Microwave digestion and inductively coupled plasma mass spectrometry (ICP-MS) method was used to determine the contents of 25 inorganic elements in basal part, meat and shell of bamboo shoots. It could be concluded that the method could be applied to determine 25 inorganic elements in bamboo shoots. The elements with a dry basis content higher than 10 mg/kg were listed in the order of content decrease as follows, basal part of bamboo shoots: K > Ca > Mg > Mn > P > Al > Fe > Zn > Na; bamboo shoots meat: K > P > Ca > Mg > Mn > Fe > Al > Zn > Na > Ba > Sr; bamboo shoots shell: K > P > Mg > Ca > Mn > Al > Fe > Na > Zn; B, Pb, Cu, Cr ranged from 1.0 - 10 mg/kg; Ga, As, Se, Cd, Sn, Sb, V, Co, Ni were lower than 0.80 mg/kg. The harmful elements Cd, As, Cr, Hg, Pb were commonly monitored in feeds. The wet basis content (mg/kg) of Cd, As, Cr was lower than: 0.028, 0.022 and 0.42 respectively; no Hg was found; the content of Pb(mg/kg) in basal part, meat and shell of bamboo shoots was 0.82, 0.35 and 0.41 respectively. The results provide basic data for the development of bamboo shoots and its byproduct.
China is the world’s main bamboo producing country, and the production of bamboo shoots is leading in the world. The production in Fujian, Zhejiang, Jiangxi and Hunan Province is the highest. About 40% of bamboo shoots are sold fresh. Others are made into boiled canned bamboo shoots, dried bamboo shoots, sour bamboo shoots and various soft-packing or canned condiments [
At present, a number of studies on the organic components of bamboo shoots and its by-products from pro- cessing have been reported [
Thus, it quickly became an important tool of elemental analysis [
ICP-MS (ThermoFisher Scientific X series II, USA), microwave digestion instrument (CEM MARS, USA), ultrapure water generator (Milli-Q Element, Millipore, France), digestion instrument (Annan DV4000, Beijing).
Bamboo shoots: Longyan in Fujian Province.
Guaranteed reagent of HNO3 (65%), Germany Merck; guaranteed reagent of H2O2 (30%), Germany Merck; high purity argon with the purity of 99.999%; mixture of hydrogen and helium (high-purity, containing 7.12% of hydrogen); ultrapure water as the experiment water (18.2 MΩ); mixed tuned liquid of Li, Co, In and U of 10 mg/L, O2si of the United States; 1000 mg/L of Re, National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials; B, Na, Mg, Al, Ca, P, K, Ca, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Sr, Cd, Ba, Hg, Pb, Fe, Se, Ge, In and Rh of 1000 mg/L, Iron & Steel Research Institute of China National Center for Quality Supervision and Testing of Iron and Steel; Sn and Sb of 500 mg/L, Iron & Steel Research Institute of China National Center for Quality Supervision and Testing of Iron and Steel; Au of 100 μg/g, National Institute of Metrology, China; and Tea Leaves GBW10016, Geophysical and Geochemical Prospecting Institute.
Each part of the bamboo shoot was taken. 0.25 kg of wet material was taken from each part with the cross quartering method, dried at 60˚C, crushed and sieved with 40-mesh screen. 0.50 g of sieved sample was accurately weighed and placed into the digestion tank. 6.0 mL of HNO3, 2.0 mL of H2O2 and 0.02 mL of Au standard liquid was added. After the same treatment of standard substance, 0.200 ml of Ga, Sn and Hg intermediate liquid (1000 ug/L) was added, respectively. It was digested for 2 h at 90˚C, cooled to room temperature, capped, sealed, and digested with microwave. The digestion conditions are shown in
In the startup optimization, the signal value of Li, Co, In and U was adjusted to the maximum. Double charge and oxide interference was reduced to the value below 3.0%. The sampling depth was 150 mm. It was 16 mm horizontally and 285 mm vertically. The rate of cooling air was 13.02 L /min, that of auxiliary gas was 0.8 L/min, and that of atomization gas was 0.93 L/min. When the CCTS technology was used, the mixed gas was hydrogen + helium with the rate of 7:93. The gas flow rate was 4.5 mL/min. Float mode was used for high-content and high-sensitivity elements. Each element was scanned for 100 times. The hold time was 10 ms. There were 3 channels. The channel spacing was 0.02 AMU.
In ICP-MS analysis, by the selection of appropriate isotope of element to be tested, equation correction or CCTS technology, mass spectrum interference can be prevented to the greatest extent. The isotope of each element to be tested includes 11B, 23Na, 24Mg, 27Al, 31P, 39K, 44Ca, 451V, 52Cr, 55Mn, 56Fe, 59Co, 60Ni, 65Cu, 66Zn, 69Ga, 75As, 80Se, 88Sr, 111Cd, 118Sn, 121Sb, 137Ba, 202Hg and 208Pb. 80Se is corrected with CCTS technology [
In order to overcome the sample matrix effect and other influences, the mixed internal standard of Ge, Rh, In and Re was added for correction of results.
Hg2+ has strong adsorption ability. To reduce the effect of memory effect on the results, when ICP-MS was used to measure the content of Hg, 0.02 mL of Au was added into the sample [
To protect the detector, according to the content of elements and sensitivity, Ca, Mg, AL, Na, P, K, V, Cr, Mn, Sr and Fe was measured with float mode and high resolution.
Ca, Mg, Al, Na, P, K, V, Cr, Mn, Sr and Fe were used to prepare a set of mixed standard solution. B, Co, Ni, Cu, Zn, Ga, As, Cd, Sn, Sb, Ba, Hg and Pb were used to prepare a set of mixed standard solution. Se was used to prepare a set of standard solution alone. Work curve of each element consists of evenly spaced 6 concentration values from 0 to the highest concentration. The highest concentration is shown in
Blank solution was determined for 10 times. The concentration corresponding to the three times of standard deviation is the detection limit of the method. Linear range, correlation coefficient and detection limit of the method are shown in
To verify the accuracy and reliability of this method, according to the experimental steps and operating conditions selected, Tea Leaves GBW10016, the national standard substance, was determined. The results are shown in
To detect bamboo shoot, bamboo shoots meat, bamboo in the content of inorganic elements using this method, the results are shown in
Step | Power (W) | Emission rate (%) | Heating up time (min) | Temperature (˚C) | Hold time (min) |
---|---|---|---|---|---|
1 | 1600 | 100 | 5 | 120 | 3 |
2 | 1600 | 100 | 3 | 150 | 3 |
3 | 1600 | 100 | 3 | 180 | 15 |
Element | Linear range (μg/L) | Correlation coefficient | Detection limit (μg/L) | Element | Linear range (μg/L) | Correlation coefficient | Detection limit (μg/L) |
---|---|---|---|---|---|---|---|
B | 0 - 100 | 0.9997 | 0.23 | Cu | 0 - 100 | 0.9997 | 0.40 |
Na | 0 - 5000 | 0.9978 | 4.3 | Zn | 0 - 100 | 0.9998 | 1.6 |
Mg | 0 - 2500 | 0.9988 | 1.0 | Ga | 0 - 10 | 1.0000 | 0.0081 |
Al | 0 - 2000 | 0.9983 | 1.2 | As | 0 - 100 | 1.0000 | 0.030 |
P | 0 - 10000 | 0.9999 | 12 | Se | 0 - 10 | 0.9996 | 0.20 |
K | 0 - 2500 | 0.9998 | 1.6 × 102 | Sr | 0 - 100 | 0.9998 | 0.015 |
Ca | 0 - 10,000 | 0.9993 | 40 | Cd | 0 - 10 | 0.9999 | 0.0023 |
V | 0 - 100 | 0.9994 | 0.019 | Sn | 0 - 10 | 0.9999 | 0.026 |
Cr | 0 - 100 | 0.9996 | 0.095 | Sb | 0 - 10 | 1.0000 | 0.0065 |
Mn | 0 - 1000 | 0.9994 | 0.26 | Ba | 0 - 100 | 0.9996 | 0.069 |
Fe | 0 - 1000 | 0.9994 | 1.9 | Hg | 0 - 10 | 0.9996 | 0.088 |
Co | 0 - 10 | 1.0000 | 0.0033 | Pb | 0 - 100 | 1.0000 | 0.028 |
Ni | 0 - 100 | 0.9996 | 0.20 |
Element | Standard value (mg/kg) | Measured value (mg/kg) | RSD (%) | Element | Standard value (mg/kg) | Measured value (mg/kg) | RSD (%) |
---|---|---|---|---|---|---|---|
B | 14 ± 1 | 13.5 | 3.2 | Cu | 18.6 ± 0.7 | 18.9 | 4.0 |
Na | 90 ± 10 | 85.0 | 5.2 | Zn | 51 ± 2 | 52.9 | 2.1 |
Mg | 1860 ± 110 | 1728 | 4.8 | As | 0.09 ± 0.01 | 0.098 | 5.1 |
Al | 940 ± 90 | 970 | 6.3 | Se | 0.098 ± 0.008 | 0.102 | 3.9 |
P | 4500 ± 300 | 4720 | 4.4 | Sr | 9.1 ± 1.2 | 10.0 | 1.1 |
K | 16,300 ± 700 | 16,900 | 3.1 | Cd | 0.062 ± 0.004 | 0.062 | 1.1 |
Ca | 3260 ± 80 | 3310 | 3.7 | Sb | 0.022 ± 0.006 | 0.019 | 3.1 |
V | 0.17 ± 0.03 | 0.20 | 2.4 | Ba | 9.6 ± 0.5 | 9.2 | 4.7 |
Cr | 0.45 ± 0.10 | 0.53 | 1.9 | Pb | 1.5 ± 0.2 | 1.7 | 3.2 |
Mn | 500 ± 20 | 485 | 2.1 | Element | Standard adding value (mg/kg) | Recovery rate (%) | RSD (%) |
Fe | 242 ± 18 | 243 | 2.4 | Ga | 0.410 | 103.3 | 3.0 |
Co | 0.22 ± 0.02 | 0.23 | 1.2 | Sn | 0.410 | 106.5 | 4.4 |
Ni | 3.4 ± 0.3 | 3.11 | 2.7 | Hg | 0.410 | 95.0 | 4.7 |
Element | Basal part | Meat | Shell | Element | Basal part | Meat | Shell |
---|---|---|---|---|---|---|---|
K (g/kg) | 27 | 35 | 9.9 | B (mg/kg) | 1.8 | 2.1 | 0.92 |
Ca (g/kg) | 0.83 | 2.9 | 0.39 | Cr (mg/kg) | 1.8 | 1.1 | 2.0 |
Mg (g/kg) | 0.73 | 1.3 | 0.43 | Sb (ng/kg) | 0.73 | 1.8 | 1.5 |
Mn (g/kg) | 0.35 | 0.34 | 0.065 | Ni (mg/kg) | 0.52 | 0.80 | 0.22 |
P (g/kg) | 0.22 | 4.4 | 0.75 | Ga (mg/kg) | 0.39 | 0.73 | 0.084 |
Al (g/kg) | 0.19 | 0.080 | 0.057 | V (mg/kg) | 0.25 | 0.14 | 0.065 |
Fe (g/kg) | 0.13 | 0.092 | 0.050 | Cd (mg/kg) | 0.12 | 0.14 | 0.019 |
Zn (mg/kg) | 44 | 60 | 10 | Se (mg/kg) | 0.11 | 0.21 | 0.032 |
Na (mg/kg) | 22 | 26 | 22 | As (mg/kg) | 0.095 | 0.13 | 0.039 |
Ba (mg/kg) | 9.9 | 20 | 1.8 | Co (mg/kg) | 0.056 | 0.040 | 0.055 |
Sr (mg/kg) | 5.9 | 16 | 1.2 | Sn (mg/kg) | ― | 0.058 | 0.025 |
Cu (mg/kg) | 5.0 | 6.9 | 2.3 | Hg (mg/kg) | ― | ― | ― |
Pb (mg/kg) | 5.0 | 4.2 | 2.9 |
“―”: not detected. Detection limit of Hg: 0.0088 mg/kg, detection limit of Sn: 0.003 mg/kg.
Pb | Cd | As | Cr | Hg | |
---|---|---|---|---|---|
Basal part | 0.82 | 0.028 | 0.022 | 0.42 | ― |
Meat | 0.35 | 0.017 | 0.015 | 0.13 | ― |
Shell | 0.41 | 0.0039 | 0.0079 | 0.41 | ― |
The method can meet the testing requirements; the ranking of content of inorganic element above 10 mg/kg is as follows. Basal part: K > Ca > Mg > Mn > P > Al > Fe > Zn > Na; meat: K > P > Ca > Mg > Mn > Fe > Al > Zn > Na > Ba > Sr; shell: K > P > Mg > Ca > Mn > Al > Fe > Na > Zn; the elements whose content in each part is 1.0 - 10 mg/kg include B, Pb, Cu, Cr, etc. The content of Ga, As, Se, Cd, Sn, Sb, V, Co and Ni are below 0.80 mg/kg.
Rich Na, K and other elements which can maintain water in human body and constant pH of body fluid are contained. Ca content in meat of bamboo shoots is as high as 2.9 × 103 mg/kg. The content of Fe, Zn, Mn and other essential microelements of human body is (10 - 3.5) × 102 mg/kg. The basal part and shall of bamboo shoots can be selectively developed into main feed of livestock. Se is the element drawing the most attention in the environment and health research field. Its content in each part of the bamboo shoots is above 0.032 mg/kg. Se content in the meat of bamboo shoots meat is 0.21 mg/kg.
Water content of basal part, meat and shell of bamboo shoots is 76.46%, 88.12% and 79.72% respectively. The calculated wet base content of Pb, Cd, As, Cr and Hg are shown in
Harmful elements often monitored in food and feed include Cd, As, Cr, Hg, Pb, etc. The wet base content of Cd, As and Cr (mg/kg) is below 0.028, 0.022 and 0.42, respectively. Hg was not detected. The wet base content of Pb in meat, basal part and shell of bamboo shoots (mg/kg) is 0.82, 0.35 and 0.41, respectively. According to the standard in the strict GB 2762-2012 Maximum Limit of Contaminants in Food, the content of Pb is a little higher. When it is developed into food, this should be considered. According to GB13078-2001 Feed Hygiene Standard, all raw materials for feed are safe.
In this paper, microwave digestion and ICP-MS method is used to measure the content of 25 kinds of inorganic elements, namely Ca, Mg, Al, Na, P, K, V, Cr, Mn, Sr, Co, Ni, Cu, Fe, B, zinc, Ga, As, Cd, Sn, Sb, Ba, Hg, Pb and Se. By measuring the national standard substance and the standard addition recovery test, the results show that the method can meet the testing requirements. Meanwhile, it tests the distribution 25 kinds of elements in bamboo shoot, bamboo shoots meat, bamboo and provides the basic data for the comprehensive utilization.
Dissimilarity Evaluation of the characteristics of the nutrient components of the plant derived agricultural products from different producing area, different growing period, different storage and fresh keeping and different consumption patterns (GJFP201601503).
Jianzhi Ye,Zipeng Su,Ling Lin,Yubing Zha,Mingyue Wang,Chunliang Yang, (2016) Determination of Inorganic Elements Content and Distribution in Bamboo Shoots by Microwave Digestion and ICP-MS. Journal of Agricultural Chemistry and Environment,05,152-157. doi: 10.4236/jacen.2016.53016