blob: c8c91bcb274c32ad81c0661620e297a1b17f68da (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
|
<!DOCTYPE html>
<!-- Generated by pkgdown: do not edit by hand --><html lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Calculation of time weighted average concentrations with mkin • mkin</title>
<!-- jquery --><script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js" integrity="sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo=" crossorigin="anonymous"></script><!-- Bootstrap --><link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.4.1/css/bootstrap.min.css" integrity="sha256-bZLfwXAP04zRMK2BjiO8iu9pf4FbLqX6zitd+tIvLhE=" crossorigin="anonymous">
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.4.1/js/bootstrap.min.js" integrity="sha256-nuL8/2cJ5NDSSwnKD8VqreErSWHtnEP9E7AySL+1ev4=" crossorigin="anonymous"></script><!-- bootstrap-toc --><link rel="stylesheet" href="../bootstrap-toc.css">
<script src="../bootstrap-toc.js"></script><!-- Font Awesome icons --><link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/all.min.css" integrity="sha256-mmgLkCYLUQbXn0B1SRqzHar6dCnv9oZFPEC1g1cwlkk=" crossorigin="anonymous">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.12.1/css/v4-shims.min.css" integrity="sha256-wZjR52fzng1pJHwx4aV2AO3yyTOXrcDW7jBpJtTwVxw=" crossorigin="anonymous">
<!-- clipboard.js --><script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.6/clipboard.min.js" integrity="sha256-inc5kl9MA1hkeYUt+EC3BhlIgyp/2jDIyBLS6k3UxPI=" crossorigin="anonymous"></script><!-- headroom.js --><script src="https://cdnjs.cloudflare.com/ajax/libs/headroom/0.11.0/headroom.min.js" integrity="sha256-AsUX4SJE1+yuDu5+mAVzJbuYNPHj/WroHuZ8Ir/CkE0=" crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/headroom/0.11.0/jQuery.headroom.min.js" integrity="sha256-ZX/yNShbjqsohH1k95liqY9Gd8uOiE1S4vZc+9KQ1K4=" crossorigin="anonymous"></script><!-- pkgdown --><link href="../pkgdown.css" rel="stylesheet">
<script src="../pkgdown.js"></script><meta property="og:title" content="Calculation of time weighted average concentrations with mkin">
<meta property="og:description" content="mkin">
<!-- mathjax --><script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/MathJax.js" integrity="sha256-nvJJv9wWKEm88qvoQl9ekL2J+k/RWIsaSScxxlsrv8k=" crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/config/TeX-AMS-MML_HTMLorMML.js" integrity="sha256-84DKXVJXs0/F8OTMzX4UR909+jtl4G7SPypPavF+GfA=" crossorigin="anonymous"></script><!--[if lt IE 9]>
<script src="https://oss.maxcdn.com/html5shiv/3.7.3/html5shiv.min.js"></script>
<script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
<![endif]-->
</head>
<body data-spy="scroll" data-target="#toc">
<div class="container template-article">
<header><div class="navbar navbar-default navbar-fixed-top" role="navigation">
<div class="container">
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<span class="navbar-brand">
<a class="navbar-link" href="../index.html">mkin</a>
<span class="version label label-default" data-toggle="tooltip" data-placement="bottom" title="Released version">1.2.3</span>
</span>
</div>
<div id="navbar" class="navbar-collapse collapse">
<ul class="nav navbar-nav">
<li>
<a href="../reference/index.html">Reference</a>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Articles
<span class="caret"></span>
</a>
<ul class="dropdown-menu" role="menu">
<li>
<a href="../articles/mkin.html">Introduction to mkin</a>
</li>
<li class="divider">
</li>
<li class="dropdown-header">Example evaluations with (generalised) nonlinear least squares</li>
<li>
<a href="../articles/FOCUS_D.html">Example evaluation of FOCUS Example Dataset D</a>
</li>
<li>
<a href="../articles/FOCUS_L.html">Example evaluation of FOCUS Laboratory Data L1 to L3</a>
</li>
<li>
<a href="../articles/web_only/FOCUS_Z.html">Example evaluation of FOCUS Example Dataset Z</a>
</li>
<li class="divider">
</li>
<li class="dropdown-header">Example evaluations with hierarchical models (nonlinear mixed-effects models)</li>
<li>
<a href="../articles/prebuilt/2022_dmta_parent.html">Testing hierarchical parent degradation kinetics with residue data on dimethenamid and dimethenamid-P</a>
</li>
<li>
<a href="../articles/prebuilt/2022_dmta_pathway.html">Testing hierarchical pathway kinetics with residue data on dimethenamid and dimethenamid-P</a>
</li>
<li>
<a href="../articles/prebuilt/2022_cyan_pathway.html">Testing hierarchical pathway kinetics with residue data on cyantraniliprole</a>
</li>
<li>
<a href="../articles/web_only/dimethenamid_2018.html">Comparison of saemix and nlme evaluations of dimethenamid data from 2018</a>
</li>
<li>
<a href="../articles/web_only/multistart.html">Short demo of the multistart method</a>
</li>
<li class="divider">
</li>
<li class="dropdown-header">Performance</li>
<li>
<a href="../articles/web_only/compiled_models.html">Performance benefit by using compiled model definitions in mkin</a>
</li>
<li>
<a href="../articles/web_only/benchmarks.html">Benchmark timings for mkin</a>
</li>
<li>
<a href="../articles/web_only/saem_benchmarks.html">Benchmark timings for saem.mmkin</a>
</li>
<li class="divider">
</li>
<li class="dropdown-header">Miscellaneous</li>
<li>
<a href="../articles/twa.html">Calculation of time weighted average concentrations with mkin</a>
</li>
<li>
<a href="../articles/web_only/NAFTA_examples.html">Example evaluation of NAFTA SOP Attachment examples</a>
</li>
</ul>
</li>
<li>
<a href="../news/index.html">News</a>
</li>
</ul>
<ul class="nav navbar-nav navbar-right">
<li>
<a href="https://github.com/jranke/mkin/" class="external-link">
<span class="fab fa-github fa-lg"></span>
</a>
</li>
</ul>
</div>
<!--/.nav-collapse -->
</div>
<!--/.container -->
</div>
<!--/.navbar -->
</header><div class="row">
<div class="col-md-9 contents">
<div class="page-header toc-ignore">
<h1 data-toc-skip>Calculation of time weighted average
concentrations with mkin</h1>
<h4 data-toc-skip class="author">Johannes
Ranke</h4>
<h4 data-toc-skip class="date">Last change 18 September 2019
(rebuilt 2023-04-20)</h4>
<small class="dont-index">Source: <a href="https://github.com/jranke/mkin/blob/HEAD/vignettes/twa.rmd" class="external-link"><code>vignettes/twa.rmd</code></a></small>
<div class="hidden name"><code>twa.rmd</code></div>
</div>
<p>Since version 0.9.45.1 of the ‘mkin’ package, a function for
calculating time weighted average concentrations for decline kinetics
(<em>i.e.</em> only for the compound applied in the experiment) is
included. Strictly speaking, they are maximum moving window time
weighted average concentrations, <em>i.e.</em> the maximum time weighted
average concentration that can be found when moving a time window of a
specified width over the decline curve.</p>
<p>Time weighted average concentrations for the SFO, FOMC and the DFOP
model are calculated using the formulas given in the FOCUS kinetics
guidance <span class="citation">(FOCUS Work Group on Degradation
Kinetics 2014, 251)</span>:</p>
<p>SFO:</p>
<p><span class="math display">\[c_\textrm{twa} = c_0 \frac{\left( 1 -
e^{- k t} \right)}{ k t} \]</span></p>
<p>FOMC:</p>
<p><span class="math display">\[c_\textrm{twa} = c_0 \frac{\beta}{t (1 -
\alpha)}
\left( \left(\frac{t}{\beta} + 1 \right)^{1 - \alpha}
- 1 \right) \]</span></p>
<p>DFOP:</p>
<p><span class="math display">\[c_\textrm{twa} = \frac{c_0}{t} \left(
\frac{g}{k_1} \left( 1 - e^{- k_1 t} \right) +
\frac{1-g}{k_2} \left( 1 - e^{- k_2 t} \right) \right) \]</span></p>
<p>HS for <span class="math inline">\(t > t_b\)</span>:</p>
<p><span class="math display">\[c_\textrm{twa} = \frac{c_0}{t} \left(
\frac{1}{k_1} \left( 1 - e^{- k_1 t_b} \right) +
\frac{e^{- k_1 t_b}}{k_2} \left( 1 - e^{- k_2 (t - t_b)}
\right) \right) \]</span></p>
<p>Often, the ratio between the time weighted average concentration
<span class="math inline">\(c_\textrm{twa}\)</span> and the initial
concentration <span class="math inline">\(c_0\)</span></p>
<p><span class="math display">\[f_\textrm{twa} =
\frac{c_\textrm{twa}}{c_0}\]</span></p>
<p>is needed. This can be calculated from the fitted initial
concentration <span class="math inline">\(c_0\)</span> and the time
weighted average concentration <span class="math inline">\(c_\textrm{twa}\)</span>, or directly from the
model parameters using the following formulas:</p>
<p>SFO:</p>
<p><span class="math display">\[f_\textrm{twa} = \frac{\left( 1 - e^{- k
t} \right)}{k t} \]</span></p>
<p>FOMC:</p>
<p><span class="math display">\[f_\textrm{twa} = \frac{\beta}{t (1 -
\alpha)}
\left( \left(\frac{t}{\beta} + 1 \right)^{1 - \alpha}
- 1 \right) \]</span></p>
<p>DFOP:</p>
<p><span class="math display">\[f_\textrm{twa} = \frac{1}{t} \left(
\frac{g}{k_1} \left( 1 - e^{- k_1 t} \right) +
\frac{1-g}{k_2} \left( 1 - e^{- k_2 t} \right) \right) \]</span></p>
<p>HS for <span class="math inline">\(t > t_b\)</span>:</p>
<p><span class="math display">\[f_\textrm{twa} = \frac{1}{t} \left(
\frac{1}{k_1} \left( 1 - e^{- k_1 t_b} \right) +
\frac{e^{- k_1 t_b}}{k_2} \left( 1 - e^{- k_2 (t - t_b)}
\right) \right) \]</span></p>
<p>Note that a method for calculating maximum moving window time
weighted average concentrations for a model fitted by ‘mkinfit’ or from
parent decline model parameters is included in the
<code><a href="../reference/max_twa_parent.html">max_twa_parent()</a></code> function. If the same is needed for
metabolites, the function <code><a href="https://pkgdown.jrwb.de/pfm/reference/max_twa.html" class="external-link">pfm::max_twa()</a></code> from the ‘pfm’
package can be used.</p>
<div id="refs" class="references csl-bib-body hanging-indent">
<div id="ref-FOCUSkinetics2014" class="csl-entry">
FOCUS Work Group on Degradation Kinetics. 2014. <em>Generic Guidance for
Estimating Persistence and Degradation Kinetics from Environmental Fate
Studies on Pesticides in EU Registration</em>. 1.1 ed. <a href="http://esdac.jrc.ec.europa.eu/projects/degradation-kinetics" class="external-link">http://esdac.jrc.ec.europa.eu/projects/degradation-kinetics</a>.
</div>
</div>
</div>
<div class="col-md-3 hidden-xs hidden-sm" id="pkgdown-sidebar">
</div>
</div>
<footer><div class="copyright">
<p></p>
<p>Developed by Johannes Ranke.</p>
</div>
<div class="pkgdown">
<p></p>
<p>Site built with <a href="https://pkgdown.r-lib.org/" class="external-link">pkgdown</a> 2.0.7.</p>
</div>
</footer>
</div>
</body>
</html>
|