Document Sample
Suen_Yung_Lee_Lily Powered By Docstoc
					Name: Suen Yung Lee (Lily)
University no.: 2005247081
Group: ECEN2802O
Name of the Journal: Science in Hong Kong.
Name of the article:
High Performance Liquid Chromatography: The Solution to the Detection of Food
Safety Problems

    In recent years, the problem of food safety has been getting more serious in

Hong Kong. From the overuse of preservatives in processed food a few years ago to

the use of non-permitted colourings in Chinese New Year foods recently, many similar

cases have increased public concern over food safety. Fortunately, in Hong Kong, the

Government Laboratory is responsible for the analysis of the food composition, food

additives, contaminants and other harmful substances in food (GL 2007a), so that

harmful substances in food can be discovered and suitable actions can be taken to

protect public health. One of the most common techniques used for food analysis is

the high performance liquid chromatography (HPLC). The purpose of this article is to

discuss how HPLC contributes to solving food safety problems in Hong Kong. The

article begins by explaining the principles of HPLC. It goes on to give examples of

the application of HPLC on the detection of harmful substances in food. Finally, it

discusses how HPLC helps the government protect public health.

    HPLC aims at the separation of every component in a given food sample

(Heftmann 2004), based on the size of the particles of each component (OSUEMSI

2004). It involves the use of two phases: the stationary phase which is immobile, and

the mobile phase which can travel freely (Nielsen 1998). Nowadays, HPLC is carried

out automatically using a machine called “high performance liquid chromatograph” in

the Government Laboratory (GL 2007b) (Figure 1). A liquid which acts as the mobile

phase is pumped from the solvent reservoir through an injector, where the sample is

loaded into the machine by injection in liquid form (OSUEMSI 2004) (Figure 2). The

mobile phase liquid assists the propagation of the liquid sample (OSUEMSI 2004) to

a long, open column packed with a special porous material which serves as the

stationary phase (Nielsen 1998). The separation of components in the sample is based

on the size of the particles of each component. Particles with sizes smaller than the

pore of the packing material can pass through the column rapidly, while those which

are larger than the pore are retained in the column and flow out less quickly

(OSUEMSI 2004). As a result, components of different particle sizes flow out of the

column at different times and are separated. Eventually, each component passes

through a detector which records the amount of the component (OSUEMSI 2004). In

this way, the quantity of food components of different particle sizes can be measured

with HPLC.

Figure 1: A high performance liquid chromatograph (Source:

Figure 2: The components of a high performance liquid chromatograph (Rounds and

Gregory, III, 1998)

     HPLC has been effective in the analysis of harmful substances present in food

products in Hong Kong. For example, with the help of HPLC, the Government

Laboratory successfully discovered the use of nitrate and/or nitrite, which are

preservatives for meat products, above the permitted level in a few traditional Chinese

preserved sausage samples in Hong Kong (CFS 2004) (Figure 3). As nitrites may

react with other components in meat to form a cancer-causing substance called

nitrosamine (CFS 2004), a level of nitrites above the permitted one must not be

allowed. In addition, HPLC helped the Government Laboratory monitor the use of

preservatives and colourings in Chinese New Year foods, for example, steamed

puddings, fried dumplings, seeds and glutinous rice balls (CFS 2000). An analysis

showed that a few steamed puddings contained benzoic acid, a non-permitted

preservative (CFS 2000) (Figure 4). Several samples of steamed puddings and fried

dumplings were also found to contain non-permitted colourings (CFS 2000). The

consumption of these foods may cause adverse health effects. With HPLC, the

Government Laboratory also discovered the types of foods which may pose risks to

the public health, so that suitable actions could be taken to protect the health of Hong

Kong people.

Figure 3: Traditional Chinese preserved sausages found in Hong Kong. Some of the

sausage samples were found to contain amounts of nitrate and/or nitrite above the

permitted level (Source: original).

Figure 4: Steamed puddings, an example of Chinese New Year foods. Some of the

samples collected in Hong Kong contained non-permitted preservatives and

colourings (Source: original).

     The data obtained from HPLC is sent to various government departments in

Hong Kong, for example, the Centre for Food Safety, so that these departments can

give advice to customers and set up guidelines for food manufacturers to ensure

public health. For example, the customers are advised to avoid buying colourful food

products which may contain non-permitted colourings or excess permitted colourings

(CFS 2000). The food manufacturers are educated to add appropriate amounts of

preservatives to food products (CFS 2004). After suitable actions are taken to protect

public health, the data from HPLC is still useful. For example, recently, the

government has used the data on the Chinese New Year foods to give advice to the

public on how to select Chinese New Year foods which are safe to consume (CFS

2007). Not only does HPLC help the Hong Kong government discover problematic

food products, it also allows the government to make plans to minimize the harmful

effects of these food products on public health.

     In conclusion, HPLC has been effective in monitoring the safety of food

products in Hong Kong. It is useful in the separation of different components in food

so that those which are under concern can be analyzed. Based on the results obtained

from HPLC, the government can take action to protect the health of Hong Kong

people. It is expected that the technology of chromatography will continue to improve,

so that it will enhance the efficiency of food analysis by the Government Laboratory.

[CFS] Centre for Food Safety. 2000. Chemical Hazard Evaluation: Use of
     Preservatives and Colouring Matter in Chinese New Year Foods [online].
    _01_04_cny.html Accessed: 2007 Mar 20.
[CFS] Centre for Food Safety. 2004. Chemical Hazard Evaluation: meat curing in
    Chinese cuisine: a risk assessment on Lap-mei [online]. Available:
    _01_03_report.html Accessed: 2007 Mar 19.
[CFS] Centre for Food Safety. 2007. Food Safety Focus [online]. Available:
    21.pdf Accessed: 2007 Mar 20.
[GL] Government Laboratory. 2007a. Government Laboratory home [online].
    Available: Accessed: 2007 Mar

[GL] Government Laboratory. 2007b. Food and Environmental Hygiene B Section
     [online].    Available:
     Accessed: 2007 Mar 18.
Heftmann E, editor. 2004. Chromatography: fundamentals and applications of
     chromatography and related differential migration methods. Amsterdam:
     Elsevier. 518p.
Nielsen SS, editor. 1998. Food analysis. Gaithersburg, MD: Aspen Publishers. 630p.
[OSUEMSI] The Ohio State University Environmental Molecular Science Institute.
     2004.                  HPLC                   [online].              Available: Accessed: 2007
     Mar 19.

References for figures:
(Figure 1) Labomatic. Undated. LABOPREP HPLC workstations [online]. Available: Accessed: 2007 Apr 14.
(Figure 2) Rounds MA, Gregory, III JF. 1998. High Performance Liquid
     Chromatography. In: Nielsen SS, editor. Food analysis. Gaithersburg, MD:
     Aspen Publishers. 630p.

Number of words: 820