Veterinary Clinical Biochemistry and Laboratory Diagnosis-II

ESTIMATION OF SERUM CHLORIDE (Mercuric thiocyante method)

Principle:

Chloride ions react with a solution of mercuric thiocyanate and ferric nitrate to form undissociated mercuric chloride and a red brown ferric thiocyanate complex, which is quantitatively proportional to the chloride ion concentration.

                            2 Cl^- + Hg (SCN)₂ → HgCl₂ + 2 (SCN)^-

                            3 (SCN)^- + Fe³⁺ → Fe (SCN)₃

Reagents:

• Color reagent (Mercuric thiocyante, Mercuric chloride, Ferric nitrate, Nitric acid, stabilizers, Surface active agents & inactive ingredients)
• Chloride standard (100 mmol/l)

Procedure:

Pipette into two clean, dry test tubes labelled blank (B), standard (S), and test (T) as follows:

S.No	Reagents	B	S	T
1.	Chloride Reagent	1.0 ml	1.0 ml	1.0 ml
2.	Standard Chloride	-	10 m l	-
3.	Serum	-	-	10 m l
4.	Deionised water	1.5 ml	1.5 ml	1.5 ml

Mix well, wait for 1 minute at room temperature and read the absorbance of standard (S) and test (T) against blank at 510nm or with a green filter in a photoelectric colorimeter within 60 minutes.

Calculations :

Chloride (mmol/L) =                    O.D (T)

                                                     ----------- x 100

                                                         O.D (S)

Result:

The Chloride content of given serum = mmol / l or meq / l

Clinical Significance:

• Chloride is a major extra cellular anion, which is significantly involved in the maintenance of water distribution, osmotic pressure and cation-anion balance in the extra cellular fluid compartment.
• High serum values may be observed in dehydration and in conditions causing decreased renal blood flow such as congestive heart failure.
• Low values may be observed in salt-losing nephritis, diabetic acidosis and renal failure. Lower CSF chloride values may be seen in meningitis, especially untreated tubercular meningitis.