Dear Debasree Purkayastha, 

The most common method for chitin extraction from insects involves two steps, an acidic step to remove catechols and a basic step to remove the cuticle proteins. Generally, the acidic treatment conditions used for extraction from insects are moderate in comparison to crustacean exoskeletons. The reason for this is that insects have low levels of inorganic material (less than 10%) as compared to crustacean shells (20–40%).

Isolation of Chitin from Adult H. parallela

Adult H. parallela were captured in July in peanut fields in the suburbs of Qingdao, Shandong Province, China, as part of the usual control of this pest. The beetles were starved for 48 h to eliminate gut contents, washed with water and killed by freezing. They were allowed to thaw at room temperature and then air-dried at 50 °C for 2 days. The dried beetles were milled to a powder to pass through a 20-mesh screen and stored at 4 °C in airtight containers. The powder (5 g) was treated

with 1 M HCl solution (250 mL) at 100 °C for 30 min to remove minerals and catechols. The demineralization step was followed by rinsing with distilled water until neutrality was reached. Deproteinization was performed using alkaline treatment with 1 M NaOH (250 mL) solution at 80 °C for 24 h, and the product was washed with distilled water until the pH became neutral. For the purpose of

decolorization, the precipitate was treated further with 1% potassium permanganate solution (100 mL) for 1 h. Finally, lightly brown chitin was washed with distilled water and dried at 50 °C in a dry heat sterilizer.

 Infrared Spectra (IR) Analysis

Chitin samples were characterized from 4,000 to 400 cm−1 by infrared spectrophotometry (WGH-30/30A, Gangdong Technology Ltd., Tianjin, China) in KBr pellets. Commercial chitin from shrimp (Sigma) was used as standard. The DA of both chitin samples was determined by comparing the absorbance of the measured peak to that of the reference peak. The DA was calculated from the

absorbance (A) ratios according to the following equation:

DA = (A1655/A3450) × 100 (1)

Elemental Analysis

Elemental analysis was performed using a Vario EL III analyzer (Elementar, Hanau, Germany) at the Institute of Chemistry, Qingdao University of Science and Technology according to the standard operation procedures provided by the manufacturer.

X-ray Chitin Powder Diffraction

XRD analysis was used to detect the crystallinity of chitins prepared, and their patterns were recorded using a D/Max-rA diffractometer (Rigaku, Tokyo, Japan) with Cu radiation at the Institute of Chemistry, Qingdao University of Science and Technology. Data were collected at a scan rate of 1°/min with the scan angle from 5° to 40°. The crystalline index (CrI) was determined by the following equation:

Molecules 2012, 17 4610 CrI110 = [(I110 − Iam)/I110] × 100 (2)

where I110 is the maximum intensity at 2θ ≌ 20° and Iam is the intensity of amorphous diffraction at 2θ ≌ 16°.

Scanning Electron Microscopy (SEM)

The surface morphology of chitin was examined with JSM-6700F scanning electron microscope (JEOL, Tokyo, Japan) at the Institute of Chemistry, Qingdao University of Science and Technology. The dried samples were ground, fixed on an adhesive tape and then coated with a thin gold layer by a sputter coater. The SEM was conducted at 5.0 kV.

 Composition Analysis

Moisture and ash were assayed according to the Association of Official Analytical Chemists methods (AOAC, 2006) (AOAC methods 934.01 and 942.05). Nitrogen content was measured by the Kjeldahl method (AOAC method 984.13).

Zhang, M.; Haga, A.; Sekiguchi, H.; Hirano, S. Structure of insect chitin isolated from beetle larva cuticle and silkworm (Bombyx mori) pupa exuvia. Int. J. Biol. Macromol. 2000, 27, 99–105.

Majtan, J.; Bilikova, K.; Markovic, O.; Grof, J.; Kogan, G.; Simuth, J. Isolation and characterization of chitin from bumblebee (Bombus terrestris). Int. J. Biol. Macromol. 2007, 40, 237–241.

https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi-ptPRg9rNAhVIDsAKHZwMD9MQIAgiMAA&url=http%3A%2F%2Fwebcache.googleusercontent.com%2Fsearch%3Fq%3Dcache%3AhmweWBh7tusJ%3Awww.mdpi.com%2F1420-3049%2F17%2F4%2F4604%2Fpdf%2B%26cd%3D1%26hl%3Den%26ct%3Dclnk%26gl%3Dit&usg=AFQjCNEkw1vpgRRInFsmsO9RP26ET-pLPA

https://www.google.it/search?biw=1366&bih=643&q=related:https://www.researchgate.net/publication/24272034_Estimate_of_chitin_in_raw_whole_Insects+methods+to+isolate+and+estimate+chitin+in+insects&tbo=1&sa=X&ved=0ahUKEwi-ptPRg9rNAhVIDsAKHZwMD9MQHwgsMAE

Hoping this will be helpful,

Rafik

Article Estimate of chitin in raw whole Insects

thank u sir. can u please suggest me nay colorimetric method for chitin estimation. 

Dear Debasree,

The publication contained in the following link describes a colorimetric method for chitin determination:

Appl Environ Microbiol. 1983 Jul; 46(1): 13–16.

PMCID: PMC239259

Improved Colorimetric Determination of Cell Wall Chitin in Wood Decay Fungi

George C. Chen and Bruce R. Johnson

Author information ► Copyright and License information ►

This article has been cited by other articles in PMC.

Abstract

The Svennerholm modification of the Elson-Morgan method for glucosamine analysis was evaluated for its applicability to the rapid determination of chitin in wood decay fungi. The evaluation included extent of chromogen interference, sensitivity, color stability, and hydrolysis conditions for maximum release of glucosamine from fungal cell walls. With our further modification, the Svennerholm method was shown to be suitable for rapid quantitative determination of fungal chitin without chromatographic separation of hydrolysate chromogens.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC239259/

Hoping this will be helpful,

Rafik