=====SOP FOR FORMALIN PREPARATION AND BOUIN’S FLUID PREPARATION=====
**1. PURPOSE OF EXAMINATION:** To lay down the procedure for preparation of 10% buffered formalin &Bouin’s fluid for tissue fixation in Histo-pathology section at NCHLS Surat.

**2. PRINCIPLE AND METHOD OF PROCEDURE USED FOR EXAMINATION:** Process by which the constituents of the cells and therefore, of tissues, are fixed in a chemical and partly also in a physical state so that they will withstand subsequent treatment with various reagents with a minimum loss, significant distortion or decomposition and keep the tissue in as life like a manner as possible.  

**3. STAFF RESPONSIBLE:** lab. Technician under supervision of resident doctor/tutor.

**4. PERFORMANCE CHARACTERISTICS:** NA

**5. TYPE OF SAMPLE:** NA

**6. PATIENT PREPARATION:**NA

**7. TYPE OF CONTAINER AND ADDITIVES:** Clean, labeled plastic close container

**8. REQUIRED EQUIPMENTAND REAGENTS:**

     ***Formalin:** 40% formaldehyde, tap water, K2Hpo4, NaH2po4, 
     ***Bouin’s fluid:** Picric acid, Formaldehyde, acetic acid.

**9. ENVIRONMENTAL AND SAFETY CONTROLS:**
**Universal safety precautions**
   -**CALIBRATION PROCEDURE ( METROLOGICAL TRACEBILITY):**NA
   -**PROCEDURE(STEPS):**
**Buffered Formalin Preparation: (20 liter buffered formalin)**
  *Take 2 liter of 40% formaldehyde solution in one big container
  *Add 18 liter of tap water in container containing 40% formaldehyde.
  *Mix well and add 130 gm K2HPO4 and 80 gm NaH2PO4
  *Mix well till all ingredients have dissolved.
  *Store this solution in closed container for use. 
**Bouin’s Fluid Preparation: 100 ml**
  *Take 75 ml picric acid in one beaker.
  *Add 25 ml of 40% Formaldehyde. 
  *Add 5 ml Acetic acid in it.
  *Mix well and store in closed container.

**10. QUALITY CONTROL PROCEDURE:**NA

**11. INTERFERENCE:** Inadequate quality/improper dilution

**12. PRINCIPLE OF PROCEDURE FOR CALCULATING RESULTS INCLUDING, WHERE RELEVENT, THE MEASUREMENT OF UNCERTAINITY OF MEASURED QUANTITY VALUES:** NA

**13. BIOLOGICAL REFERENCE INTERVALS OR CLINICAL DECISION VALUES OR CLINICAL DECISION VALUES:**NA

**14. REPORTABLE INTERVAL OF EXAMINATION RESULTS:** NA

**15. INSTRUCTION FOR DETERMINING QUANTITATIVE RESULTS WHEN RESULTS IS NOT WITHIN THE MEASUREMENT INTERVAL:**NA

**16. ALERT /CRITICAL VALUES WHERE APPROPRIATE:** NA

**17. LABORATORY CLINICAL INTERPRETATION:**NA

**18. POTENTIAL SOURCE OF VARIATION:** NA

**19. REFERENCE:** Histopathological laboratory techniques by Bancroft, 6th edition