{"id":1195,"date":"2024-04-11T14:44:13","date_gmt":"2024-04-11T11:44:13","guid":{"rendered":"https:\/\/sisu.ut.ee\/lcms_method_validation\/self-test-10-4\/"},"modified":"2024-04-11T14:44:13","modified_gmt":"2024-04-11T11:44:13","slug":"self-test-10-4","status":"publish","type":"page","link":"https:\/\/sisu.ut.ee\/lcms_method_validation\/self-test-10-4\/","title":{"rendered":"Self test 10.4"},"content":{"rendered":"
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1. <\/span>An analyst has developed a LC\/MS method for determining pesticides in tomatoes. One important aspect for your method is that each analyte is analyzed in a fixed time window.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
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Time window<\/p>\n<\/td>\n

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Analyte<\/p>\n<\/td>\n

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Retention time (min)<\/p>\n<\/td>\n

m\/z<\/em> of precursor ion<\/td>\nm\/z<\/em> of product ion<\/td>\n<\/tr>\n
1<\/td>\noxamyl<\/td>\n\n

7.8<\/p>\n<\/td>\n

242<\/td>\n185<\/td>\n<\/tr>\n
2<\/td>\nthiamethoxam<\/td>\n\n

9.1<\/p>\n<\/td>\n

292<\/td>\n211<\/td>\n<\/tr>\n
carbendazim<\/td>\n\n

8.5<\/p>\n<\/td>\n

192<\/td>\n160<\/td>\n<\/tr>\n
3<\/td>\nimidacloprid<\/td>\n\n

10.3<\/p>\n<\/td>\n

256<\/td>\n209<\/td>\n<\/tr>\n
thiabendazole<\/td>\n\n

9.6<\/p>\n<\/td>\n

202<\/td>\n175<\/td>\n<\/tr>\n
4<\/td>\nacetamiprid<\/td>\n\n

11.2<\/p>\n<\/td>\n

223<\/td>\n126<\/td>\n<\/tr>\n
vamidothion<\/td>\n\n

10.9<\/p>\n<\/td>\n

310<\/td>\n146<\/td>\n<\/tr>\n
5<\/td>\nthiacloprid<\/td>\n\n

12.0<\/p>\n<\/td>\n

253<\/td>\n126<\/td>\n<\/tr>\n
6<\/td>\nspiroxamine<\/td>\n\n

15.2<\/p>\n<\/td>\n

298<\/td>\n144<\/td>\n<\/tr>\n
imazalil<\/td>\n\n

13.9<\/p>\n<\/td>\n

297<\/td>\n201<\/td>\n<\/tr>\n
7<\/td>\nmepanipyrim<\/td>\n\n

17.3<\/p>\n<\/td>\n

224<\/td>\n183<\/td>\n<\/tr>\n
fluquinconazole<\/td>\n\n

17.1<\/p>\n<\/td>\n

376<\/td>\n349<\/td>\n<\/tr>\n
methiocarb<\/td>\n\n

16.5<\/p>\n<\/td>\n

226<\/td>\n169<\/td>\n<\/tr>\n
8<\/td>\nbuprofezin<\/td>\n\n

18.8<\/p>\n<\/td>\n

306<\/td>\n201<\/td>\n<\/tr>\n
hexythiazox<\/td>\n\n

19.3<\/p>\n<\/td>\n

353<\/td>\n228<\/td>\n<\/tr>\n
9<\/td>\netofenprox<\/td>\n\n

20.9<\/p>\n<\/td>\n

359<\/td>\n189<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Therefore it is important to verify if the method is robust enough from the retention times point of view (i.e. if the retention times are stable enough). Analyst uses isocratic elution with eluent composition 30% (v\/v) of 1 mM acetic acid buffer with pH 4.5 and 70% (v\/v) of acetonitrile. Analyst wants to study the effect of buffer concentration (0.9 mM to 1.1 mM)|pH (4.0 to 5.0) and organic modifier content (68% to 72%). Please indicate which experiments need to be carried out to evaluate the robustness with full factorial design.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
% MeCN<\/td>\npH<\/td>\nBuffer concentration (mM)<\/td>\n<\/tr>\n
68<\/td>\n4.0<\/td>\n
68<\/td>\n1.1<\/td>\n<\/tr>\n
5.0<\/td>\n0.9<\/td>\n<\/tr>\n
68<\/td>\n5.0<\/td>\n
72<\/td>\n0.9<\/td>\n<\/tr>\n
72<\/td>\n4.0<\/td>\n
5.0<\/td>\n0.9<\/td>\n<\/tr>\n
5.0<\/td>\n1.1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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2. <\/span>Imagine we want to perform a full factorial design with four factors that influence our response. How many experiments need to be performed?<\/div><\/div>