sql - PHP Variable within bind-parameter -

i have following php variable:

$qstr1;

this, when printed or echoed, shows following:

$q1, $q2, $q3, $q4, $q5

i have bind-parm code:

mysqli_stmt_bind_param($proc, "iss$is", $respondent_id, $ip, $browser, $q1, $q2, $q3, $q4, $q5);

this works fine , saves correctly database, however, when replace individual parts variable (see below), doesn't work, doing wrong?

mysqli_stmt_bind_param($proc, "iss$is", $respondent_id, $ip, $browser, $qstr1);

vardump follows:

string(49) "$q1, $q2, $q3, $q4, $q5, $q6, $q7, $q8, $q9, $q10"

it doesn't work that. method wants several parameters. no give one, holds string.

there possibilities this, eval, advise different approach. pdo example can bind using names can called in loop.

Roma