SPECTROSCOPY ANALYSIS METHOD OF TWO REACTIVE DYES USED IN TEXTILE INDUSTRY
Reactive Blue 204 and Reactive Red 183 are two reactive dyes
frequently used for textile painting and printing. Before using in chemical laboratory analysis,
these reactive dyes must be evaluated through validation methods which consists of linearity, stability of solutions, specificity, precision and accuracy. The purpose of this study is to present the validation process of these two reactive dyes. First of all it is graphical represented the dependence of absorbances obtained through spectroscopy analysis in visible domain (636 nm and 503 nm), under some values of concentrations. Statistical parameters and the concentration
domains for which the method presents linearity will be calculated. After that, stability of
solutions, specificity, precision and accuracy including some statistical parameters, will accomplish the validation of process.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
SPECTROSCOPY ANALYSIS METHOD OF TWO REACTIVE DYES USED IN TEXTILE INDUSTRY
Reactive Blue 204 and Reactive Red 183 are two reactive dyes
frequently used for textile painting and printing. Before using in chemical laboratory analysis,
these reactive dyes must be evaluated through validation methods which consists of linearity, stability of solutions, specificity, precision and accuracy. The purpose of this study is to present the validation process of these two reactive dyes. First of all it is graphical represented the dependence of absorbances obtained through spectroscopy analysis in visible domain (636 nm and 503 nm), under some values of concentrations. Statistical parameters and the concentration
domains for which the method presents linearity will be calculated. After that, stability of
solutions, specificity, precision and accuracy including some statistical parameters, will accomplish the validation of process.
2024 State of Marketing Report – by HubspotMarius Sescu
https://www.hubspot.com/state-of-marketing
· Scaling relationships and proving ROI
· Social media is the place for search, sales, and service
· Authentic influencer partnerships fuel brand growth
· The strongest connections happen via call, click, chat, and camera.
· Time saved with AI leads to more creative work
· Seeking: A single source of truth
· TLDR; Get on social, try AI, and align your systems.
· More human marketing, powered by robots
ChatGPT is a revolutionary addition to the world since its introduction in 2022. A big shift in the sector of information gathering and processing happened because of this chatbot. What is the story of ChatGPT? How is the bot responding to prompts and generating contents? Swipe through these slides prepared by Expeed Software, a web development company regarding the development and technical intricacies of ChatGPT!
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...Applitools
During this webinar, Anand Bagmar demonstrates how AI tools such as ChatGPT can be applied to various stages of the software development life cycle (SDLC) using an eCommerce application case study. Find the on-demand recording and more info at https://applitools.info/b59
Key takeaways:
• Learn how to use ChatGPT to add AI power to your testing and test automation
• Understand the limitations of the technology and where human expertise is crucial
• Gain insight into different AI-based tools
• Adopt AI-based tools to stay relevant and optimize work for developers and testers
* ChatGPT and OpenAI belong to OpenAI, L.L.C.
Product Design Trends in 2024 | Teenage EngineeringsPixeldarts
The realm of product design is a constantly changing environment where technology and style intersect. Every year introduces fresh challenges and exciting trends that mold the future of this captivating art form. In this piece, we delve into the significant trends set to influence the look and functionality of product design in the year 2024.
How Race, Age and Gender Shape Attitudes Towards Mental HealthThinkNow
Mental health has been in the news quite a bit lately. Dozens of U.S. states are currently suing Meta for contributing to the youth mental health crisis by inserting addictive features into their products, while the U.S. Surgeon General is touring the nation to bring awareness to the growing epidemic of loneliness and isolation. The country has endured periods of low national morale, such as in the 1970s when high inflation and the energy crisis worsened public sentiment following the Vietnam War. The current mood, however, feels different. Gallup recently reported that national mental health is at an all-time low, with few bright spots to lift spirits.
To better understand how Americans are feeling and their attitudes towards mental health in general, ThinkNow conducted a nationally representative quantitative survey of 1,500 respondents and found some interesting differences among ethnic, age and gender groups.
Technology
For example, 52% agree that technology and social media have a negative impact on mental health, but when broken out by race, 61% of Whites felt technology had a negative effect, and only 48% of Hispanics thought it did.
While technology has helped us keep in touch with friends and family in faraway places, it appears to have degraded our ability to connect in person. Staying connected online is a double-edged sword since the same news feed that brings us pictures of the grandkids and fluffy kittens also feeds us news about the wars in Israel and Ukraine, the dysfunction in Washington, the latest mass shooting and the climate crisis.
Hispanics may have a built-in defense against the isolation technology breeds, owing to their large, multigenerational households, strong social support systems, and tendency to use social media to stay connected with relatives abroad.
Age and Gender
When asked how individuals rate their mental health, men rate it higher than women by 11 percentage points, and Baby Boomers rank it highest at 83%, saying it’s good or excellent vs. 57% of Gen Z saying the same.
Gen Z spends the most amount of time on social media, so the notion that social media negatively affects mental health appears to be correlated. Unfortunately, Gen Z is also the generation that’s least comfortable discussing mental health concerns with healthcare professionals. Only 40% of them state they’re comfortable discussing their issues with a professional compared to 60% of Millennials and 65% of Boomers.
Race Affects Attitudes
As seen in previous research conducted by ThinkNow, Asian Americans lag other groups when it comes to awareness of mental health issues. Twenty-four percent of Asian Americans believe that having a mental health issue is a sign of weakness compared to the 16% average for all groups. Asians are also considerably less likely to be aware of mental health services in their communities (42% vs. 55%) and most likely to seek out information on social media (51% vs. 35%).
AI Trends in Creative Operations 2024 by Artwork Flow.pdfmarketingartwork
This article is all about what AI trends will emerge in the field of creative operations in 2024. All the marketers and brand builders should be aware of these trends for their further use and save themselves some time!
A report by thenetworkone and Kurio.
The contributing experts and agencies are (in an alphabetical order): Sylwia Rytel, Social Media Supervisor, 180heartbeats + JUNG v MATT (PL), Sharlene Jenner, Vice President - Director of Engagement Strategy, Abelson Taylor (USA), Alex Casanovas, Digital Director, Atrevia (ES), Dora Beilin, Senior Social Strategist, Barrett Hoffher (USA), Min Seo, Campaign Director, Brand New Agency (KR), Deshé M. Gully, Associate Strategist, Day One Agency (USA), Francesca Trevisan, Strategist, Different (IT), Trevor Crossman, CX and Digital Transformation Director; Olivia Hussey, Strategic Planner; Simi Srinarula, Social Media Manager, The Hallway (AUS), James Hebbert, Managing Director, Hylink (CN / UK), Mundy Álvarez, Planning Director; Pedro Rojas, Social Media Manager; Pancho González, CCO, Inbrax (CH), Oana Oprea, Head of Digital Planning, Jam Session Agency (RO), Amy Bottrill, Social Account Director, Launch (UK), Gaby Arriaga, Founder, Leonardo1452 (MX), Shantesh S Row, Creative Director, Liwa (UAE), Rajesh Mehta, Chief Strategy Officer; Dhruv Gaur, Digital Planning Lead; Leonie Mergulhao, Account Supervisor - Social Media & PR, Medulla (IN), Aurelija Plioplytė, Head of Digital & Social, Not Perfect (LI), Daiana Khaidargaliyeva, Account Manager, Osaka Labs (UK / USA), Stefanie Söhnchen, Vice President Digital, PIABO Communications (DE), Elisabeth Winiartati, Managing Consultant, Head of Global Integrated Communications; Lydia Aprina, Account Manager, Integrated Marketing and Communications; Nita Prabowo, Account Manager, Integrated Marketing and Communications; Okhi, Web Developer, PNTR Group (ID), Kei Obusan, Insights Director; Daffi Ranandi, Insights Manager, Radarr (SG), Gautam Reghunath, Co-founder & CEO, Talented (IN), Donagh Humphreys, Head of Social and Digital Innovation, THINKHOUSE (IRE), Sarah Yim, Strategy Director, Zulu Alpha Kilo (CA).
Trends In Paid Search: Navigating The Digital Landscape In 2024Search Engine Journal
The search marketing landscape is evolving rapidly with new technologies, and professionals, like you, rely on innovative paid search strategies to meet changing demands.
It’s important that you’re ready to implement new strategies in 2024.
Check this out and learn the top trends in paid search advertising that are expected to gain traction, so you can drive higher ROI more efficiently in 2024.
You’ll learn:
- The latest trends in AI and automation, and what this means for an evolving paid search ecosystem.
- New developments in privacy and data regulation.
- Emerging ad formats that are expected to make an impact next year.
Watch Sreekant Lanka from iQuanti and Irina Klein from OneMain Financial as they dive into the future of paid search and explore the trends, strategies, and technologies that will shape the search marketing landscape.
If you’re looking to assess your paid search strategy and design an industry-aligned plan for 2024, then this webinar is for you.
5 Public speaking tips from TED - Visualized summarySpeakerHub
From their humble beginnings in 1984, TED has grown into the world’s most powerful amplifier for speakers and thought-leaders to share their ideas. They have over 2,400 filmed talks (not including the 30,000+ TEDx videos) freely available online, and have hosted over 17,500 events around the world.
With over one billion views in a year, it’s no wonder that so many speakers are looking to TED for ideas on how to share their message more effectively.
The article “5 Public-Speaking Tips TED Gives Its Speakers”, by Carmine Gallo for Forbes, gives speakers five practical ways to connect with their audience, and effectively share their ideas on stage.
Whether you are gearing up to get on a TED stage yourself, or just want to master the skills that so many of their speakers possess, these tips and quotes from Chris Anderson, the TED Talks Curator, will encourage you to make the most impactful impression on your audience.
See the full article and more summaries like this on SpeakerHub here: https://speakerhub.com/blog/5-presentation-tips-ted-gives-its-speakers
See the original article on Forbes here:
http://www.forbes.com/forbes/welcome/?toURL=http://www.forbes.com/sites/carminegallo/2016/05/06/5-public-speaking-tips-ted-gives-its-speakers/&refURL=&referrer=#5c07a8221d9b
ChatGPT and the Future of Work - Clark Boyd Clark Boyd
Everyone is in agreement that ChatGPT (and other generative AI tools) will shape the future of work. Yet there is little consensus on exactly how, when, and to what extent this technology will change our world.
Businesses that extract maximum value from ChatGPT will use it as a collaborative tool for everything from brainstorming to technical maintenance.
For individuals, now is the time to pinpoint the skills the future professional will need to thrive in the AI age.
Check out this presentation to understand what ChatGPT is, how it will shape the future of work, and how you can prepare to take advantage.
A brief introduction to DataScience with explaining of the concepts, algorithms, machine learning, supervised and unsupervised learning, clustering, statistics, data preprocessing, real-world applications etc.
It's part of a Data Science Corner Campaign where I will be discussing the fundamentals of DataScience, AIML, Statistics etc.
Time Management & Productivity - Best PracticesVit Horky
Here's my presentation on by proven best practices how to manage your work time effectively and how to improve your productivity. It includes practical tips and how to use tools such as Slack, Google Apps, Hubspot, Google Calendar, Gmail and others.
The six step guide to practical project managementMindGenius
The six step guide to practical project management
If you think managing projects is too difficult, think again.
We’ve stripped back project management processes to the
basics – to make it quicker and easier, without sacrificing
the vital ingredients for success.
“If you’re looking for some real-world guidance, then The Six Step Guide to Practical Project Management will help.”
Dr Andrew Makar, Tactical Project Management
Unlocking the Power of ChatGPT and AI in Testing - A Real-World Look, present...Applitools
During this webinar, Anand Bagmar demonstrates how AI tools such as ChatGPT can be applied to various stages of the software development life cycle (SDLC) using an eCommerce application case study. Find the on-demand recording and more info at https://applitools.info/b59
Key takeaways:
• Learn how to use ChatGPT to add AI power to your testing and test automation
• Understand the limitations of the technology and where human expertise is crucial
• Gain insight into different AI-based tools
• Adopt AI-based tools to stay relevant and optimize work for developers and testers
* ChatGPT and OpenAI belong to OpenAI, L.L.C.
1. Cromatografie Repere istorice
1906 : Mikhail Tswett separa pigmenti vegetali
colorati din frunze pe o coloana umpluta cu carbonat
de calciu pulbere, pigmentii fiind antrenati cu eter de
petrol
1940 : Martin si Synge dezvolta practica si teoria
cromatografica, obtinand premiul Nobel in 1952
1952: punerea la punct a cromatografiei in faza
gazoasa (GC)
1968 : punerea la punct a cromatografiei de lichide de
inalta performanta (HPLC)
1979 : prima separare chirala prin HPLC
Prezentul material este folosit în scop didactic și se adresează în numai studentilor inscriși la acest curs.
2. Descrierea generala a metodei
Intr-o separare cromatografica, diferiti componenti ai unei probe
sunt transportati cu o faza mobila (gazoasa, lichida, sau fluide
supercritice). Faza mobila (eluent) trece printr-o faza stationara.
Solutii din proba se partitioneaza diferit datorita interactiilor cu
fazele mobila si stationara. Solutii care prezinta interactii mai
puternice cu faza stationara se vor deplasa mai lent prin aceasta, iar
cei care nu interactioneaza cu faza stationara se vor deplasa foarte
rapid.
eluent
Banda initiala ce
contine
componentii de
separat A et B
FS + FM
disc poros
eluat
B A
3. Termeni utilizati in cromatografie
• Faza stationara (FS) : imobilizata in coloana sau fixata pe un
suport plan
• Faza mobila (FM) : se deplaseaza in permanent contact cu faza
stationara
• Elutie : procesul prin care un component este antrenat prin
deplasarea fazei mobile care traverseaza faza stationara
• Viteza FM prin coloana este exprimata: prin debitul D-volumul
de solvent care traverseaza coloana in unitate de timp (mL/min)
sau prin viteza liniara u-distanta parcursa prin coloana in unitate
de timp (cm/min)
5. Clasificarea metodelor cromatografice
In functie de fenomenele fizice care stau la baza proceselor de
schimb intre FM si FS:
adsorbtie
partitie
schimb ionic
excludere sterica
afinitate biochimica
In functie de natura fazei mobile:
lichida
gazoasa
In functie de scop:
cromatografie analitica
cromatografie preparativa
6. Schema generala a instrumentelor
cromatografice
coloana (FS)
injector
debimetru detector
signal
temps
Traitement
du signal
Interpretare
semnal
temps
Intrare proba
de analizat
eluent lichid sau gazos (FM)
Iesire eluat
7. Marimi de retentie in cromatografie
• Timpul de retentie
• Volumul de retentie
• Coeficientul de distributie
• Factorul de retentie
8. Marimi de retentie in cromatografie
Timpi de retentie: tR
Timpul scurs intre momentul injectarii si acela al
aparitiei maximului picului cromatografic
9. Marimi de retentie in cromatografie
Timpi de retentie corectati : tR’
tR’= tR – tM
tM ou t0 : timp mort : timpul necesar unui component
neretinut sa traverseze coloana cromatografica
10. Marimi de retentie in cromatografie
Volumul de retentie VR sau volumul de elutie :
Volumul de faza mobila necesar pentru migrarea unui
component prin coloana:
VR = tR . D
D: debitul fazei mobile (constant)
11. Marimi de retentie in cromatografie
Coeficientul de distributie: KA
retentie
APM APS
elutie
KA
raportul intre concentratia compusului in FS si
concentratia compusului in FM
reflecta importanta relativa a fortelor intermoleculare
dintre compusul de analizat si cele doua faze
PM
PS
A
A
A
K
12. Marimi de retentie in cromatografie
Factorul de retentie k’ sau k
(sau de capacitate):
Reflecta afinitatea coloanei pentru un component
Este independent de debitul FM si de dimensiunile
coloanei
k’ se poate determina din cromatograma
M
R
t
t
k'
'
13. Marimi de retentie in cromatografie
tR = tM + tR’
Pentru un compus neretinut pe FS:
tR = tM= tFM : timpul petrecut in FM
tR’= tFS: timpul petrecut in FS
daca mT = mFM + mFS
k’ este independent de mT
PM
PS
A
PM
PM
PS
PS
PM
A
PS
A
M
R
V
V
.
K
.V
A
.V
A
m
m
t
t
k'
A
'
14. Marimi de retentie in cromatografie
Factorul de retentie k’ si tR :
tR = tM ( 1 + k’ )
tR = tM( 1 + K / β)
⇒ permite calculul coeficientului de distributie
In practica, k’ nu are valori mai mari decat 10
k’ < 1: compusul iese prea repede
k’ ≈ 2-5
15. Marimi de retentie in cromatografie
permite precizarea pozitiilor relative ale doua picuri
consecutive:
α este intotdeauna > 1
α indica capacitatea unui sistem cromatografic de a
separa componentii
A
B
K
K
α
A
B
k'
k'
α
A
R
B
R
)
(t'
)
(t'
α
Factorul de separare sau de selectivitate α
16. Marimi de retentie in cromatografie
Rezolutia
Rezolutia reflecta buna separare a picurilor consecutive.
Pentru doua molecule A et B :
W b = 4
(A))
w
(B)
(w
2
1
(A)
t
(B)
t
R
b
b
R
R
S
timp
semnal
tR
Wb (A) Wb (B)
tR(A) tR (B)
17. Marimi de retentie in cromatografie
Rezolutia
RS = 1 daca tR = 4σ
O rezolutie de 1.5 este nécesara in analiza cantitativa ( tR = 6σ)
signal
temps
signal
2σ
3σ
4σ 6σ
Résolution = 1.5
Résolution = 0.50 Résolution = 0.75
Résolution = 1
temps
18. Efectul factorilor de capacitate si a
selectivitatii asupra rezolutiei
k’= factorul de capacitate mediu al celor doi compusi de separat
Cand α tinde spre 1
k'
1
k'
*
α
1
α
*
H
L
4
1
R
k'
1
k'
*
1)
-
(α
*
4
N
R
19. Calitatea unei separari
Doi factori contribuie la o buna separare
cromatografica:
diferenta intre timpii de retentie
largimea picurilor
20. Cum se optimizeaza o separare
cromatografica pe coloana ?
Scop: obtinerea gradului de separare dorit in timpul cel
mai scurt
Cresterea lui N
Modificarea lui k’
cresterea lui α
k'
1
k'
*
α
1
α
*
N
4
1
R
21. Cum se optimizeaza o analiza cromatografica
pe coloana?
Scop : obtinerea rezolutiei dorite intr-un minim de timp
Cresterea lui N:
↗ L : daca L se dubleaza, atunci R creste cu √2
dar durata separarii creste
↘ H :
• ↘∅ particule suport (↘termenul A )
• ↘∅ coloanei (↘ termenul C)
• ↘T°(GC) (↘ termenul B)
• ↘ grosimea filmului lichid(GC) (↘ termenul C)
• ↘ viscozitatea FM ( HPLC) (↘ termenul C)
• optimizarea lui u ( viteza liniara a FM)
22. Cum se optimizeaza o analiza cromatografica
pe coloana?
Modificarea lui k’:
k’B optim: 1-5
evitarea k’B >10 (durata de elutie mare)
Modificarea lui T° (GC)
Modificarea compozitiei FM (HPLC)
Diminuarea grosimii filmului lichid si cresterea diametrului intern al
coloanei (modificarea lui in GC)
Cresterea lui α cat mai aproape 1 (mentinerea 1< k’< 10)
modificarea T° coloanei
modificarea compozitiei FS
modificarea compozitiei FM (HPLC)
23. Cum se optimizeaza o analiza cromatografica
pe coloana?
Modificarea k’ in cursul elutiei :
Cu un gradient de compozitie sau raportul de combinare al solventilor:
cresterea gradata sau continua a tariei eluentului in cursul elutiei (HPLC)
Modificarea lui k’, α si H
Reducerea lui N si R
Prin programarea temperaturii:
cresterea gradata sau continua a temperaturii coloanei pe durata elutiei
(GC)
Modificarea lui k’, α si H
Reducerea lui N si R
24. Picuri asimetrice?
pic gausian ↔ K = CS/CM independent de
concentratia compusului in coloana
pic asimetric daca K variaza in functie de concentratia
in solutie
26. Picuri asimetrice
factorul de asimetrie
(Fa sau As)
Valori normale: intre 1.0 si 1.5
Pentru o coloana noua
valorile sunt usor mai mari decat
in conditii reale
27. Picuri asimetrice ?
Fronting sau difuzia
frontala:
Ft <1
Fa<1
Tailing sau efectul de
trena:
Ft >1
Fa>1
28. Degradarea fazei stationare
Performantele unei coloane sunt evaluate prin:
Factorul de retentie al unui standard (k’)
Numarul de talere (N)
Asimetria picurilor
30. Analiza calitativa
In general timpul de retentie al solutului este un
indicator calitativ al analitului respectiv, fiind in
general comparat cu acela al standardului.
Daca atat standardul cat si analitul au acelasi timp de
retentie, acest lucru reprezinta o indicatie ca pot fi
identici.
31. Analiza cantitativa
Separarile cromatografice ofera informatii extrem de
precise din punct de vedere cantitativ, in acest scop
putand fi utilizate atat ariile, cat si inaltimile
picurilor.
In general ariile picurilor sunt mai mult utilizate in
analiza cantitativa, deoarece integrarea ariilor ofera
informatii mai exacte referitoare la concentratii.
32. Metoda standardului intern
Incertitudinile legate de injectarea probelor pot fi
evitate prin utilizarea standardelor interne.
In aceasta metoda, o cantitate cunoscuta de standard
intern se adauga atat in solutia etalon, cat si in proba
de analizat, masurandu-se raportul semnalului
analitului fata de semnalul standardului.
33. Proprietatile unui compus ce poate fi utilizat ca standard
intern includ:
Timpii de retentie ai standardului intern si ai analitului
trebuie sa fie diferiti, iar cele doua picuri trebuie sa
fie bine separate, R >1.25
Factorul de raspuns al detectorului pentru analit si
pentru standardul intern trebuie sa fie acelasi.
Utilizarea standardelor interne imbunatateste precizia
masuratorii cu cel putin 1%.
34. Metoda normalizarii ariei
Aceasta tehnica elimina incertitudinile asociate injectarii
probelor. In aceasta metoda este necesara elutia completa
a tuturor componentilor, ariile acestora fiind integrate si
calculate in functie de raspunsul detectorului.
Concentratia analitului reprezinta raportul dintre aria
corectata a picului si suma ariilor celorlalte picuri.
Metoda este mai putin versatila fata de metoda
standardului intern, fiind foarte importanta definirea
factorului de raspuns si modul de calcul al acestuia.
35. Se pot utiliza doua modalitati de calcul:
Factorul de raspuns de masa = %wt(standard)/Aria
(standard)
In acest caz, factorul de raspuns trebuie multiplicat cu
aria compusului necunoscut.
Sau:
Factorul de raspuns al detectorului = Aria (standard)/wt
(standard)
In acest caz factorul de raspuns trebuie impartit la aria
compusului necunoscut.
36. Referinte bibliografice:
"Quantitative Chemical Analysis", D.C. Harris, Freeman, 6th Edition, 2003.
" Practical problem solving in HPLC" , S. Kromidas, WILEY-VCH, 2005
« Analiza instrumentala - Aplicatii», Ion Ion, Alina Catrinel Ion, Dragos
Stefan Nicolae, Editura Printech, Bucuresti, 2007
« Metode de separare si analiza cromatografica », Victor David, Andrei
Medvedovici , Editura Universitatii din Bucuresti, 2007