stm32 fast adc sampling rate

[codev123]

sir, thank you for amazing platform. i am reading analog signal using
unsigned long time_start = micros();
for (int i = 0; i < 100; i++){
temp = analogRead(PA0);
}
unsigned long time_end = micros();
but for 100 samples its taking 6616uS while as advertized it should take 1-6uS per sample not 66uS per sample. how to make this sampling faster for stm32l051c8 and stm32f103c8 stm microcontrollers.
thank you.