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80金币求助英译汉：关于《分析与质谱方面》
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The current criteria are not based on objective or empirical forms of measurement, but are based on arbitrary criteria using subjective assessments about the degree of selectivity provided by different MS techniques. The assessments are generally correct, but there are many exceptions, depending on the analyte-matrix pair, the concentration, the MS ions detected, the analytical technique, and the importance of the results. The current rates of false negatives are thought to be too high in both types of application (enforcement and non-enforcement) because the identification criteria are too stringent. Furthermore, spurious errors are not typically addressed to reduce false positives, which are best addressed through confirmatory analysis. As the word implies, ‘‘confirmation’’ requires the results from at least two analyses (which should ideally be orthogonally selective and at least one of them should involve MS detection after an analytical separation), which, in enforcement applications, must agree with each other in terms of analyte identity and concentration. For non-enforcement purposes, a single analysis using MS detection should be satisfactory, or two analyses using non-MS methods, provided that there has been an empirical demonstration that acceptably low rates of false positives and false negatives occur for the analytes at an adequately low concentration in the targeted matrices. An MS qualitative screening approach may be the best option, followed by a different method to make the confirmation and to improve the quantitative determination. We summarize the arguments and the points made in this article in the following proposed sequence for quantitative and qualitative method validation. (1) Define the need for the analysis (scope of analytes and matrices, concentration ranges, acceptable degree of accuracy, and tolerable rate of false negatives); (2) Define the primary analytical method(s) to meet the needs of the analysis most effectively and efficiently (e.g., GC-MS, LC-MS2, GC with selective detection, LC-fluorescence, and others); (3) Conduct method validation of the primary method(s) for the targeted analyte(s) and matrix(es) (or representative analytes and matrices) to determine quantitative characteristics of the method(s) according to accepted practices; (4) At the same time as quantitative method validation, empirically determine MS criteria using samples of known concentrations on different days in fortified matrices to achieve the desired identification limit (with set criteria to minimize false negatives); (5) Measure rates of false positives while also training analysts through analysis of blind fortification samples(P10–20 blanks from different sources and a similar number of fortified samples at a variety of concentrations); [Note: this can be done over time during routine analyses, and such tests should be part of the QC requirements]; (6) Devise a second approach to be used for independent confirmation of suspected violative samples from the initial analysis, and conduct blind analyses of extracts to estimate rates of false positives and false negatives vs concentration, as in Step (5). The proposed validation sequence covers only general factors, but, in future, we hope that more specific, practical procedures can be described, just as in the case of quantitative method validation for chemical residue analysis. Further scientific study of the degree of selectivity of MS techniques coupled with analytical separations is needed. Ideally, a systematic approach based on sound theory can be devised to assess accurately the degree of accuracy in qualitative MS analysis, but, until that time, we believe that the proposed general approach is more scientific and better fits the purposes of chemical-residue analysis than the arbitrary criteria currently in place. |
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sixmonths
铁杆木虫 (著名写手)
清歌一曲月如霜
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2楼2009-02-01 18:59:33
3楼2009-02-02 08:37:02
qingfeng877680
木虫 (著名写手)
清枫笨小虫
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★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
zxp131415(金币+20,VIP+0):谢谢你，如果对金币数量不满意可以直接向我反馈，谢谢 2-4 13:59
zxp131415(金币+20,VIP+0):谢谢你，如果对金币数量不满意可以直接向我反馈，谢谢 2-4 13:59
|
The current criteria are not based on objective or empirical forms of measurement, but are based on arbitrary criteria using subjective assessments about the degree of selectivity provided by different MS techniques. The assessments are generally correct, but there are many exceptions, depending on the analyte-matrix pair, the concentration, the MS ions detected, the analytical technique, and the importance of the results. 当前的标准不是基于客观或经验的测定形式，而是基于随机的，即根据不同质谱技术的选择程度来进行主观评估。这样的评估常常正确，但由于待测物-基体对、浓度、质谱所检测的离子、分析技术以及分析结果的重要性的差异，评估往往会有例外，即出现错误。 The current rates of false negatives are thought to be too high in both types of application (enforcement and non-enforcement) because the identification criteria are too stringent. Furthermore, spurious errors are not typically addressed to reduce false positives, which are best addressed through confirmatory analysis. 因为识别标准规定地过于严格，所以在两种类型的应用（强制性和非强制性）中，当前的误测率都太高了。进而导致不能得出代表性水平的失真误差来减少错误率，而在验证性实验中，错误率能够有效报道。 As the word implies, ‘‘confirmation’’ requires the results from at least two analyses (which should ideally be orthogonally selective and at least one of them should involve MS detection after an analytical separation), which, in enforcement applications, must agree with each other in terms of analyte identity and concentration. 正如这个词所暗示的，“定性”要求结果必须由不少于两次的分析（两次分析应该用正交实验法来选择，且至少其中之一在分析分离后应该包括质谱检测方法）所得。在强制性执行应用中，其必须与分析物的性质和浓度一致。 |
4楼2009-02-02 23:19:40
qingfeng877680
木虫 (著名写手)
清枫笨小虫
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5楼2009-02-02 23:21:44
sixmonths
铁杆木虫 (著名写手)
清歌一曲月如霜
- 应助: 0 (幼儿园)
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6楼2009-02-02 23:32:30
qingfeng877680
木虫 (著名写手)
清枫笨小虫
- 应助: 0 (幼儿园)
- 贵宾: 1.017
- 金币: 2466
- 散金: 1102
- 红花: 9
- 帖子: 1034
- 在线: 64.4小时
- 虫号: 570669
- 注册: 2008-06-08
- 专业: 高分子物理与高分子物理化
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
zxp131415(金币+10,VIP+0):谢谢你，如果对金币数量不满意可以直接向我反馈，谢谢 2-4 14:00
zxp131415(金币+20,VIP+0):谢谢你了 2-5 08:41
zxp131415(金币+10,VIP+0):谢谢你，如果对金币数量不满意可以直接向我反馈，谢谢 2-4 14:00
zxp131415(金币+20,VIP+0):谢谢你了 2-5 08:41
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For non-enforcement purposes, a single analysis using MS detection should be satisfactory, or two analyses using non-MS methods, provided that there has been an empirical demonstration that acceptably low rates of false positives and false negatives occur for the analytes at an adequately low concentration in the targeted matrices. An MS qualitative screening approach may be the best option, followed by a different method to make the confirmation and to improve the quantitative determination. 对于非强制性执行的应用，如果已经有了经验性报道，即分析物在被测基体中浓度很低，但实验的低假阴性率和假阳性率能够被接受，则一个简单的质谱检测分析或是非质谱法检测两种分析物的实验结果是令人满意的。质谱质量分离方法与另外一种定性并能提高定量检测水平的方法联用，可能是最好的选择。 We summarize the arguments and the points made in this article in the following proposed sequence for quantitative and qualitative method validation. 在这篇文章中，我们针对提出的定性和定量方法的有效性做了以下几点总结。 |
7楼2009-02-02 23:45:05
qingfeng877680
木虫 (著名写手)
清枫笨小虫
- 应助: 0 (幼儿园)
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- 在线: 64.4小时
- 虫号: 570669
- 注册: 2008-06-08
- 专业: 高分子物理与高分子物理化
8楼2009-02-02 23:46:00
9楼2009-02-03 10:23:12
10楼2009-02-03 10:26:50
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