Dept of Chemistry by Tarmizi

WEEK ONE UNTIL WEEK FIVE
JAN 03, 2011 – FEB 02, 2011
DEPARTMENT OF CHEMISTRY, PENANG.

At this Department of Chemistry, I was placed at the Mycotoxin Service Centre. This centre is also related to the food because the analysis has done to the mycotoxin that present in the food such as peanuts, grains and milk. The mycotoxins are new and interesting things that I must learned at here. The analyses that always do are to detect the Aflatoxin (B and G) in the peanut product, Aflatoxin (M1) in the milk, Ochratoxin A (OTA) and Zearalenone (ZON) in the corn, barley, grain and wheat flour. The food samples are basically come from Ministry of Health, Hospital/Department of Health, and Department of Veterinary.


The first analysis was doing is Determination Organophosporus (OP) in Fruits and Vegetables QuEChERS Method. This experiment is doing to identify the level of OP that use in the fruits/vegetables by running
the extract of sample using Gas Chromatography (GC). Then, the second analysis was doing is Determination of the Aflatoxin B and G in the Peanuts based product. There are eight sample that must be to extract such as kacang tumbuk, peanut butter, kacang manis, pau kacang and others including two spiking sample that must spike with Afla BG standard 1ppm and 5 ppm which must be running using the Fluorescence Detector High Perfomance Liquid Chromatography (HPLC). Based on the Food Act 1983, the maximum level that allowed in microgram per kilogram for the peanuts (Alfatoxin B and G) is 15, milk (Alfatoxin M1) is 0.5 and others finish product that have mycotoxins is 5.


My supervisor, Mr. Nor Shifa Bin Shuib give me the two project that I must have done during my industrial training. The first project is “Determination of Deoxynivalenol (DON) in the Raw Wheat, Wheat Flour
and Wheat Based Products. The selected molds that produce DON is Fusarium graminearium and the food susceptible to contamination are wheat, corn, barley, malted barley and oat. When the people consume
the high level of this DON toxin the effect to the health is damage to digestive tract, bone marrow, spleen, weight loss, vomiting and fees refusal.


 So, the preparation to this project was starting from week two until week six. Before analyze DON by using the Ultra-Violet Detector HPLC, there are some procedure that must be follow. Firstly, the Ultra-
Violet Spectrophotometer must be calibrating to determine the Correction Factor (CF) in the range 0.95-1.05. When measuring of CF in that range, the calibration of DON standard was doing to identify the
absorbance and maximum wavelength (highest peak) which using in the set up the wavelength at the UV Detector HPLC. The absorbance can be use to measure the concentration of the DON standard before diluted with Acetonitrile (ACN) until 10ppm and 20ppm.


The samples that I was collected are wheat grain, barley, oat, yellow noodles, instant noodle, and wheat flour. There are two procedures to determine the DON in food which are extraction and the Immunoaffinity
Column (IAC). For the extraction method, the 25g sample was added with the 5 g Polyethylene Glycol (PEG) and 100ml purified water. The mixture was blended for 1 minute and filter via the filter paper and
then, via the micro fiber filters paper. For the IAC, the 2ml of extract sample was pipette into the column and wash with 5ml purified water. The excess water removes and pushes the air until the column dry. Then, 1ml of HPLC Grade Methanol was pipette into the column to collect elute into the vial. The vial was drying using the nitrogen gas and pipette the 1 ml Injection Solvent [Water (9): ACN (1)] into the vial, ad then shake the vial homogenize.


Before run the sample, the DON standard must be prepared first. The 0.5ml of 20ppm DON standard is pipette into vial and dry using the nitrogen. Then, 1 ml of IS was added into vial and shake completely.
The DON standard is ready to run and determine the peak of the standard. After determine the peak of DON standard, the vial of food samples can be run using the UV detector HPLC. The retention time for
DON standard is at 5.24 minutes. From the foods samples that run, the entire samples show no peak (negative) at this retention time. I assume that the DON in the sample are absent or present in little
amount that cannot be detected using the HPLC because no sensitive. There are some precaution step protection equipment that must be follow up because there are handling the solvent and chemical compound
when doing the analysis such as wearing the gloves, mask, use the fume cupboard and others.


At here, I was learned the application of the HPLC, UV Spectrophotometer and others equipments that used for the analysis. The all staff at this department is nice and friendly (especially girl..huhu) to teach me the new and the procedure that I didn’t know to do. There are no foreign workers especially “abg la”…just have the sweet black skin people (kulit hitam manis) because the area of “anak mami”…huhu…

Please wait for the next post in my second project..=D

Dept of Chemistry by Farhana

Assalamualaikum & Good Day..

It’s a bit late to share my experience in this group, but I’ll continue updating it after this. ^-^
Doing practical in DOC, for sure it is 100% research-oriented. Every branch in Malaysia has at least 8 labs. But in Penang, only four will carry out food-related analysis (Food Lab, Mycotoxin Lab, IKTD Lab, &
Microbiology Lab).


Food Section provides three main services;
        1) Additives & contaminants (major)
        2) Standards & specifications (nutrition labeling)
        3) Pesticide residue.


But for now, pesticide analysis already is in charge of Mycotoxin Lab. Halal analysis not offered here. If there are any Halal-related cases, it will be sent to HQ (Petaling Jaya) for DNA analysis. Some urgent
cases like foreign matters analysis (especially those involve pest like cockroach) or melamine cases also will be referred straight to HQ as it equipped with better technique and equipment.



These are brief list of my activities in DOC through January
(Week1 – Week4):



1)      Learn safety rules & equipment
I have been taught to choose suitable PPE (Personal Protective Equipment) according to experiment. For common analysis, we can use latex gloves and mask. But when handling hazardous chemical, face
shield, glass/goggle and respirator are applied. Nitrile gloves and carbon-free mask even recommended. Lab workers also must know how to operate and check efficiency of emergency response equipment (eye-wash
station, shower, fire blanket).


2)      Learn basic handling of apparatus & equipment
Although it looks simple, but not all peoples know how to use common apparatus in correct way, include me.  Sometimes due to inadequate equipment, we don’t have the opportunity to handle the apparatus in
lab session. So, I do recommend our faculty to do basic lab skill workshop (practically) for our junior (maybe senior also…).


3)      Compile most of test method manual used in DOC
For DOC, each method is continually validated and improved. Modification will be done by HQ if there is any better analytical method.
 

4)      Be involved in handling of food sample sent by client
•     Important client: Health Department, army, private company
•     Food sample registered and described in sample forms and worksheet
•      Case determined formal/informal or urgent/TUL/common
•     Unused sample stored in storage room (in cabinet/oven/freezer/ chiller)
•     After analysis, calculation and result compiled with worksheet
•     Status of case determined (compiled or not)
•     Duplicate test done for non-compiled case
•     Sample used disposed and result sent to client (For army cases, result:30 days after sample sent, other cases: 50 days)


5)      Analysis of heavy metal by using AAS
This is my major task in Food lab, but still focusing on dried form sample. Previously, the analysis is done by Mr.Ramli, but he just transferred to HQ. Most food sample is tested for presence of Pb and Cd by using Avanta software. Examples of common sample received are sardines in tomato sauce, milk powder, MSG, dried squid, and energy drink.

From 15 samples, only one (dried seaweed) is not complied in term of its cadmium level. Duplicate test must be carried out in this case. For mercury analysis in food, mercury analyzer is used as alternative. AAS only used for non-food analysis of mercury. Until now, Food Lab has remaining 52 samples to be analyzed with AAS.


6)      Analysis of foreign matter by using FTIR
The sample is tamarind paste, which contaminated with plastic and hair. By using OMNIC software, absorbance curve are obtained (FTIR is the simplest equipment I ever handled). After ATR and baseline
correction done, result compared with library database. The plastic detected as polyethylene and polypropylene. But the hair shown result for wheat gluten flour. So, it was sent to Criminalistic lab for
better analysis (also to check whether it is animal or human hair)


7)      Research Project : Determination of Boric Acid in Noodles by using UV- spectrophotometer
For this project, alcoholic turmeric extract will be used as indicator in qualitative test. If cherry-red color formed, the sample can be preceded to quantitative test by using UV-spectrophotometer.  But I
still stuck in the calibration of Boron standard solution. Personally, I do think it such a difficult project. I heard that previous practical student also got this project, give up and change her research last minute (she even crying, which make me want to do it too … T-T). Dealing with extra-hazardous (everything is highly
concentrated), plus highly unstable chemicals, we already taken maximum safety precaution. Yet the result of standard graph remained fluctuated (I already repeated it 7X).          I will continue trying, and maybe request another research project at the same time as alternative. But handling 500ml concentrated H2SO4 by my own in preparation of Carmine reagent is such a great experience (shaking so much, but feel like newly-born after do that...hehe).


My Plan for February activities
     Continue research project of boric acid
     Planning for alternative research project (any suggestion?)
     Carry out wet sample analysis wit AAS
     Learn operation of GC (determination of % alcohol in wine, rum, gin, & vodka)