Chloride in milk

In animals, high doses of soluble tin salts induce neurological dismrbances. Subcutaneous injection of animals with sodium stannous tartrate at a daily dose of 12.5mg/kg was fatal. Death was preceded by vomiting, diarrhea, and paralysis with twitching of the limbs. Daily administration to a dog of stannous chloride in milk at a level of 500mg/kg produced paralysis after 14 months. ... 

Van Staden reported a rapid, reliable automated method for direct measurement of the chloride content in milk based on the principles of flow injection analysis and the use of a dialyser to remove interferents. Dialysed chloride was measured by means of a coated tubular chloride ion-selective electrode. Potential changes arising from the interference of casein were thus avoided and baseline stability ensured. The results obtained for chloride in milk compared well with those provided by standard recommended methods. The linear range for chloride was 250-5000 pg/mL for 30 pL of sample, and the coefficient of variation was better than 0.5%. The throughput was ca. 120 samples/h [132],... 

J. F. van Staden, Flow-Injection Analysis of Chloride in Milk with a Di-alyzer and a Coated Tubular Inorganic Chloride-Selective Electrode. Anal. Lett., 19 (1986) 1407. 

Helmerson 2881, and more recently Bartels 2891, determined chloride in serum by adding excess silver and then measuring the excess silver ion in the filtrate. Ezell 29°) used a similar procedure to determine chloride in plant liquors and Gutsche etal.29 determined chlorine in milk by measuring the excess silver by flame photometry. 

The most remarkable observation is that all 22 minerals considered to be essential to the human diet are present in milk. Some of these are sodium (Na), potassium (K), and chloride (Cl). The electroneutrality of milk is maintained by free ions (negatively charged to lactose). 

Di(2-ethylhexyl) phthalate is ubiquitous in the general environment as a result of its widespread use in poly(vinyl chloride) products. It is found in ambient air at levels usually below 100 ng/m. The highest levels of di(2-ethylhexyl) phthalate in foods are found in milk products, meat and fish and in other products with a high fat content, where concentrations up to 10 mg/kg have been reported. The leaching of di(2-ethyl-hexyl) phthalate Ifom flexible plastics used in medical devices, such as during dialysis and transfusion, can result in large direct exposures. 

Figure 5.3 Changes in the concentration of chloride in bovine milk during lactation.

For the purpose of this discussion, milk salts are considered as ionized or ionizable substances of molecular weight 300 or less. Ionizable groups of proteins are not included here, although, of course, they must be taken into account in a complete description of ionic balance and equilibria. Trace elements, some of which are ionized or partially so in milk, are considered in a later section of this chapter. Milk salts include both inorganic and organic substances thus they are not equivalent to either minerals or ash. The principal cations are Na, K, Ca, and Mg, and the anionic constituents are phosphate, citrate, chloride, carbonate, and sulfate. Small amounts of amino cations and organic acid anions are also present. 

The milk lipase system is reported to be activated by mercuric chloride. Raw milk preserved with corrosive sublimate sometimes contains a much larger concentration of free fatty acids that do unpreserved samples. Pasteurized milk preserved in a similar fashion does not show an increase in free fatty acids (Manus and Bendixen 1956). 

Willart, S. and Sjostrom, G. 1959. The effect of sodium chloride on the hydrolysis of the fat in milk and cheese. 15th Int. Dairy Congr. Proc. 3, 1482-1486. 

Direct conductivity measurements do not provide a satisfactory index of added water in milk. However, it has been reported (Rao et al. 1970) that measurement of conductivity in nonaqueous solvents can be useful in detecting adulteration. The conductivities of extracts using two different solvent systems were correlated with the percentage of added water in the original milk. One solvent system consisted of 10 ml acetone and 90 ml methanol plus 3 g sodium chloride, and the other contained 2.65 g formic acid in 100 ml acetone. 

Mussenden, S., Hodges, J. and Hiley, P. G. 1977. Sodium and chloride in cows drinking water and freezing point of milk. J. Dairy Sci. 60, 1554-1558. 

Despite important physiological functions and its presence in milk al about 0.I l%. chloride is a neglected element in large animal nutrition. The practice of adding sodium chloride lo concentrate mixtures and free-choice feeding seems to have precluded the possibility of a practical deficiency problem. When salt was omitted from the diet, researchers found that under the conditions used in their study, sodium was the first limiting element. This was true because sodium is present in most natural ingredients at much lower levels, relative lo the cow s requirements, than is chloride. 

Oilier examples of this type of reaction are file conversion of the antibiotic streptomycin sulfate to its corresponding chloride hy means of anion exchange, the exchange of Na ions in milk for the K ion. and the conversion of NaCKdj to H CiOi by cation exchange The latter process is used extensively in the plaling industry to concentrate ICCrO, Iron rinse waters, with subsequent reuse of a toxic chemical ami reuse of ihe rinse water in what might be termed a closed system. 

Determinative and confirmatory methods of analysis for PIR residue in bovine milk and liver have been developed, based on HPLC-TS-MS (209). Milk sample preparation consisted of precipitating the milk proteins with acidified MeCN followed by partitioning with a mixture of -butylchloride and hexane, LLE of PIR from aqueous phase into methylene chloride, and SPE cleanup. The dry residue after methylene chloride extraction was dissolved in ammonium hydroxide, and this basic solution was transferred to the top of Cl8 SPE column. The PIR elution was accomplished with TEA in MeOH. For liver, the samples were extracted with trifluoroacetic acid (TFA) in MeCN. The aqueous component was released from the organic solvent with n-butyl chloride. The aqueous solution was reduced in volume by evaporation, basified with ammonium hydroxide, and then extracted with methylene chloride. The organic solvent was evaporated to dryness, and the residue was dissolved in ammonium acetate. The overall recovery of PIR in milk was 94.5%, RSD of 8.7%, for liver 97.6%, RSD of 5.1 %. A chromatographically resolved stereoisomer of PIR with TS-MS response characteristics identical to PIR was used as an internal standard for the quantitative analysis of the ratio of peak areas of PIR and internal standard in the pro-tonated molecular-ion chromatogram at m/z 411.2. The mass spectrometer was set for an 8 min SIM-MS acquisition. Six samples can be processed and analyzed in approximately 3 hours. 

This is formed of the nitrogenous substances (casein, albumin) and fats contained in milk, separated by coagulation (by rennet or by acidification). As a result of special fermentations which occur during the maturation of the cheese, these give rise to soluble albuminoid substances (albumoses, peptones, etc.), amino-adds (phenylaminopropionic add, tyrosine, leucine, etc.), ammoniacal products, fatty adds (lactic, propionic, caproie), etc. Cheese also contains water and mineral salts, including added sodium chloride. 

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