Settings API

gistfile1.php

<?php
  //Options Page Configuration
	function admin_init_callback() {

		register_setting( 'msp_settings', 'msp_duration' );

		add_settings_section( 'msp_settings', __('Multisite Posts Configuration'), false, 'general' );

		add_settings_field( 'msp_duration', __('Cache Duration'), array($this, 'msp_settings_callback'), 'general', 'msp_settings', array(
			"id"	  => "msp_duration",
			"type"	=> "dropdown",
			"values"=> array(
				array(
					"name"	=> __('Every 6 hours'),
					"value"	=> 60 * 60 * 6,
				),
				array(
					"name"	=> __('Every 12 hours'),
					"value"	=> 60 * 60 * 12,
				),
				array(
					"name"	=> __('Every 24 hours'),
					"value"	=> 60 * 60 * 24,
				),
				array(
					"name"	=> __('Every 48 hours'),
					"value"	=> 60 * 60 * 48,
				),
				array(
					"name"	=> __('Every Week'),
					"value"	=> 60 * 60 * 24 * 7,
				),
			)
		) );

		return;

	}

  function msp_settings_callback($args) {

		$value = get_option( $args["id"] );

		if("dropdown" == $args["type"]) {

			var_dump($value);
			?>
			<select name="<?php echo $args["id"]; ?>">
				<?php
					foreach ($args["values"] as $option) {
						echo '<option value="' . $option["value"] . '" ';
						checked( $value, $option["value"], $echo = true );
						echo '>' . $option["name"] . '</option>';
					}
				?>
			</select>
			<?php

		}

	}
?>