The determination of manganese content in pulp, paper and paperboard can be done by sodium periodate spectrophotometry (referred to as Method A). It can also be done by flame atomic absorption spectrophotometry (referred to as Method B). The two methods are equally effective. GB 8943.3-1988 Determination of manganese content in pulp, paper and paperboard GB8943.3-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of manganese content in pulp, paper and board Pulp paper and board--Determination of manganese GB8943.3-88
The determination of manganese content in pulp, paper and board can be determined by sodium periodate spectrophotometry (referred to as method A). It can also be determined by flame atomic absorption spectrophotometry (referred to as method B). The two determination methods have equal validity. This standard is equivalent to the international standard ISO1830-1982 "Determination of manganese content in pulp". Part I Method A Sodium periodate spectrophotometry
Ashe the sample and dissolve the ash in hydrochloric acid. Use sodium periodate to oxidize manganese (I) to manganese (VI) in the presence of phosphoric acid. Then use spectrophotometry. Measure at a wavelength of 525nm. 1 Reagents
All reagents used in the test should be analytically pure (AR), and the water used in the test should be distilled water or deionized water. ：1.1 Sodium sulfite (HGB1073): 50g/L;1.2 Hydrochloric acid (GB622): about 6mol/L;
1.3 Sodium periodate-phosphoric acid solution 1.70g/mL, each liter contains 50g sodium periodate (NaIO4) and 200mL phosphoric acid (H,PO4) (GB 1282).
1.4 Standard manganese solution I is equivalent to 0.1g manganese per liter. Weigh 0.2749g manganese sulfate (MnSO) dried at 450℃, dissolve it with distilled water, transfer it to a 1000mL volumetric flask, dilute it to the scale with distilled water and mix it evenly. 1mL of this standard solution contains 0.1mg manganese.
1.5 Standard manganese solution I1: Transfer 100mL of standard manganese solution I to a 1000mL volumetric flask. Dilute it to the scale with distilled water and mix it evenly. 1ml of this standard solution contains 0.01mg manganese. This solution is unstable and should be prepared on the day it is used. 2 Instruments
2.1 General laboratory instruments and spectrophotometer; 2.2 Evaporating blood or crucible, which needs to be soaked in hydrochloric acid and washed repeatedly. It is best to use platinum instrument III, and its stains should be scrubbed clean with fine sand. 3 Sample collection and preparation
Pulp samples should be collected in accordance with the provisions of GB740 "Method for collecting average samples of chemical pulp". The collection of average samples of paper and paperboard should be carried out in accordance with the provisions of GB450 "Collection of paper and paperboard samples". Tear the air-dried samples into pieces of appropriate size, but do not use shearing, punching or other tools that may cause metal contamination to prepare samples.
4 Test steps
4.1 Drawing of standard curve
Put a certain volume of standard manganese solution shown in Table 1 into 25mL volumetric flasks respectively. Approved by the Ministry of Light Industry of the People's Republic of China on April 12, 1988, and implemented on August 1, 1988
GB 8943.3-88
Standard manganese solution 11
Equivalent mass of manganese
Without dilution, directly place the volumetric flask in a water bath to heat the solution, and add 1ml of sodium periodate-phosphoric acid solution (2.3) to each volumetric flask. Continue to heat each volumetric flask in a water bath for 5 minutes. Take it out and add 5 drops of 6mol/l hydrochloric acid. Immediately dilute with water to the scale and mix well. Allow it to cool to room temperature and further dilute with water to the scale. The temperature of the solution in each volumetric flask shall not differ by ±3. Use a spectrophotometer to measure the absorption value at a wavelength of 525nm. Use the compensation solution without the standard manganese solution 1i as the reference solution, adjust the instrument's absorption value to 0, and then measure the remaining absorption values. Draw a calibration curve with the mass of manganese (mg) contained in 25mL solution as the abscissa and the corresponding absorption value as the ordinate.
4.2 Determination of samples
4.2.1 Weighing and ashing of samples
Weigh two samples of 10g (accurate to 0.01g) for each sample. If the manganese content of the sample is known to exceed 5mg/kg, only weigh 5g. At the same time, determine the moisture content of the sample according to GB741 "Determination of moisture content of pulp analysis samples" or GB462 "Determination of moisture content of paper and paperboard". Place the weighed sample in an evaporating dish or crucible. For controversial samples, use platinum instrument III for arbitration. Pulp samples are ashed and burned according to GB742 "Determination of ash content of pulp", and paper samples are ashed and burned into ash according to GB463 "Determination of ash content of paper and paperboard". 4.2.2 Treatment of sample ash
Add 3 drops of sodium sulfite solution (1.1) to the ash and dissolve it in no more than 5ml of hydrochloric acid solution (1.2). Place it on a steam bath and evaporate it to dryness. Add 5 drops of 6mol/L hydrochloric acid and transfer the contents of the ash to a 25mL volumetric flask with distilled water. Place the volumetric flask in a water bath and heat it. Add 1mL of sodium periodate-phosphoric acid solution (1.3) and continue to heat the volumetric flask in a water bath for 5min. Dilute to the mark with distilled water and shake. Allow it to cool to room temperature and dilute to the mark with distilled water. The temperature of this solution should not differ by more than ±3°C from that of the standard colorimetric solution. If the solution is turbid, remove the turbidity by centrifugation, but do not filter the solution. 4.2.3 Absorption value measurement
Measure the absorption value with a spectrophotometer at a wavelength of 525nm. The measurement method and steps are the same as those for drawing the calibration curve (4.1). 5 Calculation of results
The manganese content of the sample is expressed in mg/kg and is calculated as follows: Mn =
Where: ml
×1000
The manganese content of the test solution obtained from the calibration curve, mg; -The absolute dry mass of the sample, g.
Use the average of the two measurements, rounded to one decimal place, and report the result. Part II Method B Flame Atomic Absorption Spectrophotometry Ash the sample and dissolve the ash in hydrochloric acid. Inhale the test solution into the flame of N,-acetylene or air-acetylene. Measure the absorption value of the 279.5nm spectral line emitted by the 470
GB 8943.3-88
center cathode lamp of the manganese ion. 6 Reagents
All reagents used in the test should be analytically pure (AR), and the water used in the test should be distilled water or deionized water. 6.1 Hydrochloric acid solution: about c (HCI) = 6 mol/L6.2 Standard manganese solution 1: each liter is equivalent to 0.1g manganese, the same as A method 1.4. 6.3 Standard manganese solution I: each liter is equivalent to 0.01g manganese, the same as A method 1.5. 6.4 Hydrogen peroxide (GB1616) 30% solution. 7 Instruments
General laboratory instruments and atomic absorption spectrophotometer, equipped with NO-acetylene burner or air-acetylene burner. 7.2 Manganese hollow cathode lamp
Evaporation III or, stains need to be scrubbed clean with fine sand. 8 Sample collection and preparation
Same as A method 3.
9 Test steps
9.1 Drawing of calibration curvebzxZ.net
9.1.1 Preparation of standard comparison solution
Add 10mL of 6mol/L hydrochloric acid solution and a certain volume of standard manganese solution 1 shown in Table 2 to a 50mL volumetric flask respectively. Then dilute to the mark with distilled water and mix well. Sequence
Standard manganese solution W,mL
Equivalent mass of manganese, mg
9.1.2 Calibration of instrument
Install the manganese hollow cathode lamp on the lamp holder of the atomic absorption spectrophotometer, turn on the instrument according to the operating steps specified by the instrument, connect the current and stabilize the current. According to the conditions for measuring manganese in the instrument, adjust and fix the wavelength to 279.5nm, and then adjust the current, sensitivity, slit, burner head height, gas/fuel ratio, air flow rate, suction volume, etc. If N,-acetylene is used, special attention should be paid to safety to prevent explosion. N,O-acetylene burner should be used. Before connecting N,O-acetylene, the burner must be ignited with air-acetylene.
9.1.3 Absorption value measurement
After the instrument is normal and the flame is burning stably, the standard comparison solution is sucked into the flame in turn, and the absorption value of each solution is measured. The measurement is accompanied by the empty test solution as a control, and the absorption value of the instrument is adjusted to 0, and then the remaining samples are measured. During the entire process of preparing the calibration curve, attention should be paid to keeping the instrument usage conditions constant. After each measurement, water should be sprayed through the burner for cleaning. 471
9.1.4 Drawing the curve
GB 8943.3-88
Draw the calibration curve with the weight of manganese (in milligrams per 50ml of standard comparison solution) as the horizontal axis and the corresponding absorption value as the vertical axis.
9.2 Determination of samples
9.2.1 Weighing and ashing of samples
Same as in Method A, 4.2.1.
9.2.2 Treatment of sample ash
First add a few drops of distilled water to the ash (9.2.1), moisten it, and then add 5 mL of hydrochloric acid solution (6.1) and evaporate to dryness on a steam bath. Repeat this operation once, then treat the residue with 5 mL of hydrochloric acid solution and heat it on a steam bath for 5 minutes. Transfer the contents of the crucible into a 50 mL volumetric flask with water. To ensure complete extraction, add 5 mL of hydrochloric acid solution to the residue in each crucible and heat it on a steam bath. Transfer this last part of the contents into a volumetric flask with water, combine it with the main sample solution, dilute to the scale with water and mix well. If the solution contains suspended matter, wait for the precipitate to sink and use the clear solution to measure the absorption value.
9.2.3 Calibration of instrument
Same as 9.1.2.
9.2.4 Measurement of absorption value
Same as 9.1.3.
10 Calculation of results
The manganese content of the sample is expressed in mg/kg and is calculated as follows: m×1000
Mn(mg/kg)
Where: mi-
The manganese content of the test solution obtained from the calibration curve, mg; mo—absolute dry weight of the sample, g.
Use the average of two measurements, rounded to one decimal place, and report the result. Note: ① In atomic absorption spectrophotometry, the determination of the absorption value of the calibration curve series should be carried out simultaneously with the determination of the absorption value of the sample to overcome the error caused by changes in test conditions.
②When measuring the manganese content in paper, since manganese dioxide may be burned in the ash, if it is found, add 6mol/l. hydrochloric acid to produce an insoluble brown precipitate; a few drops of 30% hydrogen peroxide can be added to help dissolve it. Then evaporate it on a steam bath. Additional notes:
This standard is drafted and managed by the Paper Industry Science Research Institute of the Ministry of Light Industry. 472
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.