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1.
Thin Layer Drying of African Breadfruit (Treculia africana) Seeds: Modeling and Rehydration Capacity
African breadfruit (ABF) seeds are underutilized plant resources, which have been reported to have high potential for novel
food and industrial uses. The kinetics of moisture removal during air drying of the whole (WS) and dehulled (DS) seeds was
studied at temperatures of 40–70 °C. Five empirical models were tested for predicting the experimental data. Drying of ABF
seeds followed an exponential decay pattern, while drying predominantly took place during the falling rate periods. All the
drying models predicted the experimental data above 90% accuracy while the Henderson–Pabis model gave the best fit (0.95 < r
2 < 0.99) at most of the experimental conditions. Effective moisture diffusivity, D
eff, ranged from 3.65 to 7.15 × 10−9 m2/s and 3.95 to 6.10 × 10−9 m2/s for WS and DS, respectively. D
eff showed significant dependence on the moisture content (p < 0.01). Rehydration capacity of DS was not significantly affected by drying temperature while that of WS increased with
drying temperature. 相似文献
2.
Elsa Uribe Margarita Miranda Antonio Vega-G��lvez Issis Quispe Rodrigo Claver��a Karina Di Scala 《Food and Bioprocess Technology》2011,4(2):320-326
Mathematical modelling was used to study the effect of process temperature on moisture and salt mass transfer during osmotic
dehydration (OD) of jumbo squid with 6% (w v
−1) NaCl at 75, 85 and 95 °C. The diffusion coefficients for moisture and salt increased with temperature. Based on an Arrhenius-type
equation, activation energy values of 62.45 kJ mol−1 and 52.14 kJ mol−1 for moisture and salt, respectively, were estimated. Simulations of mass transfer for both components were performed according
to Newton, Henderson and Pabis, Page, Weibull and logarithmic mathematical expressions. The influence of drying temperature
on the kinetic parameters was also studied. Based on statistical tests, the Weibull and logarithmic models were the most suitable
to describe the mass transfer phenomena during OD of jumbo squid. 相似文献
3.
Mass Transfer Coefficients for the Drying of Pumpkin (Cucurbita moschata) and Dried Product Quality 总被引:3,自引:0,他引:3
Raquel Pinho F. Guiné Francisca Henrriques Maria Jo?o Barroca 《Food and Bioprocess Technology》2012,5(1):176-183
The aim of this work was to determine the mass transfer properties of pumpkin (Cucurbita moschata) exposed to air drying. The drying temperatures tested ranged between 30°C and 70°C, and the kinetic behavior was studied
in this temperature band. The samples were analyzed in terms of moisture content, acidity, proteins, lipids, and crude fiber,
both in the fresh state and after drying. From the chemical analyses made, it was possible to conclude that drying induces
some reductions in acidity, lipids, fibers, and proteins. As to the influence of the drying temperature on the process, it
was observed that a temperature rise from 30°C to 70°C led to a 70% saving in drying time. The results obtained by fitting
the experimental data to the kinetic models tested allowed concluding that the best model for the present case is Henderson–Pabis,
and the worst is Vega–Lemus. Furthermore, in this work, it was possible to determine the values of the diffusion coefficient
at an infinite temperature, D
e0, and activation energy for moisture diffusion, E
d, which were, respectively, 0.0039 m2/s and 32.26 kJ/mol. Similarly, the values of the Arrhenius constant and the activation energy for convective mass transfer,
respectively, h
m0 and E
c, were also calculated, the first being 3.798 × 108 m/s and the latter 86.25 kJ/mol. These results indicate that the activation energy for convective mass transfer is higher
than that for mass diffusion. 相似文献
4.
Indrajit D. Thorat Debabandya Mohapatra R. F. Sutar S. S. Kapdi Dipali D. Jagtap 《Food and Bioprocess Technology》2012,5(4):1379-1383
The vacuum-drying characteristics of ginger (Zingiber officinale R.) slices were investigated. Drying experiments were carried out at a constant chamber pressure of 8 kPa, and at four different
drying temperatures (40 °C, 50 °C, 60 °C, and 65 °C).The effects of drying temperature on the drying rate and moisture ratio
of the ginger samples were evaluated. Efficient model for describing the vacuum-drying process was chosen by fitting five
commonly used drying models and a suggested polynomial was fitted to the experimental data. The effective moisture diffusivity
and activation energy were calculated using an infinite series solution of Fick’s diffusion equation. The results showed that
increasing drying temperature accelerated the vacuum-drying process. All drying experiments had only falling rate period.
The goodness of fit tests indicated that the proposed two-term exponential model gave the best fit to experimental results
among the five tested drying models. The average effective diffusivity values varied from 1.859 × 10−8 to 4.777 × 10−8 m2/s over the temperature range. The temperature dependence of the effective moisture diffusivity for the vacuum drying of the
ginger samples was satisfactorily described by an Arrhenius-type relationship with activation energy value of 35.675 kJ/mol
within 40–65 °C temperature range. 相似文献
5.
The moisture sorption isotherms of grain and kernel of barnyard millet (Echinochloa frumentacea) were determined at 20, 30, 40, and 50 °C. A gravimetric static method was used under 0.112–0.964 water activity (a
w) range for the determination of sorption isotherms. The models were compared using the coefficient of determination (r
2), reduced chi-square (χ
2) values, and on the basis of residual plots. In grain, modified Chung–Pfost (r
2 > 0.99; χ
2 < 0.7) and modified Oswin (r
2 > 0.99; χ
2 < 0.55) models were found suitable for predicting the M
e
–a
w relationship for adsorption and desorption, respectively. Modified Henderson model was found to give the best fit (r
2 > 0.99 and χ
2 < 0.55) for describing the adsorption and desorption of the kernel. The isosteric heat, calculated using Clausius–Clapeyron
equation, was varied between 46.76 and 61.71 kJ g−1 mol−1 at moisture levels 7–21% (d.b.) for grain and 47.11–63.52 kJ g−1 mol−1 at moisture level between 4% and 20% (d.b.) for kernel. The monolayer moisture content values ranged from 4.3% to 6% d.b.
in the case of adsorption of barnyard millet grain and 5.2–6.6% d.b. in the case of desorption at the temperature ranges of
50–20 °C. The monolayer moisture values of barnyard millet kernel ranged from 4.4% to 6.67% d.b. in adsorption and 4.6% to
7.3% d.b. in desorption in the temperature ranges of 50–20 °C. 相似文献
6.
Mahboube Zolfaghari Mohammad Ali Sahari Mohsen Barzegar Hamidreza Samadloiy 《Food and Bioprocess Technology》2010,3(2):239-246
Samples of Abbot, Alison, Bruno, Monty, and Hayward cultivars of kiwifruit (Actinidia deliciosa) were obtained from the Iran Research Center of Citrus (Tonekabon, located in north of Iran) and their physicochemical properties
were studied during cold storage (at T = 1 ± 1 °C, RH = 80 ± 5%) at 0-, 9-, and 18-week intervals. The mean chemical composition of the fruits were as follows:
ash = 0.66–0.96%, moisture = 75.2–84.7%, starch = 0.3–7.0%, and ascorbic acid = 54.8–261.0; K = 125.0–372.0 mg 100 g−1 fresh weight, Mg = 18.0–32.0 mg 100 g−1 fresh weight, Na = 1.4–3.1 mg 100 g−1 fresh weight, Fe = 0.17–0.52 mg 100 g−1 fresh weight, Cu = 0.04–0.24 mg 100 g−1 fresh weight, Zn = 0.16–0.49 mg 100 g−1 fresh weight, Mn = 0.04–0.10 mg 100 g−1 fresh weight, and P = 25.2–49.3 mg 100 g−1 fresh weight; glucose = 0.7–2.39%, fructose = 1.20–3.13%, and sucrose = 0.0–5.8%. At the same time, the values of the parameters
°Brix = 6.5–14.8% and acidity = 1.8–2.5% of the studied cultivars (mutual effects of cultivar and storage time) were investigated.
The increase in peroxidase (POX = 0.0–6.65 U ml−1) and the decrease in pectinesterase (PE; poor activity to 0) activities were also determined. The statistical analysis showed
that the Bruno cultivar had the highest content of ascorbic acid (115.0–261.0 mg 100 g−1 fresh weight), which is an important compound in fruits during storage, while Hayward had the best overall quality particularly
with regards to its resistance to softening. This study confirms that long-term cold storage at 1 ± 1 °C and 80 ± 5% RH is
suitable for maintaining the highest quality of Iranian grown cultivars of kiwifruit. 相似文献
7.
Clothianidin, a new generation of pesticide, was determined in spiked tap water, apple juice, and soil by square-wave adsorptive
stripping voltammetry. The method of determination is based on the hydrogen evolution reaction catalyzed by clothianidin at
the hanging mercury drop electrode. The optimal signal was detected at −1.4 V versus Ag/AgCl in citrate buffer at pH 2.2.
Various parameters such as pH, buffer concentration, frequency, amplitude, step potential, accumulation time, and potential
were investigated to enhance the sensitivity of the determination. The optimal results were recorded at an accumulation potential
of −0.35 V, accumulation time of 7 s, amplitude of 100 mV, frequency of 200 Hz, and step potential of 7 mV. The mechanism
of catalytic hydrogen evolution was considered under experimental and theoretical conditions. This electroanalytical procedure
enabled to determine clothianidin in the concentration range 9 × 10−9–4 × 10−6 mol L−1 in supporting electrolyte and tap water, 1 × 10−7–4 × 10−6 mol L−1 in diluted apple juice, and 2 × 10−7–1 × 10−6 mol L−1 in soil. The detection and quantification limits in supporting electrolyte and diluted apple juice were found to be 2.6 × 10−9, 8.6 × 10−9 and 3 × 10−8, and 1 × 10−7 mol L−1, respectively. A standard addition method was successfully used to determine clothianidin in spiked tap water, spiked apple
juice, and spiked soil. 相似文献
8.
This work describes a procedure for the simultaneous determination of vanadium and lead in some food and water samples using
adsorptive stripping voltammetric method. The method is based on the adsorptive accumulation of cupferron complexes of these
elements onto hanging mercury drop electrode, followed by reduction of adsorbed species by voltammetric scan using differential
pulse modulation. Optimal analytical conditions were found to be cupferron concentration of 8.00 × 10−5 M, pH of 4.8 (phosphate buffer), an accumulation potential at −100 mV, and a scan rate of 80 mV s−1. With an accumulation time of 50 s, the peak currents proportional to the concentration of lead and vanadium over the 0.05–80.00
and 0.10–105.00 ng mL−1 ranges with detection limit of 0.02 and 0.01 ng mL−1, respectively. The procedure was applied to simultaneous determination of vanadium and lead in some food and water samples
with satisfactory results. 相似文献
9.
Jessica López Elsa Uribe Antonio Vega-Gálvez Margarita Miranda Judith Vergara Eduardo Gonzalez Karina Di Scala 《Food and Bioprocess Technology》2010,3(5):772-777
Effect of air temperature on drying kinetics, vitamin C, antioxidant capacity, total phenolic content (TPC), colour due to
non-enzymatic browning (NEB) and firmness during drying of blueberries was studied. Drying curves were satisfactorily simulated
with the Weibull model at 50, 60, 70, 80 and 90°C. The scale parameter (β) decreased as air temperature increased and an activation
energy value of 57.85 kJ mol−1 was found. Important losses of vitamin C were reported during drying for all the working temperatures (p < 0.05). Although TPC decreased as air-drying temperature increased (p < 0.05) in comparison to its initial value, the dehydration at high temperatures (e.g., 90°C) presented high values for these
antioxidant components. Discoloration due to NEB reaction was observed at all the working temperatures showing a maximum value
at 90°C (p < 0.05). The radical scavenging activity showed higher antioxidant activity at high temperatures (80 and 90°C) than at low
temperatures (50, 60 and 70°C) (p < 0.05). A tissue firmness reduction was observed with increasing temperature (p < 0.05). 相似文献
10.
Effects of freezing/thawing, sun drying, solar drying, and foam-mat drying on physical, chemical, rheological, and sensory
attributes of okra were investigated. Average poured bulk and tapped bulk densities of sun-dried, solar-dried, and foam-mat-dried
okra were 800 and 950, 715 and 765, 355 and 367 kg/m3, respectively. Minimum and maximum porosity of sun-dried, solar-dried, and foam-mat dried okra were 55.70% and 62.60%, 50.06%
and 53.30%, 60.90% and 62.87%, respectively. Sun-dried and solar-dried okra showed higher L*, a*, and chroma values than frozen/thawed and foam-mat-dried okra. Within a temperature range of 80–40 °C, viscosity of fresh,
frozen/thawed, foam-mat-dried, solar-dried, and sun-dried okra were 0.055–0.080, 0.055–0.075, 0.050–0.073, 0.005–0.065, and
0.005–0.022 Nsm−2, respectively. Sensory evaluation showed no significant difference (p < 0.05) between fresh, frozen/thawed, and foam-mat dried okra in color, aroma, and overall acceptability. Sun-dried and solar-dried
okra were significantly poorer (p < 0.05) in color, aroma, taste, and overall acceptability. 相似文献
11.
?brahim Doymaz 《Food Analytical Methods》2012,5(4):841-848
The thin-layer drying characteristics of pomegranate arils were investigated at the temperature of 55, 65 and 75°C, and the
thin-layer drying models were used to fit the drying data. The increase in drying air temperature resulted in a decrease in
drying time. Five different thin-layer drying models were used to predict the drying characteristics. The Midilli et al. model
showed a better fit to experimental drying data as compared to other models. Effective moisture diffusivities were calculated
based on the diffusion equation for a spherical shape using Fick’s second law, and varied from 9.373 × 10−11 to 3.429 × 10−10 m2/s over the temperature range. Moisture diffusivity values increased as air temperature was increased. The dependence of moisture
diffusivity on temperature was described by an Arrhenius-type equation. The activation energies of control and pre-treated
samples were determined to be 49.7 and 40.1 kJ/mol, respectively. 相似文献
12.
Ramón Moreira Francisco Chenlo Diego M. Prieto María D. Torres 《Food and Bioprocess Technology》2012,5(3):1077-1082
The adsorption isotherms of chia seed (CS), black chia seed (BCS), white chia seed (WCS), and chia seed flour (CSF) were determined
at different temperatures (20, 35, 50, and 65 °C) using gravimetric method. Several saturated salt solutions were selected
to obtain different water activities in the range of 0.07 to 0.91. Adsorption isotherms were of type II, according to Brunauer’s
classification. No significant differences were found between equilibrium data of WCS, BCS, and CS samples. CSF showed lower
hygroscopic characteristics than seeds. The three-parameter Guggenheim–Anderson–de Boer (GAB) model was employed to fit the
experimental data in the water activity range. The goodness of the fittings, using several statistical parameters, was satisfactory.
The monolayer moisture content (kg (kg d.b.)−1) calculated by the GAB model was 0.019 ± 0.004 for CS, BCS, and WCS and 0.015 ± 0.005 for CSF. The net isosteric sorption
heat, calculated by means of the Clausius–Clapeyron equation, indicated that water is strongly bounded to chia at moisture
content below 0.05 kg (kg d.b.)−1. 相似文献
13.
Antonio Vega-Gálvez Elsa Uribe Gipsy Tabilo-Munizaga Purificación Garcia-Segovia Karina Di Scala 《LWT》2011,44(2):384-391
The effect of High Hydrostatic Pressure (HHP) and other pretreatments on the drying kinetics, antioxidant activity, firmness and microstructure of Aloe vera gel was investigated during convective drying at 70 °C. The pretreatments analyzed were high hydrostatic pressure, blanching, enzymatic and microwaves. Simulation of drying curves was studied through the application of several mathematical models such as Newton, Henderson and Pabis, Page, Modified Page, Wang and Singh, and Weibull. Among them, the Weibull model provided the best fit for the experimental data. All pretreatments increased the water diffusion coefficient compared to the control sample. Microwaves followed by HHP presented the fastest drying rates. All pretreatments modified the microstructure and hence the texture of the product. HHP and microwaves increased firmness while blanching and enzymatic treatments produced a softer final product. Blanching, microwaves and HHP enhanced A. vera antioxidant activity. However, the HHP pretreated samples showed the highest antioxidant activity compared to the rest. Based on these results, HHP together with convective drying offers the chance of producing dried aloe with high antioxidant attributes. 相似文献
14.
Ankit Patras Nigel P. Brunton B. K. Tiwari Francis Butler 《Food and Bioprocess Technology》2011,4(7):1245-1252
The effect of storage time and temperature on degradation of bioactive compounds such as ascorbic acid, anthocyanins, total
phenols, colour and total antioxidant capacity of strawberry jam were investigated. The results indicated that lightness (L) value decreased significantly (p < 0.05) over 28 days of storage at 4 and 15 °C, with lower values measured at higher temperatures. Anthocyanins, ascorbic
acid and colour degradation followed first-order kinetics where the rate constant increased with an increase in the temperature.
The reaction rate constant (k) increased from 0.95 × 10−2 day−1 to 1.71 × 10−2 day−1 at 4 and 15 °C for anthocyanins. Similarly, k increased from 2.08 × 10−2 day−1 to 4.54 × 10−2 day−1 at 4 and 15 °C for ascorbic acid. In general, total antioxidant activity for strawberry jam samples stored for 28 days at
4 and 15 °C exhibited lower values as compared to control (day 0). The results showed greater stability of nutritional parameters
at 4 °C compared to 15 °C. 相似文献
15.
P. Esakkiraj G. Immanuel S. M. Sowmya P. Iyapparaj A. Palavesam 《Food and Bioprocess Technology》2009,2(4):383-390
Extracellular protease production by Bacillus cereus isolated from the intestine of fish Mugil cephalus has been investigated in shake-flask experiment using different preparations of tuna-processing waste such as raw fish meat,
defatted fish meat, alkali hydrolysate, and acid hydrolysate as nitrogen source. Among the tuna preparations tested, defatted
fish meat supported the maximum protease production (134.57 ± 0.47 U ml−1), and 3% concentration of the same was found to be optimum for maximizing the protease production (178.50 ± 0.28 U ml−1). Effect of carbon sources on protease production in the optimized concentration of defatted tuna fish meat revealed that
galactose aided the higher protease production (259.83 ± 0.04 U ml–1) than the other tested carbon sources and a concentration of 1.5% galactose registered as optimum to enhance the protease
production (289.40 ± 0.16 U ml−1). The halotolerancy of B. cereus for protease production indicated that 3% of sodium chloride was optimum to yield maximum protease (301.63 ± 0.20 U ml−1). Among the surfactants tested, protease production was high in Triton X 100-added medium (298.63 ± 0.12 U ml−1) when compared to other surfactants, and its optimum concentration recorded was 0.8% (320.57 ± 0.17 U ml−1) for more protease production. Partial characterization of crude enzyme revealed that pH 7.0 (278.90 ± 0.08 U ml−1) and 60°C temperature (332.37 ± 0.18 U ml−1) were optimum for better protease activity by B. cereus. 相似文献
16.
Nilg??n ?zt??rk Muzaffer Tun?el Ulku Dilek Uysal Elif Mine Oncu-Kaya Onur Koyuncu 《Food Analytical Methods》2011,4(3):300-306
This study describes a method development for the determination of rosmarinic acid (RA) by using a gradient high-performance
liquid chromatography (HPLC) and its application to certain plant materials. The analysis was performed by utilizing a two
solvents system [A: methanol/water/formic acid (10:88:2; v:v:v); B: methanol/water/formic acid (90:8:2; v:v:v)] on a reverse-phase column. The flow rate and injection volume were 1 ml min−1 and 10 μl, respectively. Signals were detected at 280 nm. In addition, an internal standard (IS) technique was applied for
the analysis of RA to increase precision, and propylparaben was employed for this purpose. The repeatability results as RSD%
were 1.66, 1.17 and 1.26 for intra-day and 1.38 was for inter-day with the employment of (3.67 × 10−5 M) RA. A limit of linearity (LOL) was observed in a wide (1.13 × 10−5–5.65 × 10−4 M) concentration range. Linearity parameters were also examined in the range of 5.95 × 10−6–7.14 × 10−5 M RA, and very good correlation was observed. The limit of detection (LOD) and limit of quantification (LOQ) (for inter-day)
were 1.60 × 10−6 M (signal/noise [S/N] = 3.3) and 4.80 × 10−6 M (S/N = 10), respectively. The method was applied to the extracts of certain Lamiaceae plants (Salvia candidissima Vahl. subsp. candidissima, S. sclarea L., S. verticillata L. subsp. verticillata and R. officinalis L.), and reasonable results were obtained. 相似文献
17.
Ali Ganjloo Russly Abdul Rahman Azizah Osman Jamilah Bakar Mandana Bimakr 《Food and Bioprocess Technology》2011,4(8):1442-1449
Thermal treatment of seedless guava (Psidium guajava L.) cubes was carried out in the temperature range of 80–95 °C. The kinetics of peroxidase inactivation and color changes
due to thermal treatments were determined. Peroxidase inactivation followed a first-order kinetic model, where the activation
energy was 96.39 ± 4 kJ mol−1. Color was quantified in terms of L, a, and b values in the Hunter system. The color changes during processing were described by a first-order kinetic model, except total
color difference which followed a zero-order kinetic model. The temperature dependence of the degradation followed the Arrhenius
relation. The activation energies (E
a) for L, a, b, and total color difference (ΔE) were 122.68 ± 3, 88.47 ± 5, 104.86 ± 5, and 112.65 ± 5 kJ mol−1, respectively. The results of this work are a good tool to further optimize seedless guava thermal treatment conditions. 相似文献
18.
Brahim Bchir Souhail Besbes Romdhane Karoui Hamadi Attia Michel Paquot Christophe Blecker 《Food and Bioprocess Technology》2012,5(5):1840-1852
The drying of pomegranate seeds was investigated at 40 °C, 50 °C and 60 °C with air velocity of 2 m/s. Prior to drying, seeds
were osmodehydrated in 55 °Brix sucrose solution for 20 min at 50 °C. The drying kinetics and the effects of osmotic dehydration
(OD) and air-drying temperature on antioxidant capacity, total phenolics, colour and texture were determined. Analysis of
variance revealed that OD and air-drying temperature have a significant influence on the quality of seeds. Both anthocyanin
and total phenolic contents decreased when air-drying temperature increased. The radical diphenylpicril-hydrazyl activity
showed the lowest antioxidant activity at 60 °C. Both chromatic parameters (L*, C* and h°) and browning index were affected by drying temperatures, which contributed to the discolouring of seeds. The final product
has 22%, 20% and 16% of moisture; 0.630, 0.478 and 0.414 of a
w; 151, 141 and 134 mg gallic acid equivalent/100 g fresh matter (FM) of total phenolics; 40, 24, 20 mg/100 g FM of anthocyanins
and 46%, 39% and 31% of antioxidant activity, for drying temperatures of 40 °C, 50 °C and 60 °C, respectively. In view of
these results, the temperature of 40 °C is recommended as it has the lowest impact on the quality parameters of the seeds.
Differential scanning calorimetry data provided complementary information on the mobility changes of water during drying.
Glass transition temperature (Tg′) depends on moisture content and as consequence, on drying conditions. In fact, Tg′ of seeds
dried at 60 °C (Tg′ = −21 °C) was higher than those dried at 50 °C (Tg′ = −28 °C) or 40 °C (Tg′ = −31 °C) and osmodehydrated
seeds (Tg′ = −34 °C). During OD and drying process, the texture of seeds changed. The thickness of seeds shrank by 55% at
60 °C. 相似文献
19.
S. Adinarayana Reddy K. Janardhan Reddy S. Lakshmi Narayana Y. Subba Rao C. Ramachandraiah A. Varada Reddy 《Food Analytical Methods》2009,2(2):141-148
Synthesized a new reagent 2, 6-Diacetylpyridine bis-4-phenyl-3-thiosemicarbazone (2, 6-DAPBPTSC) characterized and is proposed
as a sensitive and selective analytical reagent for the extractive spectrophotometric determination of molybdenum(VI) at pH 3.5
to form a yellowish orange colored 1:1 chelate complex. The absorbance was measured at a maximum wavelength, 500 nm. This
method obeys Beer’s law in the concentration range 0.90–9.00 μg mL−1 and the correlation coefficient of Mo(VI)–2,6-DAPBPTSC complex is 0.954, which indicates an adequate linearity between the
two variables with good molar absorptivity and Sandell’s sensitivity, 1.212 × 104 L mol−1cm−1, 0.0079 μg cm−2, respectively. The precision and accuracy of the method is checked with calculation of relative standard deviation (n = 5), 0.894% and the detection limit value is 0.0056 μg mL−1. The instability constant of the method has been calculated by Asmus’ method as 6.476 × 10–5, at room temperature. The interfering effect of various cations and anions has also been studied. The method was successfully
applied for the determination of Mo(VI) in food and water samples. The validity of the present method was evaluated in terms
of Student ‘t’ test and Variance ‘f’ test, which indicates the significance of the present method an inter comparison of the experimental values, using atomic
absorption spectrometer. 相似文献
20.
A simple and sensitive spectrophotometric method for determination of nitrite has been described. The method is based on the
oxidation of brilliant cresyl blue (BCB) by nitrite in acidic medium, which results in the decrease in absorbance at 636 nm.
The decrease in absorbance is directly proportional to nitrite concentration obeying Beer’s law. The sensitivity is largely
enhanced in the presence of β-cyclodextrin (β-CD) because of inclusion complexation. It was calculated that β-CD and BCB could
form 1:1 inclusion complexation with a formation constant of 546.6 L/mol. Linear calibration graphs were obtained for 0.02 × 10−3–0.8 × 10−3 g/L sodium nitrite at 636 nm. The detection limit for the analytical procedure was 4.0 × 10−6 g/L sodium nitrite. The relative standard deviation for determination of 0.1 × 10−3 g/L and 0.5 × 10−3 g/L sodium nitrite were 0.69% and 0.38%, for ten determinations, respectively. Twenty-two coexistent ions or species were
examined, and no serious interference for most of ions was observed. The method has been applied to determine nitrite in water
and vegetable samples with satisfactory results. 相似文献