Calcium interference is avoided by the addition of ethylene-bis-(oxyethylene-nitrilo)-tetraacetic acid (EGTA) and interference by heavy metals by using cyanide. 

The quest for improved uranyl sensors has rested with ionophores. lonophores suitable for calcium (5) and lithium (28) are subject to sodium and calcium interferences (Table 3.17) whereas amongst newer ones, (34) particularly is considered to provide a UOj device of unrivalled specificity (65). 

Hurley, T. W. Ryan, M. R Brinck, R. W. Changes of cytosolic calcium interfere with measurements of cytosolic magnesium using Mag-Fura-2. Am. J. Physiol. 1992, 263, C300-C307. 

Isotopically enriched iron tablets have been used to study absorption of iron from nutritional sources. Iron is a very problematic element for ICP-MS in biological samples because there are significant interferences from Ar-based and Ca-based molecular ions. Vanhaecke et compared sector-field ICP-MS with a collision cell ICP-MS for the determination of iron isotopes in semm The problem exists mostly because typical levels of calciumin semm are approximately 50 times higher than those of iron. This study found that sector-field ICP-MS at a mass resolution of 3000 allows accurate determination of iron isotope ratios in human serum but only Fe/ Fe ratios could be determined with sufficient accuracy and precision using CO as a reaction gas with a DRC-ICP-MS. This was due to the DRC-ICP-MS not being able to correct for both the argon and calcium interferences. 

The amount of calcium in a sample of urine was determined by a method for which magnesium is an interferent. The selectivity coefficient, Rca.Mg> for the method is 0.843. When a sample with a Mg/Ca ratio of 0.50 was carried through the procedure, an error of-3.7% was obtained. The error was +5.5% when a sample with a Mg/Ca ratio of 2.0 was used. 

Minimizing Chemical Interferences The quantitative analysis of some elements is complicated by chemical interferences occurring during atomization. The two most common chemical interferences are the formation of nonvolatile compounds containing the analyte and ionization of the analyte. One example of a chemical interference due to the formation of nonvolatile compounds is observed when P04 or AP+ is added to solutions of Ca +. In one study, for example, adding 100 ppm AP+ to a solution of 5 ppm Ca + decreased the calcium ion s absorbance from 0.50 to 0.14, whereas adding 500 ppm POp to a similar solution of Ca + decreased the absorbance from 0.50 to 0.38. These interferences were attributed to the formation of refractory particles of Ca3(P04)2 and an Al-Ca-O oxide. 

Analgesic tablets are ground into a fine powder, dissolved in HCl, and analyzed for calcium by atomic absorption. A releasing agent of La + is used to prevent an interference due to the formation of calcium pyrophosphate. 

Calcium Absorption. Phytates in cereal grains have also been reported to interfere with the absorption of calcium. However, a long-term study indicated a retention of calcium in subjects that consume large amounts of bread made with high extraction of flour (19). 

Direct Metal Analyses. Calcium ion can be detected to a lower limit of 10 M hy Aequorea bioluminescence. Strontium interferes to a minor extent (270,271). 

Proteins and Meals. Nutritional properties of the oilseed protein meals and their derived products are deterrnined by the amino acid compositions, content of biologically active proteins, and various nonprotein constituents found in the defatted meals. Phytic acid (3), present as salts in all four meals, is beheved to interfere with dietary absorption of minerals such as 2inc, calcium, and iron (67) (see Food toxicants, naturally occurring Mineral nutrients). ... 

Clinical stresses which interfere with vitamin metabohsm, can result in calcium deficiency leading to osteomalacia and osteoporosis (secondary vitamin D deficiency). These stresses include intestinal malabsorption (lack of bile salts) stomach bypass surgery obstmctive jaundice alcoholism Hver or kidney failure decreasing hydroxylation of vitamin to active forms inborn error of metabohsm and use of anticonverdiants that may lead to increased requirement. 

Calcium and magnesium can be titrated readily with disodium ethylenediaminetetraacetate, with Eriochrome Black T as the indicator. The solution is buffered at pH 10.0. Certain metal ions interfere with this procedure by causing fading or indistinct end points. Cyanide, sulfide, or hydroxjiamine can be used to eliminate or minimise the interferences. 

Theoretically, controUed deposition of calcium carbonate scale can provide a film thick enough to protect, yet thin enough to allow adequate heat transfer. However, low temperature areas do not permit the development of sufficient scale for corrosion protection, and excessive scale forms in high temperature areas and interferes with heat transfer. Therefore, this approach is not used for industrial cooling systems. ControUed calcium carbonate deposition has been used successhiUy in some waterworks distribution systems where substantial temperature increases are not encountered. 

The calcium antagonists interfere with the entry of calcium through the membrane slow calcium channel and therefore prevent intraceUular calcium... 

Health and Safety Factors (Toxicology). Manufacture of cyanamide and calcium cyanamide does not present any serious health hazard. Ingestion of alcohoHc beverages by workmen within several hours of leaving work sometimes results in a vasomotor reaction known as cyanamide flush. Cyanamide interferes with the oxidation of alcohol and accumulation of acetaldehyde probably accounts for this temporary phenomenon. Although extremely unpleasant, it has not been known to result in serious illness or to have any permanent effect. 

Sugar Processing. Dispersants are used in the production of cane and beet sugar to increase the time between evaporator clean outs. Typical scales encountered include calcium sulfate, calcium oxalate, calcium carbonate, and silica. Dispersants are fed at various points in the process to prevent scale buildup, which would interfere with efficient heating of the vessels. Only certain dispersants, conforming to food additive regulations, can be used, since a small amount of the dispersant may be adsorbed on the sugar crystals. 

Hardness Calcium, magnesium, barium and strontium salts expressed as CaCOa Chief source of scale in heat exchange equipment, boilers, pipe lines, etc. forms curds with soap interferes wKh dyeing, etc. Softening, distillation, internal boiler water treatment, surface active agents, reverse osmosis, electrodialysis... 

Hardness Calcium and magnesium salts in the forms of CaCOj, Ca, Mg. This is the primary source of scaling in heat exchange equipment, boilers, pipelines/transfer lines, etc. Tends to form curds with soap and interferes with dyeing applications as well. 

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