Milk powder Central Asia nitrate testing program.

after Fonterra exposed Botox contamination of dairy raw materials, another New Zealand dairy company products problems. New Zealand local time on August 19, China's State Administration of Quality Inspection, New Zealand's Ministry of Primary Industry (MPI) and New Zealand dairy company Westland announced that Westland's production of 390 kg of lacto iron protein detected excess nitrate content, the problem products are all exported to China.
nitrites in food mainly refer to sodium nitrite. Nitrites oxidize the low iron hemoglobin, which is normally oxygen-carrying in the blood, into high-iron hemoglobin, thus losing the ability to carry oxygen and causing hypoxia
tissues
the disease. There are literatures that say its semi-lethal mass is 22 mg/kg. According to the requirements of GB 2762-2012 National Standard for Food Safety, the limit of pollutants in food products, infant milk-based foods in Central Asia nitrate (in NaNO2) must not exceed 2.0 mg/kg. RephiLe launched a nitrate testing program for milk powder in Central Asia in accordance with gb 5009.33-2010 National Standard for Food Safety Food Central Asian Nitrate and Nitrate Determination.I. Experimental principle
the milk powder sample was precipitated
protein
, fat removed, after extraction and purification, potassium hydroxide solution for gonorrhea, anion exchange column separation, conductivity detector detection. To preserve the time qualitative, external standard legal quantity 2, instrument and
reagents
ICS-2000 ion
chromatography
instrument (Dionex), AS11-HC anion
chromatography column
(Dionex), PURIST UV ultra-pure water system (RephiLe).
RephiQuik Nylon Needle Filter. All chromatography reagents are chromatography pure., the test method
1.Sample pre-treatment
The sample is loaded into a covered container that can hold up to 2 times the size of the sample, and the sample is fully mixed by repeated shaking and reversing the container until the sample is homogenized.
2.Extract
called sample 2.5 g (accurate to 0.01 g), place in a 100 ml capacity bottle, add ultra-pure water 80 ml, shake well, ultrasound 30 min, add 3 % acetic acid solution 2 ml, place 20 min at 4 degrees C, remove and place at room temperature, dilute with water to scale. The solution is filtered by
filter
, and the liquid is used as a backup.
take the above spare sequentium about 15 ml, discard the front 3 ml (if the chloride ion is greater than 100 mg/L, you need to pass the needle filter, C18 column, Ag column and Na column in turn, discard the front 7 ml) and remove the front 7 ml) to collect the back wasculation to be measured.
3.Reference chromatography
(1) column: AS11-HC anion column.
(2) gonorrhea: potassium hydroxide solution at a concentration of 5 mmol/L to 50 mmol/L;
(3) suppressor: ASRS 300.
(4) detector: conductivity detector, detection pool temperature of 30 degrees C.
(5) sample volume: 50 sl.
4.Measurement
(1) standard curve
take nitrite standard liquid, dilute with water, make a series of standard solutions, containing nitrite ion concentration of 0.00 mg/L, 0.02 mg/L, 0.04 mg/L, 0.06 mg/L, 0.08 mg/L, 0.10 mg/L, 0.15 mg/L, 0.20 mg/L standard solutions, from low to high concentrations in turn. A chromatography of the above-mentioned concentration standard solutions is obtained. The standard curve or linear regression equation is drawn with the concentration of nitrite ions (mg/L) as the horizontal coordinates and the peak height (s) or peak area as the ordinate. (2) sample determination
draw blanks and sample solution 50 μL, respectively, under the same operating conditions, in turn injected into the ion chromatography, recording chromatography. Based on the retention time characterty, the peak height or peak area of the blank and sample is measured separately.
5. Statement of the analysis results
Sample Central Asian nitrate (in NO2- meter) content by type (1) calculated: :
X - sample Central Asian nitrate ion content, unit mg/kg;
c - determination of nitrite ion concentration in sample solution, unit mg/L;
c0 - concentration of reagent blank liquid Central Asian nitric acid ions, unit mg/L;
V - sample solution liquid product, unit ml;
f - sample solution dilution multiplied;
m - sample size, unit g.
Note: The nitrite ion content measured in the sample is multiplied by the conversion factor of 1.5, i.e. the nitrite
(in terms of sodium nitrite) content;
6. Precision
difference between the two independent measurements obtained under repetitive conditions must not exceed 10 % of the arithmetic average .
method, the detection limit for nitrates in Central Asia is 0.2 mg/kg, respectively.
in ion chromatography, various contaminants, particulate impurities, ions, organic matter and bacteria in water have a very large impact on instrument life and test results.
First, particulate matter can clog pumps and lines, causing damage to equipment or chromatography columns, second, ion impurities in water can interfere with normal analysis to a great extent, making it more difficult for experimenters to work, the presence of organic matter will reduce the life of chromatography columns and interfere with the determination and analysis, and bacteria will continue to release ions and small molecules of organic matter, on the other hand, bacteria can also be regarded as particles, causing damage to the instrument.
In order to achieve satisfactory experimental results and ensure the accuracy of the analysis, RephiLe specifically recommends that the research staff use the PURET UV ultrapure water system, which is a particularly suitable for instrument analysis to provide ultrapure water products, compact and easy to use.
PURIST UV ultrapure water meter using an ultra-large capacity of four-tube purification column, while the use of internal ultrapure water timed circulation system, with dual wavelength UV lamp can effectively remove ion impurities in the water, control the ultrapure water system organic matter and
microorganisms
content. Water resistance can be up to 18.2 M. cm. The terminal uses a filter of 0.22 m to effectively remove particles and bacteria.
, RephiLe offers customers a full range of pure water, ultra-pure water use solutions - Direct-Pure EDI and PURIST UV combined pure water treatment systems.
this combination can provide both secondary and ultra-pure water to meet the user's water needs in different situations in instrument analysis. Direct-Pure EDI level 2 pure water system, using Siemens EDI module, water quality is stable and reliable, its water production as purist UV water, can maximize the effectiveness of PURIST, to ensure that users in the use of water worry-free.
In addition, RephiLe offers Direct-Pure UP ultra-pure water all-in-one machine, which is watered with tap water while preparing reverse osmosis RO water and high-quality ultra-pure water, one machine and two water, giving customers more choice.
about RephiLe:
. RephiLe is a professional manufacturer and supplier of water purification and laboratory separation purification products with a deep technical background in the field of pure water and filtration in the laboratory. RephiLe is available in three main categories:
1. Laboratory pure water system
2. Millybo pure water meter compatible with
supplies
3. Needle filters, disc membranes, stainless steel filters and other sample preparation products
Currently RephiLe products have been exported to more than 60 countries around the world.
welcome users to contact us at 400 690 0090/021-24284200 or by email: info@rephile.com .