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msmnainar ★ India, 2012-06-24 11:06 (5103 d 14:23 ago) Posting: # 8836 Views: 9,009 |
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Hello everyone Can anybody explain how to back calculate (formula captured below) to compare the results of phosphate binding capacity. Langmuir equation: Ceq/(x/m)=1/k1·k2+Ceq/k2 Where Ceq is the concentration, in mM, of phosphate remaining in solution at equilibrium or the unbound concentration. x/m is the amount of phosphate bound per weight of polymer in mmol/g. k1 Affinity Constant k2 Capacity Constant — Sundar. M |
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ElMaestro ★★★ Denmark, 2012-06-24 13:12 (5103 d 12:17 ago) @ msmnainar Posting: # 8837 Views: 8,008 |
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Hi msmnainar, ❝ Can anybody explain how to back calculate (formula captured below) to compare the results of phosphate binding capacity. ❝ Langmuir equation: Ceq/(x/m)=1/k1.k2+Ceq/k2 Do you mean isolating Ceq? Let a=(x/m) C/a=1/(k1k2)+(C/k2) <=> C/a-C/k2=1/(k1k2) <=> C(1/a-1/k2)=1/(k1k2) <=> C=(1/(k1k2))/((1/a-1/k2)) or C=(1/(k1k2))/((1/(x/m)-1/k2)) The latter can be re-arranged as necessary. — Pass or fail! ElMaestro |
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msmnainar ★ India, 2012-06-25 07:12 (5102 d 18:17 ago) @ ElMaestro Posting: # 8838 Views: 8,020 |
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Thanks for your response. — Sundar. M |
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msmnainar ★ India, 2012-06-25 10:46 (5102 d 14:43 ago) @ ElMaestro Posting: # 8839 Views: 7,912 |
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Dear ElMaestro Post to your response am having few queries reg back calculation, kindly guide me, For eg., Obtained Total Bound Bile acid Concentration, mM (x/m) Concentration Product XObtained Total Unbound Bile acid Concentration, mM (ceq) Concentration Product XObtained k1 and k2 values: k1 = 1.2071 k2 = 5.4189 Back calculated value for Ceq = 2.9970 using mean data (x/m), as per the provided formula C = (1/(k1k2))/((1/(x/m)-1/k2)) Kindly guide me, if am correct this value should matches with obtained Ceq value for product x mean value or any further comparison should be done. ---------- Hello Helmutji It was very nice to meet you at Budapest during 3rd international regulatory conference. Need your expertise in this regard. — Sundar. M |
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ElMaestro ★★★ Denmark, 2012-06-25 12:36 (5102 d 12:53 ago) @ msmnainar Posting: # 8840 Views: 7,923 |
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Hi msmnaimar, ❝ Kindly guide me, if am correct this value should matches with obtained Ceq value for product x mean value or any further comparison should be done. Sorry, I have to confess that I do not have any insight into the Langmuir stuff or ad(/b)sorption phenomena. What I merely did was rearranging an equation. From the description and data you gave I cannot make sense of the task. I will be happy to take a closer look if you can describe what's going on in mathematical terms: You have what plotted against what? What term of the equation are you trying to backcalculate given which value of which other term? Many thanks and I am sorry for having little insight into the practical use of the equation. — Pass or fail! ElMaestro |
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msmnainar ★ India, 2012-06-25 12:59 (5102 d 12:30 ago) @ ElMaestro Posting: # 8841 Views: 7,898 |
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Dear ElMaestro Thanks for your swift reply, A plot of Ceq/(x/m) versus Ceq was depicted to obtain k1 and k2 values. Ceq/(x/m) values are depicted for your ready reference. Concentration Ceq/(x/m)Regression analysis applied to yield a slope (a) and intercept (b) of the line. The affinity constant, k 1, and capacity constant, k 2, are calculated from the slope and intercept as follows: K1=a/b K2=1/a Here, actually we need to confirm whether the calculated steps/values are reproducible using back calculation. Hope I am explained properly. M. Sundar, India — Sundar. M |
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ElMaestro ★★★ Denmark, 2012-06-25 13:03 (5102 d 12:26 ago) @ msmnainar Posting: # 8842 Views: 7,878 |
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Hi msnaimar, ❝ A plot of Ceq/(x/m) versus Ceq was depicted to obtain k1 and k2 values. ❝ (...) Here, actually we need to confirm whether the calculated steps/values are reproducible using back calculation. What do you wish to back-calculate? And when you do it, which is the input parameter (and at which value) that you want an output from? — Pass or fail! ElMaestro |
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msmnainar ★ India, 2012-06-25 13:26 (5102 d 12:03 ago) @ ElMaestro Posting: # 8843 Views: 7,956 |
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Dear ElMaestro ❝ ❝ A plot of Ceq/(x/m) versus Ceq was depicted to obtain k1 and k2 values. ❝ Please explain the bold part. Obtained Total Unbound Bile acid Concentration, mM (ceq) Obtained Total Bound Bile acid Concentration, mM (x/m) ❝ What do you wish to back-calculate? And when you do it, which is the input parameter (and at which value) that you want an output from? The results obtained from Langmuir equation (Ceq/(x/m) =1/k1.k2+Ceq/k2) to be back calculated. Inputs are, k1 = 1.2071 k2 = 5.4189 Obtained Ceq values for 9 different concentrations, mean and sum values are presented below, Concentration (ceq)Obtained Ceq/(x/m) values Concentration Ceq/(x/m)— Sundar. M |
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ElMaestro ★★★ Denmark, 2012-06-25 13:35 (5102 d 11:54 ago) @ msmnainar Posting: # 8844 Views: 7,866 |
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Hi msnaimar, ❝ Obtained k1 and k2 values: ❝ k1 = 1.2071 ❝ k2 = 5.4189 So far so good. I can reproduce your values using this code in R: x.by.m=c(1.2595, 1.9113, 3.2978, 4.3539, 4.8442, 6.251, 5.843, 5.772, 4.6759)When I look at the summary and the plot, the curve does not strike me as necessarily linear all across. — Pass or fail! ElMaestro |
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msmnainar ★ India, 2012-06-25 14:00 (5102 d 11:30 ago) @ ElMaestro Posting: # 8845 Views: 7,927 |
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Dear ElMaestro Thanks for your response. — Sundar. M |
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ElMaestro ★★★ Denmark, 2012-06-25 15:19 (5102 d 10:10 ago) @ msmnainar Posting: # 8846 Views: 7,848 |
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Hi msmnainar, it strikes me as very odd if you want to back-calculate Ceq on basis of a mean of a range of x/m calibrators. — Pass or fail! ElMaestro |
Ing. Helmut Schütz