Xi'An, China
CIPAC Meeting 2027
CIPAC Meeting 2027

MT 92 - Determination of lead


Content Handbook F

 

Outline of method

92.1 Dithizone general method

After destruction of organic matter and separation from interfering substances, lead is extracted with a solution of 1,5-diphenyl-3-hiocarbazone (dithizone) at pH 9.0 to 9.5, and determined absorptiometrically as the pink complex.
For the preliminary separation, two methods are given: in method MT 92.1.1, lead is extracted with dithizone from an alkaline citrate and hexametaphosphate solution, and is then transferred to nitric acid.
Method MT 92.1.2 requires additional manipulative work, and should be used only when the first method is unsuitable, i.e. for samples which have so high a content ofcalcium, magnesium or phosphate that sodium hexametaphosphate and triammonium citrate in the stated amounts will not prevent their precipitation, and interference with the quantitative extraction under the alkaline conditions of 1.1. A preliminary extraction of lead from acid solution with a solution of diethylammonium diethyldithiocarbamate is therefore substituted for the hexametaphosphate procedure.

 

Scope

92.1 Dithizone general method

Suitable for lead contents up to 5 ìg/g, but the range may be extended by using a suitable amount of sample. The method is widely applicable, although bismuth will interfere. An absorbance measurement at 490 nm as well as at 520 nm may be useful in deciding whether interference from bismuth is considerable. It has been found that, with a solution of pure lead dithizone complex, the absorbance at 490 nm is approximately 0.84 times that at 520 nm; with a solution of the pure bismuth complex, the absorbance at 490 nm is approximately 1.20 times that at 520 nm. When considerable interference from bismuth is indicated, the modified procedure
1.3 is used.

 


Failed to start the session because headers have already been sent by "D:\www\www83\plugins\system\debug\src\Extension\Debug.php" at line 377. (500 Whoops, looks like something went wrong.)

RuntimeException RuntimeException

HTTP 500 Whoops, looks like something went wrong.

Failed to start the session because headers have already been sent by "D:\www\www83\plugins\system\debug\src\Extension\Debug.php" at line 377.

Exceptions 2

RuntimeException

in D:\www\www83\libraries\vendor\joomla\session\src\Storage\NativeStorage.php (line 454)
  1. if ($this->isActive()) {
  2. throw new \RuntimeException('Failed to start the session: already started by PHP.');
  3. }
  5. if (ini_get('session.use_cookies') && headers_sent($file, $line)) {
  6. throw new \RuntimeException(
  7. sprintf('Failed to start the session because headers have already been sent by "%s" at line %d.', $file, $line)
  8. );
  9. }
  11. if (!session_start()) {
NativeStorage->start() in D:\www\www83\libraries\src\Session\Storage\JoomlaStorage.php (line 313)
  1. $this->setId($session_clean);
  2. $cookie->set($session_name, '', ['expires' => time() - 3600 ]);
  3. }
  4. }
  6. parent::start();
  8. // Try loading data from the session
  9. if (!empty($_SESSION['joomla'])) {
  10. $this->data = unserialize(base64_decode($_SESSION['joomla']));
  11. }
JoomlaStorage->start() in D:\www\www83\libraries\vendor\joomla\session\src\Session.php (line 396)
  1. {
  2. if ($this->isStarted()) {
  3. return;
  4. }
  6. $this->store->start();
  8. $this->setState(SessionState::ACTIVE);
  10. // Initialise the session
  11. $this->setCounter();
Session->start() in D:\www\www83\libraries\vendor\joomla\session\src\Session.php (line 327)
  1. * @since 1.0
  2. */
  3. public function has($name)
  4. {
  5. if (!$this->isActive()) {
  6. $this->start();
  7. }
  9. return $this->store->has($name);
  10. }
Session->has() in D:\www\www83\libraries\src\Session\Session.php (line 194)
  2. $name = $args[2] . '.' . $name;
  3. }
  4. }
  6. if (parent::has($name)) {
  7. // Parent is used because of b/c, can be changed in Joomla 6
  8. return parent::get($name, $default);
  9. }
  11. /*
Session->get() in D:\www\www83\libraries\src\Factory.php (line 372)
  1. __CLASS__
  2. ),
  3. E_USER_DEPRECATED
  4. );
  6. $instance = self::getApplication()->getSession()->get('user');
  8. if (\is_null($id)) {
  9. if (!($instance instanceof User)) {
  10. $instance = User::getInstance();
  11. }
Factory::getUser() in D:\www\www83\libraries\src\Document\Renderer\Html\ModulesRenderer.php (line 46)
  1. {
  2. $renderer = $this->_doc->loadRenderer('module');
  3. $buffer = '';
  5. $app = Factory::getApplication();
  6. $user = Factory::getUser();
  7. $frontediting = ($app->isClient('site') && $app->get('frontediting', 1) && !$user->guest);
  8. $menusEditing = ($app->get('frontediting', 1) == 2) && $user->authorise('core.edit', 'com_menus');
  10. foreach (ModuleHelper::getModules($position) as $mod) {
  11. $moduleHtml = $renderer->render($mod, $params, $content);
ModulesRenderer->render() in D:\www\www83\libraries\src\Document\HtmlDocument.php (line 578)
  2. $cbuffer[$hash] = $tmpdata;
  4. $cache->store($cbuffer, 'cbuffer_' . $type);
  5. } else {
  6. $this->setBuffer($renderer->render($name, $attribs, null), $type, $name, $title);
  7. }
  9. return parent::$_buffer[$type][$name][$title];
  10. }
HtmlDocument->getBuffer() in D:\www\www83\libraries\src\Document\HtmlDocument.php (line 897)
  1. $replace = [];
  2. $with = [];
  4. foreach ($this->_template_tags as $jdoc => $args) {
  5. $replace[] = $jdoc;
  6. $with[] = $this->getBuffer($args['type'], $args['name'], $args['attribs']);
  7. }
  9. return str_replace($replace, $with, $this->_template);
  10. }
  11. }
HtmlDocument->_renderTemplate() in D:\www\www83\libraries\src\Document\HtmlDocument.php (line 650)
  2. if (\array_key_exists('csp_nonce', $params) && $params['csp_nonce'] !== null) {
  3. $this->cspNonce = $params['csp_nonce'];
  4. }
  6. $data = $this->_renderTemplate();
  7. parent::render($caching, $params);
  9. return $data;
  10. }
HtmlDocument->render() in D:\www\www83\libraries\src\Document\ErrorDocument.php (line 139)
  1. $this->debug = $params['debug'] ?? false;
  2. $this->error = $this->_error;
  4. $params['file'] = 'error.php';
  6. return parent::render($cache, $params);
  7. }
  9. /**
  10. * Render the backtrace
  11. *
ErrorDocument->render() in D:\www\www83\libraries\src\Error\Renderer\HtmlRenderer.php (line 70)
  1. ob_end_clean();
  2. }
  4. $this->getDocument()->setTitle(Text::_('Error') . ': ' . $error->getCode());
  6. return $this->getDocument()->render(
  7. false,
  8. [
  9. 'template' => $template->template,
  10. 'directory' => JPATH_THEMES,
  11. 'debug' => JDEBUG,
HtmlRenderer->render() in D:\www\www83\libraries\src\Exception\ExceptionHandler.php (line 142)
  1. 'subject' => $app,
  2. 'document' => $renderer->getDocument(),
  3. ])
  4. );
  6. $data = $renderer->render($error);
  8. // If nothing was rendered, just use the message from the Exception
  9. if (empty($data)) {
  10. $data = $error->getMessage();
  11. }
ExceptionHandler::render() in D:\www\www83\libraries\src\Exception\ExceptionHandler.php (line 76)
  1. * @since 3.10.0
  2. */
  3. public static function handleException(\Throwable $error)
  4. {
  5. static::logException($error);
  6. static::render($error);
  7. }
  9. /**
  10. * Render the error page based on an exception.
  11. *
ExceptionHandler::handleException() in D:\www\www83\libraries\src\Application\CMSApplication.php (line 334)
  1. );
  3. // Trigger the onError event.
  4. $this->dispatchEvent('onError', $event);
  6. ExceptionHandler::handleException($event->getError());
  7. }
  9. // Trigger the onBeforeRespond event.
  10. $this->dispatchEvent(
  11. 'onBeforeRespond',
CMSApplication->execute() in D:\www\www83\index.php (line 35)
  2. // Run the application - All executable code should be triggered through this file
  3. require_once dirname(__FILE__) . '/includes/app.php';
  5. $app = JFactory::getApplication('site');
  6. $app->execute();

RuntimeException

Failed to start the session because headers have already been sent by "D:\www\www83\plugins\system\debug\src\Extension\Debug.php" at line 377.

in D:\www\www83\libraries\vendor\joomla\session\src\Storage\NativeStorage.php (line 454)
  1. if ($this->isActive()) {
  2. throw new \RuntimeException('Failed to start the session: already started by PHP.');
  3. }
  5. if (ini_get('session.use_cookies') && headers_sent($file, $line)) {
  6. throw new \RuntimeException(
  7. sprintf('Failed to start the session because headers have already been sent by "%s" at line %d.', $file, $line)
  8. );
  9. }
  11. if (!session_start()) {
NativeStorage->start() in D:\www\www83\libraries\src\Session\Storage\JoomlaStorage.php (line 313)
  1. $this->setId($session_clean);
  2. $cookie->set($session_name, '', ['expires' => time() - 3600 ]);
  3. }
  4. }
  6. parent::start();
  8. // Try loading data from the session
  9. if (!empty($_SESSION['joomla'])) {
  10. $this->data = unserialize(base64_decode($_SESSION['joomla']));
  11. }
JoomlaStorage->start() in D:\www\www83\libraries\vendor\joomla\session\src\Session.php (line 396)
  1. {
  2. if ($this->isStarted()) {
  3. return;
  4. }
  6. $this->store->start();
  8. $this->setState(SessionState::ACTIVE);
  10. // Initialise the session
  11. $this->setCounter();
Session->start() in D:\www\www83\libraries\vendor\joomla\session\src\Session.php (line 327)
  1. * @since 1.0
  2. */
  3. public function has($name)
  4. {
  5. if (!$this->isActive()) {
  6. $this->start();
  7. }
  9. return $this->store->has($name);
  10. }
Session->has() in D:\www\www83\libraries\src\Session\Session.php (line 194)
  2. $name = $args[2] . '.' . $name;
  3. }
  4. }
  6. if (parent::has($name)) {
  7. // Parent is used because of b/c, can be changed in Joomla 6
  8. return parent::get($name, $default);
  9. }
  11. /*
Session->get() in D:\www\www83\libraries\src\Factory.php (line 372)
  1. __CLASS__
  2. ),
  3. E_USER_DEPRECATED
  4. );
  6. $instance = self::getApplication()->getSession()->get('user');
  8. if (\is_null($id)) {
  9. if (!($instance instanceof User)) {
  10. $instance = User::getInstance();
  11. }
Factory::getUser() in D:\www\www83\libraries\src\Application\SiteApplication.php (line 565)
  1. *
  2. * @since 3.2
  3. */
  4. protected function initialiseApp($options = [])
  5. {
  6. $user = Factory::getUser();
  8. // If the user is a guest we populate it with the guest user group.
  9. if ($user->guest) {
  10. $guestUsergroup = ComponentHelper::getParams('com_users')->get('guest_usergroup', 1);
  11. $user->groups = [$guestUsergroup];
SiteApplication->initialiseApp() in D:\www\www83\libraries\src\Application\SiteApplication.php (line 237)
  1. * @since 3.2
  2. */
  3. protected function doExecute()
  4. {
  5. // Initialise the application
  6. $this->initialiseApp();
  8. // Mark afterInitialise in the profiler.
  9. JDEBUG ? $this->profiler->mark('afterInitialise') : null;
  11. // Route the application
SiteApplication->doExecute() in D:\www\www83\libraries\src\Application\CMSApplication.php (line 304)
  1. $this->sanityCheckSystemVariables();
  2. $this->setupLogging();
  3. $this->createExtensionNamespaceMap();
  5. // Perform application routines.
  6. $this->doExecute();
  8. // If we have an application document object, render it.
  9. if ($this->document instanceof \Joomla\CMS\Document\Document) {
  10. // Render the application output.
  11. $this->render();
CMSApplication->execute() in D:\www\www83\index.php (line 35)
  2. // Run the application - All executable code should be triggered through this file
  3. require_once dirname(__FILE__) . '/includes/app.php';
  5. $app = JFactory::getApplication('site');
  6. $app->execute();

Stack Traces 2

[2/2] RuntimeException 
RuntimeException:
Failed to start the session because headers have already been sent by "D:\www\www83\plugins\system\debug\src\Extension\Debug.php" at line 377.

  at D:\www\www83\libraries\vendor\joomla\session\src\Storage\NativeStorage.php:454
  at Joomla\Session\Storage\NativeStorage->start()
     (D:\www\www83\libraries\src\Session\Storage\JoomlaStorage.php:313)
  at Joomla\CMS\Session\Storage\JoomlaStorage->start()
     (D:\www\www83\libraries\vendor\joomla\session\src\Session.php:396)
  at Joomla\Session\Session->start()
     (D:\www\www83\libraries\vendor\joomla\session\src\Session.php:327)
  at Joomla\Session\Session->has()
     (D:\www\www83\libraries\src\Session\Session.php:194)
  at Joomla\CMS\Session\Session->get()
     (D:\www\www83\libraries\src\Factory.php:372)
  at Joomla\CMS\Factory::getUser()
     (D:\www\www83\libraries\src\Document\Renderer\Html\ModulesRenderer.php:46)
  at Joomla\CMS\Document\Renderer\Html\ModulesRenderer->render()
     (D:\www\www83\libraries\src\Document\HtmlDocument.php:578)
  at Joomla\CMS\Document\HtmlDocument->getBuffer()
     (D:\www\www83\libraries\src\Document\HtmlDocument.php:897)
  at Joomla\CMS\Document\HtmlDocument->_renderTemplate()
     (D:\www\www83\libraries\src\Document\HtmlDocument.php:650)
  at Joomla\CMS\Document\HtmlDocument->render()
     (D:\www\www83\libraries\src\Document\ErrorDocument.php:139)
  at Joomla\CMS\Document\ErrorDocument->render()
     (D:\www\www83\libraries\src\Error\Renderer\HtmlRenderer.php:70)
  at Joomla\CMS\Error\Renderer\HtmlRenderer->render()
     (D:\www\www83\libraries\src\Exception\ExceptionHandler.php:142)
  at Joomla\CMS\Exception\ExceptionHandler::render()
     (D:\www\www83\libraries\src\Exception\ExceptionHandler.php:76)
  at Joomla\CMS\Exception\ExceptionHandler::handleException()
     (D:\www\www83\libraries\src\Application\CMSApplication.php:334)
  at Joomla\CMS\Application\CMSApplication->execute()
     (D:\www\www83\index.php:35)
[1/2] RuntimeException 
RuntimeException:
Failed to start the session because headers have already been sent by "D:\www\www83\plugins\system\debug\src\Extension\Debug.php" at line 377.

  at D:\www\www83\libraries\vendor\joomla\session\src\Storage\NativeStorage.php:454
  at Joomla\Session\Storage\NativeStorage->start()
     (D:\www\www83\libraries\src\Session\Storage\JoomlaStorage.php:313)
  at Joomla\CMS\Session\Storage\JoomlaStorage->start()
     (D:\www\www83\libraries\vendor\joomla\session\src\Session.php:396)
  at Joomla\Session\Session->start()
     (D:\www\www83\libraries\vendor\joomla\session\src\Session.php:327)
  at Joomla\Session\Session->has()
     (D:\www\www83\libraries\src\Session\Session.php:194)
  at Joomla\CMS\Session\Session->get()
     (D:\www\www83\libraries\src\Factory.php:372)
  at Joomla\CMS\Factory::getUser()
     (D:\www\www83\libraries\src\Application\SiteApplication.php:565)
  at Joomla\CMS\Application\SiteApplication->initialiseApp()
     (D:\www\www83\libraries\src\Application\SiteApplication.php:237)
  at Joomla\CMS\Application\SiteApplication->doExecute()
     (D:\www\www83\libraries\src\Application\CMSApplication.php:304)
  at Joomla\CMS\Application\CMSApplication->execute()
     (D:\www\www83\index.php:35)