What kind of question dose analytical epidemiological research focus on? ()
A.When
B. How
C. What
D. why
- · 有2位网友选择 A,占比25%
- · 有2位网友选择 D,占比25%
- · 有2位网友选择 C,占比25%
- · 有2位网友选择 B,占比25%
A.When
B. How
C. What
D. why
A、The main analytical techniques used for determination of trace elements in environmental samples include:
B、Atomic absorption spectrometry (flame or electrothermal) (AAS, ET-AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma optical (or atomic) emission spectrometry (ICP-OES or ICP-AES), neutron activation analysis (NAA), X-ray fluorescence (XRF), proton-induced X-ray emission (PIXE), spark source or isotope dilution mass spectrometry (SSMS, IDMS), electrochemical (anodic stripping voltammetry and polarography) or inductively coupled plasma-mass spectrometry (ICP-MS).
C、The main limitations for most of these analytical methods are sensitivity or precision problems due to interferences and sample matrix effects.
D、In some cases these problems have been reduced or eliminated by the use of pre-analysis separation schemes, matrix-matching of reagent blanks, calibration standards and samples; the inclusion of instrument background correction (AAS) or the coupling of hydride generation (HG), electro thermal vaporization (ETV), cold vapor (CV), flow injection (FI), ultrasonic nebulisation (USN) or laser ablation (LA) devices to the trace element detector.
A、The ideal analytical technique for measuring trace elements in environmental samples must offer: (a) very low detection limits, (b) a wide linear dynamic range, (c) simple interference–free data,
B、The choice of analytical method for making trace element measurements of environmental or biological samples depends not only on availability but on a variety of factors: a. multi or single element determination; b. required detection or determination limits; c. required type of sample preparation; d. possible matrix or interference effects;
C、e. total dissolved solids content; f. liquid or solids analysis; g. required levels of precision and accuracy; h. one-off or routine analysis; i. throughput and cost per determination.
D、(d) qualitative , semi-quantitative and quantitative analysis, (e) possible simultaneous multielement capability, (f) simple sample preparation, (g) high throughput and low cost per determination.
为了保护您的账号安全,请在“简答题”公众号进行验证,点击“官网服务”-“账号验证”后输入验证码“”完成验证,验证成功后方可继续查看答案!